Recent Developments in Cationic Polymerization - ACS Symposium

Jul 23, 2009 - The fifth meeting was organized in Kyoto (1979) (5); the previous meetings were in Akron ... ACS Symposium Series , Volume 285, pp 69â€...
3 downloads 0 Views 4MB Size
5 Recent Developments in Cationic Polymerization VIRGIL P E R C E C

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

Department of Macromolecular Science, Case Western Reserve University, Cleveland, O H 44106

Ring Opening Polymerization General Considerations Initiation Propagation Termination and Transfer Processes L i v i n g Cationic Ring-Opening Polymerization New Polymers by Cationic Ring-Opening Polymerization Graft Copolymers Block Copolymers Cationic Polymerization of Olefins General Considerations Graft Copolymers I n i f e r Technique Q u a s i - l i v i n g Carbocationic Polymerization Proton Traps Block Copolymers Heterogeneous Graft Copolymerization Polymers with Functional End Groups Polymers with Two Functional End Groups: Telechelics Polymers with One Functional End Group: Macromonomers

C a t i o n i c p o l y m e r i z a t i o n of heterocyclic and vinylic monomers i s currently one of the most active areas of polymer c h e m i s t r y . In the past two years four monographs dedicated to different topics i n t h i s field were published (1-4). Cationic polymerization is a l s o one of the few areas of polymer science that has its own scientific meeting. The fifth meeting was organized i n Kyoto (1979) (5); the previous meetings were i n Akron (1976) (6); Rouen (1973) (7); Keele (1952) (8); and Dublin (1949) (9). At the 26th International Union of Pure and A p p l i e d Chemistry (IUPAC) International Symposium on

0097 6156/85/0285-0095S09.75/0 © 1985 American Chemical Society

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

96

A P P L I E D P O L Y M E R SCIENCE

Macromolecules in Mainz (1979), four of the 33 main lectures were dedicated e n t i r e l y to the field of c a t i o n i c polymerization (10-13). A short history of cationic p o l y m e r i z a t i o n was p u b l i s h e d i n 1975 (14, 15). An excellent collection of classic papers was published i n 1963 (16). The first recorded c a t i o n i c polymerization was d e s c r i b e d i n 1789 (17), and the first industrial polymer prepared by c a t i o n i c polymerization, b u t y l rubber, appeared on the market in 1943 (14). In s p i t e of these achievements and many o t h e r s , our b a s i c knowledge about c a t i o n i c p o l y m e r i z a t i o n s t a r t e d to d e v e l o p o n l y very recently. The main reason i s that the electrophilic species through which cationic p o l y m e r i z a t i o n takes p l a c e (carbenium, oxonium, s u l f o n i u m , phosphonium, and ammonium i o n s ) are very reactive. C o n s e q u e n t l y , i n a d d i t i o n to propagation r e a c t i o n s , chain transfer, termination, and reactions with traces of nucleo-philic impurities take place. Only h i g h l y sophisticated techniques such as high-vaccuum r e a c t i o n c o n d i t i o n s , adiabatic calorimetry, and Fourier transform NMR measurements made progress p o s s i b l e i n t h i s area of chemistry. Even so, a large difference e x i s t s between our knowledge of r i n g - o p e n i n g p o l y m e r i z a t i o n and v i n y l i c polymerization. Cationic polymerization of v i n y l i c monomers takes p l a c e w i t h carbenium i o n s , which are more r e a c t i v e than oxonium, s u l f o n i u m , phosphonium, or ammonium i o n s . Chain t r a n s f e r to monomer can be decreased o n l y at very low polymerization temperature. Consequently, polymers with high molecular weights can be obtained by reaction conditions that are not of i n t e r e s t to industry. Ring-opening polymerization can be followed by NMR techniques; therefore, d i r e c t evidence for the polymerization mechanism could be obtained (1, _4, 17). Our knowledge about v i n y l i c polymerization mechanisms i s obtained mainly from i n d i r e c t evidence. The present s t a t e of both r i n g - o p e n i n g (X, 4_, J J , 17-20) and v i n y l i c p o l y m e r i z a t i o n (_2, _3, 14) was r e c e n t l y r e v i e w e d . The present review w i l l present the most recent developments i n both areas m a i n l y i n regard to the p r e p a r a t i v e power of c a t i o n i c polymerization. Only a few basic achievements of the mechanistic aspects w i l l be considered. Ring-Opening Polymerization General Considerations. The r e a c t i v i t y of h e t e r o c y c l i c monomers i s governed by the s i z e of the r i n g , nature of the heteroatom and i t s e l e c t r o n e g a t i v i t y and bond s t r e n g t h w i t h the carbon atom, and steric factors. A d e t a i l e d d i s c u s s i o n of a l l these f a c t o r s i s presented by Penczek et a l . (_1). Two b a s i c p r i n c i p l e s w i l l be o u t l i n e d here. They w i l l r e f e r to the most s i m p l e h e t e r o c y c l i c monomers only. The s i z e of the r i n g , that i s , the number of atoms i n the r i n g , c o n t r o l s the r i n g s t r a i n by two factors. The f i r s t factor refers to the difference between the bond angles that r e s u l t from normal o r b i t a l o v e r l a p and the bond a n g l e s t h a t are a f u n c t i o n of the number of atoms i n the r i n g , that i s , the angle s t r a i n . The second f a c t o r i s the consequence of the i n t e r a c t i o n s of the nonbonded atoms. For a c e r t a i n geometry of the molecule, nonbonded atoms are s i t u a t e d i n a c l o s e p r o x i m i t y t h a t g i v e s r i s e to t h i s k i n d of i n t e r a c t i o n . Both bond a n g l e s and nonbonding i n t e r a c t i o n s are In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

5.

Recent Developments in Cationic Polymerization

PERCEC

97

r e s p o n s i b l e f o r the h e t e r o c y c l e r i n g s t r a i n . Consequently, with the e x c e p t i o n of the three-membered r i n g s , a l l r i n g s e x h i b i t a noncoplanar conformation of minimum energy. As a function of the number of atoms i n the r i n g , the r i n g s t r a i n i s dominated by angle s t r a i n or by nonbonded atom i n t e r a c t i o n s . Table I summarizes the r i n g s t r a i n values for the most conventional rings. According to the r i n g s t r a i n energies presented i n Table I , the h e t e r o c y c l i c d e r i v a t i v e s c o n t a i n i n g s i x atoms i n the r i n g are g e n e r a l l y u n p o l y m e r i z a b l e . An e x c e p t i o n i s s y m - t r i o x a n e which polymerizes under conditions i n which the polymer can c r y s t a l l i z e . The r e a c t i v i t y of the r i n g opening toward a c a t i o n i c mechanism i s m a i n l y d i c t a t e d by the n u c l e o p h i l i c i t y or the b a s i c i t y of the monomer. The n u c l e o p h i l i c i t y of a monomer, that i s , i t s a b i l i t y to combine with e l e c t r o p h i l i c species, i s determined by k i n e t i c a l l y c o n t r o l l e d c o n d i t i o n s , and u n f o r t u n a t e l y , no g e n e r a l order of n u c l e o p h i l i c i t y i s known. The monomer b a s i c i t y , t h a t i s , i t s a b i l i t y t o i n t e r a c t w i t h a p r o t o n , can be measured from thermodynamically c o n t r o l l e d c o n d i t i o n s . The most common method used to determine the b a s i c i t y i s based on the p r o p o r t i o n of hydrogen-bonded compound measured at e q u i l i b r i u m . The b a s i c i t y decreases i n the f o l l o w i n g order: R3N > R3P > R 0 > R S , although R S i s more basic than R 0 when the a b i l i t y of bonding with softer a c i d s i s measured. In the case of c y c l i c ethejrs, the b a s i c i t y order i s as f o l l o w s : C @ H ) > tf(CH ) > # ( C H ) > ^ £ p H ) . U s u a l l y the b a s i c i t y o f ^ h e t e r o c y c l i c compound i s a f f e c t e d i n t h e e x p e c t e d o r d e r by the i n d u c t i v e e f f e c t s , c o n j u g a t i o n , s t e r i c e f f e c t s , and r i n g s i z e (I). The order of b a s i c i t i e s i s the only estimation of the monomer n u c l e o p h i l i c i t i e s , and i t r e f l e c t s f a i r l y w e l l the o v e r a l l r e a c t i v i t y observed i n ring-opening c a t i o n i c polymerization. 2

2

2

2

2

2

3

2 4

2

5

2

4

2

Initiation. The most r e c e n t c l a s s i f i c a t i o n of i n i t i a t o r s f o r c a t i o n i c ring-opening polymerization was presented and discussed by Penczek et a l . (T). Only a few c l a s s e s of i n i t i a t o r s that are very u s e f u l both f o r m e c h a n i s t i c s t u d i e s as w e l l as f o r s y n t h e s i s of w e l l - d e f i n e d polymers w i l l be presented here. Protonic Acids. The simplest way of i n i t i a t i o n and polymerization by a protonic acid i s the f o l l o w i n g : k HA

H

+ zQ



^QA~

H - ( Z - ) —

H

+

- zQ

+ n Z +

Z 3 A "

A-

(Z—)—*\^)k - ^ H — ( Z — >

N

+

1

~

A

When A~ i s a noncomplex anion, that i s , Cl"~, FSO3", CF3COO"", C10 "~, or CF0SO3"", competition always e x i s t s between the propagation (k ) and the recombination o f the g r o w i n g m a c r o c a t i o n w i t h t h e counteranion (k*.). The r a t i o k /k^ w i l l c o n t r o l the polymerization degree of the obtained polymer. The k /k^ i s determined mainly by t h e r a t i o o f t h e monomer n u c l e o p h i l i c i t y t o t h a t o f the counteranion. F1uorosu1fonic acid (FSO3H and trifluoromethanesulfonic acid (CF3SO3H) are the most conventional i n i t i a t o r s used both for k i n e t i c studies as w e l l as for new monomer 4

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

98

A P P L I E D P O L Y M E R SCIENCE

r e a c t i v i t y testing studies. They a l r e a d y have r e p l a c e d the c o n v e n t i o n a l Lewis a c i d s such as A I C I 3 or B F f o r two r e a s o n s : Their anions are weak n u c l e o p h i l e s , and i n the case of h e t e r o c y c l i c monomers the i n i t i a t i o n t a k e s p l a c e by d i r e c t and q u a n t i t a t i v e protonation. At the other extreme of t h i s s i m p l e i n i t i a t o r c l a s s i s H C l . I t s anion i s a strong n u c l e o p h i l e , and only h i g h l y n u c l e o p h i l i c N7 substituted amines can be polymerized by H C l . Simple a d d i t i o n of the i n i t i a t o r to the f i r s t monomer m o l e c u l e takes p l a c e i n other cases: 3

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

+ HCl

> C1-CH -CH -0H 2

2

Stable Carbenion and Onium Ions and Their Covalent Precursors. The most representative i n i t i a t o r s from t h i s c l a s s are the f o l l o w i n g : 1. 2. 3. 4. 5.

+

+

Carbenium i o n s : R C , [(C^Hc) C A"] Alkoxycarbenium i o n s : ROCH , (CHoOCH? ^") Oxocarbenium i o n s : R-C=0 , (C^HrCio+A ) Onium i o n s : R X+, [(C H )o0 A ] Covalent i n i t i a t o r s : RA, [CH 0S0 CF , ( C F S 0 ) 0 , C H I , 3

3

4

2

+

+

n

2

5

2

3

3

3

2

2

3

etc.]

Carbenium Ions. S t a b l e carbenium i o n s ( t r i p h e n y l m e t h y 1 and tropylium s a l t s ) were developed by Ledwith (21-23). Their merit i s t h a t they can i n i t i a t e the p o l y m e r i z a t i o n of c e r t a i n o l e f i n s by d i r e c t a d d i t i o n . These i n i t i a t o r s are very u s e f u l i n k i n e t i c studies, e s p e c i a l l y when weak n u c l e o p h i l e s such as SbF^~ or AcF^~ are used as counteranions. Stable t r i t y l s a l t s , which might lead to systems devoid of side reactions, do not, however, i n i t i a t e the polymerization of the majority of h e t e r o c y c l i c monomers by d i r e c t a d d i t i o n (24, 25). On the other hand these i n i t i a t o r s can be produced i n s i t u by the reaction of a s u i t a b l e organic h a l i d e with a silver salt: R R-C-X + AgSbF R

6

R-C ! R

+

SbFl + AgX +

Richards et a l . (26-29) i n v e s t i g a t e d the i n i t i a t i o n of t e t r a hydrofuran (THF) p o l y m e r i z a t i o n induced by a l a r g e v a r i e t y of organic h a l i d e s i n conjunction with AgPF^. The r e a c t i v i t y of the saturated a l k y l h a l i d e s are i n the anticipated sequence: i o d i d e > bromide > c h l o r i d e > f l u o r i d e . Cynnamyl bromide and jp_raethylbenzyl bromide are the most useful i n i t i a t o r s (28, 29), and 1 , 4 - d i b r o m o - 2 - b u t e n e and a , a ' - d i b r o m o x y l e n e are e x c e l l e n t difunctional i n i t i a t o r s . Franta et a l . (30) studied the e f f i c i e n c y and the mechanism of i n i t i a t i o n of the polymerization induced by s e v e r a l a l k y l h a l i d e s and AgSbF^. The i n i t i a t i o n occurs by a d d i t i o n , proton e l i m i n a t i o n , and/or hydride abstraction.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

Recent Developments in Cationic Polymerization

PERCEC

Addition:

^

-f

+ fj>

CH„0 - &I SbF~ + HCl 0

CH OCH 3

2

A more d e t a i l e d discussion w i l l be presented i n another chapter. l , 3 - D i o x o l a n - 2 - y l i u m (Dioxolenium) S a l t s . Triphenylmethy1ium s a l t s react with dioxolane by hydride transfer to form the corresponding dioxolenium s a l t s (33), which react with nucleophiles e x c l u s i v e l y by a d d i t i o n . Ph Ph4

Ph

+

SbF^

+

< £ ] - >

Ph

Ph S b F

O

+n-l

«* >£-i

26.9 — 5.8 -0.15 —

19.8 19.7 1.97 -0.3 3.5

2

Reaction Path i n the System RX + THF + AgSbF (a=addition, H =proton e l i m i n a t i o n , and H = hydride abstraction)

6

+

A l k y l Halide (corresponding cation) +

(C H ) C 6

5

3

Mechanism of I n i t i a t i o n (X=Br) (X=C1) (X=I) H"

H"

H"

+

(C H ) C H 6

5

C H CH 6

a

2

5

+

a(29)

p—CH C^H CH2^" 3

4

(CH ) C 3

+

H

3

(CH ) CH 3

+

2

=

CH2 CH—CH2^" a

AgPF

6

H+

a

2

a

+

a

H+ H+ a/H

+

salt

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

H

+

5.

Recent Developments in Cationic Polymerization

PERCEC

101

+

Onium Ions. Trialkyloxonium ions (R 0 A~) became the conventional i n i t i a t o r s f o r the c a t i o n i c r i n g - o p e n i n g p o l y m e r i z a t i o n of a l l c l a s s e s of h e t e r o c y c l e s ( c y c l i c a c e t a l s , e t h e r s , s u l f i d e s , l a c t o n e s , phosphates, and amines). They are prepared by two methods d e v e l o p e d by Meerwin (38) and Olah (39). Another more general and convenient synthesis method was recently developed by Penczek et a L (40): 3

R-C

ft

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

N

R f

+ 6

X

MtX

V

rI

R-CH5:

n

V

R—C—of

2 +/

+ Mtx

R

\

N

+

1

F

, + Q

n-1

MtX . . 1

R - C - O R ' + R ~0 MtX . ,

3

R f

n+l

Trialkyloxonium ions are strong a l k y l a t i n g agents and i n i t i a t e the polymerization of h e t e r o c y c l i c monomers by simple a l k y l a t i o n of the most n u c l e o p h i l i c s i t e of the monomer. The i n i t i a t i o n occurs q u a n t i t a t i v e l y and without side reactions when s t a b l e anions are used. Consequently, these i n i t i a t o r s are very useful for k i n e t i c measurements. The i n i t i a t i o n was f o l l o w e d d i r e c t l y by NMR spectroscopy i n the case of THF (41), c y c l i c s u l f i d e s (42), and c y c l i c e s t e r s of phosphonic a c i d such as 2 - m e t h o x y - 2 - o x o - l , 3 , 2 dioxaphosphorinane (43). +

+

2

5

C H - QQBF

3

2

5

_

+

A

(C H ) O 2

5

2

C o v a l e n t I n i t i a t o r s . The i n i t i a t i o n w i t h a l k y l a t i n g compounds depends both on the a b i l i t y of the i n i t i a t o r to form a c a t i o n and on the monomer n u c l e o p h i l i c i t y . Strong a l k y l a t i n g agents such as e s t e r s of s u p e r a c i d s ( C F S 0 R , F S 0 R , and C1S0 R) are a b l e to i n i t i a t e d i r e c t l y w i t h o u t s i d e s r e a c t i o n s both s t r o n g and weak n u c l e o p h i l i c monomers (44, 45). 3

C H OS0 CF 2

5

2

3

3

+ ( Q = =

3

3

+

C H - oQcF S0 2

5

3

3

Weak cationating agents such as a l k y l iodine, benzyl h a l i d e s , and methyl-j>-toluenesulfonate are able to i n i t i a t e the polymerization of strong n u c l e o p h i l i c monomers such as c y c l i c amines (46, 47) and c y c l i c imino ethers (48-52). C o m p e t i t i o n always e x i s t s between the n u c l e o p h i l i c i t y of the counteranion and that of the monomer when these types of i n i t i a t o r s are used. In the case of THF polymerization with superacid ester

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

102

A P P L I E D P O L Y M E R SCIENCE

i n i t i a t o r s , macroions and macroesters are i n e q u i l i b r i u m (44, 45). The polymerization of c y c l i c imino ethers takes place with either macroions or covalent species. The c l a s s i c example i s 2-methyl-2o x a z o l i n e , which p o l y m e r i z e s e x c l u s i v e l y v i a c o v a l e n t l y bonded a l k y l c h l o r i d e s p e c i e s ( b e n z y l c h l o r i d e i n i t i a t o r ) or v i a oxazolinium species (benzyl bromide i n i t i a t o r ) (51). C H CH X + 6

5

2

N

V

C

0

H

H

C

O

0

CH

X -



D I

|

Z

Z

c=o

I

I CH,

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

C^H CH -N-CH -CH ~X

X

6 5^ 2-V/ c

I CH

3

3

Cl

Cl,Br

The mechanistic difference i s e x p l a i n e d by the d i f f e r e n t n u c l e o p h i l i c i t i e s of the c o u n t e r a n i o n s C l ~ and B r " . D i c a t i o n i c a l l y terminated macromolecules can be o b t a i n e d by the i n i t i a t i o n w i t h anhydrides of s t r o n g p r o t o n i c a c i d s such as trifluoromethanesulfonic anhydride (53, 54). CF.SO^ ¥ ° 2 \ 0 + 0 CF S0 3

21 THF*

CF S0 3

|CF S0 3

2

3

THF

2

vl

CF -S0 -K)-(CH ) -O, 3

2

2

4

CF S0 3

3

P h o t o i n i t i a t o r s for Cationic Polymerization. Recently a c l a s s of p h o t o i n i t i a t o r s f o r c a t i o n i c p o l y m e r i z a t i o n was d i s c o v e r e d by C r i v e l l o et a l . (55). This c l a s s includes diaryliodonium ( S t r u c t u r e I) (56, 57), t r i a r y l s u l f o n i u m ( S t r u c t u r e I I ) (58-62), d i a l k y l p h e n a c y l s u l f o n i u m (Structure I I I ) (63), d i a l k y l - 4 - h y d r o x y phenylsulfonium s a l t s (Structure I V ) (64), and t r i a r y l s e l e n o n i u m s a l t s (Structure V) (65). Ar

Ar

V

Ar-S

+

ArCCH^-S 0

II Ar I + Ar-Se I Ar

where:

R'

III

BF,

AsF,

PF,

SbF,

In the absence of l i g h t these s a l t s are s t a b l e even at h i g h temperatures and do not e x h i b i t c a t a l y t i c a c t i v i t y . On i r r a d i a t i o n , for example i n the case of d i a r y l i o d o n i u m s a l t s , the major photochemical process that occurs i n v o l v e s the homolytic cleavage of a c a r b o n - i o d i n e bond to produce a s t r o n g a c i d HX ( i . e . , HBF^, HAsF^, HPF^, or HSbF^). These acids are among the strongest known

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

Recent Developments in Cationic Polymerization

and are e x c e l l e n t i n i t i a t o r s f o r c a t i o n i c p o l y m e r i z a t i o n . mechanism i s o u t l i n e d as f o l l o w s :

103

This

hv Major

+

+

Arl X~

> [Ar I X~] 2

+

[Ar I X~]*

> A r - I * + Ar + X""

A r - I * + Y-H

-> Ar-I -H+Y'

2

+

where Y i s a solvent or a monomer. +

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

Ar-I -H Minor

> A r - I + H+

+

+

[ A r l X ~ ] * + Y-H

> [Ar-Y-H] + A r l + X"

f

+

[Ar-Y-H] > ArY + H Both v i n y l i c (styrene, a-methylstyrene, and v i n y l ethers) and h e t e r o c y c l i c monomers ( c y c l i c ethers or epoxide, oxetane, THF, and trioxane; c y c l i c s u l f i d e s or propylene s u l f i d e and thietane; and lactones and spiro b i c y c l i c orthoesters) were polymerized at room temperature by p h o t o i n i t i a t i o n at wavelengths shorter than 360 nm. The photodecomposition of diaryliodonium s a l t s can be s e n s i t i z e d at wavelengths longer than 360 nm by the use of dyes such as Acridine orange, Acridine y e l l o w , Phosphine R, B e n z o f l a v i n , and S e t o f l a v i n T (66). T r i a r y l s u l f o n i u m , dialkylphenacylsulfonium, and d i a l k y l (4hydroxypheny1) s u l f o n i u m s a l t s were s e n s i t i z e d by p e r y l e n e and other p o l y n u c l e a r hydrocarbons (65, 67). Under these conditions, p h o t o i n i t i a t e d c a t i o n i c p o l y m e r i z a t i o n can be p e r f o r m e d by incandescent l i g h t sources or even ambient s u n l i g h t . The polymerization rate depends on both the monomer r e a c t i v i t y and the n u c l e o p h i l i c i t y of the counteranion of the i n i t i a t o r s a l t . The order of r e a c t i v i t y i n photoinduced polymerization c o r r e l a t e s w e l l with the known r e l a t i v e n u c l e o p h i l i c i t i e s of the anions, that i s , SbF^" > A s F " > P F - > B F ~ . During the photodecomposition, f r e e - r a d i c a l species (Ar* and Y ) are a l s o produced as transient intermediates. Therefore, the p h o t o l y s i s of the sulfonium s a l t s should a l s o i n i t i a t e the freer a d i c a l p o l y m e r i z a t i o n (59). The a m p h i f u n c t i o n a l c h a r a c t e r of s u l f o n i u m s a l t s was demonstrated by the f o l l o w i n g s e r i e s of experiments. I r r a d i a t i o n of an equimolar mixture of l,4cyclohexene oxide and methyl methacrylate with P h g S ^ b F ^ as the p h o t o i n i t i a t o r g a v e a m i x t u r e of two homopo1ymers. Thus, both c a t i o n i c (cyclohexene oxide) and f r e e - r a d i c a l ( m e t h y l methacrylate) p o l y m e r i z a t i o n s took p l a c e i n d e p e n d e n t l y . The same system containing 2 , 6 - d i - t e r t - b u t y l - 4 - m e t h y 1 phenol ( r a d i c a l i n h i b i t o r ) gave only poly(cyclohexene oxide). A l t e r n a t i v e l y the system with t r i e t h y l a m i n e (poison for c a t i o n i c species) y i e l d e d only poly(methyl methacrylate). Monomers such as g l y c i d y l a c r y l a t e and g l y c i d y l methacrylate that c o n t a i n f u n c t i o n a l groups c a p a b l e of c a t i o n i c and f r e e - r a d i c a l p o l y m e r i z a t i o n s are c o n v e r t e d i n t o a c r o s s - l i n k e d i n s o l u b l e polymer. The use of these hybride photoi n i t i a t o r s i s very i n t e r e s t i n g i n the synthesis of interpenetrating network s t r u c t u r e s . 6

6

4

#

-

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

104

I r r a d i a t i o n of d i a l k y l p h e n a c y l s u l f o n i u m s a l t s a l s o produces strong protonic acids (63). 0

0 X

Ar-O-CH^-S^



Ar-C-CH»S' N

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

"R

+ HX R

However, u n l i k e the triary1su1fonium s a l t s , these compounds undergo r e v e r s i b l e photoinduced y l i d f o r m a t i o n r a t h e r than h o m o l y t i c carbon-sulfur bond cleavage. Because the rate of the thermal back reaction i s appreciable at room temperature, o n l y those monomers t h a t are more n u c l e o p h i l i c than the y l i d w i l l p o l y m e r i z e . Epoxides, v i n y l ethers, and c y c l i c a c e t a l s undergo f a c i l e c a t i o n i c p o l y m e r i z a t i o n when i r r a d i a t e d i n the presence of d i a l k y 1 phenacy 1 su 1 fonium s a l t s as p h o t o i n i t i a t o r s . The photodecomposition of d i a l k y 1-4-hydroxy phenyl sulfonium s a l t s (64) g i v e s r i s e to a r e s o n a n c e - s t a b i l i z e d y l i d and an a c i d HX. Styrene oxide, 1,4-cyclohexene oxide, trioxane, and v i n y l

/ S-Q-OH R

A

K

+ HX

^

3

S

+ / + \ J ether were polymerized with s a t i s f a c t o r y rates. However, THF, ecaprolactone, and a-methylstyrene could not be polymerized (64). Recently, Ledwith (68) continuing h i s i n t e r e s t i n the chemistry of cation r a d i c a l s (69, 70) demonstrated that the p h o t o i n i t i a t i o n by t r i a r y l a m i n i u r a , s u l f o n i u m , and iodonium s a l t s o c c u r s by a mechanism that i s different from that proposed by C r i v e l l o . Ar N 3

+ Ar N + H + 3

A r

A r

2

N

JF\ 3 I H ( J - R ^

0* Both c a t i o n r a d i c a l s and protons are r e s p o n s i b l e f o r the p h o t o i n i t i a t i o n w i t h these i n i t i a t o r s . S t a b l e c a t i o n r a d i c a l s based on phenothiazine or i t s d e r i v a t i v e s , and t r i a r y l p y r y l i u m and t h i o p y r y l i u m s a l t s are e x c e l l e n t p h o t o i n i t i a t o r s f o r d i f f e r e n t h e t e r o c y c l i c monomers (68). P h o t o i n i t i a t e d c a t i o n i c p o l y m e r i z a t i o n s are w i d e l y used f o r p h o t o c u r a b l e c o a t i n g s f o r c o a t i n g s of metal c o n t a i n e r s , wood, paper, and f l o o r t i l e s , and a l s o have c o n s i d e r a b l e promise i n a p p l i c a t i o n s i n v o l v i n g photoimaging. Epoxy-based photoresists with high r e s o l u t i o n have been developed, and the use of these m a t e r i a l s i n photography and p l a s t i c flexographic p r i n t i n g p l a t e s has been demonstrated. I n i t i a t i o n of C a t i o n i c P o l y m e r i z a t i o n by Free-Radical I n i t i a t o r s . A new procedure for the i n i t i a t i o n of c a t i o n i c polymerization was developed by Ledwith (13, 23, 2 L 21). This procedure consists of

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

Recent Developments in Cationic Polymerization

105

the o x i d a t i o n of the e l e c t r o n - d o n o r r a d i c a l s by a r y l d i a z o n i u r a , d i a r y l i o d o n i u m , and t r i a r y 1 s u l f o n i u m s a l t s c o n t a i n i n g a s t a b l e c o u n t e r a n i o n . The parent r a d i c a l can be o b t a i n e d by t h e r m a l or photochemical decomposition. AIBN

or hv

f

R' + THF

Ar I PF7 — ^ & n 2

RH +



Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

\ PF~ + A r l + Ar

e

A

*

I

+

R + CH *CH —RCH„-CH — 2 i 2 | -e OR OR' 2

1

P

F

6

+

*> RCH -CH PF, 2 I 6 OR' 0

-

+ A r l + Ar

f

2, 2 - A z o b i s ( 2 - m e t h y l p r o p i o n i t r i l e ) (AIBN), b e n z o y l p e r o x i d e , phenylazotriphenylmethane, and b e n z p i n a c o l were used as thermal r a d i c a l i n i t i a t o r s . Phenylazotriphenylmethane i s e s p e c i a l l y an i n t e r e s t i n g r a d i c a l i n i t i a t o r because by i t s r a d i c a l oxidation, a well-known s t a b l e carbenium s a l t i s obtained. hv PhN = NCPho J

+

Ph C* + P h S P F " 3

3

-> Ph* + N + *CPho 9

z

or A 6

3

+

> Ph C PF ~ + Ph S + Ph* 3

6

2

2,2-Dimethoxy-2-phenylacetophenone, benzophenone, b e n z i l , and many o t h e r r a d i c a l p h o t o i n i t i a t o r s were used to induce the c a t i o n i c polymerization i n the presence of different oxidants. Transformation of Anionic P o l y m e r i z a t i o n i n t o C a t i o n i c P o l y m e r i z a t i o n . R i c h a r d s et a l . (26, 27, 73-75) proposed s e v e r a l methods for the transformation of a l i v i n g anionic polymeric chain end i n t o a c a t i o n i c one. Such a process r e q u i r e s t h r e e d i s t i n c t s t a g e s : polymerization of a monomer I by an anionic mechanism, and capping of the propagating end w i t h a s u i t a b l e but p o t e n t i a l l y r e a c t i v e functional group; i s o l a t i o n of polymer I , d i s s o l u t i o n i n a s o l v e n t s u i t a b l e f o r mechanism (2.), and a d d i t i o n of monomer I I ; and reaction, or change of conditions, to transform the f u n c t i o n a l i z e d end i n t o propagating species I I that w i l l polymerize monomer I I by a c a t i o n i c mechanism (73). Two s i m p l e ways are the r e a c t i o n of p o l y s t y r y l l i t h i u m w i t h excess bromine or ot,a -dibromoxylene. The c a t i o n i c i n i t i a t i o n can be c a r r i e d out by r e a c t i n g the l a b i l e h a l i d e end group w i t h a s i l v e r s a l t containing a weak n u c l e o p h i l i c anion. f

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

106

«M L i + B r

A*. MBr + L i B r +

n

— MBr + AgX —>*-M X + AgBr +

^~*f L i

+

- M C H - ^ J ; - C H B r + LiBr

+ BrCH -«)>-CH Br 2

2

2

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

—CH^Br + AgX

2

-CH

MCH 2

X + AgBr +

2

In both cases Wurtz condensation reactions do not a l l o w high chain end f u n c t i o n a l i t y to be obtained. •MBr



•M-M

-+ LiBr

The t r a n s f o r m a t i o n of a n i o n i c l i v i n g c h a i n ends i n t o a G r i g n a r d l e s s r e a c t i v e chain end a l l o w s the Wurtz condensation reaction to be completely eliminated (75). Y i e l d s as high as 95% were obtained by using t h i s procedure. M"Li

+

-MMgBr + L i B r

+ MgBr

Even so, f o r p o l y s t y r e n e , b e n z y l bromide c h a i n ends were p r e f e r r e d over 1-bromoethylbenzene c h a i n ends f o r c a t i o n i c i n i t i a t i o n . 1-Bromoethylbenzene f u n c t i o n a l groups possess h y d r o gens on the 3-carbon atom and do not i n i t i a t e the p o l y m e r i z a t i o n e n t i r e l y by an a d d i t i v e p r o c e s s . The p r i n c i p a l s i d e r e a c t i o n i s one of B-hydrogen e l i m i n a t i o n (28). CH.-CHBr + AgPF J I , o r

»AgBr* + CH.-CH PF, J I o

CK =€H + HPF, 0

Propagation. The s t r u c t u r e of the growing s p e c i e s ( t e r t i a r y oxonium i o n s ) i n r i n g - o p e n i n g p o l y m e r i z a t i o n of s e v e r a l monomers was a l r e a d y c h a r a c t e r i z e d by NMR spectroscopy ( T a b l e I I I ) . Carbenium-oxonium e q u i l i b r i a were a l s o evidenced and measured. c/-jiast^ -OCH CH CH CH -O^J| — Slow The S^2 mechanism of propagation i n polymerization of h e t e r o c y c l i c monomers was g e n e r a l l y accepted. ^OCH CH CH CH 2

2

2

2

N

1

2

2

2

2

One of the most important achievements was the demonstration that the rate constant of propagation by free ions does not d i f f e r from t h a t by i o n p a i r s . A l s o the r a t e constant of p r o p a g a t i o n i s not affected by the counteranion nature (45).

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

Recent Developments in Cationic Polymerization

PERCEC

107

T a b l e I I I . Growing s p e c i e s i n C a t i o n i c P o l y m e r i z a t i o n of Heterocyclic Monomers Observed D i r e c t l y by H-NMR Spectroscopy Monomer

Structure of growing species (anions omitted)

r\

+

V

H

2-CH,

~~-CH -V

2

»

2

2

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

C

/

76

2

v

CH CH CH 0

0

0

-v^CH-V

77 C

,

,

0

0

H

,CH„CH 2-2-2 (

CH -0-CH 9

32

2

CH -0-CH 2

C

H

CH. H.C CH \ / 3

3

\

C

« 3 /

C

H

3

+

/

C

f

3

C t H

>

CH.

\

/ CH — S +

••

78

2

6CH3

3

2

y

— - C H -v- r

P 0

9

/ ^ ~ C H - 0

N

0

Reference

H

t H

2

2

X

/

C

79

3

H

3 80

— CH -N 2

CH CH

C H 3

m

2

3

3

ai -ai 2

N.

.6

V C H

3

-—CH -N' 2

+

N

f

CH

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

51

108

A P P L I E D P O L Y M E R SCIENCE

The l o n g d i s p u t e of the growing s p e c i e s s t r u c t u r e i n the polymerization of c y c l i c a c e t a l s seems to be at i t s end. Penczek et a l . (32) showed c l e a r l y t h a t propagation proceeds on l i n e a r growing species. Growth by r i n g expansion seems to be u n l i k e l y on the basis of the e x i s t i n g experimental evidence. The presence of the end groups was c l e a r l y demonstrated by H - , P [ H ] - N M R , and UV. D P c a l c u l a t e d from the end groups agrees w e l l w i t h the UP determined osmometrically. A l l e q u i l i b r i u m constants were measurea recently for t h i s propagation scheme: A

3 1

1

n

CH OCH

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

3

+ 2

+ S~J

^

C H

3

O C H

2

-

+

0 ^ ?

CH-^'^J

2

kj/ke^ = 3 • 10 , and explains the tendency of isomerization of l e s s s t a b l e (more s t r a i n e d ) five-membered r i n g s i n t o l e s s s t r a i n e d seven-membered ones. A more d e t a i l e d discussion on t h i s topic can be found i n a recent review (T). T e r m i n a t i o n and T r a n s f e r P r o c e s s e s . C l e a r e v i d e n c e about the mechanism of t e r m i n a t i o n and c h a i n t r a n s f e r processes can be obtained from the polymer chain end structure. One polymer chain end i s c o n t r o l l e d by the i n i t i a t i o n mechanism, and the second one i s c o n t r o l l e d by termination and/or chain transfer. The chemical s t r u c t u r e of the end groups has been s t u d i e d i n a few cases o n l y (I). S e v e r a l p e c u l i a r i t i e s of these r e a c t i o n s w i l l be o u t l i n e d here. Temporary T e r m i n a t i o n : R e v e r s i b l e Recombination with Noncomplex Anions. Temporary termination was evidenced for the f i r s t time i n the polymerization of c y c l i c imino ethers (51).



~^ ~N-CH CH Br 2

2

2

0=0 CH

0

The same r e a c t i o n was r e c e n t l y evidenced i n the case of THF polymerization with CF3SO3" or F S O 3 " counteranions (I):

•V~O-(CH ) -O£) 2

4

/S^CH(CH ) - R - PTHF+PF " + N0C1 6

Recently Dreyfuss et a l . (113, 114) developed a new method for the d e t e r m i n a t i o n of the number of poly(THF) branches i n a g r a f t copolymer. The method i s based on the t e r m i n a t i o n of the l i v i n g c a t i o n i c c h a i n ends w i t h NH^OH-NH^Cl buffer and r e a c t i o n w i t h fluorescamine. The c h a i n ends c o n c e n t r a t i o n i s determined by fluorescent spectroscopy. Franta et a l . (115) synthesized graft copolymers by i n i t i a t i o n of THF polymerization from chloromethylated polystyrene, p a r t i a l l y brominated 1,4-polybutadiene, and a random copolymer of styrene and methacryloyl c h l o r i d e i n the presence of AgSbF^.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

Recent Developments in Cationic Polymerization

PERCEC

113

A l a r g e number of g r a f t copolymers were obtained by Dreyfuss and Kennedy (126-128) by g r a f t i n g of pendant epoxy groups of a v a r i e t y of polymer backbones. This grafting mechanism i s based on Saegusa's f i n d i n g s t h a t s e v e r a l r i n g compounds are a b l e , i n conjunction with Lewis acids, to generate t e r t i a r y oxonium ions, the true i n i t i a t i n g species (129). Q>:BF

tjH

+

3

— ^

2

[>MH

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

0

2

60BF

3

(CH ) S] CH CH CH CH 0-CH -CHOBF " 2

4

n

2

2

2

2

2

3

Chloromethylated c r o s s - l i n k e d polystyrene was used to i n i t i a t e the g r a f t c o p o l y m e r i z a t i o n of s e v e r a l 2-substituted-2-oxazoline d e r i v a t i v e s (130, 131). A l l y l i c c h l o r i d e from 1 - c h l o r o - l , 3 butadiene-butadiene copolymer and from p o l y ( v i n y l c h l o r i d e ) was used to i n i t i a t e the graft copolymerization of 2-methyl-2-oxazoline (132, 133). The grafting onto method was used to prepare graft copolymers by deactivation reaction onto a backbone f i t t e d with n u c l e o p h i l i c sites. Franta et a l . (134) used t h i s technique to synthesize graft copolymers of poly(THF) w i t h n u c l e o p h i l i c backbones poly(j>dimethylaminostyrene) and p o l y ( 2 - v i n y l p y r i d i n e ) . f

?

h

^ 3

6

\

CH

3

CH

3

SbF

6

Richards et a l . (135) succeeded i n q u a n t i t a t i v e graft copolymeriz a t i o n of poly(THF) onto p o l y ( 4 - v i n y l p y r i d i n e ) . Goethals et a l . (89) a l s o used the grafting onto method to prepare graft copolymers i n a q u a n t i t a t i v e y i e l d by r e a c t i n g a l i v i n g p o l y ( N - t e r t b u t y l a z i r i d i n e ) w i t h p o l y ( 2 - v i n y l p y r i d i n e ) as a " d e a c t i v a t i n g " polymer. Block Copolymers. Several methods have already been used for the synthesis of block copolymers. The most conventional method, that i s , the addition of a second monomer to a l i v i n g polymer, does not produce the same spectacular r e s u l t s as i n anionic polymerization. Chain t r a n s f e r to polymer l i m i t s the u t i l i t y of t h i s method. A recent example was afforded by Penczek et a l . (136). The addition of the 1,3-dioxolane to the l i v i n g b i f u n c t i o n a l poly(l,3-dioxepane) leads to the formation of a block copolymer, but before the second monomer p o l y m e r i z e s c o m p l e t e l y , the t r a n s a c e t a l i z a t i o n process ( t r a n s f e r to polymer) l e a d s to the c o n v e r s i o n of the i n t e r n a l homoblock to a more or l e s s (depending on time) s t a t i s t i c a l copolymer. Thus, c o m p e t i t i o n of h o m o p r o p a g a t i o n and t r a n s a c e t a l i z a t i o n i s not i n f a v o r of f o r m a t i o n of the b l o c k copolymers with pure homoblocks, at l e a s t when the second block, being b u i l t on the a l r e a d y e x i s t i n g homoblock, i s formed more s l o w l y t h a n t h e p a r e n t h o m o b l o c k t h a t i s r e s h u f f l e d by transacetalization. In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

114

In systems d e v o i d of c h a i n t r a n s f e r to polymer, f o r example, c y c l i c imino e t h e r s , t h i s method g i v e s r i s e to pure b l o c k copolymers (137, 138). A r e l a t e d method was d e v e l o p e d by Pepper and G o e t h a l s (139). Taking advantage of the dormant character of polystyrene prepared at low temperature w i t h p e r c h l o r i c a c i d ( i n the form of a macroester) they prepared w e l l - c h a r a c t e r i z e d b l o c k copolymers of polystyrene with c y c l i c amines. ABA and AB block copolymers were synthesized by the i n i t i a t i o n of 2 - o x a z o l i n e p o l y m e r i z a t i o n by a polymer c o n t a i n i n g t o s y l a t e (140-143) or a l k y l h a l i d e end groups (144-147). I n i t i a t i o n of THF polymerization from p o l y s t y r e n e or p o l y b u tadiene containing l a b i l e h a l i d e s as chain ends i n conjunction with s i l v e r s a l t s was used by R i c h a r d s et a l . (26, 27, 74) to i n i t i a t e the block copolymerization of THF. Richards et a l . (148) developed a new route f o r p r e p a r i n g b l o c k copolymers by a macrocation to macroanion t r a n s f o r m a t i o n . T h i s process c o n s i s t s i n r e a c t i n g l i v i n g poly(THF) w i t h the l i t h i u m s a l t of c i n n a m y l a l c o h o l to prepare a polymer p o s s e s s i n g a s t y r y l t e r m i n a l group. This reaction i s q u a n t i t a t i v e . The second stage i n v o l v e s the reaction of t h i s product with n-butyl l i t h i u m i n benzene to form an adduct to which a monomer such as styrene or isoprene i s added to prepare a b l o c k copolymer a n i o n i c a l l y . T h i s l a s t stage u n f o r t u n a t e l y operates with only 20% e f f i c i e n c y . The c o u p l i n g of an a n i o n i c l i v i n g polymer w i t h a c a t i o n i c l i v i n g polymer gives r i s e to AB or (AB) block copolymers. In the case of polystyrene with poly(THF) the coupling e f f i c i e n c y seems to depend on the n u c l e o p h i l i c i t y of the c o u n t e r a n i o n and of the a n i o n i c c h a i n ends. For example, the g r a f t i n g y i e l d i s very low when poly(THF) w i t h BF^~ c o u n t e r a n i o n i s used (188), and i t i n c r e a s e s i n the case of FSO^" c o u n t e r a n i o n (179). The y i e l d i s q u a n t i t a t i v e when c a r b o x y l a t i n g p o l y s t y r e n e anions are used (37, 150). M u l t i b l o c k copolymers ( A B ) were obtained by c o u p l i n g of d i a n i o n i c p o l y s t y r e n e w i t h d i c a t i o n i c poly(THF) (151, 152). The c o u p l i n g of l i v i n g a n i o n i c p o l y ( a - m e t h y l s t y r e n e ) w i t h c a t i o n i c l i v i n g poly(THF) occurs with only 20% e f f i c i e n c y . Proton transfer and h y d r i d e t r a n s f e r g i v e s r i s e t o p o l y ( T H F ) and p o l y ( a methylstyrene) with v i n y l i c end groups as byproducts (153). Attempts to produce b l o c k copolymers by c o u p l i n g of l i v i n g c a t i o n i c p o l y ( | l - t e r t - b u t y l a z i r i d i n e ) with l i v i n g anionic p o l y styrene f a i l e d because the r e s u l t was a mixture of the two homopo 1 ymers. H o w e v e r , when the c a r b a n i o n of the a n i o n i c polystyrene was f i r s t converted into a t h i o l a t e anion by reaction w i t h propylene s u l f i d e , c o u p l i n g with l i v i n g p o l y ( N - t e r t - b u t y l a z i r i d i n e ) was s u c c e s s f u l i n producing a b l o c k copolymer (89). ABA-type block copolymers were synthesized by reaction of a l i v i n g p o l y ( N - t e r t - b u t y l a z i r i d i n e ) w i t h t e l e c h e l i c amino- or c a r b o x y terminated polymers h a v i n g p o l y b u t a d i e n e or p o l y b u t a d i e n e - c o a c r y l o n i t r i l e as backbones (89). Chain t r a n s f e r to a second polymer can be e x p l o i t e d as a possible avenue for block copolymer synthesis. The homopolymerization of a given monomer A i n the presence of a preformed polymer B or the i n t e r a c t i o n between two homopolymers i n the presence of a c a t i o n i c i n i t i a t o r (_1, 153, 154) produce i n the f i r s t step of the reaction block copolymers. Synthesis of other block copolymers was n

n

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

115

Recent Developments in Cationic Polymerization

PERCEC

reviewed by Yamashita et a l . (152). Trimethy l c e l l u l o s e - [ ] > p o l y ( T H F ) ] - s t a r b l o c k copolymers were s y n t h e s i z e d by Feger and Cantow (156, 157). T r i m e t h y l c e l l u l o s e containing a l a b i l e c h l o r i n e end group was used to i n i t i a t e the l i v i n g polymerization of THF i n the presence of AgSbF^. The l i v i n g c h a i n end of t h i s AB b l o c k copolymer was reacted with p o l y ( 4 - v i n y l p y r i d i n e ) oligomers to form star-shaped block copolymers.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

Cationic Polymerization of Olefins General Considerations. This f i e l d was presented i n a few recent monographs (_2, 3», L4, 158). Carbenium species are more a c t i v e than oxonium, sulfonium, or ammonium. Side reactions, or transfer to monomer and n u c l e o p h i l i c attack of the aromatic r i n g i n the case of styrene polymerization (to produce a 3-phenylindane type end groups) lead to low molecular weight polymers. The only way to avoid these side reactions i s to decrease the polymerization temperature. The f i r s t carbenium ion was observed by C - N M R spectroscopy i n 1979 (159). In these conditions a l l the mechanistic approaches are supported by i n d i r e c t evidence o n l y . In the case of r i n g - o p e n i n g p o l y m e r i z a t i o n , s e q u e n t i a l and f u n c t i o n a l polymers are s y n t h e s i z e d by u s i n g our knowledge of p o l y m e r i z a t i o n mechanisms. In the case of o l e f i n p o l y m e r i z a t i o n , s e q u e n t i a l copolymers are e v i d e n c e f o r the suggested mechanism of polymerization. Information about the propagation rate constants with free ions are o b t a i n e d , as i n the case of r i n g - o p e n i n g p o l y m e r i z a t i o n , by u s i n g s t a b l e carbenium i o n s as i n i t i a t o r s (23). Unfortunately these i n i t i a t o r s can be used only for the polymerization studies of very a c t i v e c a t i o n i c monomers ( i . e . , s t r o n g bases such as v i n y l e t h e r s or v i n y l d e r i v a t i v e s c o n t a i n i n g s t r o n g e l e c t r o n donor pendant groups) (23). Another way to determine propagation r a t e c o n s t a n t s w i t h free i o n s i s to use r a d i a t i o n - i n d u c e d i o n i c polymerization techniques (160). A new method for the study of nonstationary polymerization i s the flow and stopped-flow spectroscopy developed by Sawamoto and Higashimura (161, 162). A l t h o u g h these methods o f f e r the o n l y a v a i l a b l e data about polymerization k i n e t i c s through known species, t h e i r p r e p a r a t i v e a p p l i c a t i o n s are v e r y l i m i t e d . A number of useful discoveries are coming from Kennedy's laboratory (163-175). P a r t of these d i s c o v e r i e s w i l l be presented l a t e r . Kennedy's r e s e a r c h p h i l o s o p h y c o n s i s t s i n understanding the mechanisms of polymerization of conventional monomers, and i t s use i n the design of new polymeric materials (163) has proven very productive. 13

Graft Copolymers. As i n the case of ring-opening polymerization, l a b i l e h a l i d e s can be used i n conjunction with a Lewis acid i n t h i s case to produce carbenium species. I f the i n i t i a t i o n takes place by addition, graft copolymers can be obtained by the grafting from technique when the l a b i l e h a l i d e i s p a r t of a polymer c h a i n (10, 163-165). M P-Cl + E t A l C l > [P Et AlCl ~] > P - poly(M) + E t A l C l +

2

2

2

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2

116

A P P L I E D P O L Y M E R SCIENCE

A large variety of graft copolymers was prepared by t h i s technique and some are presented i n the box (159). Under s u i t a b l e r e a c t i o n c o n d i t i o n s , g r a f t copolymers free of homopolymers c o u l d be prepared. I n i t i a t i o n of graft copolymerization by radiation-induced c a t i o n i c mechanism was recently reviewed by Stannett (160). This method i s e s p e c i a l l y u s e f u l f o r c a t i o n i c graft copolymerization from i n e r t polymer supports. I n i f e r Technique. I n i f e r s are b i f u n c t i o n a l i n i t i a t o r - c h a i n t r a n s f e r agents t h a t have been used f o r the p r e p a r a t i o n of a,0)d i f u n c t i o n a l p o l y i s o b u t y l e n e c a r r y i n g ^ ~ C H C ( C H q ) C l end groups Q 0 . 164, 166-168). The mechanism of the i n i f e r system based on dicumyl c h l o r i d e BClg and isobutylene i s o u t l i n e d below.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

9

9

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

Recent Developments in Cationic Polymerization

PERCEC

117

Representative Graft Copolymers Prepared by Carbocationic Techniques I.

Elastomeric backbones A.

Elastomeric branches

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

a

Poly(butadiene-g-isobutylene) Poly[chloroprene-g-(isobutylene-co-isoprene)] Poly[isobutylene-co-isoprene)-g-chloroprene]

a

B.

Glassy branches a

Poly[(ethylene-co-propylene)-g-styrene] Poly[(isobutylene-co-isoprene)-g-styrene] '" Poly(butadiene-g-a-methylstyrene) a

a

C.

Two branches (bigrafts) 1.

A glassy and an elastomeric branch Poly[ethylene-co-propylene-co-1,4-hexadiene) -£-styrene-g-isobutylene] a , b

2.

Two glassy branches Poly[(ethylene-co-propylene-co-1,4-hexadiene) -g^styrene-g-a-methylstyrene] ' a

II.

b

Glassy backbones A.

Elastomeric branches P o l y ( v i n y l chloride-g-isobutylene) Chloromethylated polystyrene^g-polyisobutylene

B.

Glassy branches P o l y ( v i n y l chloride-^-styrene)

a

L i g h t l y chlorinated backbone used.

b

L i g h t l y brominated backbone used.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

118

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

The f u n c t i o n a l i t y of the obtained t e l e c h e l i c polyisobutylenes i s a f f e c t e d m a i n l y by the i n t r a m o l e c u l a r c y c l o a l k y l a t i o n of the initiator.

temperature and s o l v e n t mixture c o n d i t i o n s (169, 170). By u s i n g tricumyl c h l o r i d e - B C ^ t r i n i f e r system, three-arm star t e l e c h e l i c polyisobutylenes carrying exactly three -C(CH ) C1 end groups have been synthesized by Kennedy et a l . (171, 172). 3

3

Q u a s i - l i v i n g Carbocationic P o l y m e r i z a t i o n . R e c e n t l y , Kennedy et a l . (165, 173) developed p o l y m e r i z a t i o n systems i n which under well-defined conditions (a s p e c i a l manner of continuous mixing of monomer w i t h i n i t i a t i n g systems), c h a i n t e r m i n a t i o n and c h a i n t r a n s f e r to monomer are r e v e r s i b l e or a v o i d a b l e , and f o r a l l p r a c t i c a l purposes the system behaves as i f R and R ^ are equal to zero. Fast R^ was achieved by premixing the ingredients of the i n i t i a t i n g systems. K i n e t i c equations have been d e r i v e d a c c o r d i n g to which the molecular weight of the polymer can be c o n t r o l l e d by the cumulative amount o f monomer a d d e d and i n i t i a l concentrations of i n i t i a t o r : B? = M -./[I] . This equation i s very s i m i l a r to that defining l i v i n g conditions: DP = [ M ] / [ I ] . A few studied systems that polymerize under q u a s i - l i v i n g conditions are HoO-BClo-a-methylstyrene, C ^ H ^ ^ ^ C l - B C ^ - a - m e t h y l s t y r e n e , tert-BuCl-TiCl -isobutylene. t

t Q t a

t x

Q

n

Q

4

Proton Traps. 2 , 6 - D i - t e r t - b u t y l - 4 - m e t h y l pyridine (DBMP) and 2,6d i - t e r t - b u t y l p y r i d i n e (DtBP) are hindered bases i n c a p a b l e of r e a c t i n g w i t h e l e c t r o p h i l e s other than p r o t o n i c a c i d s . Consequently, they can be s u c c e s s f u l l y used for the trapping of protons during t h e i r transfer to monomer (174, 175). At the same time they can disseminate between the two major i n i t i a t i o n mechanisms encountered i n c a t i o n i c p o l y m e r i z a t i o n , t h a t i s , p r o t o n i c i n i t i a t i o n or carbenium i n i t i a t i o n (176). Block Copolymers. Two conventional techniques were applied for the s y n t h e s i s of b l o c k c o p o l y m e r s : i n i t i a t i o n o f monomer polymerization from a preformed polymer containing an i n i t i a t o r as chain end or ends, and the addition of a second monomer to a l i v i n g polymerization of the f i r s t one.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5. PERCEC

Recent Developments in Cationic Polymerization

Poly(a-methy1 s t y r e n e - ] ) - i s o b u t y l e n e - J ^ - a - m e t h y l s t y r e n e ) was prepared by the i n i t i a t i o n of a-methylstyrene polymerization from a d i t e l e c h e l i c polyisobutylene containing t e r t - c h l o r i n e end groups. A l E t 2 C l was used as c o i n i t i a t o r (177). Poly(isobutylene-b-styrene) and poly(isobutylene-_b-ot-methy 1 s t y r e n e ) were prepared by the i n i t i a t i o n of s t y r e n e and a-methylstyrene polymerization from an asymmetric t e l e c h e l i c p o l y i s o b u t y l e n e , t h a t i s , (CHo^-CsCh-CH?" PiB—CH -C(CH ) C1 and A l E t C l (178). Addition of a second monomer to a l i v i n g polymer chain was used to produce block copolymers from N - v i n y l c a r b a z o l e and v i n y l ethers by u s i n g s t a b l e carbenium s a l t s as i n i t i a t o r s (179). The same avenue was used by Higashimura et a l . (180) to produce a b l o c k copolymer by i n i t i a t i o n of the p o l y m e r i z a t i o n of i s o b u t y l v i n y l e t h e r from a l o n g - l i v e d po 1 y - j ) - m e t h o x y s t y r e n e . Living p o l y m e r i z a t i o n of j)-methoxystyrene | N - v i n y l c a r b a z o l e has s u c c e s s f u l l y been achieved by using iodine as i n i t i a t o r (180, 181). By using a programmed successive a d d i t i o n of monomers, G i u s t i (182) s u c c e s s f u l l y p r e p a r e d b l o c k c o p o l y m e r s from s t y r e n e and isobutylene. A d e t a i l e d d e s c r i p t i o n of the sequential copolymer synthesis by carbocationic polymerization i s presented i n a recent book (3). 2

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

119

3

2

2

a n (

Heterogeneous G r a f t Copolymerization. P o l y ( v i n y l c h l o r i d e ) f i l m s and powders (183) and chlorinated polypropylene (184) f i b e r s were g r a f t e d w i t h s t y r e n e , i s o b u t y l e n e , and s t y r e n e , r e s p e c t i v e l y . Grafting from techniques were used. By using the same technique a s i l i c a surface f i r s t treated with c h l o r o s i l y l functional groups was grafted with polyisobutylene and b u t y l rubber (185, 186): CHo CHo J "HCl ) -Si-OH + Cl-Si-CH CH2CH Cl2 > -SiO-SiQ^Ch^dCh^Cl + A l E t C l 3

3

2

2

2

^H^ isobutylene

-Si-g-polyisobutylene

Grafting on technique was used to produce a graft copolymer s i l i c a & - p o l y ( J N - t e r t - b u t y l a z i r i d i n e ) (187). The technique used was the c o u p l i n g of a s i l i c a - c o n t a i n i n g amine group w i t h a t e m p o r a r i l y l i v i n g poly(tert-butylaziridine). -0*f -OH

+ (Et 0) Si-(CH ) NH 3

3

2

3

—*

poly (TBJ^+N^J

poly (TBA^ N^J t r

-0^Si(CH ) NH 2

3

2

+

^Si(CH ) N^poly(TBA) 2

3

\

or +

2

-I- N H ( C H ) S i ( O E t ) — ^ poly ( i B ^ - p o l y (TBA)NH(CH > Si(OEt) 2

2

3

3

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

2

3

3

A P P L I E D P O L Y M E R SCIENCE

120

These heterophase methods are very i n t e r e s t i n g academic as w e l l as t e c h n o l o g i c a l point of view.

from both an

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

Polymers with Functional End Groups Polymers w i t h Two F u n c t i o n a l End G r o u p s : T e l e c h e l i c s . In accordance w i t h t h e i r h i s t o r i c a l appearance, polymers w i t h two functional end groups w i l l be considered f i r s t . A very large range of t e l e c h e l i c p o l y i s o b u t y l e n e s ( P I B ) were s y n t h e s i z e d and characterized by Kennedy and h i s coworkers (165). These data were a l r e a d y reviewed s e v e r a l times (_3, 165, 188). A few avenues f o r PIB t e l e c h e l i c s preparation based on the i n i f e r technique w i l l be presented. The dehydrochlorination of a,u>-di(t:ert-chloro)polyisobutylene led to a,a>-di(isopropenyl)polyisobutylene (189) i n the quantitative y i e l d . The r e g i o s e l e c t i v e hydroboration of a,a)d i ( i s o p r o p e n y l ) p o l y i s o b u t y l e n e f o l l o w e d by a l k a l i n e hydrogen peroxide o x i d a t i o n l e d to a new t e l e c h e l i c polyisobutylene d i o l carrying two terminal primary hydroxyl end groups (190), that i s , a, u)-di( hydroxy) poly isobutylene.

tBuOK THF

The same chemistry was used f o r the three-arm s t a r t e l e c h e l i c polyisobutylene synthesis (171). These two functional groups (that i s , p r o p e n y l and h y d r o x y l ) a f f o r d the p o s s i b i l i t y of almost any k i n d of f u n c t i o n a l groups to be i n t r o d u c e d at the c h a i n ends of polyisobutylene. By d e r i v a t i o n of hydroxyl and propenyl terminated polyisobutylene, t e l e c h e l i c s c o n t a i n i n g c a r b o x y l i c (191, 192), - S i C l and H-SiH (193, 194), a c r y l o y l and m e t h a c r y l o y l (195), o x y c a r b o n y l (196), amine, cyanato (197), e t h y n y l , n i t r i l e (198), p h e n o l , and epoxy (199) groups have been s y n t h e s i z e d . These materials are useful for a large v a r i e t y of a p p l i c a t i o n s such as chain extension, networks, and block copolymers.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

Recent Developments in Cationic Polymerization

121

a , U ) - D i ( a c r y l o y l ) p o l y ( T H F ) and a,o)-di(raethacryloyl)poly(THF) were prepared by the p o l y m e r i z a t i o n of THF i n i t i a t e d by p r o t o n i c acids (HSbF^ or CF3SO3H) i n the presence of a c r y l i c or methacrylic anhydride as a transfer agent (200). On the basis of the fact that t r a c e s of a c r y l i c o r m e t h a c r y l i c a c i d s a c c e l e r a t e the polymerization, the f o l l o w i n g mechanism of reaction was proposed: n — > A ^ A

+ AcOH

&

^ ^

~-0Ac + H-0 2

4

N

2

RfO(CH ) ]4Q-CH-CH 2

4

2

Copolymers w i t h s t y r e n e and a l k y l methacrylates were synthesized a l s o . The coupling method was i n i t i a l l y developed by Asami et a l . (200, 210) who succeeded i n preparing polymerizable oligomers from l i v i n g poly(THF) by coupling with v i n y l phenolate (CHo=CH-C H -0") or w i t h v i n y l b e n z y l a l c o h o l a t e ( C H = C H - C H - C H 0 ~ ) . The homopolymerization and c o p o l y m e r i z a t i o n of these Macromers were s t u d i e d (209). Another Macromer was designed by G o e t h a l s and V l e g e l s (211). The deactivation of the a c t i v e species (aziridinium ions) of l i v i n g 6

2

6

4

2

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

4

5.

PERCEC

Recent Developments in Cationic Polymerization

p o l y ( l - t e r t - b u t y l a z i r i d i n e ) by m e t h a c r y l i c a c i d corresponding polyamine-methacrylate ester Macromer. ^ < J

CF S0

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

3

+

C F

3

S 0

3

C H CH

3

C F

3

led

123 to

the

S O

3

3

^SN^ + "0-5-

-

2

Additional Research Reports The 6th I n t e r n a t i o n a l Symposium on C a t i o n i c P o l y m e r i z a t i o n and Related Processes was held i n Ghent, Belgium (August 30 - September 2, 1983). I t s Proceedings were published as a book (212). Recent review a r t i c l e s on the f o l l o w i n g topics were published: the controversy concerning the c a t i o n i c ring-opening polymerization of c y c l i c a c e t a l s ( 2 1 3 ) , p h o t o i n i t i a t o r s for cationic p o l y m e r i z a t i o n ( 2 1 4 ) , l i v i n g p o l y m e r i z a t i o n and s e l e c t i v e dimerization (215), macromonomers (216), and f u n c t i o n a l polymers and sequential copolymers by carbocationic polymerization (217). Two s p e c i a l i s s u e s c o n t a i n i n g Kennedy's work on the use of s t e r i c a l l y hindered amines i n c a r b o c a t i o n i c polymerization (218) and on q u a s i - l i v i n g carbocationic p o l y m e r i z a t i o n (219) were a l s o published. Acknowledgment The author wishes to e x p r e s s h i s g r a t i t u d e to S. Penczek f o r h i s c a r e f u l r e a d i n g and c r i t i c i s m of t h i s manuscript and to J . P. Kennedy f o r many d i s c u s s i o n s . The f i n a n c i a l support of the N a t i o n a l S c i e n c e Foundation i s g r a t e f u l l y acknowledged. (Grant DMR: 82-13895) L i t e r a t u r e Cited 1. 2. 3. 4. 5. 6. 7. 8. 9.

Penczek, S.; K u b i s a , P.; M a t y j a s z e w s k i , K. Adv. Polym. Sci. 1980, 37, 1. K u b i s a , P.; Penczek, S. " E n c y c l . Polym. Sci. T e c h n o l . S u p p l . " ; W i l e y : New York, 1977; Vol. 2, p. 161. Gandini, A.; Cheradame, H. Adv. Polym S c i . 1980, 34/35. 1. Kennedy, J. P.; M a r e c h a l , E. " C a r b o c a t i o n i c P o l y m e r i z a t i o n " ; Wiley: New York, 1982. Dreyfuss, P. "Poly(tetrahydrofuran)"; Gordon and Breach: New York, 1982. Polymer J. 1980, 12, 9. Kennedy, J. P . ; J. Polym. Sci. Polym. Symp. Ed. 1977, 56. Kern, W.; Sigwalt, P. Makromol. Chem. 1974, 175, 1017. " C a t i o n i c P o l y m e r i z a t i o n and R e l a t e d Complexes"; Plesch, P. H., Ed.; W. Heffer and Sons: Cambridge, 1973. Pepper, D. C. Sci. Proc. Roy. Dublin Soc. 1950, 25, 131.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

124

A P P L I E D P O L Y M E R SCIENCE

10. 11. 12. 13. 14. 15. 16.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

Kennedy, J. P. Makromol. Chem., Suppl. 1979, 3, 1. Penczek, S. Makromol. Chem., Suppl. 1979, 3, 17. Szwarc, M. Makromol. Chem., Suppl. 1979, 3, 327. Ledwith, A. Makromol. Chem., Suppl. 1979, 3, 348. Kennedy, J . P. " C a t i o n i c P o l y m e r i z a t i o n of O l e f i n s : A Critical Inventory"; Wiley: New York, 1975. Kennedy, J . P. In " A p p l i e d Polymer Science"; C r a v e r , J . K . ; Tess, R. W., Eds.; American Chemical S o c i e t y : Washington, D.C., 1975; p. 195. "The Chemistry of C a t i o n i c P o l y m e r i z a t i o n " ; P l e s c h , P. H . , Ed.; Pergamon Press, 1963. Watson, Bishop "Chemical Essays, 5th Ed."; J. Evans: London, 1789; Vol. III. Dunn, D. J. "Developments in P o l y m e r i z a t i o n " ; Howard, R. N., Ed.; A p p l . Sci. Publ.: London, 1979; Vol. 1, p. 45. "Ring-Opening P o l y m e r i z a t i o n " ; Saegusa, T.; G o e t h a l s , E. J., Eds.; ACS SYMPOSIUM SERIES No. 59, American Chemical Society: Washington, D.C., 1977. " P o l y m e r i z a t i o n of H e t e r o c y c l e s " ; Penczek, S., Ed.; Pergamon Press: Oxford, 1977. B i l l i n g h a m , N. C. "Developments i n Polymerization"; Howard, R. N., Ed.; A p p l . Sci. Publ.: London, 1979; p. 47. L e d w i t h , A.; S h e r i n g t o n , D. C. Adv. Polym. Sci. 1974, 19, 1. Ledwith, A. Pure Appl. Chem. 1979, 51, 159. Dreyfuss, M. P.; W e s t f a h l , J . C.; Dreyfuss, P. Macromolecules 1968, 1, 437. Penczek, S. Makromol. Chem. 1974, 175, 1217. Burgess, F. J.; Cunliffe, A. V . ; M a c C a l l u m , D. R.; R i c h a r d s , D. H. Polymer 1977, 18, 719. I b i d . , 726. Burgess, F. J.; Cunliffe, A. V . ; R i c h a r d s , D. H.; Thompson, T. Polymer 1978, 19, 334. Richards, D. H.; Thompson, T. Polymer 1979, 20, 1439. Zilliox, J . G.; Reibel L . ; Scheer, M . ; S c h w e i c k e r t , J . C.; Franta, E. IUPAC, I n t . Symp. M a c r o m o l . , M a i n z , 1979; P r e p r i n t s , Vol. I, p. 56. Olah, G. A.; Svoboda, J. J. Synthesis 1973, 52. K u b i s a , P . ; S z y m a n s k i , R.; P e n c z e k , IUPAC I n t . Symp. Macromol., Strasbourg, 1981; Preprints, V o l . I , p. 256. S t o l a r c z y k , A.; K u b i s a , P.; Penczek, S. J. Macromol. Sci., Chem. 1977, A11, 2047. O l a h , G. A . ; Kuhn, S. J.; Toglyesi, W. S.; B a k e r , E . B. J. Am. Chem. Soc. 1962, 84, 2733. F r a n t a , E . ; Reibel, L . ; Lehmann, J . ; Penczek,S. J . Polym. S c i . Polym. Symp. 1976, 56, 139. Kubisa, P . ; Penczek, S. Makromol. Chem 1978, 179, 445. Yamashita, Y . ; H i r o t a , M . ; N o b u t o k i , K.; Nakamura, Y . ; N i r a o , A.; Kozawa, S.; C h i b a , K.; M a t s u i , H.; Hatori, G.; Okada, M. J. Polym. Sci., P a r t B 1970, 8, 481. Meerwin, H. In "Houben-Weyl Methoden der Organikhen Chemie"; Muller, E., Ed.; 4th ed., Vol. VI/3, Stuttgart, George Thieme V e r l a g , 1965; p. 325. O l a h , G. A . ; O l a h , J. A . ; Suoboda, J . J. S y n t h e s i s 1973, 490.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

40. 41. 42. 43. 44. 45.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

46. 47. 48. 49. 50. 51. 52. 53. 54.

55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72.

Recent Developments in Cationic Polymerization

125

S z y r a a n s k i , R.; W i e c z o r e k , H . ; K u b i s a , P . ; P e n c z e k , S. Chem. Commun. 1976, 33. S a e g u s a , T.; K i m u r a , Y . ; Fujii, H.; Kobayashi, S. Macromolecules 1973, 6, 657. D r i j v e r s , W.; Goethals, E. J . Makromol. Chem. 1971, 148, 311. Penczek, S. Pure A p p l . Chem. 1976, 48, 363. Penczek, S. J. Polym. Sci. Polym. Symp. 1980, 67, 149. Saegusa, T.; Kobayashi, S. J. Polym. Sci. Polym. Symp. 1976, 56, 241. Penczek, S.; M a t y j a s z e w s k i , K. J. Polym. Sci. Polym. Symp. 1976, 56, 255. Nekrasov, A. V . ; Pushchaeva, L . M . ; Morozova, I . S.; Markevich, A1. Berlin, M. A.; Ponomarenko, A. T.; Enikolopyan, N. S. J. Macromol. Sci. Chem. 1974, A8, 241. G o e t h a l s , E. J.; Schacht, E. H . ; Bogaert, K. E . ; Ali, S. I . ; Tezuka, Y. Polym. J. 1980, 12, 571. Saegusa, T. Pure Appl. Chem. 1974, 39, 81. Saegusa, T.; Kobayashi, S. "M. T. P. I n t . Rev. Sci.: Phys. Chem. Ser. Two"; Bawn, C. E. H . , Ed.; B u t t e r w o r t h s , 8, 153 (1975). Saegusa, T. Makromol. Chem. 1974, 175, 1199. Saegusa, T.; K o b a y s h i , S.; Yamada, A. Makromol. Chem. 1976, 177, 2271. Saegusa, T.; Kobayashi, S. " E n c y c l . Polym. Sci. T e c h n o l . , S u p p l . " ; Mark, H. F . , Bikales, N. M . , Eds.; W i l e y : 1976; Vol. 1, p. 220. Smith, S.; Hubin, A. J.; J . Macromol. Sci.-Chem. 1973, A - 7 , 1399. Smith, S.; S c h u l t z , W. J.; Newmark, R. A. In "Ring-Opening P o l y m e r i z a t i o n " ; Saegusa, T.; G o e t h a l s , E. J., Eds.; ACS SYMPOSIUM SERIES No. 59, A m e r i c a n C h e m i c a l Society: Washington, D.C., 1977; p. 13. C r i v e l l o , J. V. CHEMTECH 1980, 624. Crivello, J. V . ; Lam, H. J. W. Macromolecules 1977, 10, 1307. Crivello, J . V . ; Lam, H. J. W. J. Polym. Sci. Symp. 1976, 56, 383. Crivello, J . V . ; Lam, H. J. W. J. Polym. Sci. Chem. Ed. 1979, 17, 977. Crivello, J . V . ; Lam, H. J. W. J. Polym. Sci. Polym. L e t t . Ed. 1979, 17, 759. Crivello, J. V . ; Lam, H. J. W. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 2677. I b i d . , 2697. I b i d . , 1047. I b i d . , 2877. I b i d . , 1021. I b i d . , 1059. I b i d . , 2441. Crivello, J. V . ; Lam. H. J. W. Macromolecules 1981, 14, 1141. Ledwith, A. Polym. Prepr. 1982, 23(1), 323. Ledwith, A. Ann. N . Y . Acad. Sci. 1969, 155(2), 482. Ledwith, A. Acc. Chem. Res. 1972, 5, 133. Ledwith, A. Polymer 1978, 19, 1217. A b d u l - R a s o u l , F. A. M . ; L e d w i t h , A . ; Y a g c i , Y. Polymer 1978, 19, 1219.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

126

73. 74. 75. 76. 77.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 105. 106. 107.

Burgess, F. J.; Cunliffe, A. V . ; R i c h a r d s , D. H . ; S h e r r i n g t o n , D. C. J. Polym. Sci. Polym. L e t t . Ed. 1976, 14, 471. Burgess, F. J.; Cunliffe, A. V . ; Dawkins, J. V . ; R i c h a r d s , D. H. Polymer 1977, 18, 733. Burgess, F . J.; Richards, D. H. Polymer 1976, 17, 1020. Matyjaszewski, K.; Penczek, S. J. Polym. Sci. Polym. Chem. Ed. 1974, 1 2 , 1905. M a t y j a s z e w s k i , K.; B r z e z i n s k a , K.; Penczek, S. IUPAC I n t . Symp. Macromol., Strasbourg; Preprints, V o l . I , p. 260, 1981. Lapienis, G . ; Penczek, S. Macromolecules 1974, 7, 166. Goethals, E. J.; D r i j v e r s , W. Makromol. Chem. 1973, 165, 329. G o e t h a l s , E. J.; Schacht, E. H. J. Polym. Sci. Polym. L e t t . Ed. 1973, 11, 497. Goethals, E . J. J. Polym. Sci. Polym. Symp. 1976, 56, 271. Saegusa, T.; Matsumoto, S. J. Polym. Sci. P a r t A-1 1968, 6, 1559. B r z e z i n s k a , K.; Chwialkowska, W.; K u b i s a , P.; M a t y j a s z e w s k i , K.; Penczek, S. Makromol. Chem. 1977, 178, 2491. Dreyfuss, P . ; Dreyfuss, P. M. Polym. J. 1976, 8, 81. Black, P. E.; Worfold, D. J. Can. J. Chem. 1976, 54, 3325. Bucquoye, M . ; Goethals, E. J.Makromol. Chem. 1978, 179, 1681. Goethals, E. J. Adv. Polym. Sci. 1977, 23, 103. J a a c k s , V. ADVANCES IN CHEMISTRY SERIES No. 91, American Chemical Society: Washington, D.C., 1969; p. 371. G o e t h a l s , E. J.; M u n i r , A.; Bossaer, P. Pure A p p l . Chem. 1981, 53, 1753. Lapienis, G.; Penczek, S. Macromolecules 1977, 10, 1301. Percec, V. Polym. Bull. 1981, 5, 651. Dreyfuss, P.; Dreyfuss, P. M. Adv. Polym. Sci. 1967, 4, 528. Brzezinska, K.; Matyjaszewski, K.; Penczek, S. Makromol. Chem. 1978, 179, 2387. Penczek, S.; Kubisa, P. ACS SYMPOSIUM SERIES No. 59, American Chemical Society: Washington, D.C., 1977; p. 60. K u b i s a , P.; Penczek, S. Makromol. Chem. 1978, 179, 445. Uryn, T.; I t o , K.; Kobayashi, K. I.; M a t s u z a k i , K. Makromol. Chem. 1979, 180, 1509. Schuerch, C. Adv. Polym. Sci. 1972, 10, 173. Schuerch, C. Acc. Chem. Res. 1973, 6, 184. Schuerch, C. " E n c y c l . Polym. Sci. T e c h n o l . , S u p p l . " ; Vol. 1, 1976, p. 510. Schuerch, C. Adv. Carbohydr. Chem. Biochem. 1981, 39, 157. K o s i n s k i , P.; Penczek, S. IUPAC I n t e r n . Symp. Macromol., S t r a s b o u r g , 1981, Vol. I , p. 279. Penczek, S. In "Phosphorus Chemistry D i r e c t e d Towards B i o l o g y " ; S t e c , W. J., Ed.; Pergamon P r e s s : Oxford and New York, 1980; p. 133. Sumitomo, H . ; Okada, M Adv. Polym. Sci. 1978, 28, 47. Yokoyama, Y . ; Hall, H. K., Jr.; Adv. Polym. Sci. 1982, 42, 107. S c h u l z , R. C.; A l b r e c h t , K.; T h i , Q. V. T.; Nienburg, J . ; E n g e l , D. Polym. J. 1980, 12, 639. S c h u l z , R. C.; A l b r e c h t , K.; H e l l e r m a n n , W.; Kane, A . ; Thi, Q. V. T. Pure A p p l . Chem. 1981, 53, 1763. H e l l e r m a n n , W.; S c h u l z , R. C. Makromol. Chem., Rapid Commun. 1981, 2, 585.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

108. 109.

110. 111. 112.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

113. 114. 115. 116. 117. 118. 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135.

Recent Developments in Cationic Polymerization

127

Kops, J . ; H v i l s t e d , S.; Spanggaard, H. Pure Appl. Chem. 1981, 53, 1777. B a i l e y , W. J.; Sun, R. L.; K a t s u k i , H.; Endo, T.; Iwama, H . ; Tsushima, R.; S a i g o u , K.; Bitritto, M. M. ACS SYMPOSIUM SERIES No. 59, American Chemical Society: Washington, D.C., 1977; p. 38. Endo, T.; Okawara, M . ; Bailey, W. J. Polym. J. 1981, 13, 715. Trathnigy, B.; Hippmann, G. Angew. Makromol. Chem. 1982, 105, 9. Saegusa, T; Kobayashi, T.; Kobayashi, S.; Couchman, S. L.; V o g l , O. Polym. J. 1979, 11, 463. Vogl, 0 . ; Muggel, J.; Bansleben, D. Polym. J. 1980, 12, 677. Okada, M . ; Sumimoto, H.; Kakezawa, T. Makromol. Chem. 1972, 162, 285. Dreyfuss, P.; Kennedy, J. P. J. Polym. Sci. Polym. Lett. Ed. 1976, 14, 135. I b i d . , 139. Dreyfuss, P.; Kennedy, J . P. J. Polym. Sci. Symp. 1976, 56, 129. Lee, K. I . ; Dreyfuss, P. ACS SYMPOSIUM SERIES No. 59, American Chemical Society: Washington, D.C., 1977; p. 24. Adaway, P. D. T; Kennedy, J . P. J. Appl. P o l y m . Sci., Polym. Symp. 1977, 30, 183. E c k s t e i n , Y . ; Dreyfuss, P. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 1799. E c k s t e i n , Y . ; Dreyfuss, P. J. I n o r g . N u c l . Chem. 1981, 43, 23. E c k s t e i n , Y . ; Dreyfuss, P. J. Polym. Sci. Polym. Chem. Ed. 1979, 17, 4115. Seung, N . ; F e t t e r s , L . J.; Dreyfuss, P. IUPAC I n t . Symp. Macromol., Strasbourg, 1981; V o l . I , p. 245. Lee, D. P.; Dreyfuss, P. J . Polym. Sci. Polym. Chem. Ed. 1980, 18, 1627. E c k s t e i n , Y . ; Lee, D. P.; Q u i r k , R. P.; Dreyfuss, P. Polym. S c i . Polym. Chem. Ed. 1980, 18, 2021. F r a n t a , E . ; Taromi, F. A . ; Rempp, P. Makromol. Chem. 1976, 177, 2191. Dreyfuss, P.; Kennedy, J. P. J. A p p l . Polym. Sci. Symp. 1977, 30, 153. I b i d . , 165. I b i d . , 179. Saegusa, T.; Matsumoto, S.; Hashimot, Y. Polym. J. 1970, 1, 31. Saegusa, T.; Kobayashi, S.; Yamada, A. M a c r o m o l e c u l e s 1975, 8, 390. Simionescu, C. I . ; Denes, F . ; Percec, V . ; Totolin, M . ; Kennedy, J. P. IUPAC I n t . Symp. Macromol., S t r a s b o u r g , 1981; Vol. I . , p. 298. Saegusa, T.; Yamada, A . ; Kobayashi, S. Polym. J. 1978, 11, 53. Trivedi, P. D.; S c h u l z , D. N. Polym. Bull. 1980, 3, 37. Dondos, A.; L u t z , P.; R e i b e l , L . ; Rempp, P.; F r a n t a , E. Makromol. Chem. 1978, 179, 2549. Cunliffe, A. V . ; Hartley, D. B . ; K i n g s t o n , S. B . ; R i c h a r d s , D. H . ; Thompson, D. Polymer 1981, 22, 101.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

A P P L I E D P O L Y M E R SCIENCE

128

136. 137. 138. 139.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

140. 141. 142. 143. 144. 145. 146. 147. 148. 149. 150. 151. 152. 153. 154. 155. 156. 157. 158. 159. 160. 161. 162. 163. 164. 165. 166. 167. 168. 169. 170. 171.

Chwialkowska, W.; K u b i s a , P.; Penczek, S. Makromol. Chem. 1982, 183, 753. Litt, M . ; Herz, J. Polym. Prepr. 1969, 20(2) 905. Litt, M . ; Matsuda, T ADVANCED CHEMISTRY SERIES No. 142; Platzer, N. A. J., E d . ; A m e r i c a n C h e m i c a l Society: Washington, D.C., 1975; p. 321. Bossar, P. K.; G o e t h a l s , E. J.; Hackett, P. J.; Pepper, D. C. Eur. Polym. J. 1977, 13, 489. Saegusa, T . ; Ikeda, H. Macromolecules 1973, 6, 805. Percec, V. Polym. Bull. 1981, 5, 643. Percec, V. Polym. Prepr. 1982, 23(1), 301. Percec, V . ; G u h a n i y o g i , S. C.; Kennedy, J . P.; I v a n , B. Polym. Bull. 1982, 8, 25. Seung, S. L. N . ; Young, R. N. J. Polym. Sci. Polym. Lett. Ed. 1979, 17, 233. Seung, S. L . N . ; Young, R. N. Polym. Bull. 1979, 1, 481. Seung, S. L. N . ; Young, R. N. J. Polym. Sci. Polym. Lett. Ed. 1980, 18, 89. Morishima, Y.; Tanaka, T.; Nozakura, S. Polym. Bull. 1981, 5, 19. Abadie, M. J. M . ; Schue, F . ; S o u e l , T.; H a r t l e y , D. B . ; R i c h a r d s , D. H. Polymer 1982, 23, 445. Simonds, R. P.; G o e t h a l s , E. J.; Spassky, N Makromol. Chem. 1978, 179, 1851. Takahashi, A.; Yamashita, Y. Polym. P r e p r . 1974, 15.(1), 184. Y a m a s h i t a , Y . ; N o b u t o k i , K . ; Nakamura, Y . , Hirota, H. Macromolecules 1971, 4, 548. R i c h a r d s , D. H.; K i n g s t o n , S. B . ; S o n e l , T. Polymer 1978, 19, 68. I b i d . , 806. Berger, G.; L e v y , M . ; Vofsi, D. J. Polym. Sci., P a r t B 1966, 4, 183. Yamashita, Y. Adv. Polym. Sci. 1978, 28, 1. Feger, C.; Cantow, H. J. Polym. Bull. 1980, 3, 407. I b i d . , 1982, 6, 321. Kennedy, J. P.; M a r e c h a l , E. J. Polym. Sci. Macromol. Rev. 1981, 16, 123. Lyerla, J . R.; Y a n n o n i , C. S.; B r u c k , D . ; F y f e , C. A. J. Am. Chem. Soc. 1979, 101, 4770. Stannett, V. T. Pure Appl. Chem. 1981, 53, 673. Sawamoto, M . ; Higashimura, T. Polym. Prepr. 1979, 20, 727. Sawamoto, M . ; Higashimura, T. Macromolecules 1978, 11, 328. Kennedy, J. P. J. Polym. Sci. Symp. 1976, 56, 1. Kennedy, J. P. J. Appl. Polym. Sci. Symp. 1977, 30. Kennedy, J. P. Polym. J. 1980, 12, 609. Kennedy, J. P . ; Smith, R. A. Polym. Prepr. 1979, 20, 316. Kennedy, J. P.; Smith, R. A. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 1523. Wondraczek, R. H.; Kennedy, J . P.; S t o r e y , R. F. J. Polym. Sci. Polym. Chem. Ed. 1982, 20, 43. Chang, V. S. C.; Kennedy, J. P.; I v a n , B. Polym. Bull. 1980, 3, 339. Chang, V. S. C.; Kennedy, J. P. Polym. Bull. 1980, 4, 513. Kennedy, J. P . ; R o s s , L . R.; L a c k e y , J. E . ; N u y k e n , O. Polym. Bull. 1981, 4, 67.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

5.

PERCEC

172. 173. 174. 175. 176. 177. 178.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

179. 180. 181. 182. 183. 184. 185. 186. 187. 188. 189. 190. 191. 192. 193. 194. 195. 196. 197. 198. 199. 200. 201. 202. 203. 204.

Recent Developments in Cationic Polymerization

129

Kennedy, J. P.; Ross, L. R.; Nuyken, O. Polym. Bull. 1981, 5, 5. Sawamoto, M . ; Kennedy, J. P. Polym. P r e p r . 1981, 22(2), 140. Kennedy, J. P . ; Chou, R. T. Polym. Prepr. 1979, 20, 306. G u h a n i y o g i , S. C.; Kennedy, J. P. Polym. Bull. 1981, 4, 267. M a n l i s , J . M . ; C o l l o m b , J.; G a n d i n i , A . ; Cheradame, H. Polym. Bull. 1980, 3, 197. Kennedy, J. P.; Smith, R. A. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 1539. Kennedy, J . P.; Huang, S. Y . ; Smith, R. A. J. Macromol. Sci. Chem. 1980, A17, 1085. Rooney, J . M.; S q u i r e , D. R.; S t a n n e t t , V. T. J . Polym. S c i . Polym. Chem. Ed. 1976, 14, 1877. Higashimura, T.; Mitsuhashi, M.; Sawamoto, M. Macromolecules 1979, 12, 178. Higashimura, T.; T e r a n i s h i , H.; Sawamoto, M. M a c r o m o l e c u l e s 1980, 12, 393. Giusti, P. Polym. J. 1980, 12, 555. Vidal, A . ; Donnet, J . B . ; Kennedy, J . P. J . Polym. Sci. Polym. L e t t . Ed. 1977, 15, 585. Denes, F . ; P e r c e c , V . ; Totolin, M . ; Kennedy, J . P. Polym. Bull. 1980, 2, 499. Vidal, A . ; Guyot, A.; Kennedy, J. P. Polym. Bull. 1980, 2, 315. Vidal, A.; Guyot, A . ; Kennedy, J . P. IUPAC I n t e r n . Symp. Macromol., Strasbourg, 1981; Prepr. V o l . I , p. 303. M u n i r , A . ; G o e t h a l s , E. J. Macromol. Chem., Rapid Commun. 1981, 2, 693. M u n i r , A.; G o e t h a l s , E. J. IUPAC I n t . Symp. Macromol., Strasbourg, 1981; Prepr. V o l . I. 299. Kennedy, J. P. J. Macromol. Sci. Chem. 1979, A13, 695. Kennedy, J . P.; Chang, V. S. C.; Smith, R. A . ; I v a n , B. Polym. Bull. 1979, 1, 575. I v a n , B . ; Kennedy, J . P.; Chang, V. S. C. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 3177. L i a o , T. P . ; Kennedy, J. P. Polym. B u l l 1981, 5, 11. P e r c e c , V . ; G u h a n i y o g i , S. C.; Kennedy, J . P. Polym. Bull. 1982, 8, 319. Chang, V. S. C . ; Kennedy, J. P. Polym. Bull. 1981, 5, 379. Kennedy, J. P.; Chang, V. S. C.; Guyot, A. Adv. Polym. Sci. 1982, 43, 1. L i a o , T. P . ; Kennedy, J. P. Polym. Bull. 1981, 6, 135. Wondraczek, R. H . ; Kennedy, J. P. Polym. Bull. 1981, 4, 445. Percec, V . ; G u h a n i y o g i , S. C.; Kennedy, J . P. Polym. Bull. 1983, 9, 27. P e r c e c , V . ; Kennedy, J. P. Polym. Bull. 1983, 9, 570. I b i d . , 10, 31. Kennedy, J. P.; G u h a n i y o g i , S. C.; P e r c e c , V. Polym. Bull. 1982, 8, 563; ibidem, Polym. Bull. 1982, 8, 571. K r e s s , H. J.; H e i t z , W. Makromol. Chem., Rapid Commun. 1981, 2, 427. M i l k o v i c h , R. Polym. Prepr. 1980, 21(1), 40. Yamashita, Y. J. Appl. Polym. Sci., Symp. 1981, 36, 193. Rempp, P.; Masson, P.; Vargas, J . S.; F r a n t a , E. P l a s t e Kautsch. 1981, 28, 365. Saegusa, T. Topics Curr. Chem. 1982, 100, 75.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

130

205. 206. 207. 208. 209.

Downloaded by UNIV OF ARIZONA on May 18, 2013 | http://pubs.acs.org Publication Date: September 25, 1985 | doi: 10.1021/bk-1985-0285.ch005

210. 211. 212. 213. 214. 215. 216. 217. 218. 219.

APPLIED POLYMER SCIENCE

Kennedy, J . P . ; Frisch, Κ. C., Jr.; IUPAC I n t . Symp. Macromol., Florence, 1980; Preprints, V o l . 2, p. 162. Sierra-Vargas, J.; Zilliox, J . G.; Rempp, P.; F r a n t a , E. Polym. Bull. 1980, 3, 83. S i e r r a - V a r g a s , J . ; F r a n t a , E . ; Rempp, P. Makromol. Chem. 1981, 182, 2603. Masson, R.; S i e r r a - V a r g a s , J.; F r a n t a , E . ; Rempp, P. IUPAC Int. Symp. Macromol., Strasbourg, 1981; Preprints, V o l . I , p. 235. Asami, R.; T a k a k i , T.; Kita, K.; Asakura, E. Polym. Bull. 1980, 2, 713. Asami, R.; T a k a k i , M. IUPAC I n t e r n a t . Symp. Macromol., Strasbourg, 1981; Preprints, V o l . I , p. 240. Goethals, E . J. V l e g e l s , M. A. Polym. Bull. 1981, 4, 521. "Cationic Polymerization and Related Processes"; Goethals, E. J., Ed.; Academic P r e s s : London, 1984. Szymanski, R.; K u b i s a , P.; Penczek, S. M a c r o m o l e c u l e s 1983, 16, 1000. C r i v e l l o , J. V. Adv. Polym. Sci. 1984, 62, 1. Higashimura, T . ; Sawamoto, M. Adv. Polym. Sci. 1984, 62, 49. Rempp, P . ; Franta, E . Adv. Polym. Sci. 1984, 58, 1. Kennedy, J. P. Makromol. Chem., Suppl. 1984, 1, 171. Kennedy, J. P., et al. J. Macromol. Sci. Chem. 1982, A18(1), 3. Kennedy, J . P., et al. J . Macromol. Sci. Chem. 1982-83, A18(9), 1185.

In Applied Polymer Science; Tess, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.