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11 The Composition and Sequence Distribution of Dichlorocarbene-Modified Polybutadiene by C NMR 13

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Downloaded by CORNELL UNIV on May 7, 2017 | http://pubs.acs.org Publication Date: March 28, 1984 | doi: 10.1021/bk-1984-0247.ch011

CHARLES J. CARMAN, RICHARD A. KOMOROSKI, and SAMUEL E. HORNE, JR. The B.F. Goodrich Research and Development Center, Brecksville, OH 44141

Carbon-13 NMR i s being used to characterize the microstructure of a variety of chlorine-containing polymers. Among these are homopolymers, copolymers, and chemically modified polymers. In the last category i s the series of polymers obtained by addition of dichlorocarbene to the double bonds of polybutadiene. Here we use C NMR to examine a number of dichlorocarbene adducts of c i s - and trans-polybutadiene prepared i n a two phase system with phase transfer catalysis. Monomer compositions, comonomer sequence lengths, and stereochemical information are obtained for the resulting polymers. The polymers examined here were stereochemically pure and were treated as simple copolymers. Samples prepared using aqueous NaOH, CHCl and phase transfer catalyst can be described as essentially random copolymers over the entire range of monomer composition. Samples prepared using s o l i d instead of aqueous a l k a l i metal hydroxides contain a higher fraction of blocked units than a polymer of comparable composition prepared using aqueous NaOH. This blockiness can coincide with the presence of two glass transition temperatures and a two-phase morphology. Fractionation of a substantiall y blocked sample yielded a chlorine-poor fraction which was a random copolymer and a chlorine-rich fraction which was more blocked than the o r i g i n a l unfractionated material. 13

3

Portions of this work are reprinted from: R. A. Komoroski, S. E. Home, Jr., and C. J. Carmen, J. Polym. Sci, Polym. Chem. Ed, 21, 89 (1983), copyright 1983, John Wiley and Sons, Inc. Reprinted by permission of John Wiley and Sons, Inc. 1

Current address: Polysar, Inc., Stow, O H 44224. 0097 6156/84/0247 0167S06.00/0 © 1984 American Chemical Society Randall; NMR and Macromolecules ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

168

NMR AND

MACROMOLECULES

1 3

C NMR has long been the technique of choice f o r the c h a r a c t e r i z a t i o n of the molecular s t r u c t u r e of homopolymers and copolymers (1) . Recently, i t has been used with success to study c h l o r i n e containing polymers and copolymers (1-6). Among these are p o l y ( v i n y l c h l o r i d e ) (PVC) and various copolymers of v i n y l c h l o r ide and other monomers both with and without c h l o r i n e . I t has also proven to be powerful f o r c h a r a c t e r i z i n g modified polymers, i n p a r t i c u l a r the products obtained from c h l o r i n a t i o n of polyvinyl c h l o r i d e ) (7,8) and polyethylene (9). Although both c h l o r i n a t e d PVC and c h l o r i n a t e d polyethylene are simple i n t h e i r basic composition, c o n s i s t i n g predominantly of CC1 , C H C 1 , and Ch*2 groups, the many p o s s i b l e arrangements of these groups produce very complex macromolecules. Both sequence d i s t r i b u t i o n and CHC1 c o n f i g u r a t i o n must be considered. A more simple modified polymer i s c h a r a c t e r i z e d i n t h i s report. Dichlorocarbene, :CC1 , generated i n s i t u , can add to polydienes to produce novel polymer containing d i c h l o r o c y c l o p r o pane rings at the points of a d d i t i o n (10-13). The r e a c t i o n i s i l l u s t r a t e d below f o r cis-polybutadiene.


2

2

CI

CI

Polymers with a r e l a t i v e l y broad range of p h y s i c a l p r o p e r t i e s can be prepared by varying the extent of r e a c t i o n and hence c h l o r i n e content. These modified polymers can be viewed as a s e r i e s of copolymers of varying comonomer composition and treated as such with regard to sequence d i s t r i b u t i o n . We have examined the m i c r o s t r u c t u r e of a number of d i c h l o r o carbene adducts of both c i s - and trans-polybutadiene using C NMR spectroscopy. Samples were prepared i n a two phase system where dichlorocarbene was generated by the r e a c t i o n of e i t h e r concentrated aqueous or s o l i d a l k a l i metal hydroxide with chloroform i n the presence of a phase t r a n s f e r c a t a l y s t (14). Monomer compositions and sequence lengths were obtained as f o r true copolymers and were c o r r e l a t e d with g l a s s t r a n s i t i o n temperature and phase morphology. 1 3

Results In Table I are some p e r t i n e n t data f o r a number of dichlorocarbene adducts of c i s - and trans-polybutadiene. Figure 1 shows the C NMR spectra of three cis-polybutadiene-based adducts having widely d i f f e r e n t c h l o r i n e contents. At low percent CI, i . e . low extent of r e a c t i o n , the spectrum i s e s s e n t i a l l y that of cis-polybutadiene (15) with some a d d i t i o n a l smaller resonances due to the presence of modified butadiene units (Figure 1A). With i n c r e a s i n g c h l o r i n e content, these a d d i t i o n a l resonances grow r e l a t i v e to those due to 1 3

Randall; NMR and Macromolecules ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

11.

Dichlorocarbene-Modified

CARMAN ETAL.

169

Polybutadiene

Table I . Glass T r a n s i t i o n Temperatures, Compositions, and R e a c t i o n C o n d i t i o n s o f Some D i c h l o r o c a r b e n e A d d u c t s o f C i s - a n d Trans- Polybutadiene


Sample 1 2 3 4 5 6 7 8 8 A

d 8B 9 10 11 12 13

d

e

e

8

Tg ( « C )

1

-85 -93 -41 -31 -5 31 57 -78, 50 45 -76 -61 -89 -68 -56 - 3 1 , -19

Weight % CI Chemical NMR Analysis 15.,0 14..8 33 37.,8 42..1 47 51. .2 33. .9 41..9 22..0 17,.4 16 .0 31 .3

15,,9 16.,3 32.,5 39..4 43. Λ 48..0 51..2 33..6 43. .3 22,.7 25,.1 19 .0 30 .4 17 .4 31 .3

% RDB 14. 9 15.,4 40. 0 55,,8 67.,2 83. .5 97.,1 42..2 66..8 23. .6 27..1 18,.6 35,.9 16 .7 37 .7

Reaction ^ Conditions 5 0 % aqueous NaOH s o l i d NaOH 5 0 % aqueous NaOH If tf ft

s o l i d NaOH s o l i d KOH tt tt

5 0 % aqueous KOH s o l i d C OH s o l i d RS0H 5 0 % aqueous NaOH tf

a) b) c) d) e) f)

S c h o n i g e r o x y g e n f l a s k method. s e e r e f e r e n c e 14. a c e t o n e - s o l u b l e f r a c t i o n o f sample 8. a c e t o n e - i n s o l u b l e f r a c t i o n o f sample 8. Adducts o f trans-polybutadiene. M e a s u r e d u s i n g a P e r k i n E l m e r DSC-2 d i f f e r e n t i a l s c a n n i n g calorimeter. g) The s t a r t i n g p o l y m e r s were >98% c i s - o r t r a n s - p o l y b u t a d i e n e .


NMR AND MACROMOLECULES

JL Downloaded by CORNELL UNIV on May 7, 2017 | http://pubs.acs.org Publication Date: March 28, 1984 | doi: 10.1021/bk-1984-0247.ch011

u

J

L

JAUJL L

140

130

120

_L

no

100

90

80 ppm

60

70

50

40

30

20

F i g u r e 1. C a r b o n - 1 3 NMR s p e c t r a o f t h r e e d i c h l o r o c a r b e n e m o d i f i e d c i s - p o l y b u t a d i e n e s i n C D C 1 ; (A) Sample 2, 15.4% o f d o u b l e bonds r e a c t e d ; (B) Sample 5, 6 7 . 2 % o f d o u b l e bonds r e a c t e d ; (C) Sample 7, 9 7 . 1 % o f d o u b l e bonds r e a c t e d . ( R e p r o d u c e d w i t h p e r m i s s i o n f r o m R e f . 16.) 3


11.

C A R M A N ET A L .


171

Polybutadiene

the cis-polybutadiene (Figure I B ) . When a l l double bonds have reacted, the spectrum i n Figure 1C i s obtained. Peak assignments were made f o r the spectra i n Figure 1 on the basis of model compounds (Table I I ) , substituent e f f e c t s , s i n g l e frequency off-resonance decoupling, and peak i n t e n s i t i e s . The r e l a t i v e l y large a- and β-substitutent e f f e c t s f o r chlorine produce C NMR spectra of c h l o r i n a t e d polymers that can span the range from 25 to 100 ppm. Substituent e f f e c t s on the C s h i f t of the c e n t r a l carbon are given below f o r c h l o r i n e s u b s t i t u t i o n at various locations. Substituent e f f e c t s due to v i c i n a l l y or germinally s u b s t i t u t e d 1 3


1 3

±0.5 CI

+9.0 CI

-3.2 CI

C - C - C - C - C - C - C t CI +34.0 chlorines are not a d d i t i v e , a feature which can sometimes compli cate assignments f o r h i g h l y c h l o r i n a t e d polymers (8). I t i s i n t e r e s t i n g to note that the CC1 carbon i n the small molecular weight models (Table II) and the polybutadiene adducts occurs about 20 ppm u p f i e l d of i t s usual p o s i t i o n (5). This i s due to i t s occurrence i n a cyclopropyl r i n g . Our assignments f o r the cis-adducts are i n Figure 2. A table of chemical s h i f t s and assignments f o r both the c i s and trans-adducts has been given elsewhere (16). The m u l t i p l e resonances observed f o r carbons of a given f u n c t i o n a l i t y i n d i c a t e that the C NMR chemical s h i f t s are s e n s i t i v e to the sequence d i s t r i b u t i o n of monomer u n i t s . From the changes i n the i n t e n s i t i e s of the various peaks with changing extent of r e a c t i o n , we have assigned peaks to copolymer t r i a d structures such as those i n Figure 3 . The CC1 carbon i s s e n s i t i v e to t r i a d s t r u c t u r e s , while the vinylene CH of the diene u n i t and the CH carbon of the dichlorocyclopropane u n i t i s s e n s i t i v e to dyads. The CH carbon of the dichlorocyclopropane u n i t d i s p l a y s no s e n s i t i v i t y to sequence d i s t r i b u t i o n under the present condi tions . 2

1 3

2

2

Discussion Isomerization during the course of the dichlorocarbene modifica t i o n of polybutadienes i s a p o t e n t i a l concern. Isomerization i s p o s s i b l e i n both the unreacted butadiene p o r t i o n and the c h l o r i n e containing p o r t i o n . Although the a d d i t i o n of dichlorocarbene to double bonds i s know to be s t e r e o s p e c i f i c and syn, (17) i t i s p o s s i b l e that small amounts of t r a n s - s u b s t i t u t e d cyclopropyl groups might be present i n the modified c i s polymer. We saw no a d d i t i o n a l resonances suggestive of mixed stereochemistry of the cyclopropyl group i n e i t h e r the c i s - or trans-adducts. The C 1 3


172

NMR A N D MACROMOLECULES

Table I I .

1 3

C NMR Chemical S h i f t s of Some Model Compounds

Compound

θ (ppm)

Carbon

67.4 25.9 19.0 20.4

3 CI CI


CI

CI 1 2

νΟΦν CI

CI

CH - C H

72.3 31.9,32.2 (mixture o f isomers)

CI 89.7

CClc

- C - C H - CH I CI (vinyl chloride-vinylidene c h l o r i d e copolymer) (5) 2

2

r

r

CH (AAA),CH (4)(AAB) 2

2

CH(ABA,BBA,BBB)-y

= CH(AAA,BAA)

CCI

2

ppm 1 3

F i g u r e 2. C NMR p e a k a s s i g n m e n t s f o r t h e d i c h l o r o c a r b e n e adducts o f c i s - polybutadiene.


11.

C A R M A N ET AL.


Polybutadiene

173

spectrum f o r the m o d i f i e d t r a n s - p o l y b u t a d i e n e i s s u f f i c i e n t l y different from t h a t of m o d i f i e d c i s - p o l y b u t a d i e n e t h a t each s t r u c t u r e can be d e t e c t e d s e p a r a t e l y i n a c o p o l y m e r ( 1 6 ) . A l though the C s p e c t r u m o f t r a n s - p o l y b u t a d i e n e homopolymer o v e r l a p s w i t h t h a t o f t h e m o d i f i e d c i s - p o l y b u t a d i e n e , r e l a t i v e peak a r e a s i n d i c a t e t h a t l i t t l e , i f any, t r a n s - p o l y b u t a d i e n e i s p r e s e n t (16). R e a c t i o n o f an e m u l s i o n p o l y b u t a d i e n e containing c i s , t r a n s , and v i n y l groups y i e l d s a C NMR s p e c t r u m t h a t i s much more c o m p l i c a t e d t h a n t h a t o f e i t h e r t h e t o t a l l y c i s o r t r a n s a d d u c t s , even when t h e p r e s e n c e o f v i n y l groups i s t a k e n i n t o account. We can o b t a i n monomer c o m p o s i t i o n and w e i g h t p e r c e n t CI f r o m t h e C s p e c t r a u s i n g t h e a s s i g n m e n t s i n F i g u r e 2. The amount o f r e a c t e d d o u b l e b o n d s , % RDB, i s g i v e n by t h e f o r m u l a 1 3

1 3


1 3

% RDB

=

h

A (CH, 32.4

A (CH, 32.4 pgn) ppm) + A ( a l l v i n y l e n e

1 0 0

(1)

CH)

The A terms a r e t h e a r e a s o f t h e NMR p e a k s . T a b l e I shows t h e v a l u e s f o r % RDB, as c a l c u l a t e d u s i n g C NMR d a t a . Values f o r w e i g h t % c h l o r i n e c a l c u l a t e d from NMR a r e a l s o g i v e n i n T a b l e I and a r e compared t o t h e c o r r e s p o n d i n g v a l u e s o b t a i n e d by t h e Schdniger method. Agreement between % c h l o r i n e by chemical a n a l y s i s and by NMR r a n g e s from f a i r t o e x c e l l e n t , d e p e n d i n g on sample. A number o f f a c t o r s a f f e c t s t h e a c c u r a c y and p r e c i s i o n o f q u a n t i t a t i v e FT NMR measurements o f c o m p o s i t i o n . Among t h e s e a r e signal-to-noise ratio, digitization of the frequency domain spectrum, p u l s e r e p e t i t i o n r a t e , the n u c l e a r Overhauser e f f e c t (NOE), and s p e c t r a l r e s o l u t i o n . The s i g n a l - t o - n o i s e r a t i o , t h e NOE, s p e c t r a l r e s o l u t i o n , and s p e c t r u m d i g i t i z a t i o n may be f a c t o r s t h a t reduce the accuracy of the c o m p o s i t i o n r e s u l t s . The low s i g n a l - t o - n o i s e r a t i o o f some o f t h e s p e c t r a i s p r o b a b l y a m a j o r f a c t o r , p a r t i c u l a r l y a t low e x t e n t o f r e a c t i o n . Differential NOE's and s h o r t p u l s e r e p e t i t i o n r a t e s can be m a j o r f a c t o r s when c a l c u l a t i o n s r e l y on a r e a s o r i n t e n s i t i e s o f b o t h p r o t o n a t e d and nonprotonated carbons (18). For example, the area of the CC1 p e a k o f sample 7 ( F i g u r e 1C) i s o n l y 5 7 % o f t h a t e x p e c t e d , b a s e d on t h e a r e a s o f t h e CH and CH c a r b o n p e a k s . The p u l s e r e p e t i t i o n r a t e used here w i l l not s i g n i f i c a n t l y a f f e c t the accuracy of the r e s u l t s i n T a b l e I s i n c e none o f o u r q u a n t i t a t i v e r e s u l t s r e l y on c o m p a r i s o n s o f p r o t o n a t e d and n o n p r o t o n a t e d c a r b o n a r e a s . Number-average sequence l e n g t h s f o r b o t h t h e d i c h l o r o c y c l o p r o p a n e and t h e c i s - b u t a d i e n e u n i t s can be c a l c u l a t e d from t h e C d a t a u s i n g t h e a s s i g n m e n t s i n F i g u r e 2 and s t a n d a r d e q u a t i o n s . F o r t h e c h l o r i n e - c o n t a i n i n g u n i t s (Β), n^ can be o b t a i n e d f r o m dyad c o n c e n t r a t i o n s u s i n g (I) 1 3

2

2

1 3

B

n

N =

BB

N

* ** B A \ N M

=

A(24.1 ppm

+ 24.2 ppm) + A ( 2 5 . 0 ppm) A(25.0 ppm)


(2)

174

NMR

H e r e N_._ where

and

Ν

are

A

N

Œ

BB

the

A

(

2

concentrations

4

*

1

PP

ra

+

V a l u e s f o r n ^ c a n a l s o be o b t a i n e d the CC1 resonance ( 1 ) .

2

4

·

2

AND

of the

M A C R O M O L E C U L E S

designated

Ppm)

from t r i a d c o n c e n t r a t i o n s

dyads,

(3) using

2

B


n

- K 6 5 . 6 npm) + 1 ( 6 5 . 3 ppm) + 1(65.0 ppm) 1(65.6 ppm) + \ I (65.3 ppm)

(4)

Peak i n t e n s i t i e s ( I ) were u s e d f o r t r i a d c o n c e n t r a t i o n s s i n c e t h e y were more e a s i l y and a c c u r a t e l y measured t h a n t h e c o r r e s p o n d i n g areas i n t h i s p a r t i c u l a r case. An e q u a t i o n ( E q u a t i o n 5) a n a l o g o u s t o 2 was u s e d f o r b u t a d i e n e sequence l e n g t h s . A

=

n

A ( 2 7 . 4 ppm) + A ( 2 6 . 3 ppm) A ( 2 6 . 3 ppm)

(5)

The s e q u e n c e l e n g t h s o f b o t h t h e d i c h l o r o c y c l o p r o p y l and t h e butadiene u n i t s f o r the polymers s t u d i e d here are given i n Table III. The agreement b e t w e e n n^ ( d y a d ) and n^ ( t r i a d ) , although good a t low s e q u e n c e l e n g t h s , i s p o o r a t h i g h e r s e q u e n c e l e n g t h s . The c a u s e o f t h i s d i s c r e p a n c y i s n o t known. The s p e c t r a a r e t o o s i m p l e t o a l l o w f o r t h e p r e s e n c e o f a s u b s t a n t i a l amount o f some a d d i t i o n a l s t r u c t u r a l f e a t u r e t h a t c o u l d be r e s p o n s i b l e f o r t h e discrepancy (16). The use o f peak h e i g h t s i n one c a s e and a r e a s i n a n o t h e r c o u l d a c c o u n t f o r t h e l a c k o f good a g r e e m e n t . Another p o s s i b i l i t y i s t h a t a v a r i a t i o n of n u c l e a r Overhauser enhancement i s occurring with composition f o r the peak at 24.1 ppm. T h i s r e s o n a n c e i s due t o C H c a r b o n s o f b o t h end and i n t e r i o r Β u n i t s and t h e o b s e r v e d NOE may change as t h e f r a c t i o n o f l o n g b l o c k s c h a n g e s . A l o w e r NOE m i g h t be e x p e c t e d f o r c a r b o n s i n a l o n g (>3) b l o c k t h a n i n a s h o r t b l o c k on t h e b a s i s o f e x p e c ted chain m o b i l i t y (18). S u c h an o c c u r r e n c e c a n s e v e r e l y c o m p l i c a t e q u a n t i t a t i v e NMR a n a l y s e s . As e x p e c t e d , n^ i n c r e a s e s and n ^ d e c r e a s e s w i t h i n c r e a s i n g e x t e n t o f r e a c t i o n . F o r t h e s a m p l e s p r e p a r e d u s i n g aqueous NaOH, the observed s e q u e n c e l e n g t h s a r e i n r e a s o n a b l e agreement w i t h those expected f o r a random c o p o l y m e r d i s p l a y i n g B e r n o u l l i a n s t a t i s t i c s ( T a b l e I I I ) (_1 ). The random c o p o l y m e r sequence l e n g t h s were c a l c u l a t e d u s i n g E q u a t i o n 6, where Ρ i s t h e mole f r a c t i o n o f dichlorocyclopropane units. 2

β

A

fi

=

1 / P

B

δ

Β

1 / ( 1 =

"V

(6)

F o r t h e o t h e r p o l y m e r s t h e n^ v a l u e s a r e h i g h e r t h a n c a l c u l a t e d u s i n g B e r n o u l l i a n s t a t i s t i c s , i n d i c a t i n g the presence of l a r g e r f r a c t i o n s of blocked d i c h l o r o c y c l o p r o p y l - c o n t a i n i n g u n i t s i n p o l y m e r s n o t p r e p a r e d w i t h aqueous NaOH t h a n i n c o m p a r a b l e p o l y m e r s p r e p a r e d w i t h aqueous NaOH. C o m p a r i s o n o f s a m p l e s 3 and


11.

Cl


I

175

Dichlorocarbene-Modified Polybutadiene

C A R M A N ET AL.

Cl

4

BBA / V_V \2V \=J Y Y ci ci ci ci

\

F i g u r e 3 . Two p o s s i b l e comonomer triads f o r dichlorocarbene-modified cis-polybutadiene. (Reproduced w i t h p e r m i s s i o n f r o m Réf. 16. )

T a b l e I I I . Number-Average Sequence L e n g t h s o f Some Dichlorocarbene Adducts o f C i s - P o l y b u t a d i e n e s

l

e

1 2 3 4 5 6 7 8 8A 8B 9 10 11 12 13 a) b)

A

A

n (dyad) Â

5.8 6.8 2.2 1.8 1.4 1.3

-

2.9 2.0 3.9 3.2 6.0 2.8 6.0 2.4

fi (theor.)b A

6. 7 6 , ,5 2 . .5 1, ,8 1. . 5 1. . 2 1, .0 2. .4 1, . 5 4, .2 3, .7 5. . 4 2 , .8 6 . .0 2, J

n^Idyâd)

ng(triad)

1. . 3 1. .5 1. . 6 2 . .1 2 . .5 5. .3

1. , 2 1. ,8 1. ,8 2 . ,4 3 . ,0 6. . 6

2. .5 3 . .4

3, .3 4 . .9 1, , 3 1, . 5 1, . 8 1, . 8 1 .3 1 .7

1, . 3 1, . 3 1 .4 1 .6 1 .2 1 .6

Adducts of t r a n s - p o l y b u t a d i e n e . Calculated using Bernoullian s t a t i s t i c s

n (theor.)b B

1. , 2 1. . 2 1. J 2 . .3 3 . .0 6 . ,1 34 1, . 7 3 , .0 1, . 3 1, . 4 1, . 2 1. . 6 1, . 2 1 .6

(1).



176

NMR

AND MACROMOLECULES

8 well illustrates this point. B o t h have t h e same elemental c o m p o s i t i o n , y e t sample 8, p r e p a r e d w i t h s o l i d KOH, h a s a much l a r g e r f r a c t i o n o f b l o c k e d u n i t s t h a n sample 3. The d i f f e r e n c e i s c l e a r l y r e f l e c t e d i n the s p e c t r a (Figure 4 ) . A s i m i l a r comparison can be made b e t w e e n sample 12, a n a d d u c t o f t r a n s - p o l y b u t a d i e n e prepared u s i n g aqueous NaOH, and sample 2, a c i s - p o l y b u t a d i e n e a d d u c t p r e p a r e d u s i n g s o l i d NaOH. F o r t h e s a m p l e s p r e p a r e d u s i n g aqueous NaOH, Tg i n c r e a s e s i n a smooth f a s h i o n w i t h i n c r e a s i n g e x t e n t o f r e a c t i o n and n ^ , as e x p e c t e d f o r random c o p o l y m e r s . The s i t u a t i o n f o r s a m p l e s p r e p a r e d w i t h s o l i d b a s e i s more c o m p l e x . I n some c a s e s two Tg's a r e observed. T h i s has been c o r r e l a t e d w i t h t h e o b s e r v a t i o n o f a l a r g e d o m a i n , two-phase m o r p h o l o g y u s i n g t r a n s m i s s i o n e l e c t r o n m i c r o s c o p y (TEM) ( 1 9 ) . I n t h e c a s e s where two Tg's a r e p r e s e n t , the f r a c t i o n o f blocked d i c h l o r o c y c l o p r o p y l u n i t s i s h i g h g i v e n the r e l a t i v e l y low o v e r a l l extent o f r e a c t i o n . One example i s sample 8 i n T a b l e s I and III. A q u e s t i o n a r i s e s concerning t h e homogeneity i n s o l u t i o n o f t h e p o l y m e r s w i t h two T g ' s . Can b l o c k e d segments be i s o l a t e d f r o m more random c o p o l y m e r c h a i n s ? And c a n t h e l o w and h i g h Tg's be a s s i g n e d t o b l o c k e d b u t a d i e n e and b l o c k e d d i c h l o r o p r o p y l u n i t s , respectively? Sample 8, p r e p a r e d w i t h s o l i d KOH and w i t h Tg's o f -78°C and 50°C, was f r a c t i o n a t e d u s i n g a c e t o n e . The r e s u l t s a r e i n T a b l e s I and I I I and F i g u r e 5. The s o l u b l e p o r t i o n ( 8 A ) h a d a h i g h c h l o r i n e c o n t e n t , a Tg o f 45°C, and a h i g h l y b l o c k e d s t r u c t u r e [ I g ( t r i a d ) = 4 . 9 ] . The i n s o l u b l e p o r t i o n ( 8 B ) h a d a l o w c h l o r i n e c o n t e n t , a Tg o f -76°C, and was a random c o p o l y m e r [ n ^ ( t r i a d ) = 1.3]. This experiment l i n k s the m i c r o s t r u c t u r a l f e a t u r e s , as d e t e r m i n e d b y C NMR, t o t h e t h e r m a l a n a l y s i s r e s u l t s i n a d i r e c t way. The C NMR r e s u l t s f o r t h e f r a c t i o n a t e d s a m p l e s a g r e e w i t h TEM r e s u l t s f o r o t h e r s a m p l e s ( 1 4 ) . TEM showed p h a s e s e g r e g a t i o n o f c h l o r i n e - r i c h and c h l o r i n e - p o o r r e g i o n s ( 1 9 ) . I t i s p o s s i b l e , h o w e v e r , t h a t a h i g h l y h e t e r o g e n e o u s sample l i k e 8 c o u l d be s e p a r a t e d i n t o f r a c t i o n s w i t h a continuous range o f c o m p o s i t i o n and b l o c k i n e s s and s t i l l d i s p l a y a two-phase morphology. F o r such heterogeneous polymers, s t a t i s t i c a l d e s c r i p t i o n s o f t h e s e q u e n c e d i s t r i b u t i o n s c a n be u s e d t o compare p o l y m e r s t r u c t u r e s , b u t c a n n o t be u s e d t o draw d e t a i l e d c o n c l u s i o n s a b o u t the chemistry o f p r e p a r a t i o n . A l t h o u g h o n l y a l i m i t e d number o f s a m p l e s were p r e p a r e d u s i n g a l k a l i m e t a l h y d r o x i d e s o t h e r t h a n NaOH, t h e r e a p p e a r s t o be no s t r o n g e f f e c t due t o t h e c a t i o n i n s o l u t i o n o r i n t h e s o l i d . 1 3

1 3

Experimental D e t a i l s o f t h e s a m p l e p r e p a r a t i o n a r e g i v e n i n R e f e r e n c e 16. The C NMR s p e c t r a were o b t a i n e d on a B r u k e r HX-90E F o u r i e r t r a n s f o r m s p e c t r o m e t e r a t 22.6 MHz a n d a p p r o x i m a t e l y 30°C. Samples u s u a l l y c o n s i s t e d o f 0.5 g o f p o l y m e r i n 2 m l o f C D C 1 i n 10 mm o.d. NMR tubes. C h e m i c a l s h i f t s were r e f e r e n c e d t o i n t e r n a l ( C H ) S i . The s p e c t r a l c o n d i t i o n s were : 90° r a d i o - f r e q u e n c y p u l s e s , 15 p s e c ; 1 3

3

3

4


11.

C A R M A N ET A L .


Polybutadiene


A)

Β)

1 3

F i g u r e 4. C NMR s p e c t r a o f two a d d u c t s w i t h t h e same % CI. ( A ) Sample 3, η ( t r i a d ) = 1.8. ( B ) Sample 8, η ( t r i a d ) = 3.3. B


111


NMR AND MACROMOLECULES

F i g u r e 5. C a r b o n - 1 3 NMR s p e c t r a o f Sample 8 (A) and i t s a c e t o n e s o l u b l e ( 8 a ) (B) and i n s o l u b l e ( 8 b ) (C) f r a c t i o n s i n C D C 1 . ( R e p r o d u c e d w i t h p e r m i s s i o n f r o m R e f . 16.) 3


11.

C A R M A N

Dichlorocarbene-Modified Polybutadiene

E T A L .

179

s p e c t r a l w i d t h , 6 k H z ; number o f p o i n t s ( F I D ) , 16k; p u l s e r e p e t i t i o n r a t e , 5 s ; l i n e b r o a d e n i n g due t o e x p o n e n t i a l filtering, I . 5 H z ; number o f s c a n s , 1000. Acknowledgments We t h a n k Dr.C J . Singleton f o r providing t h e Tg r e s u l t s , R. W. S m i t h f o r p r o v i d i n g t h e TEM r e s u l t s , a n d R. E. S c o u r f i e l d f o r a c q u i r i n g t h e C NMR s p e c t r a . 1 3

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Randall, J. C. "Polymer Sequence Determination", Academic: New York, 1977. 2. K e l l e r , F.; Zepnik, S.; Hösselbarth, B. Faserforsch. T e r t i l tech. 1978, 29, 490. 3. K e l l e r , F.; Mügge, C. Faserforsch. Textiltech. 1976, 27, 347. 4. Carman, C. J. ACS Symp. Ser. 1980, 142, 81. 5. Komoroski, R. Α.; Shockcor, J. P. Macromolecules 1983, 16, xx. 6. Kaplan, S. J . Polym. Sci., Polym. Chem. Ed. 1980, 18, 3307. 7. K e l l e r , F.; Hösselbarth, B. Faserforsch. Textiltech. 1978, 29, 152. 8. Komoroski, R. Α.; Parker, R. G . ; Lehr, M. H. Macromolecules 1982 15, 844. 9. K e l l e r , F.; Mügge, C. Plaste u. Kautschuk 1977, 24, 88. 10. Pinazzi, C.; Levesque, G. C. R. Acad. S c i . 1965, 260, 3393. 11. Lishanskii, I . S.; Tsitskhtsev, V. Α.; Vinogradova, N. D. Vysokom. Soedin. 1966, 8, 186. 12. L a i , J.; Saltman, W. J. Poly. S c i . A-1 1966, 4, 1637. 13. DeWitt, W.; Hurwitz, M. J.; Albright, F . J . Poly. S c i . A-1 1969, 7, 2453. 14. Horne, S. Ε . , Jr., to be published. 15. Clague, A. D. H.; van Broekhoven, J . A. M . ; Blaauw, L . P. Macromolecules 1974, 7, 348. 16. Komoroski, R. Α.; Horne, S. Ε . , Jr.; Carman, C. J. J. Polym. Sci., Polym. Chem. Ed. 1983, 21, 89. 17. Morrison, R. T . ; Boyd, R. N . "Organic Chemistry", Allyn and Bacon: Boston, 1973; p. 311. 18. Komoroski, R. A. J. Polym. Sci., Polym. Phys. Ed. 1979, 17, 45. 19. Horne, S. Ε . , Jr.; Singleton, C. J.; Smith, R. W., unpub lished results. RECEIVED September 22, 1983


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