Coordination Polymerization of Trimethylene Oxide - American

7 Coordination Polymerization of Trimethylene Oxide E.

J.

VANDENBERG

and

A.

E.

ROBINSON*

Downloaded by UNIV OF SYDNEY on October 5, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0006.ch007

Research Center, Hercules Inc., Wilmington, Del. 19899

INTRODUCTION General The p o l y m e r i z a t i o n o f oxetanes with c a t i o n i c c a t a l y s t s has been s t u d i e d by many i n v e s t i g a t o r s . (1) (2) Rose(3) i n p a r t i c u l a r , first reported the homopolymerization o f the parent compound, trimethylene oxide (TMO), with a Lewis a c i d c a t a l y s t , boron trifluoride. The use o f c o o r d i n a t i o n c a t a l y s t s to polymerize oxetanes has been reported i n the patent l i t e r a t u r e by Vandenberg. (4) In t h i s work, Vandenberg polymerized oxetanes with the aluminum trialkyl-water-acetylacetone c o o r d i n a t i o n c a t a l y s t ( r e f e r r e d t o as chelate c a t a l y s t ) that he discovered f o r epoxide polymerization(5). This paper d e s c r i b e s the homo- and co-polymerization o f TMO with these c o o r d i n a t i o n c a t a l y s t s . S p e c i f i c TMO copolymers, p a r t i c u l a r l y with unsaturated epoxides such as allyl g l y c i d y l ether (AGE), are shown t o provide the b a s i s f o r a new f a m i l y o f p o l y e t h e r elastomers. These new elastomers are compared with the r e l a t e d propylene o x i d e - a l l y l g l y c i d y l ether (PO-AGE) copolymer elastomers. The historical development and general characteristics o f p o l y e t h e r elastomers and, in particular, the propylene oxide elastomers, are reviewed below. E a r l y Polyether Elastomer Studies Charles C. P r i c e played a p i o n e e r i n g r o l e i n the p o l y e t h e r elastomer f i e l d ( 6 ) . In 1948, as reported in his 1961 Chemist article, P r i c e recognized t h a t an oxygen chain atom would c o n t r i bute g r e a t l y t o chain flexibility and thus enhance elastomeric behavior, p a r t i c u l a r l y s i n c e such polyethers should have low Hercules Research Center C o n t r i b u t i o n No. 1645 * Current address: Hercules Incorporated, Bacchus Works, Magna, Utah 84044

101

In Polyethers; Vandenberg, E.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.


102

POLYETHERS

cohesive energy between chains. At t h a t time, he suggested t h a t poly(propylene oxide) should be a s u p e r i o r elastomer but unfor t u n a t e l y soon found that the known methods o f p o l y m e r i z i n g pro pylene oxide gave o n l y low polymers, not the d e s i r e d high polymer. However, he q u i c k l y devised a simple way around t h i s impasse, i . e . , the polyurethane approach, which c o n s i s t e d o f making a pro pylene oxide adduct o f a p o l y o l and then r e a c t i n g t h i s polyfunct i o n a l p o l y e t h e r with a d i i s o c y a n a t e t o give a p o l y e t h e r urethane network. T h i s approach t o p o l y e t h e r elastomers was p r o t e c t e d by a U.S. p a t e n t ^ which r e c e n t l y r e c e i v e d the C r e a t i v e Invention Award o f the American Chemical S o c i e t y . Although these p o l y e t h e r urethane elastomers proved t o be o f tremendous value i n foam rubber, the more conventional p o l y e t h e r elastomer based on a c r o s s - l i n k a b l e high polymer remained u n a v a i l a b l e . The l a t t e r r e q u i r e d the development o f new c a t a l y s t systems f o r polymerizing propylene oxide. The f i r s t improved c a t a l y s t f o r polymerizing P0 t o high polymer was the i r o n c a t a l y s t o f P r u i t t and B a g g e t t ® , i . e . , the simple r e a c t i o n product o f f e r r i c c h l o r i d e and propylene oxide. P r i c e and O s g a n ® recognized that t h i s i r o n c a t a l y s t i n v o l v e d a new p o l y m e r i z a t i o n mechanism—coordination p o l y m e r i z a t i o n - - i n which the propylene oxide coordinates with the i r o n atom before i n s e r t i o n i n t o the propagating polymer chain. P r i c e and Osgan a l s o discovered a new c o o r d i n a t i o n c a t a l y s t f o r polymerizing propylene oxide t o high polymer, i . e . , the aluminum isopropoxidez i n c c h l o r i d e c a t a l y s t systemOH?. In subsequent work with t h i s c o o r d i n a t i o n c a t a l y s t , P r i c e d e s c r i b e d the copolymerization o f PO with an unsaturated epoxide, such as butadiene monoxide(JLL). In the same time p e r i o d o f P r i c e ' s work, H i l l , B a i l e y and F i t z p a t r i c k o f Union Carbide Corporation developed some improved c a t a l y s t s f o r polymerizing ethylene oxide t o high p o l y m e r U ) . These new c a t a l y s t s i n c l u d e d improvements on the very e a r l y sys tems o f Staudinger, i . e . , strontium, calcium, and z i n c oxides and carbonates t i l ) , as w e l l as some new, even b e t t e r , systems based on calcium alkoxides (14) and a m i d e s ( 1 6 ) B a i l e y used the l a t t e r systems i n 1958 t o make water-soluble ethylene oxide-unsaturated epoxide copolymers (iD. V u l c a n i z a t e s o f these copolymers were very water s e n s i t i v e and thus not very u s e f u l i n the conventional elastomer area. In 1957, Vandenberg d i s c o v e r e d some e s p e c i a l l y e f f e c t i v e c o o r d i n a t i o n c a t a l y s t s f o r polymerizing epoxides t o high p o l y mers. Some o f these new c a t a l y s t s were the r e a c t i o n products o f organo-compounds o f aluminum, z i n c , and magnesium with w a t e r · An e s p e c i a l l y v e r s a t i l e system was the combination o f organoaluminums with water and a c e t y l acetone. These new c a t a l y s t s were much b e t t e r than e a r l i e r epoxide c a t a l y s t s , g i v i n g g e n e r a l l y higher r a t e s a t lower temperatures, h i g h e r molecular weight, and broader u t i l i t y . As a r e s u l t o f f i n d i n g these s u p e r i o r new c a t a l y s t s , Vandenberg was able t o make many new high polymers from epox2

β


7.

VANDENBERG

A N D ROBINSON

103

Trimethylene Oxide

ides (§) CjJ), i n c l u d i n g a wide spectrum o f new p o l y e t h e r e l a s t o mers. Some o f these new p o l y e t h e r elastomers have been commerc i a l i z e d , such as the e p i c h l o r o h y d r i n elastomers a v a i l a b l e from Hercules Incorporated under the trademark HERCLOiând from B. F. Goodrich Chemical Co. a l i c e n s e e o f Hercules Incorporated, under the trademark HYDRIN. Very e a r l y i n t h i s work, Vandenberg a l s o made high molecular weight, l a r g e l y amorphous propylene oxideunsaturated epoxide copolymers and recognized i n unpublished s t u d i e s with A. E. Robinson t h e i r p o t e n t i a l value as improved elastomers. Subsequently, Gruber et a l . (12), f General T i r e , p u b l i s h e d d e t a i l e d p r o p e r t i e s o f s i m i l a r propylene oxide-unsaturated epoxide copolymer elastomers. Vandenberg a l s o f i l e d two patent a p p l i c a t i o n s on these copolymers. As a r e s u l t o f patent i n t e r f e r e n c e s i n v o l v i n g the Hercules a p p l i c a t i o n s , a Carbide patent, and a General T i r e a p p l i c a t i o n , the l a s t a P r i c e a p p l i c a t i o n , and extensive subsequent l i t i g a t i o n , Vandenberg was awarded p r i o r i t y . Two patents have i s s u e d covering these unsaturated copolymers as new compositions o f m a t t e r ( _ ) (21) T h i s new type o f p o l y e t h e r elastomer i s commercially a v a i l a b l e from Hercules Incorporated under the trademark PARE I®. PAREL elastomer i s a s u l f u r - c u r a b l e copolymer o f propylene oxide and a l l y l g l y c i d y l ether. Some o f the key p r o p e r t i e s o f PAREL elastomer v u l c a n i z a t e s are summarized i n Table I. They have e x c e l l e n t low temperature p r o p e r t i e s ; e x c e l l e n t dynamic p r o p e r t i e s , which are much l i k e those o f n a t u r a l rubber; good ozone r e s i s t a n c e ; and good heataging r e s i s t a n c e . T h i s i n t e r e s t i n g combination o f p r o p e r t i e s i s leading to s u b s t a n t i a l s p e c i a l t y markets i n such a p p l i c a t i o n s as automotive engine mounts. V u l c a n i z a t i o n and s t a b i l i z a t i o n s t u d i e s on PAREL elastomer, as w e l l as a d d i t i o n a l s p e c i f i c p r o p e r t i e s o f PAREL elastomer, are reported i n t h i s book by Boss. The work described above f o r PO copolymers has been extended to the homo- and co-polymers o f oxetanes, p a r t i c u l a r l y TMO, and are reported i n t h i s paper.


0

m

Table I KEY PROPERTIES OF PAREL ELASTOMER VULCANIZATES - E x c e l l e n t low temperature p r o p e r t i e s - E x c e l l e n t dynamic p r o p e r t i e s ( l i k e n a t u r a l

rubber)

- Good ozone r e s i s t a n c e - Good heat aging r e s i s t a n c e EXPERIMENTAL Polymerization Studies General.

Reagents and general procedures f o r making


POLYETHERS


104

c a t a l y s t s , f o r running polymerizations and f o r c h a r a c t e r i z i n g polymers were the same as d e s c r i b e d p r e v i o u s l y ( 5 ) unless other wise noted. The c h e l a t e c a t a l y s t s were prepared by the general procedure p r e v i o u s l y given f o r t h i s c a t a l y s t ® . The unmodified EtgAl-O.S H2O c a t a l y s t was made by t h i s same procedure, i n the solvent noted i n Table I I I , by o m i t t i n g the a c e t y l acetone. Monomers. Commercial, p o l y m e r i z a t i o n grade monomers were used as r e c e i v e d . The sources were: ethylene oxide (E0), propy lene oxide (PO), and e p i c h l o r o h y d r i n (ECH) from Union Carbide Corp.; a l l y l g l y c i d y l ether (AGE) from S h e l l Chemical Corp.; butadiene monoxide (BMO) from PPG I n d u s t r i e s , Inc. (no longer commercially a v a i l a b l e ) ; and 3,3-bis(chloromethyl) oxetane (BCMO) from Hercules Incorporated (no longer commercially a v a i l a b l e ) . The other monomers d e s c r i b e d below were f i n a l l y p u r i f i e d by f r a c t i o n a t i o n i n a 25-50 p l a t e column at a 25:1 r e f l u x r a t i o . Trimethylene oxide (TMO) was obtained from Farchan Research Labs, was f r e e d o f water by a z e o t r o p i c d i s t i l l a t i o n with d i e t h y l ether and then f r a c t i o n a t e d (b.p. 4 8 ° C , η£° 1.3870). 3,3-Bis(allyloxymethyl) oxetane (BAMO) was prepared by adding BCMO (31.0 g., 0 . 2 mole) over 2 h r s . t o a mixture o f a l l y l a l c o h o l (23.2 g., 0.40 mole) and NaOH ( 1 6 . 0 g., 0.4 mole) i n dimethyl s u l f o x i d e (100 ml.) a t 50°C. A f t e r the mixture was heated f o r an a d d i t i o n a l 2 h r s . at 5 0 ° C , water was added, and the w a t e r - i n s o l uble f r a c t i o n recovered, d r i e d , and f r a c t i o n a t e d (b.p. 118°/10 mm., nj50 1.4538). 3,3-Dimethyloxetane was prepared from n e o p e n t y l g l y c o l by the procedure o f Schmoyer and C a s e ( 2 2 ) The f r a c t i o n a t e d product had: b.p. 8 1 ° C , nj* 1.3921. 9

0

Polymer I s o l a t i o n . The procedures used f o r the runs i n Tables II and I I I are given below. Unless otherwise noted, products were d r i e d a t 80°C. i n vacuo (0.4 mm.). Procedure A. Ether was added and then the product was washed twice with 3% HC1 (15 min. t o 1 h r . s t i r p e r wash), and then with water u n t i l n e u t r a l . The e t h e r - i n s o l u b l e ( i f any) was c o l l e c t e d , washed twice with ether and once with 0.05% Santonox i n ether and d r i e d as the e t h e r - i n s o l u b l e f r a c t i o n . The ethers o l u b l e was s t a b i l i z e d with 0.5% Santonox (based on t o t a l s o l i d s ) , the ether s t r i p p e d o f f , and the polymer d r i e d . In Run 7, Table I I I , the e t h e r - s o l u b l e was s t a b i l i z e d with 1% phenyl 3-naphthyl amine. Procedure B. Excess n-heptane (4-6 v o l s . ) was added and the heptane-insoluble polymer was c o l l e c t e d , washed once with heptane, washed once with 0.5% HC1 i n CH3OH, washed n e u t r a l with CHÔH, washed with 0.1% Santonox i n CH3OH, and then d r i e d . Run 5, which was used i n the v u l c a n i z a t i o n s t u d i e s , was s t a b i l i z e d with 1% phenyl 3-naphthyl amine.


7.

VANDENBERG

AND

Trimethylene

ROBINSON

Oxide

105

Procedure C. Product p r e c i p i t a t e d with 4 v o l s , o f τιheptane (ether i n Run 3, Table I I ) . The i n s o l u b l e was c o l l e c t e d , washed with η-heptane (or ether, i f used i n i t i a l l y ) , washed with 1% HC1 i n anhydrous ethanol, washed n e u t r a l with CH3OH, washed with 0.4% Santonox i n CH3OH and d r i e d . In Run 2, Table I I , the heptane-insoluble was not HC1 washed but i n s t e a d washed with 0.1% Santonox i n heptane and d r i e d . This product was then f u r t h e r sep arated by tumbling 1-gram i n 40 ml. o f H 0 overnight and then c o l l e c t i n g the w a t e r - i n s o l u b l e , washing with H2O, and d r y i n g . The water-soluble was recovered by s t r i p p i n g o f f the water and d r y i n g .


2

Procedure D. Excess ether was added, the e t h e r - i n s o l uble f r a c t i o n was c o l l e c t e d , washed with ether, washed with 0.5% HC1 i n 80-20 ether-methanol, washed n e u t r a l with 80-20 ethermethanol, washed with 0.4% Santonox i n ether, and then d r i e d i n vacuo a t 50°C. Polymer C h a r a c t e r i z a t i o n . Inherent v i s c o s i t y was determined under the f o l l o w i n g c o n d i t i o n s : TMO-ECH copolymer, 0.1%, achloronaphthalene, 1 0 0 ° C ; other TMO and DM0 homo and copolymers 0.1%, CHC1 , 2 5 ° C ; TMO-P0-AGE terpolymer and PO-BCMO copolymer, 0.1%, benzene, 2 5 ° C ; BCMO homopolymer, 1.0%, cyclohexanone, 50°C. Unsaturated copolymers were analyzed f o r the unsaturated comonomer by Kemp Bromine No. ( i n CHCI3) (21) after correcting f o r the Bromine No. o f the a n t i o x i d a n t (Santonox, 125 and phenyl 3naphthyl amine, 143). C h l o r i n e - c o n t a i n i n g comonomers were deter mined by a c h l o r i n e a n a l y s i s . The composition o f the TMO-EO co polymers was determined by C and H a n a l y s i s . The PO content o f the TMO-PO-AGE terpolymer was determined by i n f r a r e d a n a l y s i s . The r e l a t i v e r e a c t i v i t y o f monomers i n copolymerization was c a l c u l a t e d from the f o l l o w i n g equation based on i d e a l copolymer ization. In [[ MM ii ll lο ri = 3

In [M ] t 2

where r ^ 2, [M^Jo monomers t i o n s at

i s the r e a c t i v i t y r a t i o o f monomer 1 r e l a t i v e t o monomer and [ M ] are i n i t i a l monomer concentrations o f 1 and 2, and [M-Jt and [ Μ ] ^ are the monomer concentra time t during the copolymerization. t

2

n

e

0

2

V u l c a n i z a t i o n Studies V u l z a n i z a t e s were prepared by conventional m i l l i n g and com pounding a t 100°F. followed by press c u r i n g according t o the f o r mula i n Table IV unless otherwise noted. The HAF carbon b l a c k was P h i l b l a c k 0 (N-330) o f P h i l l i p s Petroleum Co. A cure r a t e study i s given i n Figure 1. G e l / s w e l l data (wt. %) were deter-


106

POLYETHERS

mined i n cyclohexanone a f t e r 4 hours a t 80°C. Tests used t o evaluate v u l c a n i z a t e s were as f o l l o w s : ASTO Test Tensile D412 (miniature, 2 Die C dumbbell) Tear D624 (miniature Die C) Hardness D676 Bashore r e s i l i e n c e D2632 Yerzley oscillograph D945 Torsional r i g i d i t y D1043 Heat Build-up D623 Oven aging D573 Solvent Resistance D1460 Downloaded by UNIV OF SYDNEY on October 5, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0006.ch007

ff

Table IV VULCANIZATION FORMULA Elastomer HAF Black ZnO Stearic Acid Sulfur Benzothiazyl d i s u l f i d e Tetramethyl thiuram d i s u l f i d e

100 50 5 1 2 1 2

Cured 30 min. a t 310°F.

CURE TIME - MINUTES AT

Figure

1.

310°F.

Effect of cure time on properties of elastomer

TMO-AGE


7.

VANDENBERG

RESULTS AND

AND

ROBINSON

Trimethylene Oxide

107

DISCUSSION

Polymerization S t u d i e s . TMO homopolymerization. The E t 3 A l - 0 . 5 H O - l . 0 acetylacetone c a t a l y s t polymerized TMO at 65°C. i n heptane d i l u e n t to a high conversion o f a very high molecular weight polymer ( n i h = 12), which was tough, rubbery, and c r y s t a l l i n e , with a 40°C. melting p o i n t (Table I I ) . The polymer was i n s o l u b l e i n η-heptane and methanol but s o l u b l e i n benzene and chloroform. T h i s homopolymer i s apparently s i m i l a r to t h a t prepared by R o s e ® with BF3 c a t a l y s t except t h a t the present product i s o f much higher molecu l a r weight and a l i t t l e h i g h e r m e l t i n g . Rose obtained an n i h o f 1.3 at 50°C. and 2.9 at -80°C. with a melting p o i n t o f 35°C. The p o l y m e r i z a t i o n o f TMO i s to be compared with that o f PO s i n c e the monomers and polymers are isomeric (Eqs. 1 and 2) 2

n


n

(-CH CH CH -0-) 2

2

2

n

Eq. 1

TMO

Eq. 2 •0' PO On the b a s i s o f our p r i o r work on PO p o l y m e r i z a t i o n , with t h i s same c h e l a t e c a t a l y s t ® , TMO polymerizes about 10 times more slowly than PO does under the same c o n d i t i o n s . A l s o , the TMO homopolymer i s much l e s s s o l u b l e than poly(propylene o x i d e ) , s i n c e the l a t t e r polymer i s s o l u b l e i n heptane and methanol, both nonsolvents f o r p o l y f t r i m e t h y l e n e o x i d e ) . The TMO homopolymer i s , o f course, c r y s t a l l i n e because o f i t s very r e g u l a r s t r u c t u r e . On the other hand, the poly(propylene oxide) prepared with the c h e l a t e c a t a l y s t i s l a r g e l y amorphous because o f t a c t i c i t y and head-tot a i l v a r i a t i o n s i n s t r u c t u r e which are not p o s s i b l e i n p o l y ( t r i methylene o x i d e ) . T h i s TMO p o l y m e r i z a t i o n with the c h e l a t e c a t a l y s t no doubt i n v o l v e s coordinate propagation and i s the f i r s t such case o f coordinate propagation o f an oxetane. Heretofore, oxetanes have been c a t i o n i c a l l y polymerized. There are s e v e r a l reasons f o r concluding t h a t t h i s c h e l a t e c a t a l y s t system i s a c o o r d i n a t i o n p o l y m e r i z a t i o n . F i r s t , the very h i g h molecular weight obtained at e l e v a t e d temperature with a low r a t e i s c h a r a c t e r i s t i c o f c o o r d i n a t i o n p o l y m e r i z a t i o n r a t h e r than o f c a t i o n i c polymeriza t i o n . A l s o , Vandenberg's work on the c i s - and trans-2,3-epoxy-



PO AGE

BMO

AGE

45(g) 5(g)

9.4

5.6(f)

n-heptane

n-heptane

n-heptane

AGE

3

Toluene

n-heptane Toluene

92

82

82

92

42

92 92

Diluent Name ml.

ECH

EO

0 20

Comonomer Name

1.0

1.0

1.0

1.0

1.0 0.5 8 4

Catalyst A c e t y l Acetone mmoles per A l (Al Basis)

10

14

.7

7.5

19 12

Time hrs.

e

65

65

65

65

65

65 30

Temp. °C.

27

85 13

Total % Conv.

2

Heptane-insol.(h) Heptane-sol.(i)

Heptane ξ CHjOHinsol.(e)

Ether-insol.(d)

Ether-insol.(d) Ether-sol., Heptane-insol.(e)

Ether-insol.(b) Water-insol.(c) Water-sol. (c)

I s o l a t e d Polymer Procedure Fraction

28 20

89

71

23

5.6 10

67 1.4 12

% Conv.

5.3 4.1

13.5

15.4

8.1

3.3 1.0

12 11.0 6.5

Hjnh

PO AGE 58 10.0 60 9.3

6.5

4.4

12.6

12 55

44 8

% Co-m

(a) Based on 10 g. t o t a l monomer. See Experimental f o r i s o l a t i o n procedure. TMO » t r i m e t h y l e n e o x i d e , EO « ethylene o x i d e , ECH • e p i c h l o r o h y d r i n , AGE = a l l y l g l y c i d y l e t h e r , BMO = butadiene monoxide, and PO * propylene o x i d e . (b) Very s t r o n g , tough, o r i e n t a b l e rubber. C r y s t a l l i n e by x-ray (m.p. • 4 0 C ) . I n s o l u b l e i n H 0, n-heptane and CH3OH. S o l u b l e i n benzene and chloroform. (c) I s o l a t e d from i n i t i a l heptane and methanol-insoluble product. (d) Largely amorphous and rubbery. (e) Amorphous and rubbery. ( f ) 20% o f t o t a l comonomer added i n i t i a l l y , remainder added i n 6 equal p o r t i o n s a t 2-hr. i n t e r v a l s . (g) Added i n 5 equal p o r t i o n s a t 2-hr. i n t e r v a l s . (h) Tough, amorphous rubber ( i ) Tack/ rubber.

No.

T

P o l y m e r i z a t i o n o f TMO w i t h E t A l - 0 . 5 H?Q-Acetyl Acetone C a t a l y s t (a)

Table I I



3

2

2.7

0.29

3.3

27

94

60

Heptane-and CHjOH-insol. Heptane- and CH*0H-insol.

Β

C

1.5

5.3 65

(a) Based on 10-g. t o t a l monomer. See Experimental f o r i s o l a t i o n d e t a i l s . TMO • t r i m e t h y l e n e o x i d e ; DMO «* 3,3-dimethyl oxetane; BAMO (allyl oxymethy1)oxetane. (b) Unless otherwise noted, c a t a l y s t prepared i n n-heptane w i t h 3 moles o f d i e t h y l e t h e r per aluminum. (c) Ether omitted frow c a t a l y s t p r e p a r a t i o n . (d) Most o f p o l y m e r i z a t i o n occurred i n a few minutes. (e) I n i t i a l l y a t a c k y rubber a f t e r d r y i n g a t 80 C. which s l o w l y c r y s t a l l i z e d t o Λ hard s o l i d o f c a . 50 C. m.p.; heptane-soluble. ( f ) Low c r y s t a l l i n i t y [poly(3,3-dimethyl oxetane) p a t t e r n ] ; heptane-soluble, (gj E t A l - u . S H 0-0.5 a c e t y l acetone c a t a l y s t . e

5.2 27 T o t a l polymer A

27

30

5

4 (g)

40

80

PO BGM0

8

1.3 92

T o t a l polymer (*)

A

92

0

0.08

4

32

n-heptane

90 10

DMO BAMO

7

A

100(d)

0

42

4

48

n-heptane

100

DMO

6

99

T o t a l polymer (e)

C

60

30

19

2 (c)

50

100

BCMO

5

50

6

2

42

Toluene

100

BCMO

4

51

30

2

4

83

Toluene

94 6

TMO BAMO

3

Β

29 47 78

30

0.5 2.0 23

5.5

4

66

48

Toluene

100

TMO

2

Heptane and CtUOH-insol.

Β

49 78

65

Hint*

0.25 2.3

I s o l a t e d Polymer % Conv.

4

48

Toluene

100

TMO

1

Fraction

Procedure

e

Total % Conv.

Catalyst(b) mmoles

Temp. C.

mU

Monomer 1 Name

No.

Time hrs.

Diluent Name

P o l y m e r i z a t i o n o f Oxetanes w i t h EtÂl-0.5 H?0 C a t a l y s t (a)

Table I I I


POLYETHERS

110

butanes c l e a r l y e s t a b l i s h e d t h a t the c h e l a t e c a t a l y s t operates by a c o o r d i n a t i o n mechanism and does not give c a t i o n i c polymerization I t i s perhaps s u r p r i s i n g t h a t TMO polymerizes ten times more slowly than PO, s i n c e i t i s a stronger base than PO by about 4 orders o f magnitude


(24)

and thus i t should coordinate much more r e a d i l y with a metal. One explanation f o r the more f a c i l e p o l y m e r i z a t i o n o f PO i s that the g r e a t e r r i n g s t r a i n i n PO, compared with t h a t i n TMO, g r e a t l y f a c i l i t a t e s the r i n g opening propagation step with PO and more than compensates f o r i t s lower c o o r d i n a t i o n tendency because o f i t s lower base s t r e n g t h . TMO polymerizes much f a s t e r (about t e n - f o l d ) with the Et-jAlO.5H2O c a t a l y s t (Table I I I ) and s t i l l gives f a i r l y high molecular weight homopolymer. In t h i s case, based on Vandenberg's p r i o r work with the 2,3-epoxybutanes, the p o l y m e r i z a t i o n could be e i t h e r c a t i o n i c or c o o r d i n a t i o n , o r both. The c a t i o n i c route would be expected t o be f a s t e r . A l s o , the lower s t e r i c hindrance a t propagation s i t e s with the unmodified organoaluminum-iÔ should a l s o permit more f a c i l e c o o r d i n a t i o n and thus f a s t e r c o o r d i n a t i o n p o l y m e r i z a t i o n . The i n c r e a s e d Lewis a c i d c h a r a c t e r o f propagation s i t e s with the unmodified c a t a l y s t could a l s o enhance the coordina t i o n step and thus propagation. TMO Copolymerization With Saturated Epoxides. Copolymerizing TMO with ethylene oxide (EO) i n an 80:20 weight r a t i o with the c h e l a t e c a t a l y s t gave a water-soluble product (90% o f the t o t a l ) which contained only 8% TMO (Run 2, Table I I ) . On the b a s i s o f an i d e a l copolymerization, the EO i s estimated t o enter the copolymer i n t h i s f r a c t i o n approximately 70 times more r e a d i l y than does the TMO. T h i s r e s u l t confirms that a l k y l e n e oxides polymerize much more r e a d i l y than oxetanes with the c h e l a t e c a t a l y s t . A small amount (10% o f the T o t a l ) o f a w a t e r - i n s o l u b l e copolymer c o n t a i n i n g 44% TMO was obtained. T h i s r e s u l t i n d i c a t e s that the c h e l a t e c a t a l y s t contains some s i t e s which give more f a v o r a b l e copolymeri z a t i o n . One p o s s i b l e explanation i s t h a t the unfavorable copolym e r i z a t i o n o f TMO a t the major s i t e s i s due t o s t e r i c hindrance which reduces the a b i l i t y o f TMO t o coordinate a t t h i s s i t e . Based on t h i s hypothesis, l e s s hindered s i t e s would be more f a v o r able f o r copolymerization. An a l t e r n a t e but u n l i k e l y p o s s i b i l i t y i s that there are a l i m i t e d number o f c a t i o n i c s i t e s i n the chelate c a t a l y s t and t h a t these give some copolymer by a more f a v o r a b l e c a t i o n i c propagation mechanism. The copolymerization o f TMO and e p i c h l o r o h y d r i n (ECH) with the c h e l a t e c a t a l y s t and a 50:50 weight r a t i o charge i s more favorable (Run 3, Table I I ) ; again, two f r a c t i o n s , both rubbery i n nature, were obtained which d i f f e r e d i n s o l u b i l i t y and composition. Thus, the c h e l a t e c a t a l y s t again appears t o c o n t a i n a t l e a s t two d i f f e r e n t copolymerization s i t e s . I t i s s i g n i f i c a n t that these two monomers, which probably have s i m i l a r s t e r i c r e quirements, do copolymerize b e t t e r , thus adding credence t o the e a r l i e r proposal that s t e r i c r e s t r i c t i o n s at c e r t a i n s i t e s a f f e c t


7.

VANDENBERG

A N D ROBINSON

Trimethylene Oxide

111


copolymerization. Of course, t h i s r e s u l t i s a l s o evidence f o r a coordination polymerization. TMO Copolymerization With Unsaturated Epoxides and Oxetanes. The low conversion copolymerization o f TMO and a l l y l g l y c i d y l ether (AGE) with the c h e l a t e c a t a l y s t and a 97:3 weight r a t i o charge gave a rubbery, l a r g e l y amorphous, high molecular weight copolymer product which contained about 13% AGE (Run 4, Table I I ) . On the b a s i s o f an i d e a l copolymerization, the AGE enters the copolymer about 14 times more r e a d i l y than TMO does. This r e s u l t i s to be c o n t r a s t e d with the i d e a l PO-AGE copolymerization, with t h i s same c a t a l y s t , i n which the copolymer has the same composit i o n as the i n i t i a l monomer charge. To compare the elastomer behavior o f t h i s TMO elastomer with a comparable PO-AGE elastomer, a procedure was developed f o r making l a r g e r samples o f r e l a t i v e l y uniform TMO-AGE copolymers c o n t a i n i n g about 4% AGE (Run 5, Table II). Thus, the copolymerization was begun with a l l the TMO i n the i n i t i a l charge along with 20% o f the t o t a l AGE used. As the p o l y m e r i z a t i o n proceeded, a d d i t i o n a l AGE was added as i n d i c a t e d i n Table I I . In t h i s way, a high conversion to heptane- and methanol-insoluble, amorphous copolymer c o n t a i n i n g 4.4% AGE was obtained. On the b a s i s o f the s u l f u r v u l c a n i z a t e data that i s presented i n the v u l c a n i z a t e property data s e c t i o n , t h i s product appears to be r e l a t i v e l y uniform. However, t h i s procedure and perhaps even the c a t a l y s t may not be optimal and some degree o f nonuniformity may s t i l l p e r s i s t . A copolymer o f TMO with butadiene monoxide (BMO) was a l s o made by u s i n g the same procedure as i n the l a r g e sample method for TMO-AGE (Run 6, Table I I ) . Since BMO gives i d e a l copolymeri z a t i o n with PO, as does AGE, with the c h e l a t e c a t a l y s t , i t was assumed that the system which worked with TMO-AGE would work with TMO-BMO. A terpolymer o f TMO-PO-AGE was a l s o made by the same general procedure used i n the l a r g e s c a l e TMO-AGE work (Run 7, Table I I ) . The terpolymer was i s o l a t e d i n two f r a c t i o n s o f s i m i l a r composit i o n (ca. 60% PO and 10% AGE), but d i f f e r e n t s o l u b i l i t y , and d i f f e r e n t molecular weight. The highest molecular weight f r a c t i o n was heptane-insoluble, confirming that TMO u n i t s c o n t r i b u t e substantial heptane-insolubility. TMO was a l s o copolymerized with an unsaturated oxetane, 3,3b i s ( a l l y l o x y m e t h y l ) o x e t a n e (BAMO) (Run 3, Table I I I ) . This work was done with the Et3Al-0.5H20 c a t a l y s t . This copolymerization appears to be a n e a r l y p e r f e c t one. Polymerization o f Other Oxetanes. The c a t i o n i c polymerizat i o n o f 3 , 3 - d i s u b s t i t u t e d oxetanes, e s p e c i a l l y 3 . 3 - b i s ( c h l o r o methyl)oxetane (BCMO), has been widely studied(±/t£?. A few experiments with t h i s type o f oxetane u s i n g the Et Al-0.5H2O c a t a l y s t are given i n Table I I I . BCMO polymerizes r e a d i l y with t h i s c a t a l y s t to give high molecular weight polymer, n i h 3.0, at 3

n


POLYETHERS

112

3 0 ° C , provided there i s no ether i n the c a t a l y s t system (Run 5, Table I I I ) . However, with ether present (Run 4, Table I I I ) , the molecular weight i s g r e a t l y reduced as i n d i c a t e d by the 0.3 inherent v i s c o s i t y . The l a r g e e f f e c t o f ether i n d i c a t e s that the E t 3 A l 0.5H O c a t a l y s t i s behaving here as a c a t i o n i c c a t a l y s t with ether a c t i n g as a chain t r a n s f e r agent. The molecular weight without ether i s , however, very high f o r an o r d i n a r y c a t i o n i c c a t a l y s t with BCMO a t these temperatures. U s u a l l y lower temperatures are r e q u i r e d t o o b t a i n high molecular weight polymer from BCMO with Lewis a c i d type c a t a l y s t s Some experiments on the p o l y m e r i z a t i o n o f BCMO with the chelate c a t a l y s t are recorded i n the patent literature(£). In t h i s work, high molecular weight polymer ( n i h P 4.3) obtained a t very high temperatures (200-250°C.) i n a continuous, bulk p o l y m e r i z a t i o n method. These data i n d i c a t e that the c h e l a t e c a t a l y s t polymerizes BCMO by a c o o r d i n a t i o n mechanism. Presumably the very high temperature works w e l l because o f the r e l a t i v e l y low b a s i c i t y o f BCMot^£). The copolymerization o f PO with BCMO u s i n g the c h e l a t e c a t a l y s t (Run 8, Table I I I ) a t 30°C. i n d i c a t e s that the PO enters the copolymers about t h i r t y f o l d more r e a d i l y than does BCMO, based on i d e a l copolymerization. This r e s u l t i s s i m i l a r t o our f i n d i n g s on the copolymerization o f TMO with ethylene oxide. S i m i l a r explanations no doubt apply. 3,3-Dimethyloxetane (DMO) polymerizes very r a p i d l y a t 0°C. with Et3Al-0.5 H 0 c a t a l y s t t o a high molecular weight, ( n ^ h * 1.6), low m e l t i n g (ca. 5 0 ° C ) , c r y s t a l l i n e polymer (Run 6, Table I I I ) . This p o l y m e r i z a t i o n i s apparently c a t i o n i c , on the b a s i s o f the v e r y r a p i d p o l y m e r i z a t i o n . The small amount o f ether i n the c a t a l y s t does not have a large chain t r a n s f e r e f f e c t , as with BCMO, presumably because o f the much higher base strength o f DMO compared with BCMO and ether. DMO was copolymerized with BAMO (Run 7, Table I I I ) . Because of the very r a p i d p o l y m e r i z a t i o n , i t was d i f f i c u l t t o o b t a i n a low conversion and t o assess the copolymerization behavior o f t h i s monomer p a i r . However, v u l c a n i z a t e p r o p e r t i e s on t h i s product (Table III) were good, i n d i c a t i n g a r e l a t i v e l y uniform copolymer and thus a f a v o r a b l e copolymerization. 2

U

t

0

w

a

s


n

2

V u l c a n i z a t e Studies The various unsaturated copolymers were v u l c a n i z e d with the s u l f u r - a c c e l a t o r system given i n Table IV. TMO-AGE Elastomers. The s u l f u r v u l c a n i z a t e o f the 96-4 TMO-AGE copolymer had high t e n s i l e , modulus, and t e a r strength a t 23°C. a t a good e l o n g a t i o n l e v e l (Table V). The hot t e n s i l e p r o p e r t i e s a t 100°C. are somewhat lower but s t i l l good. C r y s t a l l i n i t y and/or c r y s t a l l i z a t i o n on s t r e t c h i n g could enhance t e n s i l e p r o p e r t i e s a t 2 3 ° C ; apparently t h i s i s not the case, s i n c e the hot t e n s i l e r e s u l t s , which could not i n v o l v e c r y s t a l l i n i t y


7.

VANDENBERG

AND

ROBINSON

THmethylene Oxide

113

e f f e c t s , are i n l i n e with the usual e f f e c t o f increased temper ature on t e n s i l e p r o p e r t i e s . The p r o p e r t i e s obtained i n these studies are a f f e c t e d only s l i g h t l y by i n c r e a s i n g the cure time f o u r f o l d over the optimum used ( F i g . 1 ) . Table V


VULCANIZATE PROPERTIES OF TMO-AGE ELASTOMER

Tensile strength, p s i . 300% modulus, p s i . Elongation a t break, % Break s e t , % Hardness, A2 Tear Strength, p . / i . R e s i l i e n c e , Bashore, % Y e r z l e y Dynamic Data Modulus, p s i . Resilience, % Frequency, Hz K i n e t i c Energy, i n . - l b . / c u . i n . Heat Build-up, °F. Tg., °c. V o l . % Swell (5 days a t 60°C.) Toluene H 0 2

23°C. 3190 2590 400 20 82 345 65

100°C. 1800 1515 225 0 82 230

6555 67 7.5 31.7 27 -75

315 0

The TMO-AGE copolymer v u l c a n i z a t e a l s o has e x c e l l e n t r e s i l ience, low heat b u i l d - u p , and a low Tg o f -75°C. (Table V ) . Volume % s w e l l i n toluene i s high but water-swell i s low. A l though not measured, we would expect, based on the heptanei n s o l u b i l i t y o f the amorphous 96-4 TMO-AGE copolymer, that o i l r e s i s t a n c e o f TMO-AGE copolymer would be f a i r l y good. The m e t h a n o l - i n s o l u b i l i t y o f the amorphous TMO-AGE copolymer a l s o suggests that i t should have r e s i s t a n c e t o p o l a r s o l v e n t s . The gum v u l c a n i z a t i o n p r o p e r t i e s o f the TMO-AGE copolymer (Table VI) are low. These data are f u r t h e r evidence that the e x c e l l e n t t e n s i l e p r o p e r t i e s observed f o r the b l a c k - f i l l e d TMOAGE v u l c a n i z a t e s i s not due t o c r y s t a l u n i t y o r c r y s t a l 1 1 z a b i l i t y . The 91% g e l r e s u l t does support our conclusion that the TMO-AGE copolymer i s reasonably uniform. A i r aging f o r 48 hours a t 100°C. does not g r e a t l y a f f e c t the room temperature p r o p e r t i e s o f the TMO-AGE v u l c a n i z a t e (Table V I I ) . These c o n d i t i o n s would s e r i o u s l y degrade the p r o p e r t i e s o f n a t u r a l rubber and thus c l e a r l y show that TMO elastomers, l i k e PO elastomers, are s u p e r i o r i n heat aging t o n a t u r a l rubber. Unfort u n a t e l y we d i d not make an extended a i r aging study on the TMO v u l c a n i z a t e t o determine i t s long term o x i d a t i o n r e s i s t a n c e . One


114

POLYETHERS

would expect, however, that the lack o f t e r t i a r y hydrogens i n the TMO chain u n i t would be a favorable f a c t o r . Table VI


GUM VULCANIZATE PROPERTIES OF TMO-AGE ELASTOMER Tensile strength, p s i . 300% Modulus, p s i . E l o n g a t i o n at break, % Break s e t , % Hardness, A2 Tear s t r e n g t h , p / i G e l / s w e l l , %/%

515 260 515 10 48 80 91/520

Table VII EFFECT OF AIR AGING ON TMO-AGE VULCANIZATE(a) h r s . at 100°C. 0 48 Tensile strength, p s i . 200% Modulus, p s i . Elongation at break Break s e t , % Hardness, A2

3190 2590 400 20 82

3380 2630 290 10 70

(a) S t a b i l i z e d with 1% phenyl 3-naphthylamine. T o r s i o n a l r i g i d i t y versus temperature data f o r the TMO-AGE v u l c a n i z a t e and a comparable PO-AGE v u l c a n i z a t e are given i n Figure 2. The increase i n modulus f o r the TMO v u l c a n i z a t e from 0 to -60° o b v i o u s l y i s due to a low temperature c r y s t a l l i z a t i o n o f t h i s copolymer. Other samples d i d not e x h i b i t t h i s c r y s t a l l i z a t i o n problem. The data do i n d i c a t e that the TMO and PO e l a s tomers have about the same Tg at about -75°C. The low temperature c r y s t a l l i z a t i o n problem o f the TMO e l a s tomer can no doubt be e l i m i n a t e d i n a v a r i e t y o f ways, such as preparing a more uniform copolymer, adding a p l a s t i c i z e r such as an aromatic o i l , and/or a l t e r i n g the composition o f the copolymer. An approach t o a l t e r i n g the TMO-AGE copolymer composition would be to make a terpolymer c o n t a i n i n g PO as described prev i o u s l y . V u l c a n i z a t e data are given on the PO-TMO-AGE elastomers i n Table V I I I . The p r o p e r t i e s are f a i r but i n d i c a t e that the v u l c a n i z a t e s are overcured. The AGE l e v e l was e v i d e n t l y too high f o r the cure system used. The r e s u l t s do confirm the p r e p a r a t i o n o f the d e s i r e d terpolymer and i n d i c a t e that t h i s approach i s feasible.



7.

VANDENBERG

A N D ROBINSON

Figure 2.

Trimethtflene Oxide

115

Torsional rigidity vs. temperature for TMO and PO elastomers

Other Qxetane Elastomers. The TMO-butadiene monoxide (BMO) copolymer elastomer (Run 6, Table II) c o n t a i n i n g 6.5% BMO gave i n f e r i o r p r o p e r t i e s (Table VIII) t o the TMO-AGE elastomer with 4.4% AGE d e s c r i b e d i n the previous s e c t i o n . A c t u a l l y the propert i e s were even s l i g h t l y i n f e r i o r t o a 98-2 TMO-AGE copolymer v u l canizate (Table V I I I ) . Thus AGE appears about three times more e f f e c t i v e (on a weight b a s i s ) i n c o n f e r r i n g s u l f u r v u l c a n i z a b i l i t y than BMO. On a molar b a s i s , the d i f f e r e n c e i s even g r e a t e r , i . e . , AGE i s f i v e times more e f f e c t i v e . T h i s same d i f f e r e n c e between BMO and AGE was p r e v i o u s l y observed on comparing PO-BMO elastomer with PO-AGE elastomer. Bis(3,3-allyloxymethyl)oxetane (BAMO), on the other hand, appears t o have about the same order o f e f f e c t i v e n e s s f o r conf e r r i n g s u l f u r c u r a b i l i t y t o a TMO elastomer as does AGE (on an equal double-bond content b a s i s ) . The 88:12 DMO:BAMO elastomer gave only f a i r p r o p e r t i e s s i n c e i t was s u b s t a n t i a l l y overcured with the high l e v e l o f BAMO used (Table V I I I ) . The low heat-build-up does i n d i c a t e that t h i s e l a s tomer i s i n h e r e n t l y a good one. CONCLUSIONS The f i r s t p o l y m e r i z a t i o n o f an oxetane, trimethylene oxide, by c o o r d i n a t i o n p o l y m e r i z a t i o n has been d e s c r i b e d . Copolymers o f TMO with epoxides were r e a d i l y made. Such copolymers provide an i n t e r e s t i n g f a m i l y o f new elastomers. One such elastomer, the TMO-AGE copolymer, was i n v e s t i g a t e d i n some d e t a i l and found t o have a d e s i r a b l e combination o f p r o p e r t i e s . Such TMO elastomers,



(a)

88-12

93.5-6.5 98-2 (b) 93.3-6.7

58-32-10 60-31-9

Composition

99 390

625 820 270

-

94 93 100

% Swell

% Gel

1985

2090 3010 3280

2040 2030

Tensile psi.

g

char^

d

b

n

/

inh (c) 100% modulus.

P

a

= 1

S

6

6

? !f · '

0

c

e

d

u

r

e

-

1155 1035 3250

695 (c) 930 (c)

300% Modulus psi.

210

535 770 305

225 200

Elongation

a s c r i b e d i n Run 5, Table I I , u s i n g 2.6% t o t a l AGE i n t h e

(a) Products d e s c r i b e d i n Tables I I andI I I u n l e s s otherwise noted.

DMO-BAMO

TMO-BMO TMO-AGE TMO-BAMO

PO-TMO-AGE, h e p t a n e - i n s o l . " " " " -sol.

Elastomer Name

V u l c a n i z a t e P r o p e r t i e s o f V a r i o u s Oxetane Elastomers

Table V I I I


14

Heat Build-up @ 212°F.

7.

VANDENBERG

AND

ROBINSON

THmethylene Oxide

117


l i k e the PO elastomers, are e x c e l l e n t rubbers with low Tg and high r e s i l i e n c e . A l s o , the TMO elastomers give good t e n s i l e and t e a r p r o p e r t i e s and should have at l e a s t f a i r o i l r e s i s t a n c e . Although abrasion r e s i s t a n c e data has not been obtained, we would expect the good t e n s i l e and t e a r p r o p e r t i e s o f the TMO v u l c a n i z a t e s to favor good abrasion r e s i s t a n c e . There appear to be two main d i s advantages o f the TMO elastomers; f i r s t , the low temperature c r y s t a l l i z a t i o n problem which can no doubt be e a s i l y c o r r e c t e d . Second, and more important, there i s no c u r r e n t economic source of TMO. For example, trimethylene g l y c o l , a p o s s i b l e p r e c u r s o r , s e l l s f o r about $4/lb. i n volume. Thus the development o f t h i s i n t e r e s t i n g f a m i l y o f elastomers based on TMO must await the development o f a low cost route to t h i s monomer. Acknow1edgment The a s s i s t a n c e o f Hercules personnel i n the c a r r y i n g out o f t h i s work i s g r a t e f u l l y acknowledged, p a r t i c u l a r l y Dr. T. J . Prosser f o r the s y n t h e s i s o f 3,3-bis(allyloxymethyl)oxetane, Dr. F. E. Williams f o r the s y n t h e s i s o f 3,3-dimethyloxetane, and S. F. Dieckmann f o r the continuous bulk p o l y m e r i z a t i o n o f 3,3-bis(chloromethyl)oxetane c i t e d . Summary The f i r s t c o o r d i n a t i o n p o l y m e r i z a t i o n o f an oxetane, t r i methylene oxide (TMO), occurs r e a d i l y , much l i k e propylene oxide (PO) , with the Et3Al-H20-acetyl acetone c a t a l y s t at 6 5 ° C , to give high molecular weight polymer ( n ^ ^ up to 12) . TMO copolymerizes with epoxides with t h i s c o o r d i n a t i o n c a t a l y s t . For example, TMO copolymerized w e l l with a l l y l g l y c i d y l ether (AGE) which was about seven times more r e a c t i v e than TMO, i n c o n t r a s t to the PO-AGE copolymerization i n which both monomers are o f equal r e a c t i v i t y . A 96-4 TMO-AGE copolymer prepared under c o n d i t i o n s to make i t r e a sonably uniform gave an i n t e r e s t i n g s u l f u r - c u r a b l e elastomer. P r e l i m i n a r y v u l c a n i z a t e data on t h i s elastomer show good t e n s i l e and t e a r p r o p e r t i e s , a low Tg (-75°C.), high r e s i l i e n c e , and good heat r e s i s t a n c e . Further development of t h i s f a m i l y o f i n t e r e s t ing elastomers r e q u i r e s a lower cost route to TMO. Copolymerizations o f TMO with other epoxides and oxetanes as w e l l as the polymerization o f other oxetanes are a l s o d e s c r i b e d . Literature Cited 1. Boardman, Η., E n c y l . o f Chem. Tech., 2nd Supplement, 655.

(1960),

2. Dreyfuss, P. and Dreyfuss, M. P., "Polymerization o f 1,3 Epoxides" i n "Ring Opening P o l y m e r i z a t i o n " (K. C. F r i s c h and S. L. Reegen, eds.), Marcel Dekker, Inc., New York, 1969, Chap. 2-2.


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3. Rose, J. Β., J. Chem. Soc. 1956, 542, 546. 4. Vandenberg, E. J. (to Hercules Incorporated), U.S. Pat. 3,205,183 (1965). 5. Vandenberg, E. J., J. Polym. Sci., A1, (1969), 7, 525. 6. P r i c e , C. C., Chemist

(1961), 38, 131.


7. P r i c e , C. C., (assigned t o U n i v e r s i t y Pat. 2,866,774 (1958).

o f Notre Dame), U.S.

8. P r u i t t , M. E. and Baggett, J. M., (to Dow Chemical Co.), U.S. Pat. 2,706,181 (1955). 9. P r i c e , C. C. and Osgan, M., J. Amer. Chem. Soc. (1956), 78, 4787. 10. Osgan, M. and P r i c e , C. C., J. Polym. Sci., (1959), 34, 153. 11. P r i c e , C. C., (to General T i r e and Rubber Co.), Br. Pat. 893,275 (1962). 12. Hill, F. N., Bailey, Jr., F. E., and F i t z p a t r i c k , J. T., Ind. Eng. Chem., (1958), 50, 5. 13. Staudinger, H. and Lohmann, Η., Ann. Chem. (1933), 505, 41. 14. B a i l e y , Jr., F. Ε., Hill, F. N., and F i t z p a t r i c k , J. T., (to Union Carbide Corp.) U.S. Pat. 3,100,750 (1963). 15. B a i l e y , Jr., F. E., Hill, F. N., and F i t z p a t r i c k , J. T., (to Union Carbide Corp.) U.S. Pat. 2,969,402 (1961). 16. B a i l e y , Jr., F. E., Hill, F. N., and F i t z p a t r i c k , J. T., (to Union Carbide Corp.) U.S. Pat. 3,062,755 (1962). 17. B a i l e y , Jr., F. E., (to Union Carbide Corp.) U.S. Pat. 3,031,439 (1962). 18. Vandenberg, E. J., J. Polym. Sci. (1960), 47, 486. 19. Gruber, Ε. E., Meyer, D. Α., Swart, G. H., and Weinstock, Κ. U., Ind. Eng. Chem. Prod. Res. Develop. (1964), 3 ( 3 ) , 194. 20. Vandenberg, E. J. ( t o Hercules Incorporated), U.S. Pat. 3,728,320 (1973). 21. Vandenberg, E. J. (to Hercules Incorporated), U.S. Pat. 3,728,321 (1973).


7.

VANDENBERG

A N D ROBINSON

Trimethylene Oxide

22. Schmoyer, L. F. and Case, L. C., Nature (1960), 187, 592. 23. Kemp, A. R. and M u e l l e r , G. S., Ind. Eng. Chem. Anal. Ed. (1934), 6, 52.


24. Yamashita, Y., Tsuda, T., Okada, M., and Iwatsuki, S., J. Polym. Sci., A1, (1966), 4, 2121.


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Coordination Polymerization of Trimethylene Oxide - American

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