Chemical Reactions on Polymers - American Chemical Society

Chapter

4

Chemical Modification of Poly(2,6-dimethyl-1,4-phenylene oxide) and Properties of the Resulting Polymers Downloaded by UCSF LIB CKM RSCS MGMT on November 28, 2014 | http://pubs.acs.org Publication Date: December 22, 1988 | doi: 10.1021/bk-1988-0364.ch004

Simona Percec and George Li Standard Oil Research and Development, 4440 Warrensville Center Road, Cleveland, OH 44128

The chemical modification of poly (2,6-dimethyl-1,4phenylene oxide) (PPO) by several polymer analogous reactions is presented. The chemical modification was accomplished by the electrophilic substitution reactions such as: bromination, sulfonylation and acylation. The permeability to gases of the PPO and of the resulting modified polymers is discussed. Very good permeation properties to gases, better than for PPO were obtained for the modified structures. The thermal behavior of the substituted polymers resembled more or less the properties of the parent polymer while their solution behavior exhibited considerable differences. A l t h o u g h t h e use o f polymers as membrane m a t e r i a l s has i n c r e a s e d m a r k e d l y (1-3), t h e development o f s t r u c t u r e / p e r m e a b i l i t y r e l a t i o n s h i p has l a g g e d and i s an i m p o r t a n t a r e a o f f u t u r e investigations. Among t h e many a r o m a t i c polymers which p o s s e s s h i g h g l a s s t r a n s i t i o n t e m p e r a t u r e s , PPO (T =212*C) shows t h e h i g h e s t p e r m e a b i l i t y t o gases. One s i g n i f i c a n t f a c t o r i n i t s h i g h p e r m e a b i l i t y stems from l a r g e d i f f u s i o n c o e f f i c i e n t s o f gases i n PPO as compared t o o t h e r g l a s s y polymers w i t h r i g i d c h a i n backbone (4.) . In s p i t e o f t h i s , t h e r e l a t i v e l y low s e l e c t i v i t y t o gases a s s o c i a t e d w i t h t h e l a c k o f s o l u b i l i t y i n c o n v e n t i o n a l membrane forming d i p o l a r a p r o t i c solvents prevented the f a c i l e preparation of PPO membrane systems f o r a c t u a l use i n gas s e p a r a t i o n s . S e v e r a l s t u d i e s have a p p e a r e d i n t h e l i t e r a t u r e (5-9) d e s c r i b i n g t h e r e a c t i o n s o f v a r i o u s compounds w i t h PPO i n o r d e r t o change t h e p r o p e r t i e s o f t h i s polymer b u t none o f them have v a l u e d t h e c h e m i c a l s t r u c t u r e i n terms o f gas p e r m s e l e c t i v i t y b e h a v i o r . In o u r r e s e a r c h , t h r e e c h e m i c a l m o d i f i c a t i o n approaches were i n v e s t i g a t e d : bromination, s u l f o n y l a t i o n , and a c y l a t i o n on t h e a r o m a t i c r i n g . The s p e c i f i c o b j e c t i v e o f t h i s p a p e r i s t o p r e s e n t t h e c h e m i c a l m o d i f i c a t i o n on t h e PPO backbone by a v a r i e t y o f e l e c t r o p h i l i c s u b s t i t u t i o n r e a c t i o n s and t o examine t h e f e a t u r e s t h a t d i s t i n g u i s h m o d i f i e d PPO from u n m o d i f i e d PPO w i t h r e s p e c t t o gas p e r m e a t i o n p r o p e r t i e s , polymer s o l u b i l i t y and t h e r m a l b e h a v i o r . G

0097-6156/88/0364-0046$06.00/0 © 1988 American Chemical Society

In Chemical Reactions on Polymers; Benham, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1988.

4. PERCEC AND LI

Poly(g,6-dimethyl-l,4-phenylene

oxide)

47

Experimental

Downloaded by UCSF LIB CKM RSCS MGMT on November 28, 2014 | http://pubs.acs.org Publication Date: December 22, 1988 | doi: 10.1021/bk-1988-0364.ch004

Materials.. The s t a r t i n g PPO was purchased from A l d r i c h Chemical Co. Two r e p r e c i p i t a t i o n s from chloroform into methanol served to p u r i f y the polymer. The bromine, chlorosulfonic acid, s u l f o n y l chlorides, a c i d chlorides as well as a l l other reagents and solvents were purchased from A l d r i c h Chemical Co. and were used without further purification. Aluminum t r i c h l o r i d e was sublimated i n a Pyrex glass tube p r i o r to use. Reactions. The bromination of the aromatic r i n g was achieved at room temperature using a known procedure . The sulfonylation reaction was performed i n a two-step process. The f i r s t step involved the reaction of PPO with chlorosulfonic acid according to a l i t e r a t u r e method (11). The sulfonated PPO was hygroscopic and unstable. We succeeded (12.) i n converting the sulfonate groups into stable sulfone groups by reacting them with aromatic compounds at elevated temperatures (120°C). The f i n a l dark solution was washed with d i l u t e sodium bicarbonate, and the product p r e c i p i t a t e d i n methanol, f i l t e r e d and dried. The F r i e d e l - C r a f t s substitution reactions (.13.) were c a r r i e d out i n nitrobenzene solution i n the presence of A1C1 , under nitrogen and a temperature range of 40-80 C. Sulfonyl chlorides (R S0 C1) and carboxylic a c i d chlorides (R C(0)C1) respectively, were used as s u l f o n y l a t i n g and acylating agents. After the required reaction time, the reaction mixture was washed with water u n t i l the pH was neutral. The separated polymer solution was dried over anhydrous MgS04, f i l t e r e d and p r e c i p i t a t e d i n methanol. A f i n a l p u r i f i c a t i o n was c a r r i e d out by p r e c i p i t a t i o n of the product from chloroform solution into methanol. The polymer was then vacuum dried to constant weight. The polymer films were prepared by d i s s o l v i n g the polymer i n a suitable solvent (chloroform) to form 7 wt% solutions. The solution was then poured over a clean glass plate and spread out evenly to a uniform thickness with the a i d of a doctor blade. The films were a i r dried, removed from the glass plate and further vacuum dried at 60 C for 72 hours. 3

e

1

2

2

e

Measurements. 200 MHz !H NMR spectra were recorded from CDC1 solu tions (TMS i n t e r n a l standard) on a Nicolet NT 200 spectrometer. DSC measurements were c a r r i e d out with a DuPont D i f f e r e n t i a l Scanning Calorimeter (Model 1090) under nitrogen atmosphere. The scanning rate was 10*C/min. i n a l l cases. Indium was used as a standard. Elemental analyses were performed by Standard O i l Research and Development A n a l y t i c a l Laboratory. A modified G i l b e r t c e l l (14.) was used to determine the gas permeation properties of polymer f i l m s . The t e s t i n g area of the f i l m was 45.8 cm . The f i l m thickness was i n a range of 1.27 χ 10~ mm - 2.81 χ 10~ mm. The test side was exposed to a carbon dioxide : methane : nitrogen mixture i n a mole r a t i o 3.11 : 33.6 : 63.29. The permeant was picked up by a c a r r i e r gas, helium, and injected i n t e r m i t t e n t l y through a sample valve into a gas chromâtograph for analysis. The p a r t i a l pressure of the test gas was 29.7 p s i (0.21 MPa) while the p a r t i a l pressure of the product gas on the permeant side was held at an i n s i g n i f i c a n t l e v e l by purging with 2 9.7 p s i 3

2

2


2

48

CHEMICAL REACTIONS ON POLYMERS

(0.21 MPa) h e l i u m a t a f l o w r a t e much i n e x c e s s rate.

of the permeation

R e s u l t s and D i s c u s s i o n B r o m i n a t e d PPO. The e l e c t r o p h i l i c a r o m a t i c b r o m i n a t i o n o f t h e PPO was c a r r i e d out i n c h l o r o f o r m s o l u t i o n t o y i e l d p o l y m e r s w i t h d i f f e r e n t degrees of s u b s t i t u t i o n . F o r the h i g h l y brominated s t r u c t u r e s t h e T expanded o v e r a c o n s i d e r a b l e t e m p e r a t u r e range. A maximum v a l u e o f 273'C was o b t a i n e d f o r 100 mol % b r o m i n a t e d PPO. The s o l u t i o n p r o p e r t i e s o f t h e b r o m i n a t e d PPO d e r i v a t i v e s were s i m i l a r t o t h o s e o f t h e p a r e n t polymer. The gas p e r m e a t i o n p r o p e r t i e s o f PPO and PPO c o n t a i n i n g between 6.5% t o 100% Br groups p e r r e p e a t u n i t a r e summarized i n T a b l e I .


G

The s t e a d y s t a t e s e p a r a t i o n f a c t o r (a) f o r t h e two gases (C0 and CH ) i s d e f i n e d as t h e r a t i o o f t h e i r i n d i v i d u a l p e r m e a b i l i t i e s . The gas p e r m e a b i l i t y c o n s t a n t s (P) a r e g e n e r a l l y e x p r e s s e d by t h e amount o f t h e gas a t s t a n d a r d t e m p e r a t u r e and p r e s s u r e n o r m a l i z e d f o r t h e t h i c k n e s s , membrane a r e a , time and d i f f e r e n t i a l p r e s s u r e o f gas as i n t h e f o l l o w i n g e q u a t i o n : 2

4

ρ

(Amount o f t h e gas) (Membrane t h i c k n e s s ) =

(Membrane area)

(Time)

( D i f f e r e n t i a l p r e s s u r e o f gas) 3

2

le

where Ρ i s e x p r e s s e d i n u n i t s cm (STP) c m » c m ~ » s ~ c m H g . P e r m e a b i l i t y i s a l s o as r e p o r t e d i n B a r r i e r , one B a r r i e r b e i n g e q u a l t o 1X10~ P. I t c a n be seen from T a b l e I t h a t no change e i t h e r i n p e r m e a b i l i t y f o r C 0 o r C0 /CH s e l e c t i v i t y was o b t a i n e d when t h e d e g r e e o f b r o m i n a t i o n f o r PPO i s low (6.5 m o l e % ) . However, a t h i g h e r l e v e l s o f b r o m i n a t i o n , t h e r e were i n c r e a s e s i n b o t h p e r m e a b i l i t y f o r C 0 and C0 /CH s e l e c t i v i t y . The maximum e f f e c t s (an i n c r e a s e o f 2.47 t i m e s f o r C 0 p e r m e a b i l i t y and 1.45 t i m e s f o r C0 /CH s e l e c t i v i t y t o t h a t o f PPO) were r e a c h e d a t 100% s u b s t i t u t i o n degree o f the aromatic r i n g . 10

2

2

2

4

2

4

2

2

4

S u l f o n y l a t e d PPO. The s u l f o n y l a t i o n i s a c h i e v e d by s u l f o n a t i o n r e a c t i o n on PPO, f o l l o w e d by t h e r e a c t i o n w i t h a r o m a t i c compounds as o u t l i n e d i n Scheme 1. No comments r e g a r d i n g t h e t h e r m a l and s o l u t i o n b e h a v i o r o f t h e p o l y m e r s o b t a i n e d by t h i s two s t e p p r o c e d u r e a r e i n c l u d e d here s i n c e t h e s e p r o p e r t i e s a r e d i s c u s s e d i n t h e next s e c t i o n f o r s u l f o n y l a t e d PPO m o d i f i e d under F r i e d e l - C r a f t s c o n d i t i o n s . The changes o f t h e C 0 p e r m e a b i l i t y and s e p a r a t i o n f a c t o r f o r C0 /CH , compared t o t h e t y p i c a l v a l u e s o f PPO s t a n d a r d a r e shown i n T a b l e I I f o r PPO m o d i f i e d w i t h d i f f e r e n t s u l f o n y l g r o u p s . The b e s t enhancement was o b t a i n e d f o r PPO c o n t a i n i n g p h e n y l s u l f o n e g r o u p s . The p r e s e n c e o f -S0 (OH) groups r e d u c e d t h e c a r b o n d i o x i d e p e r m e a b i l i t y by a f a c t o r o f t h r e e . T h i s can be e x p l a i n e d (JU5.) by t h e d e c r e a s e i n l o c a l segmental m o b i l i t y o f t h e polymer c h a i n s due t o t h e i n t e r a c t i o n s a r i s i n g from hydrogen b o n d i n g . However, t h e o v e r a l l t r a n s p o r t p r o c e s s f o r t h i s polymer membrane i s more c o m p l i c a t e d and i n v o l v e s a more pronounced d i s c r i m i n a t i o n a g a i n s t methane m o l e c u l e s due t o t h e h i g h l y p o l a r n a t u r e o f t h e polymer. T h i s l e a d s t o a t w o f o l d i n c r e a s e i n t h e C0 /CH s e p a r a t i o n f a c t o r . 2

2

4

2

2

4


4.

PERCEC AND LI

Table I .


No.

Poly(2,6'dimethyl-l,4-phenylene

The P e r m e a b i l i t y

Polymer

Substitution

49

oxide)

t o Gases o f B r o m i n a t e d PPO

*co

3

Degree )

«002/^4

2

b

(mol%)

(barrer) >

1.

PPO

0.0

64.00

16.40

2.

BRPPO

6.5

64.00

16.72

3.

BRPPO

21.5

67.20

17.71

4.

BRPPO

46.0

78.08

19.35

5.

BRPPO

61.0

99.84

18.04

6.

BRPPO

100.0

158.08

23.73

a)

Determined by elemental

b)

1 Barrer = 10"

10

analysis

[cm (STP) cm] / [cm «sec •cmHg] 3

2

α = Separation f a c t o r

SO,

CH

3

"

Ar Scheme 1. on PPO.

Two s t e p p r o c e d u r e o f s u l f o n y l a t i o n

reaction


50



Table I I .

No.

R

1.

2.

3.


t o Gases o f S u l f o n y l a t e d

Substitution Degree

Η Ο - S - C H CH 6

4

3

- S - C H (CH ) O 6

3

4.

Ο - S - C H

5.

-

6.

- S - OH 6

6

3

5

S - C H C H Ο 6

2

4

2

5

D e t e r m i n e d by e l e m e n t a l

a )

P

C0

a 2

(mol%)

(barrer)

0

64

PPO

C0 /CH 2

4

16.4

60

89.60

21.81

23

72.96

20.00

38

99.20

27.38

31

73.60

16.40

—

19.84

32.80

analysis.


4. P E R C E C A N D LI

Poly(2,6-dimethyl-l,4-phenylene oxide)

51

F r i e d e l - C r a f t s R e a c t i o n s on PPO and P r o p e r t i e s o f t h e R e s u l t i n g Polymers. There a r e two hydrogens on t h e a r o m a t i c r i n g o f PPO which can r e a c t t h r o u g h F r i e d e l - C r a f t s r e a c t i o n s . The s u b s t i t u t i o n o f t h e f i r s t a v a i l a b l e p o s i t i o n from t h e a r o m a t i c r i n g o c c u r s e a s i l y by t h e t r e a t m e n t o f t h e PPO w i t h s u l f o n y l c h l o r i d e o r a c i d c h l o r i d e s i n t h e presence of a F r i e d e l - C r a f t s c a t a l y s t . The r e m a i n i n g a r o m a t i c hydrogen c o u l d n o t be removed by a second a b s t r a c t i o n r e a c t i o n , and c o n s e q u e n t l y o n l y m o n o s u b s t i t u t i o n was a c h i e v e d . Table I I I p r e s e n t s t h e experimental r e a c t i o n c o n d i t i o n s used i n t h e s u l f o n y l a t i o n and a c y l a t i o n o f t h e PPO backbone and t h e degrees of s u b s t i t u t i o n obtained. The s u b s t i t u t i o n degree d e t e r m i n e d by H NMR s p e c t r o s c o p y was between 17.5% and 7 9 . 4 % , depending on t h e r e a c t i o n c o n d i t i o n s and s u l f o n y l a t i n g o r a c y l a t i n g agent. A complete s u b s t i t u t i o n o f t h e PPO a r o m a t i c r i n g s was n o t o b t a i n e d under t h e s e e x p e r i m e n t a l conditions. The p r e s e n c e o f one c a r b o n y l o r s u l f o n y l group a t t a c h e d t o a PPO p h e n y l r i n g , d r a s t i c a l l y d e c r e a s e s t h e n u c l e o p h i l i c i t y o f t h e r e m a i n i n g u n s u b s t i t u t e d p o s i t i o n and, t h e r e f o r e , no d i s u b s t i t u t i o n o f t h e p h e n y l e n i c u n i t s was r e a l i z e d . T h i s i s due t o t h e s t r o n g e l e c t r o n w i t h d r a w i n g c h a r a c t e r o f t h e c a r b o n y l and s u l f o n y l groups. A t t h e same time, when b u l k y s u b s t i t u e n t s a r e a t t a c h e d t o t h e PPO backbone, s t e r i c h i n d r a n c e a l s o d e c r e a s e s t h e a c c e s s a b i l i t y o f nearby u n s u b s t i t u t e d p o s i t i o n s (JL£) . Consequently, e l e c t r o n i c f a c t o r s r e t a r d t h e second e l e c t r o p h i l i c s u b s t i t u t i o n on t h e same PPO p h e n y l r i n g w h i l e s t e r i c f a c t o r s a l s o c o n t r i b u t e t o l i m i t t h e degree o f m o n o s u b s t i t u t i o n t o about 80%. T y p i c a l ^-H NMR s p e c t r a o f t h e s u l f o n y l a t e d PPO and a c y l a t e d PPO a r e p r e s e n t e d i n F i g u r e s 1-2 t o g e t h e r w i t h t h e assignment o f t h e i r p r o t o n i c r e s o n a n c e s (JJ7) . M u l t i p l e resonances from t h e a l i p h a t i c r e g i o n i n F i g u r e 1 a r e due t o t h e sequence d i s t r i b u t i o n o f t h e structural units. I t i s d i f f i c u l t t o p r o v i d e an e x a c t assignment f o r t h i s region at t h i s time. The p e r c e n t o f s u b s t i t u t i o n o f t h e PPO a r o m a t i c u n i t s was d e t e r m i n e d from t h e r a t i o o f t h e i n t e g r a l s o f p r o t o n r e s o n a n c e s due t o u n s u b s t i t u t e d 2 , 6 - d i m e t h y l - l , 4 - p h e n y l e n e u n i t s ( s i g n a l H a t 5=6.5 ppm) and s u b s t i t u t e d u n i t s ( s i g n a l at δ = 6 . 0 ppm).


1

a

In a l l c a s e s m o n o s u b s t i t u t i o n was demonstrated by m e a s u r i n g t h e r a t i o between t h e i n t e g r a l s o f t h e u n s u b s t i t u t e d a r o m a t i c p r o t o n o f t h e s u b s t i t u t e d p h e n y l e n i c u n i t s and some r e p r e s e n t a t i v e p r o t o n s from t h e newly a t t a c h e d pendant groups. F o r example, t h e r a t i o between t h e s i g n a l s c and e from s p e c t r a I I and I I I ( F i g u r e 1 ) , t h e r a t i o between t h e s i g n a l s c and f from t h e s p e c t r a IV and VI ( F i g u r e 2 ) , and c and e from t h e s p e c t r a VI ( F i g u r e 2) were u s e d t o demonstrate m o n o s u b s t i t u t i o n . Both t h e r m o g r a v i m e t r i c a n a l y s i s and d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r i c s t u d i e s were c a r r i e d out on m o d i f i e d and u n m o d i f i e d PPO samples. T a b l e IV p r e s e n t s t h e weight l o s s e s and t h e g l a s s t r a n s i t i o n t e m p e r a t u r e s o f t h e most r e p r e s e n t a t i v e p o l y m e r s . As was e x p e c t e d , t h e s u b s t i t u t i o n o f PPO w i t h r i g i d and b u l k y s i d e groups d e c r e a s e s t h e f l e x i b i l i t y o f t h e polymer c h a i n and t h e g l a s s t r a n s i t i o n t e m p e r a t u r e s o f m o d i f i e d polymers i n c r e a s e s . T h i s


52


Table I I I .

M o d i f i c a t i o n o f PPO under F r i e d e l - C r a f t s (PPO 5% S o l u t i o n i n N i t r o b e n z e n e )

Reaction Conditions


No.

Modifying

PPO:M.A.:A1C1

Agent

(mol:mol:mol)

Sulfonyl

3

Time

Conditions

Substitution

Temperature e

degree

(hours)

( C)

(mol %)

Chlorides

1.

N(CH ) S0 C1

1. 0: 1. 5: 0. 55

5. 0

70

32. 3

2.

C H S0 C1

1. 0: 1. 0: 1. 10

7 .0

80

60. 7

3.

BrC H S0 Cl

1. 0::1. 0: 1. 10

9.,5

80

59. 0

4.

CH C H S0 C1

1..0::1.,0::1.,10

7.,5

80

66. 6

3

6

2

5

2

2

6

4

3

6

2

4

2

5.

(CH ) C H S0 C1

1.,0::1.,0::1.,10

7..0

60

46. ,3

6.

j^^j^^j^o ci

1..0::1..0::1..10

8..5

80

63. ,5

1..0 :1 .0::1 .10

4 .0

50

42, .7

3

3

a

6

2

2

2

Acid Chlorides : 7 . C H C0C1 2

5

8.

CH (CH ) C0C1

1 .0 :1 .0 :1 .10

3 .0

50

58 .6

9.

CH (CH ) C0C1

1 .0 :1 .0 :1 .10

6 .0

50

59 .0

10. . C H ( C H ) C 0 C 1

1 .0 :0 .5 :0 .55

3 .0

50

17 .5

11. , C H ( C H ) C 0 C 1

1 .0 :1 .0 :1 .10

6 .0

50

55 .0

12. , C H ( C H ) C 0 C 1

1 .0 :1 .0 :1 .10

6 .5

50

50 .0

13. , C H C H C 0 C 1

1 .0 :0 .5 :0 .55

6 .0

50

29 .2

14. , C H C H C 0 C 1

1 .0 :1 .0 :1 .10

8 .0

60

79 . 4

3

2

3

2

3

2

3

6

)

2

5

3

1 Q

2

3

a

2

1 2

1 2

1 4

2

6

4

1

d e t e r m i n e d by H NMR M.A. - m o d i f y i n g agent


P E R C E C A N D LI

Poly(2,6-dimethyl-l,4'phenylene

oxide)


4.

10

8

6

4

2

δ (ppm) 1

Figure 1. H NMR spectra of PPO ( I ) , PPO modified with benzene sulfonyl chloride (Sample No. 2, Table III) ( I I ) , and PPO modified with p-toluenesulfonyl chloride (Sample No. 4, Table III) (III) Reproduced with permission from Ref. 17. Copyright 1987, Wiley.)


54


I.CH3

yCH

"CH

t

3

a

φι:: CH t f

3

3


VI

CH

3

OCH t a

c =o

3

3

I CH -f I CH *-e I 2

2

(CH ) -g CH, *-d 2

2.0

1 0

d

\

1.0

CH

Q-o-dI^CH C = 0 I ÇH -f

p CC H f

3

3

O3

t

2

6.5

1.75

c

Vf

10

3.0

\

6

4 δ

M

I

2

CH -d 3

IV

(ppm)

Figure 2. H NMR spectra of PPO acylated with propionyl chloride (Sample No. 8, Table III) (IV), PPO acylated with myristoyl chloride (Sample No. 11, Table III) (V), and PPO acylated with £-toluoyl chloride (Sample No. 14, Table III) (VI). (Reproduced with permission from r e f . 17. Copyright 1987 Wiley.)


In Chemical Reactions on Polymers; Benham, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1988. 0-150

10

11

PPO a c y l a t e d w i t h myristoyl chloride

PPO a c y l a t e d w i t h myristoyl chloride

Source:

0-250

PPO s u l f o n y l a t e d with dimethyl sulfamoyl chloride

Reproduced with permission from Ref. 17.

0-200

100-200

PPO s u l f o n y l a t e d with p-toluenesulfonyl chloride

CO

75-175

Table I I I

200-300

150-300

250-325

200-300

175-300

CO

0.1

0.7

1.9

0.2

0.6

(%)

Weight L o s s

Zone I I Temp. Range

Copyright 1987, Wiley.

0.0

0.0

0.0

0.4

0.3

(%)

Weight L o s s

Zone I Temp. Range

PPO

Polymer

Number

Thermal C h a r a c t e r i z a t i o n o f PPO M o d i f i e d by F r i e d e l - C r a f t s

Corresponding t o

T a b l e IV.

300-400

300-400

325-400

300-400

300-400

CO

Temp. Range

3.0

2.5

11.7

3.5

0.2

(%)

Weight L o s s

Zone I I I

Reactions


T

G

165

116

245

225

212

CO

56


e f f e c t was e x e m p l i f i e d by t h e PPO m o d i f i e d w i t h p - t o l u e n e s u l f o n y l c h l o r i d e which has a T o f 2 6 5 C . S i m i l a r l y an i n c r e a s e i n t h e v a l u e o f t h e T was a l s o o b s e r v e d when PPO was m o d i f i e d w i t h p o l a r s u b s t i t u e n t s such as d i m e t h y l s u l f a m o y l group. In t h i s case t h e T v a l u e was 245*C. The i n c r e a s e i n t h e l e n g t h o f t h e s i d e c h a i n r e s u l t s n o r m a l l y i n an i n t e r n a l p l a s t i c i z a t i o n e f f e c t c a u s e d by a lower p o l a r i t y o f t h e main c h a i n and an i n c r e a s e i n t h e c o n f i g u r a t i o n a l e n t r o p y . Both e f f e c t s r e s u l t i n a lower a c t i v a t i o n e n e r g y o f segmental m o t i o n and c o n s e q u e n t l y a lower g l a s s t r a n s i t i o n t e m p e r a t u r e . The m o d i f i c a t i o n o f PPO w i t h m y r i s t o y l c h l o r i d e o f f e r s t h e b e s t example. No s i d e c h a i n c r y s t a l l i z a t i o n was d e t e c t e d by DSC f o r t h e s e p o l y m e r s . The s u l f o n y l a t e d and a c y l a t e d PPO p r e s e n t s s o l u b i l i t y c h a r a c t e r i s t i c s which a r e c o m p l e t e l y d i f f e r e n t from t h o s e o f t h e p a r e n t PPO. T a b l e V p r e s e n t s t h e s o l u b i l i t y o f some m o d i f i e d s t r u c t u r e s compared t o t h o s e o f u n m o d i f i e d PPO. I t i s v e r y i m p o r t a n t t o n o t e t h a t , a f t e r s u l f o n y l a t i o n , most o f t h e polymers become s o l u b l e i n d i p o l a r a p r o t i c s o l v e n t s l i k e d i m e t h y l s u l f o x i d e (DMSO), N,Nd i m e t h y l f o r m a m i d e (DMF) and N , N - d i m e t h y l a c e t a m i d e (DMAC). A t the same t i m e i t i s i n t e r e s t i n g t o mention t h a t , w h i l e PPO c r y s t a l l i z e s f r o m methylene c h l o r i d e s o l u t i o n , a l l t h e s u l f o n y l a t e d p o l y m e r s do n o t c r y s t a l l i z e and form i n d e f i n i t e l y s t a b l e s o l u t i o n s i n m e t h y l e n e c h l o r i d e . O n l y some o f t h e a c e t y l a t e d p o l y m e r s become s o l u b l e i n DMF and DMAC, and none a r e s o l u b l e i n DMSO. The polymers a c e t y l a t e d w i t h a l i p h a t i c a c i d c h l o r i d e s such as p r o p i o n y l c h l o r i d e are a l s o s o l u b l e i n acetone. The p e r m e a t i o n p r o p e r t i e s o f s u b s t i t u t e d PPO t o a c a r b o n d i o x i d e , methane, n i t r o g e n m i x t u r e were s t u d i e d f o r s e v e r a l systems. The r e s u l t s a r e presented i n Table V I . An i n c r e a s e i n p e r m e a b i l i t y t o g e t h e r w i t h an i n c r e a s e i n s e l e c t i v i t y f o r CO2/CH4 was c l e a r l y d e m o n s t r a t e d f o r PPO s u b s t i t u t e d w i t h p - t o l u e n e s u l f o n y l c h l o r i d e and f o r PPO s u b s t i t u t e d w i t h d i m e t h y l s u l f a m o y l c h l o r i d e (Table V I ) . An i n t e r e s t i n g example i s PPO m o d i f i e d w i t h m y r i s t o y l c h l o r i d e . This long side chain s u b s t i t u t e d polymer showed an i n c r e a s e i n p e r m e a b i l i t y f o r methane of 5.19 t i m e s w h i l e i t s p e r m e a b i l i t y f o r c a r b o n d i o x i d e remained almost unchanged. T h e r e f o r e i t s s e l e c t i v i t y t o C0 /CH d e c r e a s e s d r a m a t i c a l l y compared t o t h a t o f t h e p a r e n t polymer. However i t c a n be s p e c u l a t e d t h a t by v a r y i n g t h e l e n g t h o f t h e s i d e c h a i n o f t h e m o d i f i e d s t r u c t u r e s , c e r t a i n d i f f e r e n c e s i n p e r m e a b i l i t y among d i f f e r e n t h y d r o c a r b o n gases a r e l i k e l y t o o c c u r . T h i s i s an i m p o r t a n t a s p e c t which may p r o v e u s e f u l f o r h y d r o c a r b o n / h y d r o c a r b o n separations. e

G

G


G

2

4

Conclusions C h e m i c a l m o d i f i c a t i o n s o f PPO by e l e c t r o p h i l i c s u b s t i t u t i o n o f t h e a r o m a t i c backbone p r o v i d e d a v a r i e t y o f new s t r u c t u r e s w i t h improved gas p e r m e a t i o n c h a r a c t e r i s t i c s . I t was f o u n d t h a t t h e s u b s t i t u t i o n degree, main c h a i n r i g i d i t y , t h e b u l k i n e s s and f l e x i b i l i t y o f t h e s i d e c h a i n s and t h e p o l a r i t y o f t h e s i d e c h a i n s a r e major p a r a m e t e r s c o n t r o l l i n g t h e gas p e r m e a t i o n p r o p e r t i e s o f the polymer membrane. The b r o a d range o f s o l v e n t s a v a i l a b l e f o r t h e m o d i f i e d s t r u c t u r e s enhances t h e p o s s i b i l i t y o f f a c i l e p r e p a r a t i o n o f PPO b a s e d membrane systems f o r use i n gas s e p a r a t i o n s .



Benzenesulfonyl chloride

ρ-Toluenesulfonyl c h l o r i d e

Naphthalenesulfonyl chloride

Dimethylsulfamoyl

p-Toluoyl chloride

Propionyl chloride

Lauroyl chloride

Palmitoyl chloride

Phenyl

S o l u b l e > 1 g/100 ml Insoluble

Tendency t o c r y s t a l l i z e

2.

3.

4.

5.

6.

7.

8.

9.

10.

+

+

Source:

None

1.

from

solution

+

+

+

+

+

+

+

+

+

+

-

+

+

-

-

+

+

-

+

+

+

+

-

+

+

+

±

±

DMSO

Reactions

+

+

+

+ +

+

+

DMF

Solvent

C o p y r i g h t 1987, W i l e y .

Chloroform

Methylene Chloride

o f PPO M o d i f i e d by F r i e d e l - C r a f t s

Reproduced w i t h p e r m i s s i o n from Ref. 17.

acetyl chloride

chloride

Modifying Agent

Solubility

No.

T a b l e V.

+

-

-

+

+

+

+

+

+

DMAC


+

+

+

+

+

+

+

+

+

THF

Acetone


Dimethylsulfamoyl

Myristoyl chloride (Polymer 11, T a b l e I I I )

3.

4.

Testing

Toluenesulfonyl

2.

e

t e m p e r a t u r e = 25 C

chloride

None

1.

chloride

Agent

CH 4

20.26

3.31

3.20

3.90

p


No.

Modifying

Table VI.

co 2

58.09

80.99

75.00

64.00

(barrer)

p

N 2

11.84

2.45

1.55

3.30

P

t o Gases o f PPO M o d i f i e d

a

2.87

24.47

23.40

16.40

2

C0 /CH

by F r i e d e l - C r a f t s


4

a

4

1.71

1.35

2.06

1.18

CH /N

Reactions

2


4. P E R C E C A N D LI

Poly(2,6-dimethyl-l,4-phenylene oxide)

59

References 1. A.J. Erb and D.R. Paul, J. Membr. Sci., 8, 11 (1981). 2. D.R. Paul, J. Membr. Sci., 18, 75 (1984). 3. J.W. Barlow and D.R. Paul, J. Appl. Polym. Sci., 21, 845 (1984). 4. K. Toi, G. Morel and D.R. Paul, J. Appl. Polym. Sci., 27, 2997 (1982). 5. L. Verdet and J.K. Stille, Organometallics, 1, 380 (1982). 6. R. P. Kambour, J. T. Bendler and R. C. Bopp, Macromolecules, 16, 753 (1983). 7. A.J. Chalk and A.S. Hay, J. Polym. Sci., Part A-1. 7, 691 (1968). 8. S. Xie, W.J. MacKnight and F.E. Karasz, J. Appl. Polym. Sci., 29, 1678 (1984). 9. I. Cabasso, J.J. Grodzinski and D. Vofsi, J. Appl. Polym. Sci., 18, 1969 (1974). 10. D.M. White and C.M. Orlando, ACS Symp. Series 6, 178 (1975). 11. W.J. Ward III and Robert M. Salemne (to General Electric) U.S. Pat. 3,780,496 (1973). 12. G. Li, U.S. Pat. 4,521,224 (1985). 13. E.S. Percec and G. Li, U.S. Pat. 4,596,860 (1986). 14. R.A. Pasternak, J.F. Schimscheimer and J. Heller, J. Polym. Sci., Part A-2, 8, 467 (1970). 15. C.E. Rogers, in Recent Development in Separation Science, Vol. II, N.N. Li ed., CRC Press, p. 107, 1975. 16. G.A. Olaf, S. Kobayashi and J. Nishimura, J. Am. Chem. Soc., 564 (1973). 17. S. Percec, J. Appl. Polym. Sci., 33, 191 (1987). R E C E I V E D August 27, 1987


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