Reactive Oligomers - American Chemical Society

7 Ethynyl End-Capped Polyimide Oligomers Containing Oxyethylene Linkages Synthesis and Characterization F R A N K W. HARRIS and K. SRIDHAR

Downloaded by YORK UNIV on March 2, 2015 | http://pubs.acs.org Publication Date: July 9, 1985 | doi: 10.1021/bk-1985-0282.ch007

Institute of Polymer Science, The University of Akron, Akron, O H 44325

Several ethynyl end-capped polyimide oligomers were prepared from 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,2-bis(4-aminophenoxy)ethane (1a), bis[2-(4aminophenoxy)]ethyl ether (1b), 1,2-bis[2-(4-aminophenoxy)ethoxy]ethane (1c), bis[2-(4-aminophenoxy)ethoxy]ethyl ether (1d), 1,1-bis(3-aminophenoxy)ethane (2a), bis[2-(3-aminophenoxy)ethyl]ether (2b) and 3-aminophenylacetylene. The oligomers prepared from the linear diamines 1a-d were semicrystalline and insoluble in a l l organic solvents. They also rapidly underwent crosslinking near 300°C. The DSC thermograms of the crosslinked samples showed a strong melting endotherm between 335 and 348°C. The oligomers prepared from the non-linear diamines 2a and b were amorphous and soluble in NMP, DMAC, m-cresol, and tetrachloroethane. Their Tg's ranged between 132 and 168°C. These oligomers underwent crosslinking at 300°C considerably slower than the crystalline systems. The Tg's of the crosslinked materials ranged between 147 and 245°C. The o v e r a l l g o a l o f t h i s c o n t i n u i n g r e s e a r c h e f f o r t h a s b e e n t h e d e v e l o p m e n t o f new p o l y m e r i c s y s t e m s f o r u s e a s p l a n a r i z i n g c o a t i n g s in the microelectronics industry (1-3). In a d d i t i o n t o low d i e l e c t r i c c o n s t a n t s , t h e s e m a t e r i a l s must d i s p l a y e x c e l l e n t t h e r m a l s t a b i l i t y and high s o f t e n i n g temperatures. They must a l s o b e q u i t e s o l u b l e i n o r g a n i c s o l v e n t s (20-40 wt % ) , i n o r d e r t o be a p p l i e d by t h e preferred spin coating process. Our approach t o such systems h a s i n volved the synthesis of soluble polyimide oligomers that are end-capped w i t h f u n c t i o n a l groups t h a t undergo t h e r m a l l y - i n i t i a t e d p o l y m e r i zations. Thus, t h e m a t e r i a l s c a n be a p p l i e d from s o l u t i o n and then thermally crosslinked. F u n c t i o n a l groups containing a l k y n y l moieties have been used so t h a t t h e generated c r o s s l i n k s a r e t h e r m a l l y s t a b l e . The s y s t e m s h a v e a l s o b e e n d e s i g n e d t o u n d e r g o s i g n i f i c a n t f l o w p r i o r to the i n i t i a t i o n of the cure process i n order t o a i d the p l a n a r i zation process.

0097-6156/85/0282-0081$06.00/0 © 1985 American Chemical Society

In Reactive Oligomers; Harris, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

REACTIVE OLIGOMERS

82

The m a j o r o b j e c t i v e o f t h i s r e s e a r c h w a s t o i n v e s t i g a t e t h e u s e of diamines c o n t a i n i n g o x y e t h y l e n e l i n k a g e s i n t h e p r e p a r a t i o n of oligomers of t h i s type. Such d i a m i n e s have been used i n t h e p r e p a r a t i o n of soluble, high-molecular-weight polyimides that exhibited 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 ( T g ' s ) a s l o w a s 140°C a n d good t h e r m a l s t a b i l i t y (_4 ) . The s p e c i f i c o b j e c t i v e s o f t h i s work w e r e : ( a ) t o prepare anhydride-terminated oligomers of 3,3*,4,4 -benzophenonetet r a c a r b o x y l i c d i a n h y d r i d e (BTDA) a n d 1 , 2 - b i s ( 4 - a m i n o p h e n o x y ) e t h a n e (la), bis[2-(4-aminophenoxy)]ethyl ether ( l b ) , 1,2-bis[2-(4-amino phenoxy) ethoxy]ethane ( l c ) , and b i s [ 2 - ( 4 - a m i n o p h e n o x y ) e t h o x y ] e t h y l e t h e r ( I d ) ; (b) t o end-cap t h e above o l i g o m e r s w i t h 3 - a m i n o p h e n y l acetylene (ΑΡΑ); (c) to c h a r a c t e r i z e the oligomers w i t h regard to t h e i r s o l u b i l i t i e s , t r a n s i t i o n temperatures and e f f e c t i v e curing tem p e r a t u r e ; and (d) t o e v a l u a t e t h e t h e r m a l p r o p e r t i e s o f t h e cured resins.


1

Results

and D i s c u s s i o n

Monomers. BTDA a n d Α Ρ Α w e r e o b t a i n e d f r o m G u l f C h e m i c a l s . BTDA w a s r e c r y s t a l l i z e d f r o m a c e t i c a n h y d r i d e p r i o r t o u s e , a n d ΑΡΑ was d i s t i l l e d under reduced p r e s s u r e . Diamines la-*d were p r e p a r e d f r o m 1 - f l u o r o - 4 - n i t r o b e n z e n e and t h e a p p r o p r i a t e g l y c o l a c c o r d i n g t o t h e known p r o c e d u r e ( 4 ) . As d e s c r i b e d i n the f o l l o w i n g s e c t i o n , t h e i n i t i a l oligomers p r e p a r e d f r o m l a - d were s e m i c r y s t a l l i n e and i n s o l u b l e i n o r g a n i c s o l vents. S i n c e i t was p o s t u l a t e d t h a t t h e s e p r o p e r t i e s were a s s o c i a t e d w i t h t h e h i g h d e g r e e o f symmetry p o s s e s s e d b y t h e d i a m i n e s , new n o n l i n e a r monomers w e r e s o u g h t t h a t w o u l d a f f o r d s o l u b l e , a m o r p h o u s systems. Thus, 1,2-bis(3-aminophenoxy)ethane (2a) and b i s [ 2 - ( 3 - a m i n o phenoxy) e t h y l ] e t h e r (2b) were p r e p a r e d b y t r e a t i n g t h e sodium s a l t of m-aminophenol w i t h 1,2-dibromoethane and 2 - c h l o r o e t h y l e t h e r , r e s p e c tively. The w h i t e d i a m i n e s were p u r i f i e d by r e c r y s t a l l i z a t i o n f r o m ethanol.

D

M

S

(CICH CH ) 0

0

2

H N ^^0(CH CH 0) 2

>

2

2

n x Y

^ NH Y

2

2

2

2a,b

O l i g o m e r s o f BTDA a n d L i n e a r D i a m i n e s . A series of ethynyl end-cap ped p o l y i m i d e o l i g o m e r s was s y n t h e s i z e d by t h e f o l l o w i n g r o u t e . F i r s t , a n h y d r i d e - t e r m i n a t e d , polyamic a c i d oligomers were prepared by a l l o w i n g e x c e s s BTDA t o r e a c t w i t h d i a m i n e s l a - d i n DMAC a t a m b i e n t temperature. T h e m o l a r r a t i o s o f BTDA t o d i a m i n e e m p l o y e d w e r e 2 t o 1 a n d 4 t o 3 . P r o c e d u r e s w e r e f o l l o w e d i n w h i c h BTDA w a s a d d e d t o


7.

83

Ethynyl End-Capped Polyimide Oligomers

HARRIS A N D SRIDHAR

t h e d i a m i n e and v i c e v e r s a . The t e r m i n a l a n h y d r i d e m o i e t i e s w e r e t h e n a l l o w e d t o r e a c t w i t h ΑΡΑ. The o l i g o m e r s w e r e d e h y d r a t e d b y t h e r m a l and c h e m i c a l m e t h o d s . In the t h e r m a l method, a f t e r t o l u e n e was added t o t h e p o l y a m i c a c i d s o l u t i o n s , they were h e a t e d t o n e a r 100°C where t h e w a t e r o f i m i d i z a t i o n was removed by a z e o t r o p i c d i s tillation. The p o l y a m i c a c i d s w e r e a l s o d e h y d r a t e d by t r e a t m e n t w i t h

Exes,

«·Μ0°Οζ}>

+

H^Q^fCH^O^NHa

.


io-d

HCEC

HCEC

3CH 3a-d

an e q u a l - m o l a r m i x t u r e of a c e t i c a n h y d r i d e and p y r i d i n e a t ambient t e m p e r a t u r e , and by s t i r r i n g i n r e f l u x i n g a c e t i c a n h y d r i d e . The r e s u l t i n g p o l y i m i d e s , which p r e c i p i t a t e d as the r e a c t i o n s proceeded, were i n s o l u b l e i n o r g a n i c s o l v e n t s at ambient temperature. They d i d d i s p l a y v e r y l i m i t e d s o l u b i l i t i e s ( 1 - 2 w t %) i n r e f l u x i n g m - c r e s o l a n d NMP. T h e i r i n f r a r e d s p e c t r a c o n t a i n e d s t r o n g a b s o r p t i o n bands at 1 7 8 0 a n d 720 c m " , c h a r a c t e r i s t i c o f i m i d e s . The X - r a y d i f f r a c t i o n p a t t e r n s o f 3b a n d £ w e r e c h a r a c t e r i s t i c o f h i g h l y - c r y s t a l l i n e s o l i d s The DSC t h e r m o g r a m s o f t h e o l i g o m e r s showed b a r e l y p e r c e p t i b l e b a s e l i n e s h i f t s b e t w e e n 140 a n d 175°C f o l l o w e d by b r o a d e x o t h e r m s w i t h m a x i m a n e a r 2 8 0 ° C ( T a b l e I, F i g u r e 1 ) . O l i g o m e r 3a d i d n o t d i s p l a y a t r a n s i t i o n p r i o r to the onset of i t s exotherm. TGA t h e r m o g r a m s o f o l i g o m e r s _3a a n d b_ o b t a i n e d i n a i r a n d n i t r o g e n w i t h h e a t i n g r a t e s o f 1 0 ° / m i n s h o w e d 5% w e i g h t l o s s e s n e a r 4 1 0 a n d 4 7 0 ° C , r e s p e c tively. O l i g o m e r s _3c a n d d. d i s p l a y e d 5% w e i g h t l o s s e s n e a r 3 6 5 ° C i n a i r and n e a r 460°C i n n i t r o g e n ( F i g u r e s 2 & 3 ) . Although they d i d d a r k e n s l i g h t l y n e a r 3 0 0 ° C , none o f t h e o l i g o m e r s showed any t e n d e n c y t o f l o w when t h e y w e r e h e a t e d t o 3 2 0 ° C o n a F i s h e r - J o h n s m e l t i n g point apparatus. 1

In o r d e r t o study t h e i r c u r e b e h a v i o r , samples o f each o l i g o m e r w e r e h e a t e d f o r 1 0 , 2 0 , a n d 30 m i n a t 300°C u n d e r n i t r o g e n . T h e DSC thermograms of samples h e a t e d f o r 10 m i n d i d n o t c o n t a i n c u r i n g e x o t h e r m s , and were e s s e n t i a l l y i d e n t i c a l t o t h o s e of samples h e a t e d f o r 30 m i n ( F i g u r e 1 ) . I n f a c t , t h e t h e r m o g r a m o f a s a m p l e o f 3b t h a t



84

REACTIVE OLIGOMERS

40

80

120

160

200 240 280 Temperature

F i g u r e 1. DSC t h e r m o g r a m s o f o l i g o m e r w i t h a h e a t i n g r a t e of 20°C/min.

0

100

200

300

400

320 (°C)

360

400

3c_ o b t a i n e d

500

600

Temperature F i g u r e 2. a heating

TGA t h e r m o g r a m s o f r a t e of 10°C/min.

oligomers

in

3a-d obtained

440

480

nitrogen

700 (°C) in air


with





85

86

REACTIVE OLIGOMERS

I.

Table

Thermal

3a 3b 3c 1 3c 2 3d

of

Oligomers

3a-d

a

Tg

Tc° (Onset)

Tc (Max)

TGA (Air)

TGA (N )

172 167 170 145

185 235 240 235 225

272 277 280 308 280

410 410 365 360 365

470 465 460 410 430

b

01 igomer

Properties

e

2


a.

A l l o f t h e o l i g o m e r s e x c e p t 3 c 2 w e r e p r e p a r e d f r o m a 2:1 m o l a r m i x t u r e o f BTDA t o d i a m i n e . O l i g o m e r 3c2 was p r e p a r e d f r o m a 4 : 3 molar mixture. The p o l y a m i c a c i d i n t e r m e d i a t e s were i m i d i z e d by s t i r r i n g i n r e f l u x i n g a c e t i c anhydride. b . T e m p e r a t u r e a t w h i c h a s l i g h t b a s e l i n e s h i f t o c c u r r e d i n DSC thermogram ( h e a t i n g r a t e = 20°C/min). A l l temperatures reported a r e i n °C. c . O n s e t t e m p e r a t u r e o f c u r i n g e x o t h e r m i n DSC t h e r m o g r a m . d . Maximum o f c u r i n g e x o t h e r m i n DSC t h e r m o g r a m . e . T e m p e r a t u r e a t w h i c h a 5% w e i g h t l o s s o c c u r r e d o n TGA t h e r m o g r a m (heating r a t e = 10°C/min). h a d b e e n q u i c k l y h e a t e d ( 2 0 ° C / m i n ) t o 3 0 0 ° C i n t h e DSC c e l l a n d t h e n a l l o w e d t o c o o l o n l y c o n t a i n e d a v e r y weak e x o t h e r m . Thus, t h e e t h y n y l g r o u p s must have undergone u n u s u a l l y f a s t t h e r m a l p o l y m e r i zations. T h i s b e h a v i o r i s i n marked c o n t r a s t t o t h a t of p r e v i o u s l y p r e p a r e d e t h y n y l - t e r m i n a t e d o l i g o m e r s , w h i c h have r e q u i r e d h e a t i n g c y c l e s o f s e v e r a l h o u r s t o c o m p l e t e t h e c u r i n g p r o c e s s ( 3 ) . The t h e r m o g r a m s a l s o d i d n o t show a n y b a s e l i n e s h i f t s t h a t c o u l d b e attributed to Tg s. H o w e v e r , w i t h t h e e x c e p t i o n o f _3a, t h e y d i d c o n t a i n s t r o n g m e l t i n g endotherms b e t w e e n 335 a n d 350°C ( T a b l e I I ) . f

Table

II.

Curing a

Oligomer 3b 3c 1 3c 2 3d

Study

of Oligomers 3a-d

Tm

Tm

345 340 362 337

348 343 359 335

a.

Minimum o f m e l t i n g endotherm f o r 1 0 m i n a t 300°C u n d e r N b . S a m p l e w a s h e a t e d f o r 20 m i n determination. c . Sample was h e a t e d f o r 30 m i n determination. 2

Tm

b

C

348 342

-

335

o n DSC t h e r m o g r a m . Sample was h e a t e d prior to determination. a t 300°C u n d e r N p r i o r t o 2

a t 300°C u n d e r N

2

prior

to

S u r p r i s i n g l y , t h e X - r a y d i f f r a c t i o n p a t t e r n o f a c u r e d s a m p l e o f j3c was c o n s i d e r a b l y s h a r p e r t h a n t h a t o f an u n c u r e d s a m p l e . A l l of these r e s u l t s suggest t h a t t h e e t h y n y l groups were c l o s e l y a l i g n e d i n the oligomers u n i t c e l l s and underwent p o l y m e r i z a t i o n p r i o r t o t h e crystals melting. In t h e c a s e of 3 a , t h e r m a l c r o s s l i n k i n g must have r e s u l t e d i n a m a t e r i a l w i t h a Tm h i g h e r t h a n i t s d e c o m p o s i t i o n temperature. 1


7.

87



O l i g o m e r s o f BTDA a n d N o n - L i n e a r D i a m i n e s . In an a t t e m p t t o o b t a i n s o l u b l e , a m o r p h o u s o l i g o m e r s , BTDA w a s t r e a t e d w i t h v a r i o u s a m o u n t s o f d i a m i n e s 2a_ a n d I D . The r e a c t i o n s w e r e c a r r i e d o u t a s d e s c r i b e d f o r o l i g o m e r s 3 a - d w i t h NMP a s s o l v e n t . T h e m o l a r r a t i o s o f BTDA t o d i a m i n e used were 2 : 1 , 4 : 3 , 8 : 7 , 1 0 : 9 , 1 4 : 1 3 , 20:19 and 25:24 (Table III). A f t e r the a d d i t i o n of ΑΡΑ, the p o l y a m i c a c i d s were Table III.


Oligomer 4a 4b 1 4b 2 4b 3 4b4 4b 5 4b6 4b 7 a.

Thermal P r o p e r t i e s of Oligomers

Molar R a t i o of BTDA t o D i a m i n e

Tg 168 132 135 137 143

4:3 2:1 4:3 8:7 10:9 14:13 20:19 25:24

143 146

Tfc (Onset)

Tc (Max)

270 240 227 235 250 255 255 265

308 272 280 307 315 318 323 330

4a,b

a

Γ Tg 218 245 188 168 163 147 162 157

TGÂ (N ) 2

465 457 448 446 452 445 441 436

P o l y a m i c a c i d i n t e r m e d i a t e s w e r e i m i d i z e d by s t i r r i n g i n r e f l u x i n g NMP f o r 2 h u n d e r N . For e x p l a n a t i o n of column headings see Table I. Tg o f c u r e d s a m p l e . S a m p l e w a s h e a t e d f o r 20 m i n a t 3 2 5 ° C u n d e r N p r i o r to determination. 2

b.

2

t h e r m a l l y i m i d i z e d by h e a t i n g t h e r e a c t i o n m i x t u r e t o r e f l u x and t h e n slowly d i s t i l l i n g off the evolved water w i t h solvent. Fresh solvent was c o n t i n u o u s l y added so a s t o m a i n t a i n a c o n s t a n t o l i g o m e r c o n c e n t r a t i o n o f 20 t o 25 w t %. If the d i s t i l l a t i o n - a d d i t i o n c y c l e were c a r r i e d o u t f o r more t h a n 3 h , t h e o l i g o m e r i c p r o d u c t s f o r m e d s e m i s o l i d , g e l - l i k e masses upon c o o l i n g . H o w e v e r , i f t h e h e a t i n g was stopped a f t e r 2 h, the products remained completely i n s o l u t i o n . It i s l i k e l y t h a t t h i s d i f f e r e n c e i n b e h a v i o r was due t o d i f f e r e n t d e grees of i m i d i z a t i o n . Although i n f r a r e d a n a l y s i s i n d i c a t e d t h a t the i m i d i z a t i o n p r o c e s s was o v e r 90% c o m p l e t e i n b o t h c a s e s , n o q u a n t i t a t i v e c o r r e l a t i o n s were made. The N M P - s o l u b l e o l i g o m e r s , w h i c h w e r e i s o l a t e d b y p r e c i p i t a t i o n i n e t h a n o l , w e r e a l s o s o l u b l e i n DMF, DMAC and t e t r a c h l o r o e t h a n e . The h i g h e r m o l e c u l a r w e i g h t m a t e r i a l s ( 4 b 6 , 4 b 7 ) c o u l d b e c a s t i n t o t o u g h , f l e x i b l e f i l m s f r o m NMP s o l u t i o n s . An X - r a y d i f f r a c t i o n p a t t e r n o f o l i g o m e r 4b1 d i d n o t s h o w a n y i n d i c a t i o n of c r y s t a l l i n i t y i n the sample. T h e DCS t h e r m o g r a m s o f t h e o l i g o m e r s c o n t a i n e d b a s e l i n e s h i f t s b e t w e e n 132 and 1 4 6 ° C , f o l l o w e d by s t r o n g c u r i n g e x o t h e r m s w i t h m a x i m a b e t w e e n 258 a n d 3 3 0 ° C . As seen i n T a b l e I I I , the oligomers' T g s and c u r i n g maxima i n c r e a s e d as t h e m o l e c u l a r w e i g h t i n c r e a s e d . V i s u a l o b s e r v a t i o n s on t h e F i s h e r - J o h n s a p p a r a t u s r e v e a l e d t h a t t h e r e s i n s u n d e r w e n t c o n s i d e r a b l e f l o w b e t w e e n 200 a n d 2 2 0 ° C . In f a c t , y e l l o w t r a n s p a r e n t f i l m s c o u l d be c o m p r e s s i o n molded from t h e n e a t r e s i n s a t 220°C. T h e TGA t h e r m o g r a m s o b t a i n e d i n n i t r o g e n w i t h h e a t i n g r a t e s o f 1 0 ° C / m i n s h o w e d 5% w e i g h t l o s s e s b e t w e e n 436 a n d 4 6 5 ° C . The s y s t e m s ' t h e r m a l s t a b i l i t i e s d e c r e a s e d as t h e i r m o l e c u l a r w e i g h t s increased. T h i s was most l i k e l y due t o t h e d e c r e a s e i n t h e number o f c r o s s l i n k s generated as the d i s t a n c e between c r o s s l i n k i n g s i t e s increased. f



88

REACTIVE OLIGOMERS

4α ,b

The amorphous o l i g o m e r s u n d e r w e n t t h e r m a l c r o s s l i n k i n g consider ably slower than t h e i r c r y s t a l l i n e counterparts. Although heating at 3 2 5 ° C f o r 20 m i n u n d e r n i t r o g e n p r o d u c e d s i g n i f i c a n t i n c r e a s e s i n t h e i r T g s , t h e i r DSC t h e r m o g r a m s s t i l l c o n t a i n e d c u r i n g e x o t h e r m s i n d i c a t i n g t h a t t h e c u r i n g p r o c e s s was n o t c o m p l e t e ( T a b l e I I I ) . The thermal treatment produced smaller increases i n the o l i g o m e r s ' T g s as t h e i r m o l e c u l a r w e i g h t i n c r e a s e d . T h i s can a l s o be a t t r i b u t e d t o a d e c r e a s e i n c r o s s l i n k d e n s i t y and t o a d e c r e a s e i n t h e c u r i n g r a t e as the c o n c e n t r a t i o n of s i t e s d e c r e a s e d . f

T

Conclusions E t h y n y l e n d - c a p p e d p o l y i m i d e o l i g o m e r s c a n b e p r e p a r e d f r o m BTDA a n d the l i n e a r diamines l a - d t h a t a r e h i g h l y c r y s t a l l i n e and i n s o l u b l e i n organic solvents. The o l i g o m e r s u n d e r g o r a p i d c r o s s l i n k i n g i n t h e c r y s t a l l i n e s t a t e near 280°C. The c r o s s l i n k e d r e s i n s a r e a l s o h i g h l y c r y s t a l l i n e and undergo m e l t i n g t r a n s i t i o n s n e a r 340°C. Isomers of t h e o l i g o m e r s c a n b e p r e p a r e d f r o m BTDA a n d t h e n o n - l i n e a r d i a m i n e s 2a,b t h a t a r e t o t a l l y amorphous and s o l u b l e i n s e v e r a l o r g a n i c s o l vents. These o l i g o m e r s w i l l a l s o s o f t e n and f l o w a t t e m p e r a t u r e s below those needed t o a f f e c t t h e i r t h e r m a l c u r e . The d r a m a t i c d i f f e r e n c e s i n o l i g o m e r morphology must be a s s o c i a t e d w i t h t h e c a t e n a t i o n o f t h e amine component i n t h e r e p e a t u n i t . A l l of the h i g h l y c r y s t a l l i n e m a t e r i a l s a r e p a r a c a t e n a t e d , w h i l e the amorphous systems c o n t a i n meta c a t e n a t i o n . Experimental IR s p e c t r a w e r e o b t a i n e d w i t h a P e r k i n - E l m e r M o d e l 1 3 3 0 g r a t i n g spectrophotometer. DSC t h e r m o g r a m s w e r e o b t a i n e d w i t h a D u P o n t


900

7.



89

Thermal Analyzer equipped w i t h a d i f f e r e n t i a l c a l o r i m e t r i c c e l l . TGA thermograms were o b t a i n e d on a DuPont 1090 T h e r m a l A n a l y z e r . Elemen t a l a n a l y s e s w e r e p e r f o r m e d by G a l b r a i t h L a b o r a t o r i e s , K n o x v i l l e , TN. 1,2-Bis(3-aminophenoxyethane)(2a). To a 2 5 0 - m L , 3 - n e c k e d f l a s k equipped w i t h a Dean-Stark t r a p , a condenser, a N i n l e t , a thermo m e t e r and a m a g n e t i c s t i r r i n g b a r were added 25.0 g (0.23 m o l ) of m - a m i n o p h e n o l , 50 mL o f DMS0 a n d 50 mL o f t o l u e n e . A f t e r the s o l u t i o n w a s p u r g e d w i t h N , 9 . 1 6 g ( 0 . 2 3 m o l ) o f 5 0 . 2 % NaOH w a s a d d e d . The m i x t u r e w a s h e a t e d w i t h s t i r r i n g t o 1 1 0 ° C . The w a t e r t h a t e v o l v e d f r o m t h e r e a c t i o n m i x t u r e was removed by a z e o t r o p i c d i s t i l l a t i o n . A f t e r m o s t o f t h e w a t e r h a d b e e n r e m o v e d , a n a d d i t i o n a l 20 mL o f t o l u e n e was a d d e d . The r e m a i n d e r o f t h e w a t e r was t h e n removed by i n c r e a s i n g the temperature to 120°C. The r e a c t i o n m i x t u r e w a s c o o l e d t o 5 0 ° C , a n d 2 1 . 5 g ( 0 . 1 1 m o l ) of 1 , 2 - d i b r o m o e t h a n e was s l o w l y a d d e d over a p e r i o d of 0.5 h. The e n s u i n g e x o t h e r m i c r e a c t i o n , w h i c h b e g a n i m m e d i a t e l y u p o n t h e a d d i t i o n o f 1 , 2 - d i b r o m o e t h a n e , was a c c o m p a n i e d by c o n s i d e r a b l e s a l t f o r m a t i o n . A f t e r t h i s r e a c t i o n had s u b s i d e d , t h e m i x t u r e was h e a t e d a t 6 0 ° C f o r 2 h . The s o l u t i o n w a s t h e n c o o l e d t o 50°C and f i l t e r e d t o remove N a B r . The f i l t r a t e was p o u r e d i n t o i c e c o l d w a t e r t o p r e c i p i t a t e 1 5 . 3 g (57%) of an o f f - w h i t e s o l i d t h a t was r e c r y s t a l l i z e d f r o m m e t h a n o l t o y i e l d w h i t e c r y s t a l s : mp 1 3 3 1 3 4 ° C ; IR ( K B r ) 3 3 8 0 a n d 3 3 0 0 c m " ( N H ) . Anal, calcd. for C^Hie^O* C, 6 8 . 8 5 ; H, 6 . 5 5 ; N, 1 1 . 4 7 . F o u n d : C, 6 8 . 8 0 ; H, 6 . 8 9 ; N, 1 1 . 3 4 . 2


2

1

2

2,2 -Bis(3-aminophenoxy)ethyl ether (2b). A s o l u t i o n of 25.0 g of t h e s o d i u m s a l t o f m - a m i n o p h e n o l i n DMSO, w h i c h w a s p r e p a r e d b y t h e m e t h o d d e s c r i b e d i n t h e p r o c e d u r e f o r 3la, was h e a t e d t o 1 1 0 ° C . 2C h l o r o e t h y l e t h e r ( 1 6 . 3 7 , 0.11 m o l ) was t h e n s l o w l y added o v e r a p e r i o d o f 15 m i n . A f t e r t h e r e a c t i o n m i x t u r e was h e a t e d a t 1 1 0 - 1 3 0 ° C f o r an a d d i t i o n a l 2 h , i t was f i l t e r e d t o remove t h e N a C l . The f i l t r a t e w a s c o o l e d a n d p o u r e d i n t o i c e w a t e r c o n t a i n i n g 1% N a S 0 3 a n d 2% NaOH. T h e w h i t e gummy m a s s t h a t s e p a r a t e d w a s t r i t u r a t e d w i t h h e x a n e and t h e n w i t h w a t e r t o a f f o r d 22.17g (70%) of w h i t e p o w d e r . The c r u d e p r o d u c t was r e c r y s t a l l i z e d f r o m e t h a n o l c o n t a i n i n g d e c o l o r i z i n g c a r b o n t o y i e l d w h i t e c r y s t a l s : mp 9 8 - 1 0 0 ° C ; IR ( K B r ) 3 4 1 0 a n d 3320 c m - ( N H ) . A n a l , c a l c d , f o r C i H N O : C , 6 6 . 6 6 ; H, 6 . 9 4 ; N , 9.72. F o u n d : C, 6 6 . 6 0 ; H, 6 . 8 9 ; N, 9 . 8 0 . 1

2

1

2

6

2 0

2

3

General Procedure f o r the P r e p a r a t i o n of Polyamic A c i d Oligomers. T h e d i a m i n e ( 0 . 0 0 9 m o l ) w a s d i s s o l v e d i n 35 mL o f DMAC c o n t a i n e d i n a 100-mL, 3 - n e c k e d f l a s k e q u i p p e d w i t h a t h e r m o m e t e r , a m a g n e t i c s t i r r i n g bar, a N i n l e t , and a C a C l drying tube. BTDA ( 0 . 0 1 8 m o l ) was t h e n added i n one p o r t i o n . The t e m p e r a t u r e o f t h e m i x t u r e q u i c k l y r o s e t o 35 t o 3 8 ° C a n d t h e n s l o w l y r e t u r n e d t o a m b i e n t ( 2 6 - 2 8 ° C ) . A f t e r t h e m i x t u r e was s t i r r e d f o r 3 h u n d e r N , 0.018 m o l o f ΑΡΑ was added and t h e s t i r r i n g c o n t i n u e d f o r an a d d i t i o n a l 3 h . The p o l y a m i c a c i d s o l u t i o n was s t o r e d a t 0 ° C . 2

2

2

General I n i d i z a t i o n Procedures. P r o c e d u r e 1. A c e t i c anhydride ( 2 5 mL) w a s h e a t e d t o r e f l u x i n a 3 - n e c k e d f l a s k , f i t t e d w i t h a c o n denser, a N i n l e t , and a d r o p p i n g f u n n e l . The p o l y a m i c a c i d s o l u t i o n ( 1 0 mL) w a s t h e n a d d e d d r o p w i s e o v e r a p e r i o d o f 0 . 5 h . After t h e a d d i t i o n was c o m p l e t e , t h e m i x t u r e was h e a t e d a t r e f l u x f o r a n 2


REACTIVE OLIGOMERS

90

a d d i t i o n a l 2 h and then poured i n t o e t h a n o l . The p r e c i p i t a t e t h a t formed was c o l l e c t e d by f i l t r a t i o n and washed s e v e r a l t i m e s w i t h w a t e r t o remove a c e t i c a n h y d r i d e . The p r o d u c t was d r i e d o v e r n i g h t under reduced p r e s s u r e a t 55°C. P r o c e d u r e 2 . T o 2 0 mL o f a n e q u i m o l a r m i x t u r e o f a c e t i c a n h y d r i d e a n d p y r i d i n e c o n t a i n e d i n a 100-mL f l a s k f i t t e d w i t h a N i n l e t t u b e w a s a d d e d 5 mL o f t h e p o l y a m i c a c i d solution. A f t e r t h e m i x t u r e was s t i r r e d a t ambient temperature f o r 24 h , i t w a s p o u r e d i n t o 2 0 0 mL o f w a t e r . The dark y e l l o w oligomer was c o l l e c t e d b y f i l t r a t i o n , washed s e v e r a l t i m e s w i t h w a t e r , a n d then d r i e d under reduced p r e s s u r e . P r o c e d u r e 3. The p o l y a m i c a c i d s o l u t i o n was h e a t e d t o 100°C i n a 3-necked f l a s k equipped w i t h a c o n d e n s e r , a m a g n e t i c s t i r r i n g b a r , a t h e r m o m e t e r , a n d a N . A f t e r 5 mL of t o l u e n e was added, t h e t o l u e n e - w a t e r a z e o t r o p e , which immediately began t o r e f l u x , was removed by d i s t i l l a t i o n . The t o l u e n e a d d i t i o n d i s t i l l a t i o n c y c l e was r e p e a t e d 5 t o 7 times over a p e r i o d o f 4 h . The i m i d i z e d p r o d u c t was i s o l a t e d b y p r e c i p i t a t i o n i n e t h a n o l . 2


2

G e n e r a l P r o c e d u r e f o r t h e P r e p a r a t i o n o f O l i g o m e r s 4^ BTDA ( 0 . 2 5 m o l ) w a s d i s s o l v e d i n NMP ( 2 0 % s o l i d s ) c o n t a i n e d i n a d r y 1 0 0 - m L , 3 - n e c k e d f l a s k equipped w i t h a thermometer, a N i n l e t and a s h o r t - p a t h d i s t i l l a t i o n apparatus. A f t e r t h e a p p r o p r i a t e amount o f amine w a s added i n a s i n g l e p o r t i o n t h e s o l u t i o n was s t i r r e d a t room t e m p e r a t u r e f o r 2 h . The a p p r o p r i a t e amount o f Α Ρ Α was a d d e d , a n d t h e r e a c t i o n m i x t u r e was s t i r r e d f o r an a d d i t i o n a l 2 h . The t e m p e r a t u r e o f t h e f l a s k was t h e n i n c r e a s e d u n t i l d i s t i l l a t i o n c o m m e n c e d . The o l i g o m e r c o n c e n t r a t i o n was m a i n t a i n e d a t a p p r o x i m a t e l y 20% by c o n t i n u a l l y r e p l a c i n g t h e d i s t i l l a t e w i t h f r e s h NMP. T h e d i s t i l l a t i o n - a d d i t i o n c y c l e was c a r r i e d o u t f o r 2 h . T h e m i x t u r e w a s t h e n p o u r e d i n t o e t h a n o l . The p r e c i p i t a t e t h a t f o r m e d w a s c o l l e c t e d b y f i l t r a t i o n , w a s h e d s e v e r a l times w i t h e t h a n o l , and d r i e d under reduced p r e s s u r e . 2

Acknowledgments The s u p p o r t California,

o f t h i s r e s e a r c h b y IBM R e s e a r c h L a b o r a t o r y , i s g r a t e f u l l y acknowledged.

San J o s e ,

Literature Cited 1. 2. 3. 4.

Harris, F.W.; Pamidimukkala, Α . ; Gupta, R.K.; Das, S.; Wu, T . ; Mock, G. ACS Polym. Div., Polym. Preprints 1983, 24(2), 324. Harris, F.W.; Sridhar, K . ; Das, S. ACS Polym. Div., Polym. Pre prints 1984, 25(1), 110. Harris, F.W.; Pamidimukkala, Α . ; Gupta, R.K.; Das, S.; Wu, T . ; Mock, G. J. Macromol. Sci.-Chem. 1984, A21, 1117. Feld, W.A.; Ramalingam, B . ; Harris, F.W. J. Polym. S c i . , Polym. Chem. Ed. 1983, 21, 319.

RECEIVED March 5, 1985


Reactive Oligomers - American Chemical Society

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