6 Incorporation of Metal Ions into Polyimides
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1
L. T. TAYLOR, V. C. CARVER, and T. A. FURTSCH Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 A. K. ST. CLAIR NASA Langley Research Center, Hampton, VA 23665
The effect of ionic groups on the properties of bulk polymer has normally referred to studies on polyelectrolytes in which an ionic group is covalently attached to the polymer chain which is usually neutralized by a metallic counterion. Studies of systems consisting of neutral polymers with dissolved inorganic salts are only beginning to receive considerable attention. The results of the incorporation of ions in polymers and their effect on the glass transition temperature (Tg) has been reviewed through 1969. Therefore, only the more recent and pertinent reports will be mentioned here. Large increases have been produced in the Tg of poly(propylene oxide) by dissolving LiClO in the polymer. Crystallization adducts of poly(ethylene oxide) that have been treated with HgCl or CdCl have also been reported. Solutions of Ca(NCS) and "Phenoxy" polymer have significantly different physical properties compared to the pure polymer. Increased water absorption, Tg and electrical conductivity are results of salt incorporation. Mechanical properties of these glassy polymers are also affected by the presence of dissolved salt. Investigations regarding the interaction of inorganic nitrate salts with cellulose acetate, poly(vinyl acetate), poly(vinyl alcohol), poly(methyl methacrylate) and poly (methyl acrylate) have been cited. In addition to observing large effects in Tg , large shifts in the infrared spectrum of both nitrate and polymer carbonyl frequencies have been observed. These observations have been interpreted in terms of complex formation between polymer and salt in the solid state. The change in Tg was shown to be an unusual function of metal ion concentration (i.e. Tg increases with increasing metal concentration up to (1)
2 ()
(3)
4
2
(4)
2
2
(5)
(6)
1
Current address: Department of Chemistry, Tennessee Tech-
nological University, Cookeville, TN. 38501 0-8412-0540-X/80/47-121-071$05.00/0 © 1980 American Chemical Society Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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MODIFICATION OF POLYMERS
a maximum p o i n t t h e n Tg b e g i n s t o d e c l i n e ) . The e f f e c t s o f v a r i o u s m e t a l s a l t s on t h e T and c r y s t a l l i n i t y o f some p o l y a m i d e s h a v e b e e n n o t e d M i x t u r e s of Nylon 6 and e i t h e r L i C l , L i B r o r KC1 were p r e p a r e d by m e l t i n g i n v a c u o a t 260°C an i n t i m a t e b l e n d o f t h e two c o m p o n e n t s . The e q u i l i b r i u m m e l t i n g t e m p e r a t u r e o f p u r e N y l o n 6 was c o n t i n u o u s l y d e p r e s s e d by i n c r e a s i n g s a l t c o n t e n t w i t h KC1 b e i n g t h e most effective. I n t h e s e s t u d i e s t h e s a l t c o u l d be e x t r a c t e d f r o m t h e polymer w i t h hot water w i t h complete recovery of the f u s i o n t e m p e r a t u r e w h i c h i s c h a r a c t e r i s t i c o f p u r e N y l o n 6. The o c c u r r e n c e o f a s t r o n g i n t e r a c t i o n p o s s i b l y b e t w e e n t h e amide g r o u p o f t h e amorphous p o l y m e r and s a l t s s u c h as L i C l and L i B r was predicted. In a l a t e r stud 3^)these workers i n v e s t i g a t e d the e f f e c t o f t h e s e s a l t s on t h e g l a s s t r a n s i t i o n , T . Tg i s n o t a f f e c t e d by t y p e and c o n t e n t o f m e t a l s a l t . Mecnanical data f o r u n o r i e n t e d specimen of Nylon 6 - s a l t mixtures r e v e a l t h a t below Tg t h e s h e a r m o d u l u s i s n o t a f f e c t e d by t h e s a l t . Whereas above Tg t h e m o d u l u s o f N y l o n 6 i s i n c r e a s e d by KC1 and d e c r e a s e d by L i C l and L i B r . The N e w t o n i a n m e l t v i s c o s i t y was c o n s i s t e n t l y h i g h e r f o r the mixtures than f o r pure Nylon 6 i n each case. It s h o u l d be n o t e d , h o w e v e r , t h a t L i B r and KC1 w e r e more e f f e c t i v e than L i C l i n causing the v i s c o s i t y i n c r e a s e . The employment o f t r a n s i t i o n m e t a l s a l t s w i t h n e u t r a l p o l a r polymers i s n o t i c e a b l y l a c k i n g . R e c e n t l y , the a d d i t i o n of ZnCl2 and C0CI2 t o h i g h and t o l o w m o l e c u l a r w e i g h t p o l y ( p r o p y l e n e o x i d e ) has b e e n r e p o r t e d £1) ZnCl2 was f o u n d t o i n c r e a s e t h e Tg o f b o t h h i g h and l o w m o l e c u l a r w e i g h t p o l y m e r b u t C0CI2 o n l y i n c r e a s e d t h e Tg o f t h e l o w m o l e c u l a r w e i g h t p o l y m e r . A s i n g l e p h a s e s y s t e m i n t h e ZnCl2 c a s e was i n d i c a t e d ; w h i l e a two p h a s e s y s t e m w i t h C0CI2 a c t i n g as a f i l l e r was s u g g e s t e d . In t h e z i n c c a s e , t h e e l e v a t i o n o f Tg i s b e l i e v e d t o r e s u l t f r o m t h e f o r m a t i o n o f f i v e - m e m b e r e d c h e l a t e r i n g s by c o o r d i n a t i o n o f two a d j a c e n t o x y g e n atoms i n t h e p o l y m e r c h a i n w i t h a ZnC^ molecule. I n an a n a l o g o u s s i t u a t i o n , ZnCl2 was added t o p o l y ( t e t r a m e t h y l e n e g l y c o l ) w i t h s i m i l a r r e s u l t s a l b e i t t h e Tg was r a i s e d l e s s f o r a g i v e n amount o f m e t a l c h l o r i d e . Intermolecular c o o r d i n a t i o n w i t h e t h e r o x y g e n atoms f r o m two n e i g h b o r i n g c h a i n s was p o s t u l a t e d s i n c e i n t r a m o l e c u l a r b o n d i n g t o z i n c ( I I ) w o u l d i n v o l v e t h e f o r m a t i o n o f a l e s s s t a b l e seven-membered c h e l a t e ring. A n g e l d — / h a s b r i e f l y r e p o r t e d i n a patent the a d d i t i o n of metal ions to s e v e r a l types of p o l y i m i d e s . The o b j e c t o f t h e i n v e n t i o n was a p r o c e s s f o r f o r m i n g p a r t i c l e - c o n t a i n i n g ( < l u ) t r a n s p a r e n t p o l y i m i d e shaped s t r u c t u r e s . U n l i k e the work d i s c u s s e d p r e v i o u s l y , a l l o f t h e m e t a l s w e r e added i n t h e f o r m o f c o o r d i n a t i o n c o m p l e x e s r a t h e r t h a n as s i m p l e a n h y d r o u s o r h y drated s a l t s . The p r o p e r t i e s o f o n l y one f i l m ( e . g . c a s t f r o m a N,N-dimethylformamide(DMF) s o l u t i o n of 4 , 4 - d i a m i n o d i p h e n y l m e t h a n e , p y r o m e l l i t i c d i a n h y d r i d e and b i s ( a c e t y l a c e t o n a t o ) f
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
6.
TAYLOR ET AL.
Metal Ions in
73
Polyimides
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c o p p e r ( I I ) ) were g i v e n . These p r o p e r t i e s i n c l u d e d : %Cu = 3.0%, d i e l e c t r i c c o n s t a n t = 3.6 a n d v o l u m e r e s i s t i v i t y = 8 x 1012 ohms-cm. No f u r t h e r p a t e n t s o r p u b l i s h e d w o r k i n t h i s a r e a a r e apparently availableQj). S i n c e a r o m a t i c p o l y i m i d e s have proven t o be e x c e l l e n t h i g h t e m p e r a t u r e a d h e s i v e s a n d l i m i t e d d a t a suggest that a d d i t i o n o f metal o r m e t a l l o i d m a t e r i a l as a f i l l e r may enhance£L2) a d h e s i v e p r o p e r t i e s , we w i s h t o r e p o r t o u r results r e l a t i n g to the incorporation of a series of metal ions into various polyimides. R e s u l t s and D i s c u s s i o n f
P o l y i m i d e s d e r i v e d from 3,3 ,4,4'-benzophenone t e t r a c a r b o x y l i c a c i d d i a n h y d r i d e (BTDA), I , and 3 , 3 - d i a m i n o b e n z o p h e n o n e (m,m DABP), I I A , 4 , 4 ' - d i a m i n o b e n z o p h e n o n e ( p , p - D A B P ) , I I B , o r 4 , 4 o x y d i a n i l i n e , I I C , ( a n d t o w h i c h h a v e b e e n added numerous m e t a l compounds) h a v e b e e n p r e p a r e d . The s y n t h e t i c p r o c e d u r e em1
!
f
ii 0
BTDA I
f
T
ii 0
m,m -DABP, X = C=0, I I A p,p -DABP, X = C=0, I I B p,p -0DA, X = 0, I I C !
f
p l o y e d i n v o l v e d (1) f o r m a t i o n o f t h e p o l y a m i c a c i d (20% s o l i d s ) i n e i t h e r DMF, N , N - d i m e t h y l a c e t a m i d e ( D M A C ) o r d i e t h y l e n e g l y c o l d i m e t h y l e t h e r (Diglyme) (2) a d d i t i o n o f t h e m e t a l c o m p l e x t o t h e p o l y a m i c a c i d , I I I , i n a 1:4 r a t i o (3) f a b r i c a t i o n o f a f i l m o f t h e p o l y a m i c a c i d - m e t a l compound m i x t u r e and (4) t h e r m a l c o n v e r s i o n (300°C) t o t h e m e t a l c o n t a i n i n g p o l y imide. A p p r o x i m a t e l y twenty m e t a l s i n a v a r i e t y o f forms were 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 . Several experimental problems were e n c o u n t e r e d i n f o l l o w i n g t h i s p r o c e d u r e
r
o II
o II
o II
III
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
n
74
MODIFICATION OF POLYMERS
w h i c h l i m i t e d t h e number o f good q u a l i t y f i l m s o b t a i n e d . T h e s e problems i n c l u d e : (1) m e t a l complex n o t d i s s o l v i n g i n appropriate solvent, (2) g e l f o r m a t i o n o r c r o s s - l i n k i n g o f t h e p o l y m e r o c c u r r i n g upon i n t e r a c t i o n w i t h t h e m e t a l , (3) polyamic a c i d p r e c i p i t a t i n g when t h e m e t a l c o m p l e x i s added and ( 4 ) m e t a l promoting thermal o x i d a t i v e d e g r a d a t i o n o f t h e polymer f i l m upon c u r i n g . I n g e n e r a l p o l y i m i d e s d e r i v e d f r o m BTDA + p,p -DABP y i e l d e d r a t h e r p o o r q u a l i t y , v e r y b r i t t l e f i l m s w h i c h w e r e due i n p a r t to t h e l o w v i s c o s i t y o f t h e r e s u l t i n g polyamic a c i d s o l u t i o n . This fact, coupled w i t h theobservation that theadhesive prope r t i e s o f t h e p,p -DABP i s o m e r a r e p o o r e r t h a n t h e a d h e s i v e p r o p e r t i e s o f t h e m,m -DABP isomerCL^J d i c t a t e d t h a t a n y e x t e n s i v e p h y s i c a l measurements s h o u l d be c a r r i e d o u t on t h e l a t t e r . T a b l e 1 l i s t s some o f t h e m e t a l compounds e m p l o y e d a n d t h e r e s u l t s o b t a i n e d when a t t e m p t s w e r e made t o c a s t f i l m s o f t h e r e s u l t i n g m e t a l i o n f i l l e d p o l y i m i d e d e r i v e d f r o m BTDA + m,m DABP. B r i t t l e f i l m s w e r e p r o d u c e d i n most c a s e s r e g a r d l e s s o f w h e t h e r t h e added m e t a l i o n was h y d r a t e d o r a n h y d r o u s . The r e l a tively low v i s c o s i t i e s o f ther e s u l t i n g polyamic acid-metal i o n s o l u t i o n s no d o u b t a c c o u n t e d f o r t h i s . Addition of AlCl3 6H20 o r a n y s i m p l e a l u m i n i u m s a l t t o t h e p o l y a m i c a c i d p r o d u c e d immed i a t e l y a r u b b e r y m a t e r i a l t h a t c o u l d n o t be c a s t i n t o a f i l m . A s i m i l a r r e s u l t was o b t a i n e d w i t h T i C O E t ) ^ a n d Ni(acac)2»
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f
f
f
f
#
Table 1 F i l m s Cast BTDA+m,m -DABP P o l y m e r a n d M e t a l I o n s * f
Metal Compound
Results
Results
Mn(acac)^
very b r i t t l e rubbery
material
Al(acac)^
flexible
A1C1
rubbery m a t e r i a l
Ti(OEt)
s u r f a c e DMAC
SnCl » 2 H 0
brittle
film
CrCl « 6 H 0
brittle
film
MgCl * 6H 0
brittle
film
Fe(acac)^
brittle
film
NiCl .6H 0
flexible
Cr(acac)^
brittle
film
CuCl * 4H 0
brittle
Ni(acac)
rubbery m a t e r i a l
AgN0
very b r i t t l e
brittle
CoCacac)^
• 6H 0 2
LiCl 3
CaCl
2
2
2
film
Metal Compound
film
4
2
2
2
2
2
2
2
2
3
brittle
film
film film film
film
* S o l v e n t = DMAC
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
6.
TAYLOR ET AL.
Metal Ions in
Polyimides
75
L i t h i u m c o n t a i n i n g f i l m s were u n u s u a l i n t h a t t h e f i l m a f t e r c u r i n g was damp o n t h e s u r f a c e w i t h what a p p e a r e d t o be t h e s o l v e n t , DMAC. No o t h e r f i l m s e x h i b i t e d t h i s p r o p e r t y . The AgNO^ c o n t a i n i n g f i l m had t h e appearance o f a s i l v e r m i r r o r b u t t h e f i l m was e x c e e d i n g l y b r i t t l e a n d " f l a k y - l i k e . O n l y two t r u l y f l e x i b l e f i l m s w e r e p r o d u c e d f r o m BTDA + m,m'-DABP. These c o n t a i n e d A l ( a c a c > 3 and NiCl2»6H2O r e s p e c t i v e l y . A r e p r e s e n t a t i v e s a m p l e o f many o f t h e p o l y i m i d e f i l m s t h a t were produced were s u b j e c t e d t o t h e r m o - m e c h a n i c a l a n a l y s i s (TMA), t o r s i o n a l b r a i d a n a l y s i s ( T B A ) , t h e r m a l g r a v i m e t r i c a n a l y s i s ( T G A ) , i n f r a r e d s p e c t r a l a n a l y s i s and w e i g h t l o s s o n p r o l o n g e d h e a t i n g ( e . g . i s o t h e r m a l s t u d i e s ) , TABLE I I . The s o f t e n i n g t e m p e r a t u r e a s measured b y TMA a n d TBA a r e i n g e n e r a l
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1 1
TABLE I I TMA, TBA a n d TGA o f M e t a l I o n F i l l e d o f BTDA + m,m -DABP
Polymers
3
f
METAL ION
TMA(°C)
TBA(°C)
TGA(°C)
Fe(acac)^
292
293
412
Cr(acac)^
287
279
#
NiCl
6H 0
279
495
MnCl * 4H 0
279
495
Al(acac)^
271
270
555
CaCl
2
264
266
518
Co(acac)^
268
296
480
C r C l ^ 6H 0
260
LiCl
252
264
480
252
267
520
251
252
570
2
2
2
2
2
MgCl
2
No M e t a l SnCl - 2H 0 2
a
2
460
550
237
S o l v e n t = DMAC; 0.1 g o f m e t a l polymer (20% s o l i d s )
complex ( s a l t ) p e r 4 g o f
Polymer D e c o m p o s i t i o n Temperature
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
76
MODIFICATION OF POLYMERS
i n c r e a s e d when m e t a l i o n s a r e added w i t h t h e e x c e p t i o n o f S n C l ^ * 2H2O. On t h e o t h e r hand, some t h e r m a l s t a b i l i t y h a s b e e n s a c r i f i c e d a s e v i d e n c e d b y t h e TGA d a t a . S o f t e n i n g t e m p e r a t u r e s were more d r a m a t i c a l l y i n c r e a s e d w i t h p,p'-DABP p o l y i m i d e t h a n w i t h t h e m,m -DABP b u t a t t h e e x p e n s e o f c o n s i d e r a b l e t h e r m a l s t a b i l i t y loss. No t r e n d i s a p p a r e n t i n t h e c h a n g e s b r o u g h t a b o u t b y e a c h m e t a l i o n . I n f a c t , each m e t a l i s almost a case unto i t s e l f . T h i s o b s e r v a t i o n i s f u r t h e r d r a m a t i z e d b y some r a t h e r l i m i t e d i s o t h e r m a l m e a s u r e m e n t s o n s e l e c t e d f i l m s (TABLE I I I ) . This d a t a i s t y p i c a l o f t h e m e t a l i o n f i l l e d BTDA + p,p -DABP p o l y i m i d e s w h i c h we h a v e e x a m i n e d . No c h a n g e s i n c h e m i c a l f u n c t i o n a l i t y i n the p o l y i m i d e - m e t a l f i l m were apparent as judged by i n f r a r e d s p e c t r a l comparisons o f p o l y i m i d e a l o n e and p o l y i m i d e plus metal r e g a r d l e s s o f the m e t a l employed. f
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T
Table I I I Isothermal Studies MATERIAL
%Weight
f
m,m -DABP m,m -DABP Polymer + Polymer + Polymer + Polymer + Polymer + T
65 h o u r s
C b
Al(acac)3 ' CaCl > LiClc,d Cr(acac)3 > Co(acac)3 >d b
d
2
C
d
c
Loss
3 4 5 7 13 52 13
@ 316°C
^ S o l v e n t = DMAC "Solvent *0.1
=Diglyme
g o f m e t a l complex ( s a l t ) p e r 4 g o f polymer
(20%
solids)
The b e s t s y s t e m s t u d i e d i n r e g a r d t o enhancement o f p o l y m e r properties while maintaining excellent film quality involves t r i ( a c e t y l a c e t o n a t o ) a l u m i n u m ( I I I ) a d d i t i o n t o t h e m^'-DABP polyimide. An i n s p e c t i o n o f T a b l e s I - I I I r e v e a l s t h a t w i t h A l (acac)^ t h e s o f t e n i n g temperature i s i n c r e a s e d without the l o s s o f a n y p o l y m e r t h e r m a l s t a b i l i t y , F i g u r e 1. The r e m a i n i n g f l e x i b l e f i l m , NiCl2*6H20, has a s l i g h t l y lower d e c o m p o s i t i o n temperat u r e than the "polymer-alone" f i l m although t h e s o f t e n i n g p o i n t has a g a i n been i n c r e a s e d . S i n c e t h e m,m -DABP p o l y i m i d e i s known t o b e a n o u t s t a n d i n g adhesive, l a p shear s t r e n g t h t e s t s employing t i t a n i u m - t i t a n i u m adherends and m e t a l i o n f i l l e d p o l y i m i d e s were c o n d u c t e d . Tests w e r e p e r f o r m e d a t room t e m p e r a t u r e , 250°C and 275°C e m p l o y i n g e i t h e r DMAC o r DMAC/Diglyme a s t h e s o l v e n t . A t room t e m p e r a t u r e r e g a r d l e s s o f the m e t a l i o n employed a d h e s i v e s t r e n g t h i s d e T
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
Metal Ions in
Polyimides
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TAYLOR ET AL.
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
MODIFICATION OF POLYMERS
78
creased r e l a t i v e t o the "polymer-alone" case. Again the choice of m e t a l i o n i s c r i t i c a l . The two b e s t c a s e s , i . e . , A l ( a c a c ) ^ and N i C l ^ H ^ O w e r e s u b j e c t e d t o a d h e s i v e t e s t i n g a t e l e v a t e d temperatures. Under t h e s e c o n d i t i o n s the m e t a l i o n f i l l e d p o l y i m i d e s were s u p e r i o r . The A l ( a c a c ) ^ c a s e p r o v e d t o b e e x c e p t i o n a l i n that i t e x h i b i t e d approximately f o u r times t h e l a p shear s t r e n g t h o f " p o l y m e r - a l o n e " a t 275°C. We f e e l t h a t t h i s e n h a n c e d a d h e s i v e n e s s i s due i n p a r t t o t h e i n c r e a s e d s o f t e n i n g t e m p e r a t u r e o f t h e Al(acac)« f i l l e d p o l y i m i d e . T h e s e r e s u l t s a r e somewhat a n a l o g o u s t o d a t a c o l l e c t e d b y S t . C l a i r and P r o g a r e a r l i e i E L ^ ) r e g a r d i n g t h e u s e o f aluminum m e t a l as a f i l l e r w i t h v a r i o u s p o l y imides. L a p s h e a r s t r e n g t h was f o u n d t o d o u b l e a t 250°C w i t h 7 9 % Al f i l l e d polyimide versus theu n f i l l e d polyimide. #
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2
Table IV Lap S h e a r T e s t s T i t a n i u m - T i t a n i u m Adherend BTDA-m,m'-DABP M e t a l I o n Added
25°C No
Metal
Al(acac)^
C
N i C l ^ 6H 0
C
2
LiCl
C
Cr(acac)^
3
L a p Shear
0
Strength* ( p s i )
250°C
275°C
2966 (3138)
1573
438 (496)
2378 (2400)
1891
1641 (1348)
1800
1332
608
781
—
—
830
—
—
Numbers i n p a r e n t h e s i s c o r r e s p o n d t o DMAC/Diglyme s o l v e n t m i x ture. ^Average o f f o u r 0.1
tests.
g o f m e t a l c o m p l e x ( s a l t ) p e r 4g o f p o l y m e r
(20%
solids)
S u r f a c e a n d v o l u m e r e s i s t i v i t y measurements h a v e b e e n p e r formed o n f i l m s o f p o l y m e r a l o n e a n d p o l y m e r w i t h A l ( a c a c ) ^ a d d e d . S p e c i a l c a r e was t a k e n t o i n s u r e t h a t o n l y f i l m s o f u n i f o r m l y h i g h q u a l i t y were measured. Regardless of the f i l m pret r e a t m e n t , v o l u m e r e s i s t i v i t i e s o n two i n d e p e n d e n t l y c a s t f i l m s of p o l y m e r a l o n e f a l l i n t h e l O ^ ohm-cm r a n g e . No p r e v i o u s l y p u b l i s h e d r e s i s t i v i t y i s a v a i l a b l e on t h i s p a r t i c u l a r polymer a l t h o u g h upon s u r v e y i n g s e v e r a l e t h e r p o l y i m i d e s f r o m i n d e p e n d e n t s o u r c e s we m e a s u r e d s i m i l a r v o l u m e r e s i s t i v i t i e s . 1
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
6.
TAYLOR ET AL.
Metal Ions in
79
Polyimides
Incorporation of A l ( a c a c ) into thepolyimide disappointingly shows no s i g n i f i c a n t r e d u c t i o n i n v o l u m e r e s i s t i v i t y r e l a t i v e to t h e polymer alone. R e p l i c a t e m e a s u r e m e n t s (1.59 x 1 0 - ^ and 1.12 x 1016 ohm-cm) o n two i n d e p e n d e n t l y c a s t f i l m s s u p p o r t t h i s conclusion. R e o r i e n t a t i o n o f t h e same f i l m i n t h e e l e c t r o d e assembly y i e l d e d i d e n t i c a l r e s u l t s s u g g e s t i n g u n i f o r m behavior t h r o u g h o u t t h e f i l m c o n t a i n i n g Al(acac)«. S i m i l a r r e s u l t s w e r e o b t a i n e d o n NiCl«6H 0 f i l l e d p o l y i m i d e s . ( T a b l e V) 3
2
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Table V 1
R e s i s t i v i t y D a t a o n BTDA-m,m -DABP P o l y i m i d e Film
Volume R e s i s t i v i t y
(ohms-cm) ,
Polymer
1
,
J
P o l y m e r + N i C l • 6H 0
Metal
Content
6
1.36 x 10,16 2.32 x 10
Polymer + A l ( a c a c )
Films
-
15
1.59 x 10,16 1.92 x 10
1.8% A l 2.9% A l
1.66 x 10, 1.27 x 10,16
0.9% N I
1
6
E l e c t r i f i c a t i o n P e r i o d = 1 m i n u t e @ 500 v o l t s ' S o l v e n t = DMAC S u r f a c e r e s i s t i v i t y measurements w e r e c a r r i e d o u t , b u t t h e r e i s c o n s i d e r a b l e s c a t t e r i n t h e measurements. Other w o r k e r s have a l s o noted greater u n c e r t a i n t i e s a s s o c i a t e d w i t h surface r e s i s t i v i t y measurements r e l a t i v e t o volume r e s i s t i v y measurements A g a i n , t h e A l ( a c a c ) ^ and NiCl »6H 0 c o n t a i n i n g f i l m s e x h i b i t a s u r f a c e r e s i s t i v i t y s i m i l a r t o t h e average o f t h e three data p o i n t s o b t a i n e d f o r "polymer alone" f i l m s . Numerous e f f o r t s t o prepare high q u a l i t y f i l m s i n c o r p o r a t i n g other metal ions i n t o BTDA + m,m -DABP o r p,p -DABP w e r e n o t s a t i s f a c t o r y b e c a u s e m e t a l i o n a d d i t i o n r e s u l t e d i n a decrease i n s o l u t i o n v i s c o s i t y l e a d i n g t o u n s a t i s f a c t o r y f i l m s i n s o f a r as r e s i s t i v i t y measurements a r e c o n c e r n e d . These r e s u l t s s u g g e s t t h a t d u r i n g t h e f i l m c u r i n g p r o c e s s , t h e n o n - c o n d u c t i n g A l ( a c a c ) ^ and N i C l ^ m a i n t a i n t h e i r i n t e g r i t y r a t h e r t h a n b e i n g c o n v e r t e d t o t h e more c o n d u c t i v e a l u m i n u m o r n i c k e l metal as o r i g i n a l l y e n v i s i o n e d . X-ray p h o t o e l e c t r o n s p e c t r o s c o p i c (XPS) d a t a o n t h e A l ( a c a c ) ^ c o n t a i n i n g p o l y i m i d e e m p l o y i n g a magnesium anode s u g g e s t s one t y p e o f a l u m i n u m s p e c i e s , F i g u r e 2. A b i n d i n g e n e r g y o f 118.4 eV f o r A l 2si/2 i s determined based on an ' i n t e r n a l carbon c a l i b r a t i o n C l s - ^ ^ assumed t o be 284.0 eV. T h i s v a l u e o f 118.4 eV c o u p l e d w i t n t h e f a c t s t h a t ( 1 ) no change i n b i n d i n g e n e r g y i s f o u n d f o r 2
f
2
!
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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80
MODIFICATION OF POLYMERS
123
121
119
117
BINDING
115
113
ENERGY
III
(ev)
AI(Qcac) + BTDA +m,m'- DABP 3
Figure 2.
X-ray photoelectron spectrum (Al 2s ) of BTDA + m,m -DABP Al(acac) polymer film (B.E. = 118.4 eV) 1/2
f
3
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
+
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6.
TAYLOR ET AL.
•
1
878
i
1
876
•
874
Metal Ions in
i
i
872
i
i
i
870
i
868
81
Polyimides
i
i
866
i
i
i
864
i
862
i
1
860
1
I
858
I
1 L
856
BINDING ENERGY (ev) Figure 3. X-ray photoelectron spectrum (Ni 2p / ) of BTDA + mjm'-DABP + NiCl • 6 H 0 polymer film (B.E. = 855.7 eV, 873.3 eV) 1/2
2
3
2
2
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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82
MODIFICATION OF POLYMERS
oxygen or nitrogen in the polyimide and (2) the binding energy of Al 2si/2 in Al(acac)3 * s H7.9 e V indicates that aluminum continues to be bound to acetylacetone in the polyimide. An examination of XPS data obtained on the MCI2 containing polyimide, Figure 3, leads to a similar conclusion (Ni 2p^/2 = 854.2 eV in the polyimide, Ni 2p3/2 = 855.0 eV in NiCl 2 . The smaller intensity peak centered around 862 eV is the 2p^/2 satellite photopeak which again is indicative of nickel(II) . Further work in this area is underway employing polyamic acid systems which are known to produce higher viscosity solutions (e.g. polyimides derived from 4,4f-oxydianiline and either BTDA or pyromellitic dianhydride). This is being carried out in the belief that higher viscosity solutions will give rise to higher quality, less brittle films and will, thereby, enable a broader spectrum of metal systems to be studied regarding the adhesive and electrical conductance properties of metal ion filled polyimides. Acknowledgment - Informative discussions regarding this work with T. L. St. Clair are gratefully appreciated. We also wish to thank Robert Ely for technical assistance. References 1. 2. 3.
E. P. Otocha, J. Macromol. Sci., Sci., C5, 275 (1971). A. Eisenbert, Macromolecules, 4 125 (1971). J. Moacanin and E. F. Cuddihy, J. Polym. Sci. C, 14, 313 (1966). 4. M. Yokoyama, H. Ishihara, R. Iwamoto and H. Tadokoro, Macromolecules, 2, 184 (1969). 5. M. J. Hannon and K. F. Wissbrun, J. Polym. Sci. Polym. Phys. Ed., 13, 113 (1975). 6. M. J. Hannon and K. F. Wissburn, J. Polym. Sci. Polym., Phsy. Ed., 13, 223 (1975). 7. B. Valenti, E. Bianchi, G. Greppi, A. Tealdi and A. Ciferri, J. Phys. Chem. 77, 389 (1973). 8. D. Acierno, E. Bianchi, A. Ciferri, B. DeCindio, C. Migliaresi and L. Nicolais, J. Polym. Sci., Symposium No. 54, 259 (1976). 9. R. E. Wetton, D. B. James and W. Whiting, Polym. Letters Ed., 14, 577 (1976). 10. R. J. Angelo and E. I. duPont deNemours & Co., U.S. Patent, No. 3, 073, 785 (1959). 11. Private Communication, R. J. Angelo. 12. H. A. Burgman, J. H. Freeman, L. W. Frost. G. M. Bower, E. J. Traynor and C. R. Ruffing, J. Appl. Polym. Sci., 12, 805 (1968). 13. T. L. St. Clair and D. J. Progar, Polymer Preprints, 16(1) 538 (1975). 14. D. J. Progar and T. L. St. Clair, 7th National SAMPE Technical Conference, Albuquerque, NM Oct., 1975. RECEIVED
July 12, 1979.
Carraher and Tsuda; Modification of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1980.