Ultrasonic Synthesis and Spectroscopic Characterization of Poly

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35 Ultrasonic Synthesis and Spectroscopic Characterization of Poly(phthalocyanato) Siloxane Bert J. Exsted and Marek W . Urban* Department of Polymers and Coatings, North Dakota State University, Fargo, N D 58105

A new synthetic method for the preparation of poly(phthalocyanato) siloxane is described. The method utilizes ultrasonic energy in the conversion of dichlorosilicon phthalocyanine monomer, a sodium chalcogenide, and molecular moisture to form the cofacially stacked poly(phthalocyanato) siloxane polymer [Si(Pc)O] . Of four sodium chalcogenides investigated, sodium telluride was found to be the most effective polymerizing agent with an n value (degree of polymerization) greater than 45 repeating units. Sonication reactions were carried out at room temperature conditions extending from 1 min to 8 h in length. For comparative purposes, poly(phthalocyanato) siloxane was also prepared thermally via the traditional synthetic route. Electronic and vibrational band assignments of the prepared phthalocyanine monomers and their respective polymers are presented and assigned to the inherent structure of the macrocycle. The role of water in the sonication process is also discussed. n

OROFACIAL ASSEMBLY O F M E T A L L O M A C R O C Y C L E S was p i o n e e r e d i n the late 1950s b y E l v i d g e a n d L e v e r ( I ) a n d Joyner a n d K e n n e y (2)

f o r phthalo-

eyaninogermanium a n d phthaloeyanomanganese(IV) complexes. Soon there after, it was discovered that dihydroxysilicone phthalocyanine ( S i ( P c X O H ) ) 2

c o u l d also f o r m a stacked, planar phthalocyanine moiety u p o n t h e r m a l dehydration ( 3 ) . T h e resulting p o l y (phthalocyanato) silicon oxide, [ S i ( P c ) 0 ] , n

* Corresponding author. 0065-2393/93/0236-0791$06.00/0 © 1993 American Chemical Society

In Structure-Property Relations in Polymers; Urban, M., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1993.

792

STRUCTURE-PROPERTY RELATIONS IN POLYMERS

u p o n iodine d o p i n g , has since gained w i d e attention as the cornerstone o f a n e w class o f electrically conductive macromolecules (4-7). I n traditional two-step t h e r m a l polymerization of poly(phthalocyanato) siloxane extreme parameters are r e q u i r e d : for example, h i g h v a c u u m (10 ~ torr) a n d temperature (440 ° C ) conditions over extensive periods of t i m e (12 h) (8). A s a consequence, m u c h w o r k o n the development o f [ S i ( P c ) 0 ] has b e e n i m p e d e d . T h e apparent n e e d for a m o r e convenient synthetic technique should be addressed. I n this chapter, we report a novel one-step, r o o m temperature m e t h o d for the synthetic preparation o f [ S i ( P c ) 0 ] that uses ultrasonic energy. 3


w

n

U t i l i z a t i o n o f ultrasonic waves i n c h e m i c a l applications dates back to the mid-1920s w h e n L o o m i s and Richards carried out the first studies o f h i g h frequency s o u n d wave ( > 20 k H z ) effects o n organic a n d aqueous solutions (9). I n the following decades, however, very little research u t i l i z i n g ultrasonic energy i n the p r o c u r e m e n t o f n e w c h e m i c a l compounds was investigated. Recently, however, sonochemistry has gained interest i n the area o f heteroge neous synthetic reactions, the majority o f w h i c h involve the c h e m i c a l interac tion between metallic powders a n d functionally active carbon or silicon compounds (10, 11). I n the area o f p o l y m e r synthesis a n d modification, (12). I n an effort to address this issue, w e report the use o f ultrasonic irradiation i n the synthesis o f poly(phthalocyanato) siloxane p o l y m e r ,

Experimental Details Synthetic Procedures. Synthesis of Si(Pc)Cl . Silicon phthalo cyanine dichloride was p r e p a r e d b y a modification o f the procedure o f L o w e r y et al. (13). U n d e r nitrogen, 16.45 m L (0.143 mol) o f freshly distilled silicon tetrachloride (Petrarch Systems) a n d 165 m L o f d r y quinoline solvent ( A l d r i c h ) was syringed into a 5 0 0 - m L three-neck r o u n d b o t t o m flask e q u i p p e d w i t h a nitrogen inlet, thermometer, heating mantel, mechanical stirrer, a n d dry-ice condenser ( 3 - h e p t a n o n e - d r y ice; —38 ° C ) fitted u p o n a West-type condenser. T h e solution was brought to reflux. W h e n the solution reached 200 °C, 15.000 g (0.103 mol) o f 1, 3-diiminoisoindohne ( A l d r i c h ) was added. T h e resulting solution was refluxed at 220 °C for an additional 45 m i n a n d t h e n slowly cooled to r o o m temperature. U p o n cooling, 40 m L o f c h l o r o f o r m was a d d e d to the resulting dark v i o l e t - b l u e reaction mixture i n an effort to facilitate the w o r k u p procedure. T h e crude product was centrifuged i n portions a n d B u c h n e r filtered w i t h quinoline, c h l o r o f o r m , a n d acetone, oven at 120 °C u n d e r 10 ~ torr. Analytically calculated (%) for C H N S i C l : C , 62.85; H , 2.64; N , 18.32; C l , 11.59. Found: C , 52.86; H , 2

3

3 2

1 6

8

2


35.

EXSTED & URBAN Ultrasonic

Inside an argon glovebox, s o d i u m

Synthesis of [Si(Pc)0] . n

telluride (Cerac, Inc.; 0.142 g; 8.180 X H T con

793

Poly (phthalocyanato) Siloxane

dichloride (0.500 g; 8.180 X 1 0 "

4

4

m o l ) a n d (phthaloeyanato)sili-

m o l ) were a d d e d to an o v e n - d r i e d

5 0 - m L three-neck r o u n d b o t t o m flask. T h e flask was transferred to a h o o d , tory cleaner (Bransonic m o d e l 2200) filled w i t h d e i o n i z e d water. A p p r o x i mately 10 m L o f freshly distilled tetrahydrofuran ( T H F ) d r i e d over b e n Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on October 14, 2015 | http://pubs.acs.org Publication Date: May 5, 1993 | doi: 10.1021/ba-1993-0236.ch035

zophenone a n d s o d i u m was syringed into the flask. T h e resulting mixture was sonicated at r o o m temperature over periods ranging f r o m 1 m i n to 8 h i n length, a n d cavitation was observed i n the reaction

flask.

T h e resulting

poly (phthalocyanato) silicon oxide p r o d u c t was B u c h n e r filtered w i t h tetrahy drofuran, water, a n d acetone, respectively, a n d d r i e d i n a v a c u u m oven (120 ° C ; 1 0 " torr). Similar products, w i t h lower degree o f polymerization 3

values were obtained b y substituting 8.180 X 10 ~

4

m o l o f sodium sulfide

(Pfalz a n d Bauer; 0.064 g) a n d s o d i u m selenide (Cerac,

Inc.; 0.103 g),

Chemetals C o r p . ) , however, appeared to b e ineffective. Analytically calculated (%) f o r C

3 2

H

1 6

N S i O upon 8 h of Si(Pc)Cl 8

ultrasonication w i t h

2

sodium telluride: C , 69.05; H , 2.90; N , 20.13; C l , 0.00. Found: C , 64.24; H ,

Synthesis of Si(Pc)(OH) . 2

(Phthalocyanato)

silicon dihydroxide was

p r e p a r e d i n a shghtly m o d i f i e d procedure f r o m that reported b y D a v i s o n a n d W y n n e ( 1 4 ) . Into a 2 5 0 - m L three-neck r o u n d bottom flask e q u i p p e d w i t h a thermometer, condenser, heating mantel, stir bar, a n d plate was a d d e d 1.500 g (2.45 X 1 0 ~ m o l ) o f (phthalocyanato) silicon dichloride, 75 m L o f 2 - M 3

aqueous s o d i u m hydroxide, a n d 15 m L o f p y r i d i n e cosolvent. A f t e r 12 h the hydrolyzed (phthalocyanato) silicon product was recovered b y B u c h n e r

filtra

tion w i t h distilled d e i o n i z e d water a n d acetone, respectively. Yield: 1.292 g (91.7%) Analytically calculated (%) f o r C

3 2

H

1 8

N S i 0 : C , 66.89; H , 3.16; 8

2

N , 19.50; C l , 0.00. Found: C , 60.68; H , 3.24; N , 17.85; C l , 0.00.

Thermal Synthesis of [Si(Pc)0] . n

Poly(phthalocyanato) siloxane, was

p r e p a r e d b y the traditional t h e r m a l synthetic procedure o u t l i n e d b y Joyner and

K e n n e y ( 3 ) . (Phthalocyanato)

silicon dihydroxide was p l a c e d into a

pyrolysis quartz tube a n d the axially functional m o n o m e r was heated to 440 °C i n a L i n d b e r g heavy-duty tube furnace u n d e r a continuous v a c u u m (10 ~

torr) f o r a p e r i o d o f 8 H. T h e resulting poly (phthalocyanato)

3

siloxane

was likewise recovered as a dark p u r p l e p o w d e r . Analytically calculated (%) for C

3 2

H

1 6

N S i O : C , 69.05; H , 2.90; N , 20.13; C l , 0.00. Found: C , 64.64; H , 8


794


H (Pc). N o n m e t a l l a t e d phthalocyanine m o n o m e r ( 9 8 % purity; β form) was purchased f r o m the A l d r i c h C h e m i c a l C o m p a n y , Inc. a n d spectroscopically analyzed as received without further modification. 2

Analytical Methods.

Elemental

Analysis.

E l e m e n t a l analyses ( C ,


Tucson, A Z .

Infrared Spectroscopy. Photoacoustic F o u r i e r transform i n f r a r e d ( P A - F T I R ) spectra were collected o n a spectrometer ( D i g i l a b F T S - 1 0 M ) continuously p u r g e d w i t h p u r i f i e d air (free o f hydrocarbons, carbon dioxide, nine samples enclosed i n a h e l i u m - p u r g e d photoacoustic c e l l were r e c o r d e d at a resolution o f 4 c m a n d ratioed against a carbon black reference. A l l spectra were transferred to a n A T compatible c o m p u t e r a n d analyzed w i t h the a i d o f Spectra C a l c software (Galactic Industries). -

1

Optical Spectroscopy. Solution spectra o f S i ( P c ) C l , S i ( P c ) ( O H ) , m u l t i p l e - c e l l diode array U V - v i s i b l e spectrophotometer ( H e w l e t t - P a c k a r d 8451A) e q u i p p e d w i t h a d e u t e r i u m l a m p . P u r e tetrahydrofuran ( T H F ) sol vent was u t i l i z e d as a reference. 2

2

Nuclear Magnetic Resonance Spectroscopy. I n a n effort to access the role o f the solvent i n the ultrasonication procedure, H a n d C N M R spectra o f untreated tetrahydrofuran solvent a n d tetrahydrofuran solvent (10 m L ) sonicated for 8 h i n the presence o f s o d i u m telluride (0.142 g; 8.180 X 10 ~~ mol) were r e c o r d e d o n a 4 0 0 - M H z F o u r i e r transform N M R spectrome ter ( J E O L G S X - 4 0 0 ) . A p p r o x i m a t e l y 0.05 m L o f each sample was dissolved i n 1 m L o f deuterated c h l o r o f o r m ( C D C 1 ) . C h e m i c a l shifts are reported i n measurements relative to tetramethylsilane ( T M S ) . X

1

3

4

3

Results and Discussion T o circumvent the traditional two-step synthetic procedure o f p o l y ( p h t h a l ocyanato) siloxane, [ S i ( P c ) 0 ] , w e developed a n e w ultrasonic synthetic procedure that requires only one step. B o t h reaction routes are schematically d e p i c t e d i n C h a r t I. N o t e that the formation a n d isolation o f the S i ( P c ) ( O H ) intermediate, previously r e q u i r e d i n the traditional two-step polymerization procedure o f p o l y (phthalocyanato) siloxane, has b e e n eliminated ( 3 ) . H e n c e , be u t i h z e d directly via the one-step ultransonication reaction pathway. n

2



35.

EXSTED & URBAN

795

Poly (phthalocyanato) Siloxane

25 deg. Cel., Atm. Press., Sonication Chart L Synthetic schemes for the preparation of poly (phthalocyanato) siloxane via the traditional thermal condensation route (a) and a new ultrasonic procedure (h). Before w e analyze o u r infrared absorption spectral results, let us first set the stage b y defining the bands most relevant to b o t h the m o n o m e l i c a n d p o l y m e r i c phthalocyanine macromolecular structures. Because o f the vast n u m b e r o f infrared absorptions displayed b y the phthalocyanine moiety, the first spectroscopic reports o f vibrational modes inherent to the phthalocyanine macromolecule were complicated b y a n u m e r i c scheme that was c o m m o n l y substituted f o r standard vibrational assign ment tables (15). I n addition, vibrational analyses were often disrupted b y bands attributed to the dispersive media, f o r example, m i n e r a l o i l (16, 17). Later, sublimation techniques for phthalocyanine deposition o n the surface o f potassium b r o m i d e crystals were developed to simplify the data interpretation (18). E a c h o f these I R techniques, however, was rather t i m e - c o n s u m i n g and, Fortunately, a more convenient m e t h o d o f vibrational spectroscopy n o w exists that allows i n f r a r e d spectra o f opaque insoluble powders to b e obtained v i a the use o f a F o u r i e r transform infrared spectrometer e q u i p p e d w i t h a photoacoustic cell ( P A F T I R ) ( 1 9 - 2 1 ) . This vibrational spectroscopic tech nique is also nondestructive to the sample; thus the sample can b e retrieved i n its original f o r m . Subsequently, a l l vibrational spectra were recorded b y this P A technique.

P A - F T I R vibrational data o f S i ( P c ) C l a n d S i ( P c ) ( O H ) monomers, polymers are reported i n T a b l e I. I n addition to the reported silicon phthalo cyanine vibrational bands, characteristic i n f r a r e d frequencies o f a nonmetallated phthalocyanine, H ( P c ) , are i n c l u d e d to make a more complete listing of bands that are attributed solely to the phthalocyanine moiety a n d bands 2

2

2


796


Table I. Infrared Bands of H (Pc), Si(Pc)Cl , Si(Pc)(OH) , and Both Thermally and Sonically Polymerized [Si(Pc)Ol 2

2

2

w

Vibrational Mode

c-c

b

c-c

Def. Str. Def.

c-c c-c

Si-Cl


Band No ro

β H -Pe 2

Thermal [Si(Pc)0]

Sonic [Si(Pc)0]

528 Se"

2

> S"

2

> O " . T h i s t r e n d corre 2

sponds inversely to the b o n d strength o f the silicon chalcogenide Ο

2

> S~

2

> Se"

2

> Te"

2

as reported i n the

literature (30).

series

Because

s o d i u m telluride is the most effective p o l y m e r i z i n g agent o f the four s o d i u m chalcogenides investigated w i t h a degree o f polymerization value o f 48, the observed polymerization t r e n d may b e attributed to the instability o f the silicon chalcogenide intermediate. B e i n g the least stable o f the four prospec tive silicon chalcogenide

intermediates,

the s i l i c o n - t e l l u r i d e intermediate

w o u l d be expected to be more rapidly displaced b y molecular water i n the formation o f a linear, cofacially stacked p o l y (phthalocyanato) siloxane p r o d u c t w i t h a resulting degree o f polymerization value that is very comparable i n respect to its thermally p r e p a r e d predecessor (n = 40). P A - F T I R a n d U V - v i s i b l e spectra o f b o t h thermally a n d ultrasonically p r e p a r e d poly(phthalocyanato) siloxanes display coincident spectral features.

Table IV. Optical Absorption Spectra of H (Pc), Si(Pe)Cl , Si(Pc)(OH) , and Both Thermally and Sonically Polymerized [Si(Pc)Ol 2

2

2

n

[Si(Pc)Oj Synthetic Technique

Temp.,

Sonic & N a O Sonic & N a S Sonic & N a S e Sonic & N a T e Thermal & vacuum *

25

n

2

a

2

25

2

25

2

1

Time,

(°c)

8 8 8 8 8

25

440

η Value (hours) by IR Analysis

— 2

4 48 40

°Pa_FTIR spectrum was identical to Si(Pc)Cl . Prepared at 10 ~ torr. 2

3


808


T h e i r identical vibrational a n d electronic spectra provide substantial evidence that a new, one-step synthetic procedure n o w exists f o r the preparation o f poly(phthalocyanato) siloxane that utilizes ultrasonic energy.


Summary T o circumvent the traditional t h e r m a l two-step synthetic procedure f o r the preparation o f poly(phthalocyanato) siloxane, a n alternative one-step ultra sonic synthetic procedure has b e e n developed. Ultrasonication o f S i ( P c ) C l i n the presence o f a s o d i u m chalcogenide w i t h molecular moisture results i n the formation o f poly(phthalocyanato) siloxane p o l y m e r . O f the four different sodium chalcogenides investigated ( N a 0 , N a S , N a S e , a n d N a T e ) , s o d i u m telluride was the most effective p o l y m e r i z i n g agent. F T I R a n d U V - v i s i b l e data indicate that a linear, cofacially stacked poly(phthalocyanato) siloxane w i t h various degrees o f polymerization can b e p r e p a r e d v i a this n e w synthetic route. I n addition, this n e w ultrasonic synthetic procedure can successfully b e carried out at atmospheric a n d r o o m temperature conditions, thereby p r o v i d i n g a viable alternative to the traditional two-step polymerization technique, w h i c h requires a h i g h v a c u u m a n d extreme temperatures. 2

2

2

2

2

Acknowledgment T h e authors are grateful to the N a t i o n a l Science F o u n d a t i o n ( E P S C o R program) f o r supporting this work.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

11. 12.

Elvidge, J. Α.; Lever, A. B. P. Proc. Chem. Soc. 1959, 195. Joyner, R. D.; Kenney, M . E . J. Am. Chem. Soc. 1960, 82, 5790. Joyner, R. D.; Kenney, M . E. Inorg. Chem. 1962, 1, 717. Diel, Β. N.; Inabe, T. I.; Kannewurf, C. R.; Lyding, J. W.; Marks, T. J.; Schoch, K. F., Jr. J. Am. Chem. Soc. 1983, 105, 1551. Anderson, A. B.; Gordon, T. L.; Kenney, M . E . J. Am. Chem. Soc. 1985, 107, 192. Kundalkar, B. R.; Marks, T. J.; Schoch, K. F., Jr. J. Am. Chem. Soc. 1979, 101, 7071. Dirk, C. W.; Inabe, T. I.; Lyding, J. W.; Kannewurf, C. R.; Marks, J. J. J. Polym. Symp. 1983, 70, 3. Dirk, C. W.; Inabe, T. I.; Schoch, K. F., Jr.; Marks, T. J. J. Am. Chem. Soc. 1983, 105, 1539. Loomis, A. L.; Richards, W. T. J. Am. Chem. Soc. 1927, 49, 3086. Boudjouk, P. In High-Energy Processes in Organometallic Chemistry; Suslick, K. S., Ed.; ACS Symposium Series 333; American Chemical Society: Washington, DC, 1987; Chapter 13. Cracknell, A. P. Ultrasonics; Wykeham: London, 1980. Matyjaszewski, K.; Yenca, F.; Chen, Y. L. Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1987, 28(2), 222.



35.

EXSTED & URBAN

Poly (phthalocyanato) Sibxane

809

13. Lowery, M . K.; Starshak, A. J.; Esposito, J. N.; Krueger, P. C.; Kenney, M . E. Inorg. Chem. 1965, 4, 128. 14. Davison, J. B.; Wynne, K. J. Macromolecules 1978, 11, 186. 15. Sidorov, A. N.; Kotlyar, I. P. Opt. Spectrosc. 1961, 11, 92. 16. Kobayashi, T.; Kurokawa, F.; Uyeda, N . ; Suito, E. Spectrochim. Acta, Part A 1970, 26, 1305. 17. Ebert, Α. Α., Jr.; Gottlieb, Η. B. J. Am. Chem. Soc. 1952, 74, 2806. 18. Steinbach, F.; Joswig, H.-J. J. Chem. Soc., Faraday Trans. I 1979, 75, 2594. 19. Urban, M. W. Prog. Org. Coat. 1989, 16, 321. 20. Urban, M . W. J. Coat. Technol. 1987, 59(745), 29. 21. Exsted, B. J.; Urban, M . W. Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1990, 31(2), 663. 22. Pinzuti, L.; Schurvell, H . F. Can. J. Chem. 1966, 44, 125. 23. Esposito, J. N.; Sutton, L. E.; Kenney, M. E. Inorg. Chem. 1967, 6, 1116. 24. Smith, A. L. Analysis of Silicones; Wiley: New York, 1974; p 275. 25. Arya, P.; Boyer, J.; Carré, F.; Corriu, R.; Lanneau, G.; Lapasset, J.; Perrot, M.; Priou, C. Angew. Chem. Int. Ed. Eng. 1989, 28, 1016. 26. Barton, T. J.; Paul, G. C. J. Am. Chem. Soc. 1987, 109, 5292. 27. Moser, F. L.; Thomas, A. L. The Phthalocyanines; CRC Press: Boca Raton, F L , 1983; Vol. 1. 28. Lever, A. B. P. In Advances in Inorganic Chemistry and Radiochemistry; Emeléus, H . J.; Sharpe, A. G, Eds.; Academic: Orlando, FL, 1961; Vol. 7, p 28. 29. Cuellar, Ε. Α.; Marks, T. J. Inorg. Chem. 1981, 20, 3766. 30. Armitage, D. A. In The Chemistry of Organic Silicon Compounds; Patai, S.; Rappoport, Z., Eds.; Wiley: New York, 1989; Chapter 23. RECEIVED for review July 15, 1991. ACCEPTED revised manuscript October 6, 1992.


Ultrasonic Synthesis and Spectroscopic Characterization of Poly

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