Poly methylphenylsilylene

Prepare a slurry of 5 g of NaHCOa in 50 mL of 2-propanol, and add it very slowly, with stirring, to the reaction mixture to destroy the excess Na. (The mixture may foam during the addition be prepared to collect any foam that rises out of the condenser.) Stir for an additional 2 hr to insure that all the Na was consumed. 

The oligomers can be isolated by removing the solvent from the 2-propanol-toluene solution by rotary evaporation, redissolving in hexane and extracting the hexane solution with water to remove any residual salts. Then dry the solution over MgS04 and isolate the pure oligomers by removing the hexane solvent by rotary evaporation. Yield 48.7 g (41%). 

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Figure 4 Dependency of main-chain UV cr-a absorption maximum on chain length for poly(methylphenylsilylene) (PMPS) in toluene.18 Adapted with permission from Jones, R. G. Wong, W. K. C. Holder, S. J. Organometallics 1998, 17, 59-64. 1998 American Chemical Society.

There is a brief reference to electroreductive silicon polymer formation in COMC II (1995) (chapter Organopolysilanes, p 96), but the very limited extent of the field at that time precluded further comment. Since then, the field has seen considerable progress, and the mild conditions have permitted the synthesis of functionalized polymers of moderate molecular weight (104), an example of which is the co-polymer poly(rncthyM-rncthoxymethoxyphcnylsilylene)-r -poly(methylphenylsilylene), 26, with a protected phenolic function, which was prepared with a molecular weight Mw= 19,000.96 Deprotection afforded the phenolic polymer. Several reviews on the area have been published.113-115... 

Scheme 22 Metal functionalization of poly(methylphenylsilylene) via chloromethylation.

Structural effects on properties were also studied in detail by a group from Tohoku University, who prepared poly(methylphenylsilylene) (PMPS Mv = 3,120, Mw/Mn = 1.76) and poly(phenylsilyne) (131 poly(penfafluorophenylrilyne)(PPS) 4/w = 1,090, Mw/M = 1.30) by Wurtz-type coupling using sodium and 18-crown-6 in hot toluene and compared their optical and electrical properties.359,360... 

The photoinduced electron transfer between Cgo and polysilane was investigated by laser flash photolysis9. The transient absorption spectra of the Cgo triplet (3Cgo ) (2), the Cgo radical anion (3) and the poly(methylphenylsilylene) radical cation (4, M = Si) (Scheme 2) were observed in the region 600-1600 nm in a polar solvent. 

Enokida et al. (1991) reported that ultraviolet-induced fatigue of a photoreceptor using poly(methylphenylsilylene) (PMPS) as the transport layer could be explained by photodecomposition of the transport layer. The PMPS was both decomposed and cross-linked by the ultraviolet exposures. 

In this chapter, a selective overview of technological and historical background is followed by a general discussion of the microscopic details of the transport phenomenon and experimental techniques. Key results of earlier studies on carbon-based systems are presented and then compared with corresponding data on poly(methylphenylsilylene) (PMPS), which has been taken as the prototype for studies of transport system in polymers with silicon backbones. Key points are then summarized. Those wishing to omit the extensive background section may proceed directly to the section on electronic transport in polysilylenes (page 492). 

Polysilylenes have been known for many years but were not considered interesting until the mid-1970s, when Yajima (16) and West (IT) used them as precursors for Si-C ceramics. In 1980, the first soluble high-molecular-weight polymers were synthesized (iS). Photoconductivity in poly(meth-ylphenylsilylene)-TNF (2,4,7-trinitrofiuorenone) was reported by Kepler et al. (14). Preliminary charge-transport studies showed that at 295 K hole mobility in poly(methylphenylsilylene) (PMPS) is 10 cm /V-s at about 10 V/cm, quite high for a polymer 14, 19, 20). 

C7H3NO3S, o-BenzosuIfimide (saccharin) metal complexes, 23 47 C7HgNP,PoIy[nitrilo(methyIphenyIphosphor-anylidyne)], 25 69, 72-73 C7HgSe, Poly(methylphenylsilylene), 25 56 C7H10, 1,3-CycIoheptadiene ruthenium complex, 22 179 C7Hi7F3NOPSi, Phosphinimidic acid, P,P-dimethyl-Ai-(trimethylsilyl)-... 

Silicone Polymers - Laser flash photolysis of poly(methylphenylsilylene) gives a transient absorption associated with exciton states while fullerene reduces bond scission in polysilanes. ... 

Jones et al. prepared poly(methylphenylsilylene) (p(MPSi)) using a Wurtz-type reductive coupling reaction, followed by reaction with (4-chloromethyl-phenylethyl) dimethylchlorosilylene to produce the a,co-difunctional ATRP initiator [240]. H NMR characterization indicated the presence of several different types of chains ends however, the majority of them appeared to contain the... 

Numerous examples exist of combining CRP methods with other polymerization techniques for preparation of block copolymers. Non-living polymerization methods like condensation, free-radical, and redox processes can easily be combined with CRP to produce novel materials. Transformation chemistry may be the only route to incorporate polymers like polysulfones (as described above), polyesters, or polyamides that are prepared solely through condensation processes into subsequent CRP to form block copolymers with vinyl monomers. The same can be said of polymers prepared through coupling techniques, like po-ly(phenylenevinylene) and poly(methylphenylsilylene), which can maintain their conductive or photoluminescence properties, but become easier to process... 

Recently, three types of novel poly(disilanylenebutenyne-l,4-diyls) (44) with molecular weights (Mv) of 1.0 X 10" - . 0x10 were synthesized (equation 42) from diethynyldisilanes by use of rhodium(I) catalysts . The scission of Si—Si bonds by UV-light irradiation took place easily for poly(disilanylenebutenye-l,4-diyls) in solution and in a solid film, while poly[(methylphenylsilylene)butenyne-l,4-diyl] was found to be photochemically stable. Conductivities of poly(disilanylbutenyne-l,4-diyls) doped with SbFs were 10 -10 S cm" in air and lO -lO" S cm" in vacuo. 

For general information about polysilane pwlymers see the entry for Poly(methylphenylsilylene) in this handbook. 

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