Preparation and properties of poly(tetramethyl‐p‐silphenylene‐siloxane)

Abstract

SynopsisImproved methods for the synthesis of p-bis(dimethylhydroxysily1)benzene are described. This useful monomer was prepared from p-bis(dimethylhydrogensily1)benzene which wm obtained in 60-70a/, yields from p-dibromobenzene and dimethylchlorosilane by use of an in situ Grignard technique. The great reluctance due to steric factors of the p-silphenylene-siloxane configuration to form cyclic structures has been amply demonstrated. The condensation polymerization of p-bis( dimethylhydroxy-sily1)benzene in benzene solution has yielded high molecular weight, crystalline poly-(tetramethyl-p-silphenylene-siloxanes). The heat of fusion A H , of the tetramethyl-psilphenylene-siloxane wa8 found to be 4350 cal./unit. The modified Staudinger equation relating intrinsic viscosity and weight-average molecular weight was applicable over a range of '70,000-400,000. These results are summarized in the relationship, [?] = I .12 X 10-4Mw0.75. Tetraniethyl-p-silphenylene-siloxaIies were found to be more stable than diinetliy1siloxitnes both to atmospheric oxidation and degradation through volatile formation in the temperature range 200-305°C.

Synthesis and characterization of poly(silphenylenesiloxane)s containing functional side groups, a study to high-temperature elastomer

“…1 H, 13 C and 29 Si NMR of 3b-ran were not as simple as 3b-alt though they have the same composition. 29 Si NMR shows two sets of signals at 2 0.38, 2 1.25, and 2 12.01, 2 12.76 ppm (Fig.…”

“…NMR ( 1 H, 500 MHz; 13 To the mixture of methyldichlorosilane or methylvinyldichlorosilane (0.60 mol) and magnesium turning (8.0 g, 0.33 mol) in THF (100 ml), p-dibromobenzene (35.4 g, 0.15 mol, in 60 ml THF) was slowly added, and stirred at room temperature for 8 h in preparing 1a, and at 70 8C for 20 h for 1b under argon atmosphere. The yellowish crude product, obtained from the hexane extract, was purified by fractional distillation to give the pure product as colorless liquid.…”

“…Merker reported polycondensation of BHSB to give poly[(oxydimethylsilylene)(1,4-phenylene)(dimethylsilylene)] (Scheme 1, x ¼ 0) [13], commonly called as poly(tetramethyl-p-silphenylenesiloxane) (PTMPS). This PTMPS contains the maximum number of rigid phenylene groups and the shortest disiloxane segments in the polymer backbone.…”

Synthesis and characterization of poly(tetramethylsilarylenesiloxane) derivatives bearing diphenylfluorene or diphenyldibenzosilole moieties

“…The hydrolysis of 6 to afford M2 was carried out using sodium ethoxide. 25 We have attempted to obtain M2 by the hydrolysis reaction using 5% palladium on charcoal as a manner similar to that used in the preparation of M1; however, the hydrolysis reaction hardly proceeded and the yield of M2 was extremely low plausibly because the dimerization reaction 26 would be inclined to occur in the hydrolysis of 6.…”

Structure of cyclo-1,1',4,4'-bis(1,1,3,3-tetramethyl-1,3-disiloxanediyl)dibenzene

“…This reaction gave the bis(allyldisiloxanyl)-benzene monomer and the crystalline cyclic siloxane (I). Compound (I) has been sought previously (Merker & Scott, 1964) for catalytic ring-opening polymerization, albeit with little success. Only a melting point has been given previously for (I) (Merker & Scott, 1964).…”