Electroreductive block copolymerization of dichlorosilanes in the presence of disilane additives

Abstract

The electroreductive polymerization of dichloromethylphenylsilane in the presence of triphenylsilyl group-containing disilanes such as hexaphenyldisilane followed by the electroreductive termination with chlorotriphenylsilane afforded triphenylsilyl group-terminated polymethylphenylsilane in 15-32% yield. The isolated polymethylphenylsilane (M n = 3350 g mol −1 , M w /M n = 1.4) was found to react as a macroinitiator to copolymerize with dibutyldichlorosilane under electroreductive conditions producing the corresponding block copolymer (M n = 4730 g mol −1 , M w /M n = 1.2) in 38% yield. The ratio of monomer units (-MeSiPh-to-BuSiBu-) of the copolymer was determined to be 75 : 25 using 1 H NMR analysis, which was in good agreement with the calculated ratio (74 : 26) on the assumption that molecular weight of the macroinitiator was not changed. The block structure of the resulting copolymer, poly(methylphenylsilane)-block-poly(dibutylsilane), was also confirmed by comparing its 1 H NMR and UV absorption spectra with those of polymethylphenylsilane, polydibutylsilane and a statistical copolymer prepared by electroreductive polymerization of dichloromethylphenylsilane with dibutyldichlorosilane. This method is applicable to the preparation of other types of macroinitiator such as triphenylsilyl group-terminated polydibutylsilane, and polydibutylsilane-block-polymethylphenylsilane was also obtained using this macroinitiator.

Inorganic and organometallic polymers

“…49 The controlled electropolymerisation of diorganodichlorosilanes R 2 SiCl 2 enabled the synthesis of well-defined polysilane block copolymers such as [PhSiMe] m -b-[BuSiMe] n to be prepared. 50 A series of network polygermasilanes with tunable Si/Ge ratios in 0.25 increments were synthesised via Wurtz coupling of BuECl 3 co-monomers (E = Ge and Si) in the presence of alkali metal reductants; upon increasing incorporation of Ge into the 1-2 nm sized network domains, the observed PL became red-shifted and particles with pure Ge cores exhibited intense red-coloured photoluminescence at 690 nm at 77 K. 51 Highly promising photovoltaic dithienylgermole polymers such as 13 52 have been reported by a number of groups in 2011 with solar cell power conversion efficiencies (PCEs) as high as 4%. [52][53][54][55] An inverted BHJ solar cell featuring dithienylgermoles yielded an impressive PCE of 7.3%.…”

Mono- and dinuclear zirconocene(iv) amide complexes for the catalytic dehydropolymerisation of phenylsilane

“…4 For converting silane-based monomers several different approaches are feasible. [6][7][8][9] Catalytic dehydrocoupling of hydrosilanes represents an atom-efficient method compared to the Wurtz coupling that produces stoichiometric amounts of salts as waste products and shows a poor functional-group-tolerance. 10,11 Early investigations focused on group 4 metallocene-based catalysts, although complexes of later transition metals were also studied and showed comparable catalytic performance in some cases.…”