Hydrosilylation polymerization. I. A new approach to the preparation of macromonomers containing silicon atoms

Abstract

Keywords: hydrosilylation polymerization self-polyaddition silicon containing polymer macromonomer INTRODUCTIONHydrosilylation is a well-known methodology in organic synthesis, which takes place under mild conditions to produce various alkylsilane compounds almost quantitatively.' In the polymer synthesis, addition of hydrosilyl (Si -H ) group across double bonds has been used to prepare blocks, * grafts, and network polymer^.^ However, the direct use of hydrosilylation reaction in preparation of organosilicic polymers has been limited so far. Hydrosilylation between a,@-divinyl compounds and a+-bis ( hydrosilyl ) compounds has been shown to afford organosilicic polymer^.^ However, terminal structure of these polymers obtained from such a two-component polyaddition reaction is difficult to control. Since Si -H group is inert to C -C unsaturated bonds without catalyst, the compounds possessing both vinyl and Si -H groups exist stable under normal conditions. Such compounds including dialkylvinylsilanes6 and diarylvinylsilanes have been synthesized and polymerized using y-radiation or platinum catalyst, respectively, to afford organosilicic polymers. These reactions required severe conditions, and no detail was reported about the terminal structure, the molecular weights, and characterization of the resulting polymers.We have prepared new monomers ( 3 ) having both vinyl and Si -H groups. Thus the transition metal catalyst can initiate self-polyaddition of such monomers. The resulting polymers having polymerizable vinyl group at the end of the chain are novel type of macromonomers containing silicon atoms. Thus as a typical and preliminary example, we report here the synthesis of styryl terminated organosilicic macromonomers using a self-polyaddition reaction between vinyl and Si -H groups, which we term "hydrosilylation polymerization." This is a convenient one-pot synthesis of macromonomers containing a unique structure of poly (arylene silylethylene) or poly (aralkylene silylethylene) . EXPERIMENTAL (4-Vinylphenyl)dimethylsilane ( 3a)A T H F solution of (4-vinylphenyl) magnesium chloride (70 mmol, 100 mL) was added dropwise to a solution of

New Polymer‐Supported Organosilicon Reagents

“…[4] Polymerization by hydrosilylation was developed by Itsuno et al to introduce silyl functions onto a support. [5] Lastly, a new kind of sup-tion. These supports can be used for solid-phase organic synthesis, the product being released through a Tamao-Fleming oxidation, which generates an additional hydroxy group during the cleavage along with the recycled support.…”

Preparation of functionalized precursor of SiC ceramic via hydrosilylation polymerization of 1,1-diphenylethylene derivatives

“…[21] At 100°C, I was obtained with low DP due to precipitation of platinum catalyst (insoluble black particle was obvious in the bottom of flask, which has been reported in previous work. [22]) The reaction rate constant k 1 for I was relatively lower than that of II in the DP vs. Time curve. The polymerization rate of III was relatively high due to the highest concentration of Karstedt catalyst; however, the catalyst produced excess active center and excess side reaction.…”

Selective photo-crosslinking of microphase-separated multiblock copolymers of poly(dimethylsiloxane) and phenylene diacrylate polyesters

“…a,x-Bis(hydrosilyl)-terminated siloxanes have also been reacted directly with a,x-divinyl-terminated organic compounds [30 -33]. Hydrosilation polymerization of low molecular weight monomers under the action of platinum catalysts is known as a very fast and efficient polymerization technique [34,35].…”