ACYCLIC DIENE METATHESIS POLYMERIZATION - SYNTHESIS AND CHARACTERIZATION OF UNSATURATED POLY[CARBO(DIMETHYL)SILANES]

The first equilibrium polycondensation polymerization approach to unsaturated poly[carbo(dimethyl)silanes] is presented. Diallyldimethylsilane (I), 4,4,7,7-tetramethyl-4,7-disiladeca-1,9-diene (II), and 1,4-bis(allyldimethylsilyl)benzene (III) undergo acyclic diene (metathesis (ADMET) polymerization when catalyzed by highly active tungsten alkylidenes, [(CF3)2CH3CO]2(N-2,6-C6H3-i-Pr2)W = CHC(CH3)2R, where R = CH3 or Ph. These polymerizations, which are performed under bulk conditions, continuously release ethylene to give poly(1,1-dimethyl-1-silapent-3-ene) (VI), poly(1,1,4,4-tetramethyl-1,4-disilaoct-6-ene) (VII), and poly[1-(dimethylsilyl)-4-(1,1-dimethylsilapent-3-en-1-yl)phenylene] (VIII), respectively. Polymers VI and VII produce trace amounts of the cyclic dimer and monomer, respectively, at the end of the polymerizations. Dimethyldivinylsilane (IV) does not homopolymerize; however, it does copolymerize with 1,9-decadiene (V) to give poly(1,1-dimethyl-1-silapropene)-co-octenamer (IX). All vinylsilane linkages in the copolymer are isolated. All polymers were characterized by infrared spectroscopy and H-1, C-13, and Si-29 NMR spectroscopy. Average molecular weights were determined by gel permeation chromatography and end-group analysis. Synthesis, characterization, and the current scope of this polymerization are discussed.