Acyclic Diene Metathesis Polymerization. Synthesis and Characterization of Unsaturated Poly[carbo(dimethyl)silanes]

ABSTRACT The first equilibrium polycondensation polymerization approach to unsaturated poly[carbo-(dimethy1)silanesl is presented. Diallyldimethylsilane (I), 4,4,7,7-tetramethyl-4,7-disiladeca-1,9-diene (11), and 1,4-bis(allyldimethylsilyl)benzene (111) undergo acyclic diene (metathesis (ADMET) polymerization when catalyzed by highly active tungsten alkylidenes, [ (CF~)ZCH~CO]Z(N-~,~-C~H~-~-P~Z) W=C C(CH&R, where R = CH3 or Ph. These polymerizations, which are performed under bulk conditions, continuously release ethylene to give poly(l,l-dimethyl-l-silapent-3-ene) (VI), poly ( 1,1,4,4-tetramethyl-1,4-disilaoct-6-ene) (VII), and poly [ l-(dimethylsilyl)-4-(l,l-dimethylsilapent-3-en-l-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,l-dimethyl-1-si1apropene)-co-octenamer (IX). All vinylsilane linkages in the copolymer are isolated. All polymers were characterized by infrared spectroscopy and 'H, 13C, and?Si 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