Synthesis of conjugated spirocyclic polymers: Cyclopolymerization of 1,1-dipropargyl-1-silacycloalkanes by transition metal catalysts

Cyclopolymerization of 1,1-dipropargyl-1-silacyclobutane and 1,1-dipropargyl-1-silacyclopentane was examined by various transition metal catalysts. WCl6 was found to be very effective for this cyclopolymerization to give high yields of polymers. The polymer structures were characterized to have the conjugated polymer backbone with silacycloalkane moieties. The resulting poly(1,1-dipropargyl-1-silacyclobutane) was insoluble in any organic solvents, whereas the poly(1,1-dipropargyl-1-silacyclopentane) was partially soluble. The conjugated spirocyclic polymers were mostly yellow or light-brown powders, depending on the catalyst systems used. The thermal and oxidative stabilities of the polymer were also studied and discussed.