3,5-Dimethoxy-4-(2’-vinyloxyethoxy)benzylidenemalononitrile (2) and methyl 3,5-dimethoxy-4-(2’-vinyloxyethoxy)benzylidenecyanoacetate (3) were prepared and polymerized by radical and cationic initiators. Bifunctional monomers 2 and 3 did not polymerize by radical initiators, but copolymerized readily with ethyl vinyl ether in gamma-butyrolactone solution at 65 degrees C. The trisubstituted terminal double bond participated in the vinyl polymerization and radical polymerization of 2 and 3 with ethyl vinyl ether led to swelling polymers 8 and 9 that were not soluble in common solvents due to cross-linking. Under the same polymerization conditions ethyl vinyl ether polymerized well with model compounds of 3,4,5-trimethoxybenzylidenemalononitrile (10) and methyl 3,4,5-trimethoxybenzylidenecyanoacetate (11), respectively, to give 1:1 alternating copolymers 12 and 13 in high yields. Polymers 8 and 9 showed a thermal stability up to 300 degrees C without any characteristic T-g peaks in DSC thermograms. Alternating copolymers 12 and 13 were soluble in common solvents such as acetone and DMSO, and the inherent viscosities of the polymers were in the range of 0.33-0.55 dL/g. Films of polymers 12 and 13 cast from acetone solution were cloudy and tough and T-g values obtained from DSC thermograms were in the range of 163-168 degrees C.