Synthesis and thermal properties of poly(Schiff bases) containing dicyanovinyl group and their copolymers

Abstract

Poly(Schiff bases) and their copolymers incorporating dicyanovinyl group in the main chain were prepared by the solution polymerization of a dicyanovinyl-containing monomer, p-bis[1-(4-formylphenoxy)-2,2-dicyanovinyl]benzene ((4) under bar), and terephthalaldehyde (TA) with 4-aminophenyl ether (ODA). The resulting polymers possess intrinsic viscosities 0.42 similar to 0.20 dL/g in the case of polymers <(P(1/0))under bar>similar to<(P(2/1))under bar>. The homopolymer derived from (4) under bar and ODA is easily soluble in polar aprotic solvents. However, the solubility of the polymers in NMP decreased apparently with the increase of the content of TA in the polymer chain. Attempts to prepare high-molecular weight polymers from higher content of TA were unsuccessful probably due to the precipitation of polymer during polymerization. The polymers show a large exotherm in differential scanning calorimetry and undergo a curing reaction around 350 degrees C to form insoluble material in solvent. Almost all the poly(Schiff bases) exhibited 10% weight loss between 480 similar to 540 degrees C and 88 similar to 5% residual weight at 500 degrees C in a nitrogen atmosphere.