HIGH-PRESSURE SOLID-STATE SYNTHESIS OF POLY(PARA-PHENYLENE-1,2,4-OXADIAZOLE) THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION OF PARA-CYANOBENZONITRILE N-OXIDE

Poly(p-phenylene-1,2,4-oxadiazole) was synthesized by the solid-state 1,3-dipolar cycloaddition polymerization of p-cyanobenzonitrile N-oxide under high pressure. The high pressure polymerization was carried out by using a piston cylinder type hot-pressing apparatus. Pressure and temperature accelerated the polymerization, and higher pressure (up to 750 M Pa) and higher temperature (up to 150-degrees-C) afforded the polymer with an inherent viscosity around 0.5 dl g-1. The crystallinity and thermal behavior of the polymer were discussed in connection with the polymerization conditions.