Synthesis and characterization of new polyarylate containing phthalazinone moiety

Novel polyarylates containing phthalazinone moieties (PAR-PH) were synthesized and characterized by co-solvent interfacial polymerization based on 4-(4′-hydroxyphenyl)-2,3-phthalazin-1-one (DHPZ) and isophthaloyl chloride (IPC). Effects of inorganic bases, monomer concentration, phase transfer catalysts and co-solvents on the interfacial polymerization reaction were investigated. When the organic phase solvent was cyclohexane with 3% butanone and 18-crown-6 was the phase transfer catalyst, PAR-PH achieved a maximum intrinsic viscosity (ηint) up to 0.52 dL/g. For some organic phase solvents of alkanes and chlorinated hydrocarbons, the addition of co-solvents increased the ηint of the polymer. PAR-PH exhibit excellent thermal resistance due to the introduction of rigid twisted phthalazinone moieties into the polymer main chains, with glass transition temperature (Tg) of 275°C. The 5% thermal weight loss temperature of PAR-PH was 463°C in N2 and residual mass ratios at 800°C of 52.0%, demonstrating excellent thermal stability.