Synthesis and characterization of soluble phenylethynyl-terminated imide oligomers derived from pyromellitic dianhydride and 2-phenyl-4,4′-diaminodiphenyl ether

Novel addition-type imide oligomer (degree of polymerization: n = 1-10) derived from 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 2-phenyl-(4,4'-diaminodiphenyl ether) (p-ODA) which has asymmetric and non-planar structure, and 4-phenylethynylphthalic anhydride was synthesized for the matrix resin of high heat resistant carbon fiber-reinforced composites. The uncured imide oligomers (degree of polymerization: n = 1-4) showed good solubility (more than 30 wt.%) in aprotic solvents such as N-methyl-2-pyrrolidone (NMP). These imide oligomers also showed a very low viscosity. These data were accomplished by preventing the aggregation caused by the pendant phenyl group of p-ODA. The imide oligomers were successfully converted to cross-linked structures after curing at 370 degrees C. The glass transition temperature and elongation at break (epsilon(b)) of the cured imide resin were found to be very high (almost 360 degrees C and >15%) respectively. (C) 2012 Elsevier Ltd. All rights reserved.