Synthesis and Properties of an Addition-type Imide Oligomer having Pendent Phenylethynyl Groups: Investigation of Curing Behavior

Abstract

A phenylethynyl-terminated imide oligomer having pendent phenylethynyl groups (20 mol%) was synthesized using a novel pendent diamine, 2,4-diamino-1-(1-fluoro-4-phenylethynylphenoxy) benzene. The imide oligomer exhibited excellent solubility in NMP and solutions up to 40% solids were obtainable. A detailed cure study was performed on the oligomer by staged heating to final cure temperatures of 370, 400, 420, and 450 C. Complete cure was accomplished by heating at 450 C for 10 min. In comparison phenylethynyl terminated oligomers typically require curing for 1 h or more at 370 C. The cure reaction was studied using DSC by following the disappearance of exothermic peak corresponding to the cleavage of the triple bond (i.e. phenylethynyl group). DMA showed an increase in T g and a decrease in the drop of storage modulus ( E) with increasing post-cure temperature. Likewise, thin film tensile specimens exhibited a decrease in the elongation to break with increasing post-cure temperature. Post-cure time (370 C for 1 and 2 h) did not achieve full cure.