ABSTRACT
Abstract A series of novel imide-containing phthalonitrile polymers with flexible aryl ether units have been synthesized and characterized. Bisphenol monomers were synthesized by a multi-step synthesis involving a condensation reaction between aromatic aldehydes and 2,6-dimethyl phenol. The bisphenols obtained were reacted with 4-nitrophthalonitrile to form aryl ether linkage containing bisphthalonitriles. These products were hydrolyzed to tetracarboxylic acids, which were subsequently converted into corresponding dianhydrides. The dianhydrides obtained were reacted with synthesized 4-(aminophenoxy) phthalonitrile by thermal imidization leading to the formation of imide-containing phthalonitrile monomers. The synthesized monomers were cured with 3.5 wt% of 4,4′-diaminodiphenylsulphone (DDS). Phthalonitrile end-capped oligoimides with different molecular weights were prepared by the reaction of pyromellitic dianhydride, diamine and 4-(aminophenoxy) phthalonitrile via thermal imidization. The average molecular weights of the oligoimides were determined by GPC analysis. The structure and properties of all compounds synthesized were confirmed by using elemental analysis, FT-IR, 1H-NMR, 13C-NMR, DSC, TGA and rheometric studies. The cure temperatures are found to be in the range of 283-302◦C, the temperatures for 5 and 10% weight losses from TGA were in the range of 433 and 492◦C in N2 and 424 and 478◦C in air and the char yield at 800◦C was 40-51%.
