Synthesis and characterization of polyimide/f-poss and polyimide/f-MWCNT nanocomposites

Abstract

The present research proposal is focused on the synthesis and characterization of polyimides having bulky pendant groups and their nanocomposites with f-POSS and f-MWCNT. Hence, monomers containing bulky pendant groups with heterocyclic ring were synthesized and subsequently polymerized with nanomaterials (f-POSS and f-MWCNT) to give their corresponding polyimide nanocomposites having interesting features like good film forming ability, high char yield, low moisture absorption and good electrical property. Four different diamines containing quinoline, benzimidazole, quinazoline and dithiane units were prepared. The quinoline containing diamine monomer was synthesized in two steps. The first step involves the formation of 2-chloro-3-formyl quinoline by the reaction of acetanilide with phosphorousoxytrichloride in dimethyl formamide by Vilsemeir-Haack formylation reaction. The second step involves the formation of diamine monomer BACQM from 2-chloro-3-formylquinoline and 2,6-dimethyl aniline in the presence of Con.HCl. The benzimidazole containing diamine monomer was synthesized in three steps. In the first step, 1,2-phenylene- 2,2 -bisbenzimidazole (o-PBI) was prepared by the reaction between phthalic acid and o-phenylene diamine with polyphosphoric acid. In the second step, the dinitro compound (o-P5NBI), was prepared by nitration of the o-PBI and third step involves the preparation of diamine (o-P5ABI) in good yields by the reduction of the dinitro precursor (o-P5NBI) using stannous chloride/acetic acid. The diamine monomer containing quinazoline ring was prepared in two steps. The first step involves the formation of 2,4-bis(4-aminophenylamido)- 6-chloroquinazoline (BAPCQ) from 6-chloro-2,4-diaminoquinazoline and 4-nitrobenzoylchloride. The second step involves the preparation of 2,4-bis (4-aminophenylamido)-6-chloroquinazoline by the reduction of 2,4-bis (4-nitrophenylamido)-6-chloroquinazoline using Pd/C and hydrazine monohydrate. The dithiane containing diamine monomer was synthesized in two steps.