Preparation of thermally stable, low dielectric constant, pyridine-based polyimide and related nanofoams

Reaction of 6-chloronicotinoyl chloride with p-phenylene diamine resulted in preparation of a dichloro diamide compound. Subsequently, chloro displacement of this compound with 4-amino phenoxy groups led to production of a new pyridine-based ether diamine named as N,N-(1,4-phenylene)bis(6-(4-aminophenoxy) nicotinamide). Novel polyimide was prepared through polycondensation reaction of the diamine with hexafluoroisopropylidene diphthalic anhydride (6-FDA) via two-step imidization method. In addition, new nanoporous polyimide films were produced through graft copolymerization of polyimide as the continuous phase with a thermally labile poly (propylene glycol) oligomer as the labile phase. The grafted copolymers were synthesized using reaction of the diamine and 6-FDA in the presence of poly (propylene glycol) 2-bromoacetate as thermally labile constituent via a poly(amic acid) precursor process. The labile block was decomposed via thermal treatment to release inert molecules that diffused out of the matrix to leave pores with diameters between 30 and 60 nm. The structures and properties of polyimide and polyimide nanofoams were characterized by different techniques including 1H-NMR, FTIR, TGA, DMTA, SEM, TEM, dielectric constant, and tensile strength measurement. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013