Synthesis and characterization of polyimides from bis(3-aminophenyl)-4-(1-adamantyl)phenoxyphenyl phosphine oxide

A novel diamine, bis(3-aminophenyl)-4-(1-adamantyl)phenoxyphenyl phosphine oxide (mDAATPPO), was synthesized via the Williamson ether reaction of 4-(1-adamantyl)phenol and bis(3-nitrophenyl)-4-fluorophenyl phosphine oxide, followed by reduction. The phenol group was prepared by the Friedel-Crafts reaction of 1-bromoadamantane and phenol, whereas the phosphine oxide group was synthesized by the Grignard reaction of 1-bromo-4-fluorobezene and diphenyl phosphinic chloride, followed by nitration. The monomer and its intermediate compounds were characterized with Fourier transform infrared, NMR, and melting-point apparatus. The monomer was then used to prepare polyimides with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, and pyromellitic dianhydride by the conventional two-step synthesis: the preparation of poly(amic acid) followed by solution imidization. The molecular weights of the polyimides were controlled to 20,000 g/mol by off-stoichiometry, and the synthesized polyimides were characterized with Fourier transform infrared, NMR, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. In addition, the solubility, intrinsic viscosity, dielectric constant, and birefringence of the polyimides were evaluated. Novel polyimides with mDAATPPO exhibited good solubility, high glass-transition temperatures (290-330 degrees C), excellent thermal stability (> 500 degrees C), low dielectric constants (2.77-3.01), low refractive indices, and low birefringence values (0-0019-0.0030). (c) 2006 Wiley Periodicals, Inc.