Polyimide-tethered polyhedral oligomeric silsesquioxane, (R 7R′Si8O12) (POSS), nanocomposites with well-defined architectures are prepared by the copolymerization reaction of a new type of diamine monomer: POSS-diamine, 4,4′-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). This type of polyimide-side-chain-tethered POSS nanocomposite presents self-assembly characteristics when the amount of POSS exceeds10 mol %, as evidenced by transmission electron microscopy studies. Furthermore, POSS/polyimide nanocomposites have both lower and tunable dielectric constants, with the lowest value of 2.3, and controllable mechanical properties, as compared to that of pure polyimide.

Low-dielectric-constant nanoporous films (dielectric constant, k = 2.4) with thermal integrity and controllable mechanical strength have been prepared by covalently tethering nanoporous polyhedral oligomeric silsesquioxane (POSS) molecules, 1-nm size, to the side chains of polyimide. The tethered POSS molecules in the amorphous polyimide retain a nanoporous crystal structure, but form an additional ordered architecture due to microphase separation. With this approach, the dielectric constant of the film can be tuned by the amount of POSS molecules introduced in the nanocomposite film; the polyimide molecules offer additional advantages of maintaining certain thermal and mechanical strengths.

Polyimide-tethered polyhedral oligomeric silsesquioxane, (R 7R′Si8O12) (POSS), nanocomposites with well-defined architectures are prepared by the copolymerization reaction of a new type of diamine monomer: POSS-diamine, 4,4′-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). This type of polyimide-side-chain-tethered POSS nanocomposite presents self-assembly characteristics when the amount of POSS exceeds10 mol %, as evidenced by transmission electron microscopy studies. Furthermore, POSS/polyimide nanocomposites have both lower and tunable dielectric constants, with the lowest value of 2.3, and controllable mechanical properties, as compared to that of pure polyimide.

Covalently bonded layered silicates/polyimide (BTDA-ODA) nanocomposites have been synthesized from γ-(aminopropyl)triethoxysilane (APTS) grafted kenyaite and poly(amic acid). The existence of covalent bonds between APTS and silicates and between APTS and the dianhydride end groups of the polymer have been confirmed by solid-state 13C and 29Si nuclear magnetic resonance and infrared spectroscopy, respectively. The thermal, mechanical, and moistureabsorption retardation properties of these nanocomposites were found to improve substantially over those of neat BTDA-ODA. In particular, a maximum increase of 36 °C in the degradation temperature and a maximum reduction of 54% in moisture absorption are displayed by these nanocomposites.

This report presents the synthesis and chemical modification of hyperbranched poly(ether ketones). The polymer was conveniently prepared by direct polycondensation of an AB 2 monomer, 3,5-diphenoxybenzoic acid, using phosphorus pentoxide/methanesulfonic acid (PPMA) as the condensing agent and solvent. The hyperbranched poly(ether ketone) could be modified via the electrophilic aromatic substitution of the active phenoxy groups at the chain ends with a variety of carboxylic acids. The thermal properties of the hyperbranched poly(ether ketones) depend heavily on the nature of the chain end, with glass transition temperature ranging from Ϫ 24ЊC to 180ЊC. Moreover, the length of the terminal alkyl groups significantly influences the solubility of the hyperbranched poly(ether ketones). By varying the chain ends, hyperbranched poly(ether ketones) soluble in either a polar or nonpolar solvent could be obtained.