Synthesis and Gas Permeability of Aromatic Polyamide and Polyimide Having Oligodimethylsiloxane in Main-Chain or in Side-Chain

Abstract

ABSTRACT:Aromatic polyamides and polyimide having oligodimethylsiloxane of defined length (1-4 Si atoms) in main-chain or in side-chain were synthesized by polycondensation of bis(4-aminophenyl)-functionalized oligodimethylsiloxanes with acid dichloride or pyromellitic dianhydride. Glass transition temperature and gas permeability of the polymers were markedly influenced by the introduction of oligodimethylsiloxane components into the polymer. The effects was more notable in polymers having oligodimethylsiloxane as side-chains.KEY WORDS Oligodimethylsiloxane I Polyamide I Polyimide I Glass Transition Temperature I Gas Permeation I During the last decade, remarkable progress has been made in the technology of gas separation by selective permeation through polymer membranes. However, only few significant studies on the structure-permeability relationships have been published until now, and insufficient understanding of the relationships between the chemical structure of polymers and their gas permeability makes the progress slow, hence new materials for membranes are developed only on a trial-anderror basis. For further progress, creation of new polymers which exhibit both a high selectivity for specific gases and a high intrinsic permeability based on molecular design of the polymer is essential. 1 We reported that introduction of oligodimethylsiloxane as substituents into polymer structure is an excellent method to develop selectively oxygen permeable membrane matet To whom correspondence should be addressed. rials of well-balanced property between permeability, selectivity in permeation and mechanical strength of the membrane. In order to clarify the role of siloxane linkage in permeation, and to establish the relationships between structure and permeability, glass transition temperature, several polymers having oligodimethylsiloxane side-chains have been synthesized, and their properties were estimated. 2 -7