Enhancement of atomic oxygen resistance for heat-sealable isomeric co-polyimide films by combining ether linkage with diphenylphosphine oxide

Abstract

Heat-sealable isomeric co-polyimide (CPI) films with enhanced atomic oxygen (AO) resistance and mechanical strength were synthesized from 2,3,3′,4′-oxydiphthalic anhydride (aODPA), 4,4′-oxydianiline (ODA), and 2,5-bis [(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO). We investigated how the molecular structure and diamine ratio affected the thermal properties, solubility, mechanical properties, AO resistance and heat-sealability. The diphenylphosphine oxide (DPO) side group decreased the CPI film mechanical strength and its higher ODA reactivity increased the molecular weight. At 10 mol% ODA in the aODPA-BADPO system, the CPI film exhibited increased tensile strength with no detriment to the AO resistance. Meanwhile, the CPI films demonstrated good heat-sealability indicated by a completely merged interface after heat sealing.