Intrinsically heat-sealable polyimide films derived from 2,3,3′,4′-oxydiphthalic anhydride and aromatic diamines with various ether linkages

Abstract

A series of polyimides (PIs) with good heat sealability were synthesized from an asymmetric aromatic dianhydride, 2,3,3′,4′-oxydiphthalic anhydride, and aromatic ether diamines with different structures featured by ether amounts, substituted positions of ether linkages, and substituted positions of amino groups. In detail, the effects of these three substructures in the diamine were investigated on thermal resistance, thermoplasticity, and heat sealability of the PI film. It is found that the glass transition temperatures and heat-sealing strengths of the prepared PI films are influenced to different extents by the variations of the substructures, because of their different contributions to the chain mobility. These PI films are demonstrated to possess good heat sealability evidenced by completely fused heat-sealing interfaces and high heat-sealing strengths up to 580 N m−1.