Polyimides with main-chain ethylene oxide units: synthesis and properties

This paper describes the synthesis of a new series of well-defined bis(ether anhydride)s based on ethylene oxide sequences of known length (up to six ethylene oxide units) with phthalic acid anhydride end-caps, and extends the synthesis of bisphenoxyamines based on ethylene oxide sequences to six ethylene oxide units. The dianhydrides and diamines were used in combination to synthesize a series of segmented polyimides of well-defined structures having defined sequences of from zero up to six ethylene oxide units separated by N-phenylphthalimide units. The polymers are characterized in terms of solubility, thermal stability, thermal transition behaviour, including crystal melting behaviour; glass-transition temperatures vary systematically with structure and composition. One polymer exhibits liquid crystallinity. The water absorption characteristics of the polymers, which vary from a hydrophobic aromatic polyimide to polymers containing up to 52.7 wt% ethylene oxide, were determined. The crystal melting behaviour is discussed in conjunction with data from other segmented polyimides containing similar structural units. (C) 2002 Elsevier Science Ltd. All rights reserved.