Properties of POSS-Modified Oligoimide Resins

摘要

High performance polyimides are currently utilized in a number of aerospace and microelectronic applications. Due to the inherent electronic polarity of the monomers used to synthesize many of these materials, resultant polymers often suffer from property degradation due to exposure to humid conditions, especially at elevated temperatures, often compromising their capabilities in service. The use of monomers demonstrating reduced susceptibility to hydrogen bonding with water molecules without sacrificing mechanical properties and thermo-oxidative stability would afford a new class of polyimide materials for applications currently inaccessible by the state-of- the-art. Thermoplastic polyimides reactively modified with polyhedral oligomeric silsesquioxanes have been found to exhibit a lower propensity for moisture absorption and concomitant property knockdown than their commercial analogues. Using this technology as a foundation, the objective of this work is to examine the effects of incorporating silsesquioxane anilines into the backbones of thermosetting polyimides, particularly elucidating influences on melt processing, curing kinetics, and delivered properties in the cured state. In particular, polymers synthesized from 4,4'-(hexafluoroisopropylidene)- diphthalic anhydride (6FDA) and 4,4'-oxydianiline have been shown to exhibit relatively high moisture uptake in comparison with many other polyimides. As such, these monomers have been selected to construct the backbone of the oligomers used in this study.