Abstract
AbstractThe synthesis of soluble imide oligomers of controlled molecular weight endcapped with the 3-phenylethynyl aniline endcapping agent is described. The 3-phenylethynyl aniline was employed to afford a higher curing temperature (380 - 420°C) which widens the processing window compared to commercially available acetylene endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester-acid of various dianhydrides and various aromatic diamines. The “one pot” procedure utilizes NMP as the solvent and o-dichlorobenzene as the azeotroping agent, and reproducibly exhibit fully imidized soluble polyimides with Mw/Mn values of ∼2.0 determined by gel permeation chromatography. Thermally cured samples display good solvent resistance and exhibit glass transition temperatures comparable to their high molecular weight linear analogs. These polyimides show excellent thermal stability at 700°F aged in air up to 100 hours. Mechanical testing has been performed on a pyromellitic dianhydride (PMDA) and a phosphine oxide-based system. The flow properties have been studied by parallel plate rheology and the cure cycle has been monitored using 13CNMR.
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