Tetrahydrophthalic Anhydrides as Addition Curing Polyimide End Caps'Thermal Isomerization of Methylendianiline 3,6-Diphenyltetrahydrophthalic Bisimides

摘要

Over the past decade,we have explored the mechanism of the thermal oxidative degradation of addition-curing polyimides and have shown that it is the end cap which is responsible for much of the observed weight loss.Further exploration focused on a variety of new end caps in the hope that they would prolong the useful lifetime of polyimide materials.We recently reported in this journal on our reevaluation of tetrahydro-phthalic anhydrides 3 as such an end cap.In particular,the preferred Diels-Alder endo-addition of butadienes 1 with maleic anhydride 2 conveniently yields these anhydrides (3) in a cis,cis,cis configuration.