The Utility of 2-Naphthol Derivatives As Diels–Alder Based Co-Reactants for Bismaleimides

Abstract

A number of 2-naphthols were found to undergo a Diels–Alder addition reaction with maleimides. This reaction can be used to bring about the cure of bismaleimides. The simplest co-reactant prepared in this work was 7-allyloxy-2-naphthol and satisfactory cures were obtained with appropriate bismaleimides. However, the laminate coupons made using this system had lower thermal stability than those of a comparable system using the commercial co-reactant Matrimid 5292B. The performance of this new chemistry was further tested by incorporating the naphthol/maleimide Diels–Alder addition structure into two other co-reactants. The most successful of these compounds (the diallyl ether of the adduct made from Diels–Alder addition of 2, 7-dihydroxynaphthalene and 4-hydroxyphenylmaleimide) produced cured neat resin samples having T _gs 30 °C higher than those of a comparable system cured with the standard bismaleimide co-reactant (Matrimid B) and had slightly higher tensile strength and modulus than this system. The fact that these laminate coupons had better thermal performance than the system using commercial co-reactant showed that the presence of the Diels–Alder adduct structure in the resin backbone was not detrimental to the normal performance of ene cured bismaleimides. On the other hand the same structure incorporated into phenylethynyl end-capped resins was found to compromise its thermal stability.