Synthesis of epoxy network polymers using anthracene dimers containing amino groups as decrosslinkable hardener and their application to dismantlable adhesives

Abstract

Polymerization of anthracene dimers containing amino groups and epoxy compound was investigated with the aim of synthesizing the epoxy cured materials that can be crosslinked and decrosslinked by heating. Their application to dismantlable adhesives was also studied. As primary diamines capable of undergoing covalent bonds cleavage under heating, 9-aminoanthracene dimers (A(NH2)-D) and 2-(9-anthryl)ethylamine dimers (A(C2NH2)-D) were used. A (C2NH2)-D showed higher reactivity with epoxy compounds than A(NH2)-D due to smaller steric hindrance around the amino group. Furthermore, in comparison with the previously reported 9-anthracenecarboxylic acid dimers (A(CO2H)-D),the polymerization of A(C2NH2)-D with epoxy compounds proceeded at lower temperatures. As a result, the thermal dissociation of anthracene dimer units during polymerization was suppressed and the cured materials with a higher gel fraction was obtained. Decrosslinking took place by heating at higher temperatures than the polymerization temperature.Moreover, A(C2NH2)-D resulted in better compatibility with epoxy compounds compared to A(CO2H)-D. The epoxy cured materials with A(C2NH2)-D functioned as a dismantlable adhesive, exhibiting higher lap-shear adhesion strength and better dismantlability than that with A(CO2H)-D.