A curing agent for epoxy resin has one or more five- or six-membered aromatic rings, and substituted on the one or more five- or six-membered rings at least two functionalities reactive with the epoxy selected from the group consisting of hydroxyl, amine, imidazole, azine, hydrazide, anhydride, and Lewis acid groups. Choice of functionality can provide a mixed polymer network, one with a more densely cross-linked polymer structure having a high Tg, and the other with a more linear polymer structure to contribute to stress reduction.