Spontaneous frontal polymerization and its application to the preparation of functionally gradient materials

Free-radical polymerization is auto-accelerated by Trommsdorff effect and thermal autocatalysis. Generation of propagating front at the center of the reaction system by local accumulation of the heat of reaction was observed in polymerization of methyl methacrylate. Under optimum conditions, the front was propagated throughout the whole reaction system to complete the polymerization without forming bubbles. Attempts to prepare functionally gradient materials by the spontaneous frontal polymerization were carried out. Both the addition of dopant into the polymerization system and copolymerization of two monomers were succeeded in the preparation of functionally gradient materials. In both cases, gradient in concentration transiently formed may be frozen by the polymerization.