Polymerization-induced vitrification, apparent phase separation, and reaction acceleration during bulk polymerization

A mixture of glassy polymers and small molecules (e.g., solvent, monomer, or additives) are present in many applications, including the adhesion, painting, and resin curing. The relative concentration change of the mixture, either via a chemical reaction or evaporation, can cause vitrification. During bulk polymerization, the relative concentration of the formed polymer and the monomer changes as a function of the reaction time. We have intensively investigated the bulk polymerization of methyl methacrylate. We found that an apparent phase separation occurs in the vicinity of the polymerization-induced vitrification. Furthermore, the apparent phase separation and a sudden reaction acceleration known as the Trommsdorff effect simultaneously occurred. In this focus review, we report novel aspects in understanding the Trommsdorff effect, especially the connection between polymerization-induced vitrification, apparent phase separation and the effect. Other related phenomena are then discussed as perspectives.