Phase separation of polymer mixtures driven by photochemical reactions: current status and perspectives

Phase separation of polymer mixtures induced by photo‐crosslinking and photopolymerization is summarized from the viewpoint of competing interactions in polymeric systems. First, the kinetics of photo‐crosslinking and photopolymerization are reviewed with particular emphasis on the Trommsdorff − Norrish effect in polymerization, which leads to the formation of a bimodal distribution of molecular weight at long irradiation time. The emergence of a very large molecular weight and the characteristic time for this effect to set in are utilized as a tool to control the temporal development of the resulting morphology. The shrinkage associated with the reaction and particularly its effect on the phase separation and the morphology are discussed together with the influence of the Trommsdorff − Norrish effect. Experiments on polymerization‐induced phase separation extended from binary to ternary mixtures are described where the interfacial interactions give rise to a wide variety of morphologies. Taking advantages of light, experiments using spatial and temporal modulation have been performed to control and manipulate the phase separation. These experimental results are summarized and briefly discussed in relation to the elastic deformation induced by polymerization. Finally, an overview of theoretical studies and numerical simulation of reaction‐induced phase separation is given with some comments on the complexity of the phenomena. © 2016 Society of Chemical Industry