Controlled polymer phase separation enables significant improvement of a range of mechanical characteristics such as enhanced material toughness and impact strength, reduction of photopolymerization-induced shrinkage stress, and reduced material gloss. Photo-induced phase separation (PhIPS) is a method of photopolymerization in which phase separation is utilized to produce polymeric materials with tunable physical and mechanical properties. PhIPS can be controlled by altering photopolymerization conditions (e.g. light intensity) as well as formulation chemistry. As shown in Figure 1, differences in light intensity have been shown to significantly alter the formation of phase separated domains in acrylate-dioxetane systems due to differences in reaction rate of their constituent monomers. Differences in formulation composition also affect the interplay between phase separation and gelation onset in photopolymerizing systems as has been shown in studies examining the influence of compatabilizing hybrid monomers, crosslinkers, and oligomers in acrylate-oxetane resins.

                                                                                       Figure 1. Diagram depicting hybrid photopolymerization process used in PhIPS (top)                                                                                                                                                                         and its effects on morphology (bottom right) and mechanical properties (bottom left)