Phase separation is a naturally occurring phenomenon in a blended mixture, in which a single phase composed of two or more components separates into multiple phases. The control of phase- separated structures is a key technology to develop advanced functional materials. Recently, we have serendipitously discovered the formation of periodic phase-separated polymer structures by the spatiotemporal photopolymerization using a slit of light. However, the formation mechanism of the structures is still unclear. In this study, aiming to explore the mechanism, optical analysis of periodic phase-separated structures was performed in polymer films fabricated under various photopolymerization conditions.
