Preparation of skinless polymer foam with supercritical carbon dioxide and its application to a photoinduced hydrogen evolution system

Skinless polymer foam was prepared by treating poly(methyl methacrylate) (PMMA) with supercritical carbon dioxide (scCO2). The film was immersed in scCO2 with ethanol to nucleate, and then incubated in a hot water bath to induce nuclear growth and to prepare skinless PMMA foam. The obtained polymer foam had a low density and cells were connected to each other to make channels through the skin layer. Low molecular weight PMMA formed skinless foam with larger cells through expansion. PMMA film containing tin meso-tetraphenyl porphyrin was also foamed with same procedure and the foam was used for photoinduced hydrogen evolution. A larger amount of hydrogen evolved from the photocatalyst on the skinless PMMA foam in comparison with the foam with skin. Enlargement of effective surface area of solid support and light scattering within the foam could enhance turnover number (TON) of photocatalyst.