Blowing agent free generation of nanoporous poly(methylmethacrylate) materials

In this article, we demonstrate a newly developed technique for generation of nanoporous polymer materials. Generally, the production processes of polymeric nanostructured materials require high pressure due to the handling of gaseous blowing agents. Our new approach allows to generate nanoporous polymer materials without blowing agent at ambient conditions. Starting from a crosslinked polymer gel swollen with a mixture of at least two specially selected solvents leads to a nanoporous material by sequential evaporation. We varied the pore size of the generated structures between 80 and 800 nm so that the effect of the pore size on the gaseous thermal conductivity could be analyzed. Decreasing the pore size of the materials, the gaseous thermal conductivity could be reduced considerably. Thus, we developed a blowing agent free technique which allows the generation of nanoporous polymer materials—Knudsen materials—at an ambient pressure.