Microstructures of Ultralow-Density Foam Plastics Obtained by Altering the Coagulant Alcohol

The present report describes ultralow density (2–12 mg/cm 3 ) plastic (CH 2 ) foams whose density is close to the cutoff density of the plasma for visible and near-infrared light beams (0.55–1.3 µm). These foams are prepared from a poly(4-methyl-1-pentene) gel with hexanol derivatives by extraction using supercritical fluid CO 2 . Their intended use is in laser-plasma experiments and as a laser-plasma X-ray source. Their microstructure (2–10 µm) was finer than that of the previous poly(4-methyl-1-pentene) foam and could be varied using different hexanols.