Synthesis of porous cross-linked polymer monoliths using 1,1,1,2-tetrafluoroethane (R134a) as the porogen

In this paper, we describe the synthesis of porous, cross-linked polymethacrylate monoliths by free radical polymerization using 1,1,1,2-tetrafluoroethane (R134a) as the porogenic solvent. Solvent separations were simple (boiling point R134a=-26.5 ° C) and the reactions were carried out at relatively low pressures (<20 bar). It was found that the surface area and the median pore diameter of the materials could be varied over a wide range (5–320 m^2/g and 15 nm–5 (mu)m, respectively) by varying the monomer concentration. By contrast, pressure had little influence on the structure of the materials due to the relatively incompressible nature of liquid R134a.