Structural control in porous cross-linked poly(methacrylate) monoliths using supercritical carbon dioxide as a "pressure-adjustable" porogenic solvent

The synthesis of permanently porous, highly cross-linked, poly(methacrylate) resins using supercritical CO2 is described. The pressure-adjustable solvent properties associated with supercritical fluid solvents are exploited to fine-tune the average pore size and surface area of the materials. It was found that the materials' properties varied in a discontinuous manner with respect to the CO2 pressure. A minimum in the BET surface area (and a maximum in the pore diameter) was observed at a reaction pressure of approximately 2600 psi. These trends were rationalized by the fact that the mechanisms of nucleation, aggregation, and pore formation are highly sensitive to the nature of the porogenic solvent environment.