In this work, poly(vinylidene fluoride) copolymer with hexafluoropropylene (PVDF-HFP) membrane-like aerogels have been generated for the first time. PVDF-HFP gels have been prepared from polymer-acetone solutions by adding various amounts of ethanol. A series of supercritical drying experiments have been performed at different pressures (from 100 to 200 bar) and temperatures (from 35 to 45 degrees C) and at various polymer concentrations (from 5 to 12 wt %). The effects of the process conditions on the membrane morphology have been evaluated, and structure-property relationships have been found. In all cases, the membranes exhibit interconnected structures with nanosized pores and high porosity, leading to reduced resistance to the gas mass transfer and high hydrophobic character of the surfaces. These membrane-like aerogels promise to form a new class of highly hydrophobic porous interfaces, potentially suitable to be used in membrane operations based, for example, on the contactor technology.

Membranes loaded with an active principle are one of the alternatives proposed to obtain controlled release pharmaceutical formulations. Until now, several methods have been proposed for the fabrication of membranes as drug delivery devices, such as phase inversion, gas foaming/particulate leaching, and solvent evaporation. Supercritical CO2 (SC-CO2) phase inversion offers an alternative process to obtain solvent-free membranes with short processing times, avoiding the collapse of the structure. We prepared poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF−HFP) loaded membranes by SC-CO2 phase inversion, performing experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55 °C. We selected as the base case the PVDF−HFP−acetone solution at 15% w/w polymer and modified the drug (amoxicillin) concentration from 20 to 50% w/w with respect to PVDF−HFP. Different membranes morphologies, ranging from nanometric gel-like networks (mean pores diameter of about 150 nm) to micrometric cellular structures (mean cells diameter ranging between 5 and 12 μm), and different drug distributions were obtained, depending on the process conditions. Drug-controlled release experiments were also performed to study the kinetics and duration of the release process.

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