Low-temperature, surface-mediated foaming of polymer films

Ultraporous thin polymer films (see Figure) are generated using physical constraints imposed by external surfaces (hard plates) and internal surfaces (hard nanoparticles and soft micelles) via foaming with supercritical CO2. The constraints serve as diffusion barriers and/or heterogeneous nucleation sites. Use Of CO2-philic copolymers further enables microcellular foaming at reduced pressures with liquid CO2.