Membrane and the use thereof

Membrane can be produced carrying a polymer or mixture of polymers to the desired shape, carrying a gas at a superatmospheric before or after forming pressure thereafter foaming the polymer or polymer mixture, which It is loaded with a gas at a temperature above the glass transition temperature of the mixture of one or more polymers and a gas, and finally stabilizing the foam structure, characterized in that the polymer or mixture of polymers, which is loaded with a gas, it becomes a foam with a gas concentration in the polymer or polymer mixture which is located above a critical concentration and at a temperature, which lies below the temperature critical for the respective gas concentration.