Heat-sterilisable membranes comprise at least two mutually immiscible hydrophobic polymers that have been compatibilised with each other or covalently bonded to each other, provided that at least one polymer is unstable and at least one polymer is stable under sterilisation conditions comprising treatment with satd. steam at 120 degrees C for 20 min or treatment with dry heat at 180 degrees C for 90 min.
