Groebe, A.A.GroebeChmiel, H.H.Chmiel2022-03-082022-03-081990https://publica.fraunhofer.de/handle/publica/302381The invention relates to polymer membranes based on polyvinylidene fluoride (PVDF), a method of their production and their use for ultrafiltration. Using known techniques, the membranes are made from homogeneous solutions comprising between 5 and 30 per cent PVDF by weight and between 0.01 and 30 per cent sulphonic acids and/or their salts by weight; these salts are obtained by sulphonating the polyether ketones of formula (I) or by subsequent neutralization of the sulphonic acids. The membranes are then treated with methanolic solutions comprising between 0.1 and 5 per cent of the above-mentioned sulphonic acids and/or their salts by weight. This process yields membranes with excellent hydrophilic properties, high thermal and mechanical stability and high transmembrane flows. -(-O-p-C<-6 H<-4 -O-p-C<-6 H<-4 -CO-p-C<-6 H<-4 -)<-n -de608610620660patent1989-3904544