Glassy Membranes

Glassy membranes are membranes consisting of amorphous polymers which are in their glassy state at room temperature or under the normal operation conditions, i.e., their glass transition temperature is above room temperature or the operating temperature. The high stiffness of the glassy polymer provides sufficient mechanical strength to the membranes to exist also as porous or dense integrally skinned flat films or hollow fibers. The polymer stiffness is an essential aspect in the membrane formation process by non-solvent induced phase inversion, where at a certain point of the process solidification of the polymer is required to consolidate the morphology of the membrane. In glassy polymers, this is typically by vitrification of the polymer when diffusion of the solvent from the polymer rich phase into the coagulation bath leads to a gradual increase of the glass transition temperature until this exceeds the coagulation bath temperature.