Structure Formation of Integral Asymmetric Composite Membranes of Polystyrene-block-Poly(2-vinylpyridine) on a Nonwoven

The formation of an integral asymmetric membrane composed of a cylinder‐forming polystyrene‐block‐poly(2‐vinylpyridine) on a nonwoven by using solvent casting followed by solvent/nonsolvent exchange (phase inversion) is reported for the first time. The influence of parameters such as solvent composition, evaporation time of the solution‐cast block copolymer film before phase inversion, and immersion bath temperature is demonstrated. The optimized membranes are characterized in terms of stimuli‐responsive water flux properties. The morphologies of the membranes as well as of the bulk of the block copolymer are imaged by scanning force microscopy, scanning electron microscopy, and transmission electron microscopy. Integral asymmetric composite membranes with a PS‐b‐P2VP top layer are shown for the first time. The quality of the membrane structure is discussed in terms of solvent composition, evaporation time of the cast block copolymer solution on a nonwoven before immersion, and temperature of the immersion bath. The stimuli‐responsive membranes are characterized by pH‐dependent water flux measurements.