PNIPAAm and PMAA co-grafted porous PE membranes: Living radical co-grafting mechanism and multi-stimuli responsive permeability

PNIPAAm and PMAA co-grafted porous PE membranes were prepared by a living r adical, sequential photografting method, and shown to have a di-block coval ent structure. In addition, DSC results suggest that complexes between the two blocks are formed under certain conditions. The effect of total co-graf t yield and co-graft composition on the temperature- and pH responsive memb rane permeability was examined. The results were explained using a two laye r model, and by considering the effect of a graft conformation on the perme ability of the individual layers. Finally, by imposing various combinations of temperature and pH, it was shown that the co-grafted membranes could be reversibly manipulated to exhibit more sophisticated permeability response than the singly grafted porous membranes. (C) 2000 Elsevier Science Ltd. A ll rights reserved.