N-isopropylacrylamide (NIPAAM) modified cellulose acetate ultrafiltration membranes

A potentially low fouling membrane was developed by attaching a stimuli-responsive polymer layer on the surface, which offered the potential to collapse or expand the polymer layer with change in temperature. The phase change arose from the existence of a lower critical solution temperature (LCST) such that the polymer precipitated from solution as the temperature was increased. This capability was exploited to control adsorption/desorption on a cellulose acetate membrane. A temperature decrease caused the layer to expand into a rough hydrophilic state while a temperature increase caused a collapse into a smooth hydrophobic state. By cycling the temperature of the modified membrane above and below the LCST, a dynamic surface was created with the potential to reduced fouling.I n this study, N-isopropylacrylamide (NIPAAM) was used as the temperature-responsive polymer; it has an LCST of 32 °C, and was grafted to a cellulose acetate ultrafiltration membrane surface using cerium ammonium nitrate as an initiator. While surface activation was observed at the nano-scale level, no improvements in fouling control were observed during operation.