Preparation and Morphology of SMPU/PNIPAM Semi-IPN Microporous Membrane

Microporous membranes were prepared by immersion precipitation phase inversion method from the semi-interpenetrating polymer network (semi-IPN) of shape memory polyurethane (SMPU) and poly (N-isopropylacrylamide) (PNIPAM). The influence of material compostion and preparation procedure on the morphology of membranes such as pore structure and porosity was investigated by methods including Fourier-transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM). Both sponge-like structure and large-pore structure were found in the membranes. The introduction of PNIPAM content in the semi-IPN promotes the formation of large-pore structures and increases the porosity of membranes, due to the improvement of water diffusion into the casting solution. We also found that by increasing the temperature of coagulation bath and the concentration of DMF in the coagulation solution, the formation of large pores could be impeded, and membranes with more sponge-like structure could be prepared.