Preparation And Performance Of The Thermo-sensitive Membrane Of PVDF/GO-g-PNIPAAM

Membrane separation technology has the unique advantages of low energy consumption,no phase change,high separation efficiency,no secondary pollution and easy integration with other technologies.Compared with the traditional separation method,it has a relatively wide range of applications,but because of the single function of traditional separation membrane has been far from satisfying the needs of people,so the new multi-functional intelligent separation membrane emerged.Temperaturesensitive smart membrane is a new intelligent membrane which can make sensitive reaction to the change of ambient temperature and self-adjustment,and the shape and permeability of membrane pore change with the change of ambient temperature.Polyvinylidene fluoride membrane has good chemical stability,heat resistance and good mechanical strength.And because of its low price and good film forming performance,it is widely used in industrial separation.However,the PVDF membrane has low surface energy and high hydrophobicity.When used for separation,hydrophobic substances in the liquid are adsorbed on the membrane surface,so the PVDF membrane can be modified by doping the hydrophilic inorganic nanoparticles.The oxidation of graphene(GO)in modified materials has attracted much attention because of its unique structure and good hydrophilicity.But because the GO is mixed with the base membrane material directly,the compatibility is poor and GO is easy to reunite.The GO was first grafted with a temperature sensitive N-isopropyl acrylamide(NIPAAm)to form a nano-particle with a temperature-sensitive property GO-gPNIPAAm and then mixed with the base membrane material,which will not only benefit the compatibility of GO and substrate material,but also endow the temperaturesensitive properties of the substrate membrane material.In this paper,the thermo-sensitive monomer N-isopropyl acrylamide was grafted onto the oxidized graphene(GO)by atom transfer radical polymerization(ATRP),and the nano-particle GO-g-PNIPAAm with temperature sensitivity was synthesized,and then the blend membrane was prepared by immersion precipitation phase conversion method.N,N-dimethylacetamide(DMAc)as solvent for casting film,polyvinyl pyrrolidone(PVP)as an additive,coagulation bath for distilled water.The polymer nanoparticles doped with different doping quantities were blended with PVDF,the PVDF ultrafiltration membrane with temperature sensitivity was prepared under the optimum preparation conditions(PVDF content of 20 wt%,PVP content 3 wt%,coagulation bath temperature 30 ℃),and the nano-particle with different grafting rate was blended with PVDF,through the comprehensive characterization of ultrafiltration membrane,such as temperature sensitivity,porosity,membrane structure,anti-fouling performance and mechanical strength,the best additive quantity was obtained.In summary,after doping GO-g-PNIPAAm in the PVDF base film material,the overall performance of the ultrafiltration membrane has been improved,and the grafting rate of nano-particles doped in the substrate was 13%,and the doping was 0.2 wt%,the temperature-sensitivity,the pollution resistance and the hydrophilicity of UF membranes were improved significantly.