Study On The Properties Of PVDF Film By Amphiphilic Copolymer P(AMPS-CO-MMA)

Membrane separation technology,as a new type of efficient separation technology,has developed rapidly in recent years.And it achieved remarkable results,in enegy saving and discharge decreasing,cleaner production and circular economy,especially in the field of the water resources utilization and environmental protection.Poly(vinylidene fluoride)membrane material has attracted great attention,because of the membrane with strong mechanical strength,thermal stability,chemical resistance and high hydrophobicity But many application fields need the high hydrophilicity,then the application of PVDF membrane will be limited.To solve the problem of membrane hydrophilicity,this topic will be studied the effect of P(AMPS-co-MMA)copolymers on the properties of PVDF porous films.The effect of P(AMPS-co-MMA)copolymer on the properties of PVDF films was studied by two means of grafting and phase transition.First,the method of grafting was used to process the alkaline treatment of the PVDF membrane to produce the carbon-carbon conjugated double bond,then the P(AMPS-co-MMA)copolymer was grafted onto the chain.The results showed that PVDF membrane dehydrofluorination of 3h was the best time,and the processing time too long would cause the film to be fragile and broken,and the treatment time too short would not change the membrane construction.The poly-Def-PVDF membranes had high hydrophilic,anti-fouling and greater permeability.However,there was a defect that the modified membrane can’t withstand too much membrane pressure.Therefore,it is necessary to consider the limitation of operating pressure in practical application.Because the grafting membrane pressure is not very big.so the PVDF membrane was modified again by phase conversion,namely the different concentrations of P(AMPS-co-MMA)copolymer were mixed in the membrane solution to prepare the blend PVDF membrane.The results showed,after adding P(AMPS-co-MMA)copolymer in the casting solution,it has a great influence on the structure and performance of the blend membranes:a large number pores of the modified membrane surfaces were uniformly distributed,and the membrane pores of the finger-like structure was reduced;the contact angle was decreased from 80.60 to about 720;and after pure water backwash,it has the maximum water flux,best anti-fouling performance and the highest recovery rate.However,due to the excessive concentration of polymer,the lwt%hybrid PVDF membrane pores in the membrane surface or on the membrane channel were blocked by the copolymer cluster,which reduced the membrane performance.Hence,the 0.5wt%hybrid PVDF membrane was the best modified mixed membrane.