Synthesis Of PVC-TSA-MPEG And Hydrophilic Modification To PVC Ultrafiltration Membranes

As one of widely applied materials in current membrane market,Polyvinyl chloride?PVC?presents good chemical stability,high mechanical strength and good heat resistance,but the relative low permeat flux and hydrophobicity limits its application.It is one key research project to improve the PVC ultrafiltration?UF?membrane hydrophilicity,which can be realized by grafting modification and blending modification.Firstly,PVC-TSA was obtained by the raction of PVC and salicylic acid?TSA?.Then PVC-TSA-MPEG were obtained by grafting methoxypolyethylene glycols?MPEG?with different relative molecular mass onto PVC-TSA chain.¹H-NMR and FTIR were used to characterization the relative product.The results showed that the PVC-TSA-MPEG were synthesized successfully.Then PVC-TSA-MPEG was used to hydrophilic modification PVC membranes by an immersion precipitation phase inversion method using DMAc as solvent and PVC-TSA-MPEG as hydrophilic modification agent.The effect of PVC-TSA-MPEG₇₅₀ additive amount on the structure and properties of PVC UF membrane was investigated.Attenuated total reflection Fourier transform infrared spectrometer?ATR-FTIR?was used to characterize the chemical structure of PVC membrnaes and the results indicated that the amphiphilic copolymer had embedded into PVC modified membrane.Scanning electron microscope?SEM?results indicated that the structure of PVC modified membrane did not changed obviously.However,the pores of PVC modified membrane became relative large.Water contact angle?CA?test indicated that the hydrophilicity of the modified membrane increased with the content of PVC-TSA-MPEG₇₅₀ increasing.The ultrafiltration performance of the membranes was investigated by dynamic filtration bovine serum albumin?BSA?and lysozyme?LYS?solution.The results indicated that the permeation flux and anti-fouling properties of modified membranes were improved obviously.And the membrane modified with 16 wt%PVC-TSA-MPEG₇₅₀ displayed the highest permeation flux and the best antifouling properties.Protein adsorption results proved in further that antifouing property of PVC UF membranes improved with the increase of PVC-TSA-MPEG₇₅₀ content.The effect of MPEG chain length on the properties of PVC membrane was further researched.MPEG molecules with different molecular weight 350,500,750 and 1000were grafted onto PVC-TSA to synthesize four amphiphilic copolymers PVC-TSA-MPEG_x.PVC-TSA-MPEG_x hydrophilic modified PVC membrnes were prepared by blending 16 wt%PVC-TSA-MPEG_x with pure PVC.ATR-FTIR and SEM were used to characterize the chemical structure of PVC membranes.BSA,LYS solution were used to characterize the filtration properties of PVC membranes.The results suggested that the longer of the hydrophilic MPEG chain length was,the higher the water flux and the better antifouling property of PVC membranes would be.However,PVC-TSA-MPEG₁₀₀₀ presented the best hydrophilicity and antifouling property due to more amphiphilic copolymer enriched on membrane surface and the hydrophilic chain in PVC-TSA-MPEG was relatively longer.