聚苯乙烯马来酸酐对PVDF膜结构和性能的影响

Effect of Polystyrene Maleic Anhydride on the Structure and Properties of PVDF Membranes

聚偏氟乙烯(PVDF)膜易受化学污染,常需要进行表面改性。然而,PVDF作为一种化学惰性高分子聚合物,很难直接进行化学改性。为解决该问题,本文将聚苯乙烯马来酸酐共聚物(SMA)与PVDF共混,采用非溶剂致相转化法(NIPS)制备具有丰富酸酐活性基团的PVDF/SMA共混膜,考察了PVDF和SMA聚合物相容性,探究了铸膜液中PVDF含量、SMA含量以及凝固浴温度等参数对PVDF/SMA共混膜表面结构、孔结构、纯水通量、BSA截留、润湿性等的影响。结果表明:SMA与PVDF为部分相容体系,当SMA含量低于60%时,二者具有良好相容性;水为凝固浴可制备PVDF/SMA共混膜,随着凝固浴温度升高,PVDF/SMA共混膜纯水通量上升,BSA截留率下降;随铸膜液中PVDF聚合物含量增加,膜表面亲水性下降,导致其纯水通量显著降低;铸膜液中添加剂SMA含量对膜结构和性能等均有显著影响,随着SMA含量增加,膜表面开孔率提高,平均孔径和孔隙率均上升,亲水性增强,水通量增大,与未加SMA的PVDF膜相比,通量提升了38倍。

The susceptibility of Polyvinylidene fluoride(PVDF)membranes to chemical contamination calls for surface hydrophilic modification.However,as a chemically inert polymer,PVDF presents a challenge for direct chemical modification.In this paper,a solution to this problem is presented with the addition of poly(styrene maleic anhydride)copolymer(SMA)to the PVDF polymer.The non-solvent-induced phase separation(NIPS)method was used to prepare the PVDF/SMA blended membranes,resulting in abundant active anhydride groups on both the surface and the pore surface of the membrane.The compatibility of PVDF and SMA polymers was studied.The effects of parameters such as PVDF content,SMA content and solidification bath temperature on the properties of PVDF/SMA blended membrane such as chemical structure,surface morphology,pore structure,pure water flux,BSA retention,and pure water contact angle were investigated.The results showed that SMA and PVDF are partially compatible systems,with good compatibility observed when the SMA content is below 60%.The use of water as the coagulation bath was found to effectively prepare the PVDF/SMA blended membrane.As the coagulation bath temperature increased,the pure water flux of the PVDF/SMA blended membrane also increased,while the rejection of BSA decreased.At a bath temperature of 40°C,the pure water flux and BSA rejection were found to be 379.6 L/(m2·h)and>99.0%,respectively.With the increase of PVDF content in the casting solution,the surface hydrophilicity of PVDF/SMA blended membrane decreased,which led to a significant decrease of its pure water flux.The SMA content in the casting solution has an effect on the membrane surface/section morphology,pore structure and hydrophilicity.With the increase of SMA content,the membrane surface porosity increased,the average pore size and porosity increased,the hydrophilicity increased,and the water flux increased significantly.Compared with PVDF membranes without SMA additives,the pure water flux of PVDF/SMA membrane was increased by 38 times..