Long-lasting anti-fouling membrane of polyvinylidene fluoride (PVDF) requires covalently bonded hydrophilic units, which faces challenges like multi-step treatments yet uneven modification due to heterogeneous reaction. For that, grafting hydrophilic polymer chains onto PVDF through homogeneous reaction was reported in this work. First, PVDF was dehydrofluorinated in solution by adding a small amount of ammonia water to generate C=C double bonds, and then vinyl-monomer of N-vinyl pyrrolidone (NVP) or vinyl acetate (VAc) was evenly grafted through heterogeneous reaction to provide hydrophilic side chains. The successful syntheses of the graft copolymers were confirmed using Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The grafting degrees have been controlled by the feeding amounts of the monomers. Moreover, the reaction mixture of PVDF-g-PVP was used as additive to prepare hydrophilic PVDF membrane, while the graft copolymer PVDF-g-PVAc was directly prepared into hydrophilic membrane. Water contact angles and bovine serum albumin adsorption capacities of the membranes were measured to evidence the improvements in their hydrophilicity and fouling resistance, and the porosities and water fluxes were determined to indicate their potential. The results suggest that the PVDF graft copolymers synthesized through the homogeneous reaction may find promising application in membrane field.

Graphical Abstract

中文翻译：

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均相反应改性聚偏氟乙烯制备亲水膜

聚偏二氟乙烯（PVDF）长效防污膜需要共价键合的亲水单元，面临多步处理和非均相反应导致改性不均匀等挑战。为此，本工作报道了通过均相反应将亲水性聚合物链接枝到 PVDF 上。首先，PVDF在溶液中加入少量氨水脱氟化氢，生成C=C双键，然后通过非均相反应均匀接枝N-乙烯基吡咯烷酮（NVP）或醋酸乙烯酯（VAc）乙烯基单体，得到亲水侧链。利用傅里叶变换红外光谱、氢核磁共振光谱和凝胶渗透色谱证实了接枝共聚物的成功合成。接枝度通过单体的进料量来控制。此外，以PVDF- g -PVP的反应混合物作为添加剂制备亲水性PVDF膜，而接枝共聚物PVDF- g -PVAc则直接制备成亲水性膜。测量了膜的水接触角和牛血清白蛋白吸附能力，以证明其亲水性和抗污染性的改善，并测定了孔隙率和水通量以表明其潜力。结果表明，通过均相反应合成的PVDF接枝共聚物在膜领域具有广阔的应用前景。

图形概要