Poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membrane was prepared by vapor and non-solvent-induced phase separation (VNIPS) process, and the relationships between preparation conditions, phase separation behaviors and membrane structures were discussed. The phase diagram was generated by cloud point titration, the effects of environmental relative humidity, air exposure time and casting solution temperature on the structure and performance of the resulted membrane were investigated. The addition of polyvinylpyrrolidone (PVP) additives to the casting solution made the system thermodynamically unstable and led the turbidity curve shift toward the solvent/non-solvent axis. The experimental results showed that both average pore size and porosity increased with higher relative humidity. When the relative humidity increased from 35 to 85%, the mean pore size increased from 35 to 70 nm. The effect of exposure time on membrane structure was related to the air environment. It was found that under low temperature and low humidity conditions, exposure time had little effect on membrane structure. When the relative humidity was 75%, the mean pore size and distribution increased with the exposure time extension from 1.0 to 30 s. The mean pore size of the membrane could be reduced by reducing the relative humidity. When the temperature of the casting solution increased, the membrane pore size reached maximum at 80 °C, and the spherulite on the surface of the membrane decreased. The spherulite morphology almost disappeared when the temperature of the casting solution reached 120 °C. In addition, with the increase in the casting solution temperature, large pores appeared in the sub-layer of the membrane, which gradually widened the pore distribution, leading to the decrease in the tensile strength. The preparation condition was optimized as low temperature of casting solution, low humidity and low temperature of the environment. The fabrication process showed the potential for scaling-up production of the PVDF UF membrane by the VNIPS technique.

采用气相和非溶剂相分离（VNIPS）工艺制备聚偏二氟乙烯（PVDF）超滤（UF）膜，探讨了制备条件、相分离行为和膜结构之间的关系。通过浊点滴定生成相图，研究了环境相对湿度、空气暴露时间和浇注溶液温度对所得膜结构和性能的影响。在浇铸溶液中添加聚乙烯吡咯烷酮 (PVP) 添加剂会使系统热力学不稳定，并导致浊度曲线向溶剂/非溶剂轴移动。实验结果表明，平均孔径和孔隙率都随着相对湿度的增加而增加。当相对湿度从 35% 增加到 85% 时，平均孔径从 35 nm 增加到 70 nm。暴露时间对膜结构的影响与空气环境有关。发现在低温低湿条件下，暴露时间对膜结构影响不大。当相对湿度为 75% 时，平均孔径和分布随着暴露时间从 1.0 秒延长到 30 秒而增加。可以通过降低相对湿度来减小膜的平均孔径。当浇铸液温度升高时，膜孔径在80 ℃时达到最大值，膜表面的球晶减少。当铸液温度达到120℃时，球晶形态几乎消失。此外，随着铸液温度的升高，膜的亚层出现大孔，使孔分布逐渐变宽，导致抗拉强度下降。制备条件优化为浇注液温度低、环境湿度低、温度低。制造过程显示了通过 VNIPS 技术扩大生产 PVDF UF 膜的潜力。