旋涂法制备PVDF/PTFE复合膜及其性能研究

Preparation and Properties of PVDF/PTFE Composite Membrane by Spin-coating

旋涂技术具备薄膜厚度精确可控、高性价比、节能、低污染等优点,在薄膜制备方法中脱颖而出。本文使用旋涂法制备了聚偏氟乙烯(PVDF)/聚四氟乙烯(PTFE)复合膜,并对其制备工艺进行了优化,同时对旋涂成膜机理进行了研究。通过单因素试验,分析了PVDF溶液浓度、旋涂仪的旋转速度和成膜温度对复合膜的拉伸强度和水通量的影响,利用电子扫描显微镜(SEM)对复合膜胶粘层的微孔孔径变化进行了分析,结果表明,PVDF/PTFE复合膜制备的最佳工艺:PVDF溶液浓度为6 g/L,旋涂仪的旋转速度为2500 r/min以及成膜温度为90℃。该条件下制备的复合膜的膜厚度为200μm,平均孔径为20μm,拉伸强度可达到26.34MPa,水通量可达到605.2 L/(m2·h)。此外,分析旋涂PVDF/PTFE复合膜成型的机理,其原因是由于PVDF溶胶分子与PTFE基膜之间存在范德华力等分子间力以及溶胶分子渗透到基膜微孔之间所形成的钩钉键等粘合作用。

Spin-coating technique applied to film preparation stands out among other techniques owing to its advantages in terms of affording precise control of film thickness and producing minimal pollution in addition to being cost effective and energy saving. In this study, a PVDF/PTFE composite membrane was prepared by spin-coating; the preparation process was optimized, and the mechanism of film formation in spin-coating was investigated. Through single-factor experiments, the effects of the concretion of PVDF solution, spin speed of the spin coater, and the film-forming temperature on the tensile strength and water flux of the composite membrane were examined. The variations in pore size of the composite film adhesive layer were analyzed using scanning electron microscopy. The results showed that the optimum preparation conditions for PVDF/PTFE composite membrane were as follows： PVDF solution concentration of 6 g/L; coater spin speed of 2500 r/min, and film-forming temperature of 90℃. Under these conditions, the film thickness of the prepared composite film was 200μm, the average pore size was 20μm, the tensile strength reached up to 26.34 MPa, and its water flux reached up to 605.2 L/（m2·h）. Furthermore, the mechanism of PVDF/PTFE composite film formation using spin-coating involved Van der Waals forces and other intermolecular forces acting between PVDF sol molecules and the PTFE micro-porous membrane, while the adhesive effects resulted from hook bonding and nail bonding formed by penetration of PVDF sol-gel molecules into the pores of the PTFE membrane.