超疏水聚偏氟乙烯复合微孔膜的制备及性能

提出了一种超疏水聚偏氟乙烯（PVDF）复合微孔膜的制备方法。以相转化法制备的PVDF膜为基膜，通过恒压过滤将多壁碳纳米管（MWCNTs）沉积到PVDF基膜表面，再经聚二甲基硅氧烷（PDMS）溶液修饰，可制得接触角达162°、滚动角约10°的PVDF复合微孔膜。用原子力显微镜和扫描电镜对膜表面进行结构分析，并测试了膜的接触角、气通量和机械强度等性能，考察了MWCNTs及PDMS浓度对膜结构和性能的影响。研究表明，CNTs在具有微米级粗糙度的基膜上强化了纳米结构，提高了膜的粗糙度，PDMS降低了膜的表面能，二者协同作用使复合膜的接触角大幅提高，滚动角显著下降。与高度疏水的PVDF基膜相比，PVDF复合膜的疏水性大幅提高，断裂伸长率加倍，在模拟海水真空膜蒸馏过程中，保持了较高的传质通量和截留率，具有更好的操作稳定性和抗污染性能。

Preparation and properties of superhydrophobic PVDF microporous composite membrane

A novel method is reported to fabricate superhydrophobic polyvinylidene fluoride(PVDF) microporous composite membrane. PVDF microporous membrane prepared by phase inversion was used as the support membrane. Functional multi-walled carbon nanotubes (MWCNTs) were deposited on the support membrane by constant pressure filtration, then the prepared membrane was coated with polydimethylsiloxane(PDMS). The obtained composite membrane exhibited super-hydrophobic property with the water contact angle of 162° and the sliding angle of about 10°. The morphology, contact angle, N₂ flux and the tensile strength of the membranes were tested. The effect of the concentration of MWCNTs and PDMS in the coating solution on the structure and properties of the membranes were also investigated. The results showed that the addition of MWCNTs strengthened the nanostructures of the membrane surface and improved the roughness of the membrane simultaneously. The PDMS coating reduced the surface energy of the membrane. Their synergistic effect increased the contact angle and decreased sliding angle of the composite membranes significantly. Compared with the hydrophobic PVDF support membrane, the hydrophobicity of the composite membrane was better, and the elongation at breaking was doubled. In the vacuum membrane distillation of the simulated seawater, the operational stability and antifouling property of the composite PVDF membrane prepared in this study were greater than those of the hydrophobic PVDF support membrane. And the merits of high permeation flux and rejection coefficient were maintained.