CNCs增强相分离法构建PVDF/PDMS超疏水表面

Construction of a superhydrophobic surface by phase-separation of PVDF/PDMS enhanced by CNCs addition

摘要:

采用非诱导相分离法，通过将纤维素纳米晶（CNCs）与两种聚合物（聚偏二氟乙烯和聚二甲基硅氧烷）进行结合，利用CNCs之间的静电排斥力及其高比表面积特性，有效降低相分离过程中聚合物的聚集，减小了颗粒尺寸，增强了颗粒分散性，在棉布、木板和玻璃表面构造了精细均匀的微纳米粗糙结构。采用FTIR、SEM、AFM、接触角测量仪、3D光学轮廓仪对CNCs和超疏水表面的形貌、结构和超疏水性进行表征。研究发现，棉布、木板和玻璃表面的水接触角分别最高可达158 °、156.8 °和153.8 °，滚动角最低分别为2 °、2.7 °和3.4 °，呈现出明显的超疏水特征。经过机械摩擦（500余次）、酸碱处理（pH 1～13）、温度变化（–40～40°C）以及紫外光照射（0～320 h）后，基材表面仍具有较好的超疏水性。此外，基材具有优异的自清洁性和油水分离效率，超疏水棉布的最高分离效率可达98.4%。

Abstract:

A superhydrophobic surface was fabricated via a non-induced phase separation method by combination of two polymers (polyvinylidene fluoride and polydimethylsiloxane) enhanced with cellulose nanocrystals (CNCs). The aggregation of the polymers and particle sizes were both effectively reduced during the phase separation owing to the electrostatic repulsion between CNCs and their high surface area, which led to a construction of a fine and uniform micro - and nano-structures on the surface of the substrates, correspondingly endowed them a stable superhydrophobicity. The morphology and structure of the CNCs and superhydrophobic surfaces were characterized by FTIR, SEM, AFM, contact angle measuring instrument and 3D optical profilometer. It was found that the surface of the substrates had uniform micro-nano rough structure. The water contact angle was up to 158°, and the lowest rolling angle is 2°, indicating obvious superhydrophobic characteristics. After mechanical friction (over 500 times), acid-base treatment (pH 1 ~ 13), temperature change (-40 ~ 40°C) and ultraviolet irradiation (0 ~ 320 h), the superhydrophobicity of the substrate surface was not reduced obviously. In addition, the substrates had excellent self-cleaning and oil-water separation efficiency. The maximum separation efficiency of the super hydrophobic cotton cloth was up to 98.4%.