Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo 113-8657, Japan.
ACS Appl Mater Interfaces. 2014 Aug 13;6(15):12707-12. doi: 10.1021/am502701e. Epub 2014 Jul 10.
Controlling the assembly modes of different crystalline nanoparticles in composites is important for the expression of specific characteristics of the assembled structures. We report a unique procedure for increasing water contact angles (CAs) of composite film surfaces via the assembly of two different hydrophilic components, nanocellulose fibrils and nanoclay platelets. The nanocellulose fibrils and nanoclay platelets used have ionic groups on their surfaces in high densities (∼1 mmol g(-1)) and have no hydrophobic surface. The increase in the CA of the nanocellulose/nanoclay composite films was thus analyzed on the basis of the air area fractions of their nanostructured surfaces following Cassie's law. The air area fractions were geographically estimated from the atomic force microscopy height profiles of the composite film surfaces. The CAs of the composite film surfaces were found to be well described by Cassie's law. Interestingly, the composite films consisting of two hydrophilic nanoelements with different shapes exhibited CAs larger than those of the individual neat films.
控制复合材料中不同晶态纳米粒子的组装方式对于表达组装结构的特定特性非常重要。我们报告了一种通过组装两种不同的亲水性成分（纳米纤维素原纤维和纳米粘土片层）来提高复合膜表面水接触角（CA）的独特方法。所使用的纳米纤维素原纤维和纳米粘土片层在其表面上具有高密度的离子基团（~1mmol g(-1))，并且没有疏水性表面。因此，根据 Cassie 定律，基于其纳米结构表面的空气面积分数，分析了纳米纤维素/纳米粘土复合膜的 CA 增加。通过复合膜表面原子力显微镜高度轮廓图对空气面积分数进行了地理估计。发现复合膜表面的 CA 可以很好地用 Cassie 定律来描述。有趣的是，由两种具有不同形状的亲水性纳米元件组成的复合膜表现出大于各纯净膜的 CA。
