Organogel-based Thin Films for Self-Cleaning on Various Surfaces
Organogel-based Thin Films for Self-Cleaning on Various Surfaces
复制标题
用于各种表面自清洁的有机凝胶薄膜
DOI：
10.1002/adma.201301289
复制
发表时间：
2013-08-27
影响因子：
29.4
通讯作者：
Jiang, Lei
中科院分区：
文献类型：
--
作者：
Liu, Hongliang;Zhang, Pengchao;Jiang, Lei
自清洁技术因其在工业、农业和日常生活等领域的重要基础研究和实际应用价值而受到广泛关注。[1]为了获得自清洁表面，已经制造了具有高于150的水接触角（CA）的荷叶启发的超疏水表面[2]和具有几度水CA的TiO 2基超亲水表面[3]。随着对自清洁本质的深入理解，研究人员已经认识到，它与CA滞后的关系比直接与CA的关系更大。[4]一些既不是超亲水性也不是超疏水性的表面，但具有低CA滞后值，已被制造用于自清洁。[5]然而，这些自清洁表面通常仅在空气中工作，其中涉及气-液-固系统。最近，受鱼鳞水下超疏油特性的启发，我们小组成功制备了基于水凝胶的自清洁表面，并将自清洁领域扩展到一个新的系统，即液-液-固系统。[6]这种基于水凝胶的表面显示出对水下油的优异的低粘附性，这归因于微/纳米结构水凝胶中的截留水，从而排斥不混溶的油。随后，通过将氟化油注入到用氟化硅烷预处理的结构化表面中，还制造了光滑的表面，其对各种液体[7]和细菌表现出排斥性。[8]虽然这些模型系统的自清洁性能是有前途的，但开发广泛应用的自清洁材料仍然很遥远。在此，受到基于水凝胶的水下自清洁表面[6]和注入润滑液的光滑表面[7]的成功的鼓舞，我们设计了基于有机凝胶的易滑动表面，通过简单的方法具有优异的自清洁性。这种方法是环保的，不使用氟化试剂，并且可以扩展到常见的工业金属，如铝，铜和铁。总体设计概念如图1所示。首先，制备厚度约为100 μ m的有机凝胶基膜。在衬底上形成30 nm的纳米颗粒（图1a）。其次，这种基于有机凝胶的薄膜不仅吸收油，而且还将油保持在交联网络中，厚度增加到约100%。110 nm（图1 B）;在这些条件下，水滴可以很容易地滑动，并且当表面稍微倾斜时能够去除灰尘（图1 c）。我们通过甲基丙烯酸酯单体的自由基共聚合成了基于有机凝胶的自清洁表面。在聚合之前，将基底在含有甲基丙烯酸3-（三甲氧基甲硅烷基）丙酯的甲醇中孵育以产生烯烃封端的表面。然后，通过将基材浸入含有甲基丙烯酸丁酯（BMA）和甲基丙烯酸月桂酯（LMA）作为单体和2，2 ′-偶氮二（2-甲基丙腈）（AIBN）作为引发剂的脱气甲苯中进行聚合;将温度保持在80 ℃下10小时以完成聚合（支持信息中的方案S1）。X射线光电子能谱（XPS）数据显示C1s光谱中的三个峰组分，分别对应于C-C/H、C-O和C = O物质（图S1）;这表明用薄有机凝胶膜成功改性了基材。作为演示，我们评估了水滴在有机凝胶改性的硅片上的滑动性能。首先将有机凝胶改性的硅晶片浸入硅油（20 cSt）中至少10分钟，让有机凝胶溶胀，然后保持垂直以去除多余的油。
Self-cleaning has been attracting extensive attention due to its great value in both fundamental research and practical applications in industry, agriculture, daily life, and so forth.[1] To obtain self-cleaning surfaces, lotus leaf-inspired superhydrophobic surfaces with water contact angles (CA) higher than 150 [2] and TiO 2-based superhydrophilic surfaces with water CA of several degrees [3] have been fabricated. With a deeper understanding of the essence of self-cleaning, researchers have acknowledged that it is more related to CA hysteresis than to CA directly.[4] A few surfaces that are neither superhydrophilic nor superhydrophobic–but with low CA hysteresis values–have been fabricated for self-cleaning.[5] However, these self-cleaning surfaces usually only work in air, where a gas–liquid–solid system is involved. Recently, inspired by the underwater superoleophobic property of fish scales, our group has successfully fabricated hydrogel-based self-cleaning surfaces and extended the field of self-cleaning to a new system, ie, liquid–liquid–solid systems.[6] This kind of hydrogel-based surface shows excellent low adhesion to oil under water, which is attributed to the trapped water in the micro/nanostructured hydrogel, thereby repelling immiscible oil. Subsequently, through infusing fluorinated oil into structured surfaces pretreated with fluorinated silanes, slippery surfaces have also been fabricated, which exhibited a repulsive property towards various liquids [7] and bacteria.[8] Although the self-cleaning property of these model systems is promising, the development of self-cleaning materials for widespread applications remains far-off. Herein, encouraged by the success of hydrogel-based underwater self-cleaning surfaces [6] and lubricating liquidinfused slippery surfaces,[7] we designed organogel-based easy-sliding surfaces with excellent self-cleaning through a facile approach. This approach is environmentally friendly, not using fluorinating reagents, and can be extended to common industrial metals, such as aluminium, copper, and iron. The overall designing concept is shown in Figure 1. First, an organogel-based film with a thickness of ca. 30 nm was formed on the substrate (Figure 1 a). Secondly, this organogel-based thin film not only absorbs oil, but also holds the oil in the cross-linked network with increased thickness to ca. 110 nm (Figure 1 b); under these conditions, a water droplet can easily slide and is capable of removing dust when the surface is slightly tilted (Figure 1 c).We synthesized organogel-based self-cleaning surfaces through free radical copolymerization of methacrylate monomers. Before polymerization, the substrates were incubated in methanol containing 3-(trimethoxysilyl) propyl methacrylate to generate an alkene-terminated surface. Then, polymerization was conducted by immersing the substrates in degassed toluene containing butyl methacrylate (BMA) and lauryl methacrylate (LMA) as the monomers, and 2, 2’-azobis (2-methylpropionitrile)(AIBN) as the initiator; the temperature was maintained at 80 C for 10 h to complete the polymerization (Scheme S1 in the Supporting Information). The X-ray photoelectron spectroscopy (XPS) data show three peak components in the C1s spectra, corresponding to C–C/H, C–O and C= O species, respectively (Figure S1); this indicates the successful modification of the substrates with a thin organogel film. As a demonstration, we evaluated the sliding property of water droplets on an organogel-modified silicon wafer. The organogel-modified silicon wafer was initially immersed in silicon oil (20 cSt) for at least 10 min to let the organogel swell, and then held vertically to remove excess oil …