Tunable, superhydrophobically stable polymeric surfaces by electrospinning
Tunable, superhydrophobically stable polymeric surfaces by electrospinning
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DOI：
10.1002/anie.200461092
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发表时间：
2004-01-01
影响因子：
16.6
通讯作者：
Menceloglu, YZ
中科院分区：
文献类型：
--
作者：
Acatay, K;Simsek, E;Menceloglu, YZ
超疏水表面的高拒水性是由于固体与水之间的接触面积有限，表现为高的静水接触角和低的滑动角。固液界面能不仅可以通过化学方法，而且可以通过固体表面的形貌来最小化。[1,2]例如，荷叶上的表皮蜡本质上是一种疏水性材料然而，当纳米级的蜡晶体覆盖微米级的粗糙表面时，如荷叶，WCA进一步增强到1608，这被定义为超疏水。[4-8]在这种情况下，水滴形成了一个三维的、不连续的、三相的（水-气-固）接触线[9]，这个接触线相对于宏观光滑表面上的接触线要长一些，也不那么稳定。此外，非疏水材料也可以通过化学改性，例如通过加入氟或硅，以及通过增加粗糙度，使WCA远高于1508的非疏水材料成为疏水材料。[9-14]这种极端的防水性在新的工业和实际应用中具有很高的吸引力：连续清洁建筑物、窗户和室外装饰、抗污织物、防污海洋结构和抗氧化表面。[2,8,10]目前，超疏水表面的生产是基于耗时、昂贵和/或非通用的工艺，如控制结晶、光刻、蚀刻和模板。[9 - 13,15]为了模拟荷叶的形貌并获得高WCA，我们通过简单实用的静电纺丝工艺制备了具有高粗糙度的聚合物薄膜表面静电纺丝薄膜由连续的非织造纤维网（直径在1 - 1000nm之间）组成，根据加工条件，聚合物液滴要么是孤立的球体（直径为>.1 μm），要么是串在纤维上。[17-22]这种电纺丝薄膜是通过从一个充满聚合物溶液的注射器的尖端向一个接地的收集板施加电偏压而产生的。沿着挤出的聚合物纤维的轨迹，大部分溶剂蒸发，这样一层随机排列的纤维聚集并形成薄膜。除了表面粗糙度外，还通过化学改性优化了薄膜的性能，例如添加氟以提高和稳定WCA值，以及加入交联以提高耐溶剂性。我们设计电纺丝薄膜的物理和化学特性的能力，使其在调节疏水性方面具有灵活性。丙烯腈（AN）与α， α-二甲基间异丙烯苄基异氰酸酯（TMI）在N， N-二甲基甲酰胺（DMF）中反应，然后与全氟线性二醇（氟链-d）和锡（ii）乙基己酸酯（T2EH）在DMF中混合，合成了一种热固性聚合物。溶液混合后立即静电纺到覆盖电接地屏幕的铝箔基板上。在30 min的静电纺丝周期内，采用固定的工艺参数：针尖至地距离10 cm，聚合物混合物流速12.5 μL minÀ1，纺丝电压16 kV。剩余的混合物随后被浇铸到显微镜载玻片上进行润湿比较。电纺样品和相应的铸膜随后在708℃下退火至少8小时，这使得全氟化基团重新定向到固体-空气界面静电纺膜与铸膜静态WCA的比较研究
The high water repellence of superhydrophobic surfaces is attributed to the limited contact area between the solid and water which is manifested by a high static water contact angle (WCA) and a low sliding angle. The solid–liquid interfacial energy can be minimized by engineering not only the chemistry but also the topography of the solid surface.[1, 2] For example, epicuticular wax on the lotus leaf is an intrinsically hydrophobic material.[3] However, when nano-sized crystals of wax cover a micron-level rough surface, as is the case on the lotus leaf, the WCA is further enhanced to 1608, which is defined as superhydrophobic.[4–8] In this case, the water droplet forms a three-dimensional, discontinuous, triphasic (water–air–solid) contact line [9] that is relatively longer and less stable than such a line on a macroscopically smooth surface. Moreover, a nonhydrophobic material can also be rendered hydrophobic with a WCA well above 1508 by chemical modification, for example, through the incorporation of fluorine or silicone, as well as by increasing the roughness.[9–14] Such an extreme water repellence is highly attractive for novel industrial and practical applications: continuously clean buildings, windows, and outdoor decorations, stain-resistant fabrics, antifouling marine structures, and oxidation-resistant surfaces.[2, 8, 10] Currently, the production of superhydrophobic surfaces is based on time-consuming, expensive, and/or nonversatile processes, such as controlled crystallization, lithography, etching, and templating.[9–13, 15] To mimic the topography of the lotus leaf and to achieve a high WCA, we fabricated a polymeric film surface with a high degree of roughness through a simple and practical electrospinning process.[16] Electrospun films consist of a continuous, nonwoven web of fibers (with diameters in the order of 1–1000nm) and, depending on processing conditions, with polymer droplets either as isolated spheres (> 1 μm in diameter) or strung along a fiber.[17–22] The electrospun film is produced by applying an electrical bias from the tip of a polymer solution-filled syringe to a grounded collection plate. Along the trajectory of the extruded polymer fiber, most of the solvent evaporates, such that a mat of randomly aligned fibers collects and form a thin film. In addition to surface roughness, the film properties were optimized by chemical modification, such as the addition of fluorine to enhance and stabilize WCA values and the incorporation of crosslinking for solvent resistance. Our ability to engineer both the physical and chemical properties of the electrospun films enables flexibility in tuning the degree of hydrophobicity. A thermoset polymer was synthesized by first reacting acrylonitrile (AN) and α, α-dimethyl meta-isopropenylbenzyl isocyanate (TMI) in N, N-dimethylformamide (DMF), and then mixing the resultant poly (AN-co-TMI) with a perfluorinated linear diol (fluorolink-D) and tin (ii) ethyl hexanoate (T2EH) in DMF. The solution was mixed and immediately electrospun onto an aluminum foil substrate covering the electrically grounded screen. The processing parameters used throughout this study were fixed for the 30-min electrospinning periods: tip-to-ground distance 10 cm, flow rate of the polymeric mixture 12.5 μL minÀ1, spinning voltage 16 kV. The remaining mixture was subsequently cast onto microscope slides for wetting comparison. The electrospun samples and the corresponding cast films were subsequently annealed at 708C for at least 8 h, which enabled the reorientation of the perfluorinated groups to the solid–air interface.[22] A comparison of the measured static WCA between an electrospun film and a cast version of the same …