仿生超疏水性表面的生物应用

自然给科学家和工程师带来仿生的灵感和启发. 近年来, 受自然界中荷叶的启发, 在充分考虑表面形貌和化学组成协同效应的基础上, 人们已经制备出许多仿生超疏水性表面, 这些表面在抗结冰、微流体、生物相容性等领域具有很多潜在的应用价值. 仿生超疏水性表面在生物领域的应用逐渐崭露头角, 研究发现, 超疏水性表面所俘获的空气能够减缓药物释放的速率, 因此利用此类表面作为药物的载体有望实现长期供药. 超疏水特性能在一定程度改善和提高生物体与材料表面之间的相互作用, 例如, 血小板几乎不在超疏水表面上进行粘附和活化避免了造成血栓和血凝, 因此仿生超疏水性表面可用于制备人造血管和与血液相接触的仪器. 细胞和生物分子在不同特殊润湿性表面具有不同的行为和现象, 如粘附、繁殖、吸附等差异, 这有助于进一步探索研究细胞和生物分子的信息功能, 是当前仿生超疏水性表面应用的重要研究方向之一. 本综述简单介绍了经典的润湿模型, 重点总结了仿生超疏水表面在生物领域的应用, 其主要包括控制药物释放、提高血液相容性、蛋白质吸附研究、细胞行为研究、生物分子和细胞微图案化等. 最后, 对仿生超疏水性表面在生物领域研究应用进行了展望.     

超疏水性表面的制备及应用进展

近年来,受荷叶、水黾腿、壁虎脚等天然超疏水生物表面特性的启发,研究者们进行了大量仿生超疏水表面材料的制备及应用研究。超疏水性表面因其特殊的微纳分层结构,具有自清洁、防覆冰、防腐蚀、减阻等优异性能。本文阐述了表面润湿、疏水的基本机理,以及超疏水表面研究的理论基础,对超疏水表面制备的最新研究进展进行了综述,并揭示了研究中存在的问题。最后,介绍了超疏水表面在涂料、织物、防腐、抗菌及防雾等领域中的应用,展望了其未来的研究方向和前景。     

自清洁超疏水涂膜的研究与应用

自清洁超疏水涂膜具有特殊的表面性质而受到广泛关注。本文综述了自清洁超疏水涂膜的最新研究进展。介绍了形成自清洁超疏水性涂膜的必要条件,即具有适宜的粗糙度和低的表面能。着重阐述了仿生"荷叶效应"型、有机硅型、有机氟型、氟硅型等自清洁超疏水涂膜的制备方法、特性以及在建筑、交通运输、纺织、防腐蚀等领域的应用,并展望了今后的研究方向。     

仿生超疏水性表面的最新应用研究

近年来,除了荷叶表面,更多具有特殊润湿性的动植物表面同样受到关注。通过研究这些表面微观结构,人们成功地仿生制备出各种功能化超疏水表面,从而更好地满足工业中实际应用的需要。该综述简单地介绍了表面润湿的基本模型和最新的几种特殊表面结构,重点介绍近几年仿生超疏水表面应用的最新研究进展,主要包括超疏水表面在超疏油、表面润湿转换、外界刺激下的润湿行为调控、微流体、抗结冰等方面的应用。最后,对超疏水表面研究的未来发展进行了展望。     

三角紫叶酢浆草叶面的超疏水性

三角紫叶酢浆草叶面有很好的超疏水性,水滴在其表面的接触角约为150°,滚动角约为15°。研究发现,在三角紫叶酢浆草的叶面,分布有微纳米二元复合阶层结构的"星型"微凸体,微凸体之间有大量凹槽和空隙,复合阶层结构表面能吸附一层空气膜,液滴与其表面的接触是液、固、气的复合接触。此外,植物的叶面有低表面能的蜡状物,微纳米级的复合阶层结构及其表面的低表面能物质的协同效应使其表面显示出优异的超疏水性能。该研究有望为仿生超疏水材料的制备提供有益的启示与借鉴。     

超疏水性生物表面的研究进展

介绍了几种天然超疏水生物表面的研究进展,包括蛾翅膀、蝉翼、蝴蝶翅膀、白蚁翅膀、甲虫,蚊子的腿、翅及其复眼,水黾的腿部和荷叶的表面。 对现有的仿生超疏水材料的制备方法及常用作表面修饰的低表面能材料做了简单的归纳与总结。 对超疏水材料研究面临的挑战及以后的发展趋势做了展望。     

利用软模板和紫外光固化技术制备超疏水表面

研究了一种制备超疏水表面的新方法.该方法以复制了荷叶表面结构的聚二甲基硅氧烷(PDMS)弹性体为软模板.利用可紫外光交联预聚物在模板压印条件下固化成型,得到了具有微乳突结构的仿荷叶表面.制备的仿荷叶表面表现出了超疏水性能.通过对紫外光固化体系中的单体含量、交联剂含量、引发剂含量、以及紫外曝光时间等因素的研究,得到了使仿荷叶表面的疏水性优化的条件.     

超疏水表面黏附性的研究进展

结合作者课题组的相关工作,简要地论述了超疏水表面固液黏附性的主要影响因素和评价标准,介绍了天然和人工仿生具有特殊黏附性超疏水表面的研究进展,包括超疏水高黏附表面、超疏水低黏附表面、可控黏附性超疏水表面、各向异性黏滞力超疏水表面、黏滞力响应性智能超疏水表面以及超亲/超疏水图案表面制备及运用.特别介绍了作者研究小组在仿生可控黏滞力超疏表面制备以及超亲/超疏水图案表面运用的研究.最后对具有特殊黏附性超疏表面的研究进行总结和展望.     

液滴在超疏水植物叶面的沉积：实验和分子动力学模拟

农药液滴在靶标植物叶面的动态沉积对于提高农药利用率具有重要的意义,特别是在超疏水植物叶面的动态沉积。在本文中,我们利用生物基表面活性剂和甘油之间的氢键作用来增强液滴在超疏水植物叶面的有效沉积。在较低浓度的山梨醇-烷基胺表面活性剂溶液中,添加0.001%的甘油,可有效抑制液滴在不同超疏水/疏水植物叶片表面的弹跳和飞溅行为。结果表明,甘油的加入并没有显著改变山梨醇-烷基胺表面活性剂溶液的表面张力、粘度和聚集体的形态。核磁共振波谱(DOSY)显示,甘油加速了山梨醇-烷基胺表面活性剂分子的扩散速度。利用分子动力学模拟,对山梨醇-烷基胺表面活性剂/甘油体系的能量演化及表面活性剂相对于固体表面距离的分布进行了研究。这项目工作不仅为抑制液滴在植物叶面的弹跳飞溅提供了一种建设性的方法,而且为选择农用表面活性剂提供了理论基础。     

花生叶表面的高黏附超疏水特性研究及其仿生制备

花生是一种常见的豆科作物.与低黏附超疏水的荷叶不同,花生叶表面同时具有超疏水和高黏附特性.水滴在花生叶表面的接触角为151±2°,显示出超疏水特性.此外,水滴可以牢固地附着在花生叶表面,将花生叶翻转90°甚至180°,水滴均不会从表面滚落,显示了良好的黏附性(黏附力超过80μN).研究发现,花生叶表面呈现微纳米多级结构,丘陵状微米结构表面具有无规则排列的纳米结构.花生叶表面特殊的微纳米多尺度结构是其表面呈现高黏附超疏水特性的关键因素.结合实验数据,对花生叶表面特殊浸润性机理进行了简要阐述.受此启发,利用聚二甲基硅氧烷复形得到了与花生叶表面微结构类似的高黏附疏水表面.本文以期为仿生制备高黏附超疏水表面提供新思路.     

铝表面ZnO/Zn-Al LDH微米-纳米结构及其超级疏水性能

A multi-dimension bionic-like super-hydrophobic material， ZnO/Zn-Al LDH， was fabricated by modifying the Al surface in alkaline conditions at room temperature. After coated by ZnO/Zn-Al LDH， the aluminum surface shows both micro- and nano-bionic-like structures of lotus leaves.     

The surface modification of cellulose fibres to create super-hydrophobic, oleophobic and self-cleaning properties

The surface modification of cellulose fibres was performed with the use of low-pressure water vapour plasma, followed by the application of a pad-dry-cure sol–gel coating with the water- and oil-repellent organic–inorganic hybrid precursor fluoroalkyl-functional siloxane (FAS), with the aim of creating the “lotus effect” on the cotton fabric surface. The tailored “lotus effect” was confirmed by measurements of the contact angle of water (154°) and n-hexadecane (140°), as well as by measurements of the water sliding angle (7°), which were used to identify the super-hydrophobic, oleophobic and self-cleaning properties of the modified fibres. The chemical and morphological changes caused by modifications of the fibres were investigated by XPS, FTIR, AFM and SEM. The results show that the plasma pre-treatment simultaneously increased the surface polarity, average roughness, and surface area of the fabric. The application of the FAS coating after plasma pre-treatment caused only a slight increase in the surface roughness, accompanied by a decrease in the surface area, indicating that the architecture of the surface was significantly changed. This result suggests that the surface pattern affected the “lotus effect” more than the average surface roughness. The plasma pre-treatment increased the effective concentration of the FAS network on the fabric, which resulted in enhanced repellency before and after repetitive washing, compared with that of the FAS-coated fabric sample without the plasma pre-treatment. Despite the fact that the plasma pre-treatment increased the concentration of the oxygen-containing functional groups on the fabric surface, this phenomenon insignificantly contributed to the adhesion ability and, consequently, the washing fastness of the FAS coating.     

仿荷叶表面研究进展

近年来,荷叶表面的自清洁功能引起人们极大的研究兴趣,这种自清洁功能源自于表面形貌与低表面能物质的共同作用.目前,已用不少方法来制备仿荷叶表面.本文回顾近年来仿荷叶表面研究成果,探讨仿荷叶表面研究与发展趋势.     

用含氟丙烯酸酯无规共聚物制备超疏水膜

用微乳液聚合法制备了丙烯酸全氟烷基乙酯和甲基丙烯酸甲酯的无规共聚物,并对其进行了表征.采用溶剂挥发成膜法一步制备了具有超疏水性的该聚合物膜,水滴在该聚合物膜上的静态接触角可达151°~160°,滚动角小于3°.通过扫描电子显微镜观察发现该聚合物膜表面分布了许多乳突状突起和微孔洞,并具有微米和纳米尺度相结合的复合杂化结构.该类超疏水表面的形成是由适度粗糙的表面和低表面能相互结合引起的.探讨了该类超疏水膜的形成机理.     

铝合金表面原位自组装超疏水膜层的制备及耐蚀性能

采用阳极氧化法在铝合金表面原位构造粗糙结构, 经表面自组装硅氧烷后得到超疏水自清洁表面, 与水滴的接触角最大可达157.5°±2.0°, 接触角滞后小于3°. 通过傅立叶变换红外(FT-IR)光谱分析仪、场发射扫描电子显微镜(FE-SEM)、能谱仪(EDS)、原子力显微镜(AFM)和接触角测试对阳极氧化电流密度、硅氧烷溶液中水的含量和自组装时间等参数进行了分析, 并得到制备超疏水自清洁表面的最优工艺参数. FE-SEM及AFM的测试结果表明, 由自组装硅氧烷膜层的无序性形成的纳米结构和阳极氧化构造的微米级粗糙结构与硅氧烷膜层的低表面能的协同作用构成了稳定的超疏水表面. 电化学测试(动电位极化)的结果表明, 原位自组装超疏水膜层极大地提高了铝合金的耐蚀性.     

Nelumbo nucifera leaves as source of water-repellent wax: Extraction through polar and non-polar organic solvents

Nelumbo nucifera leaves are rich source of natural wax possessing super-hydrophobic properties. It provides protection to them from ecological turbulences and climatic wear and tear. In this study, various experiments have been conducted to observe the yield of extraction and the determination of various functional groups, which are present in natural wax, derived from Nelumbo nucifera leaves. The natural wax has been extracted from lotus leaves through non-polar (hexane) and polar (ethanol) solvent via different extraction methods. The superhydrophobic wax has been successfully extracted with hexane. Whereas, ethanol did not extract the water-repellent wax of lotus leaf. Considering the cumulative amount, i.e. (desired + undesired), the maceration shows the extraction of 2.9% (%w/w, through hexane) and 10.2% (%w/w, through ethanol), while it was found 2.5% (%w/w, cycle period 15 min) and 9.0% (%w/w, cycle period 26 min) respectively, in case of Soxhlet extraction technique. For this specific case of natural wax recovery from biomass (lotus leaf), the maceration (traditional method) resulted a little bit superior extraction yield in comparison to the Soxhlet extraction method for extraction of crude wax. In the case of non-polar solvent (hexane), an extraction yield of 1.97% (%w/w) through maceration method was observed while in the case of non-polar solvent (ethanol), an extraction yield of 1.62% (%w/w) through Soxhlet extraction was observed. The TLC analysis on both types of extracts was performed. For the detection of various hydrocarbon chains in the crude wax extracts, FTIR was also performed. Topography of wax surface and wax-coated waterproof fabric was compared through SEM.     

Contact-angle hysteresis on super-hydrophobic surfaces

The relationship between perturbations to contact angles on a rough or textured surface and the super-hydrophobic enhancement of the equilibrium contact angle is discussed theoretically. Two models are considered. In the first (Wenzel) case, the super-hydrophobic surface has a very high contact angle and the droplet completely contacts the surface upon which it rests. In the second (Cassie-Baxter) case, the super-hydrophobic surface has a very high contact angle, but the droplet bridges across surface protrusions. The theoretical treatment emphasizes the concept of contact-angle amplification or attenuation and distinguishes between the increases in contact angles due to roughening or texturing surfaces and perturbations to the resulting contact angles. The theory is applied to predicting contact-angle hysteresis on rough surfaces from the hysteresis observable on smooth surfaces and is therefore relevant to predicting roll-off angles for droplets on tilted surfaces. The theory quantitatively predicts a "sticky" surface for Wenzel-type surfaces and a "slippy" surface for Cassie-Baxter-type surfaces.     

Cathodic etching for fabrication of super-hydrophobic aluminum coating with micro/nano-hierarchical structure

A facile method for fabricating super-hydrophobic surfaces on the magnetron sputtering aluminum film by cathodic electrochemical etching followed by the modification of myristic acid was presented in this article. The morphologies and the compositions of the films were characterized by means of scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion behavior of the super-hydrophobic film was evaluated by potentiodynamic polarization measurement, linear polarization measurement, and electrochemical impedance spectroscopy. After the treatment with cathodic electrochemical etching, the thin aluminum film remained unbroken and the bulk structure of the aluminum coating maintained a microcrystalline morphology while the surface of the coating presented a petal-shaped microstructure dotted with nano-sized floccules. Aluminum myristate was formed on the nano/microstructural surface of the coating when the sample was modified in melting myristic acid. The static water contact angle on the surface was larger than 165°, which demonstrated that a super-hydrophobic film was prepared on the magnetron sputtering aluminum coating. The corrosion resistance of the aluminum coating was enhanced remarkably because of the super-hydrophobic modification.     

氨气腐蚀法制备黏附性能可控的超疏水铜表面

采用简单便捷的方法制备出了具有不同黏附性能的超疏水表面. 通过控制氨气对金属铜表面的腐蚀时间, 分别制备了具有微米球及微米棒状结构的表面. 利用低表面能氟硅烷(FAS)修饰后, 2种表面均表现出超疏水特性(接触角均大于150°), 然而其黏附性能却截然相反. 具有微球结构的表面呈现出高黏附特性, 而具有微米棒状结构的表面则显示出低黏附特性. 研究发现, 表面不同的微观结构导致了液滴在其表面上分别处于Cassie-impregnating wetting态及Cassie态, 从而呈现出了不同的黏附性能.     

Recent Studies on Super-Hydrophobic Films

Summary.  Films whose water contact angle is higher than 150° have been the subject of great interest and enthusiastic study in recent years. These films, which are called super-hydrophobic, are fabricated by combining appropriate surface roughness with surfaces of low surface energy. Here we briefly review the fundamental theories on the wettability of a hydrophobic rough solid surface, together with recent works on the processing and properties of super-hydrophobic films. Though the practical application of these films is still limited, the obstacles to application are gradually being surmounted, providing a great opportunity for the development of various industrial products. Received June 23, 2000. Accepted (revised) September 4, 2000