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.     

形状记忆聚合物表面微结构及黏附性能的可逆调控

采用模板法在形状记忆聚合物表面构筑了微纳米等级结构,获得了一种具有低黏附性的超疏水表面.在外压作用下,表面微结构发生坍塌,失去超疏水性,同时呈高黏附性.在120℃热处理后,表面微结构恢复到原始状态,同时表面恢复到低黏附状态.通过外压及热处理过程可实现对表面微结构及其黏附性能的可逆调控.研究结果表明,表面不同的微结构状态赋予了表面不同的黏附性能,即在原始表面上,液滴处于低黏附的Cassie态,而在坍塌结构表面上水滴处于高黏附的Wenzel态.     

喷砂-阳极氧化-氟化处理构筑铝合金超疏水表面

为研究复合法制备超疏水表面过程中主要工艺参数对表面形貌及超疏水性能的影响, 开发了一种喷砂-阳极氧化复合方法, 在铝合金表面构筑了微米-纳米二级结构, 经氟化处理后获得了超疏水特性. 结果表明, 喷砂处理在铝合金表面通过冲蚀的凹坑构筑出微米结构, 阳极氧化则在铝合金表面通过蜂窝状氧化膜构筑纳米结构. 但单纯构筑粗糙结构或单纯改变表面化学组成均不能在铝合金表面获得超疏水特性. 单纯的微米结构或纳米结构, 即使有低表面能聚合物修饰也不能获得超疏水特性. 只有微米-纳米二级结构和低表面能聚合物的协同作用, 才能有效构筑铝合金超疏水表面. 这种铝合金与水滴接触时, 形成的气阱可减小固体表面与水滴的接触面积, 降低表面与水滴间的热量交换, 从而减缓水分子的凝结, 提高铝合金的抗霜冻性. 同时, 气阱还可有效减缓海水的腐蚀, 提高铝合金的耐海水腐蚀性.     

可粘贴超疏水薄膜的制备

通过聚二甲基硅氧烷(PDMS)与碳纤维织物复合, 采用模板法在PDMS聚合物表面构筑微阵列结构, 制备了一种具有可重复粘贴性的超疏水薄膜. 研究结果表明, 该薄膜微结构表面的接触角为154°, 滚动角为14°, 具有低黏附的超疏水特性. 而PDMS与碳纤维织物的紧密结合, 赋予了超疏水薄膜较高的黏接力和力学性能, 断裂强度达到116.96 MPa. 所制备的超疏水薄膜可粘贴于多种材料表面, 同时经过30 d的长时间粘贴以及50次的循环粘贴后, 该薄膜依然保持着较高的黏附性能及超疏水特征, 表明超疏水薄膜具有良好的力学稳定性及耐久性, 满足长时间可重复使用的要求, 可应用于对破损超疏水涂层的快速、 大面积粘贴修复.     

形状记忆聚合物表面水下油黏附性的可逆调控

采用模板法在形状记忆聚合物表面获得一种具有形状记忆特征的表面微结构, 在氧等离子作用下, 表面呈现低黏附的水下超疏油特性. 在外压作用下, 表面微结构发生坍塌, 失去水下超疏油性, 同时表面对油滴呈高黏附特征. 在120 ℃热处理后, 表面微结构恢复到了原始状态, 在等离子进一步作用下, 表面即可恢复到最初的低黏附水下超疏油状态. 因此通过外压、 热处理及等离子作用即可实现对表面微结构及其水下油黏附性能的可逆调控. 研究表明, 表面不同的微结构状态赋予表面不同的黏附性能, 在原始表面液滴处于低黏附的Cassie态, 而在坍塌结构表面水滴处于高黏附的Wenzel态.     

双级微结构上二氧化硅粒子对微注压成型PP表面润湿特性的影响

提出一种柔性复制法,采用微注射压缩(μ-ICM)成型具有微拓扑结构的仿生聚丙烯(PP)表面.通过复制模板上的双级微结构,所成型的PP材料表面上呈现具有锥形顶面的双级微结构,即微棱和高纵横比的微锥体.由于微锥体之间的间隙较大,水滴浸润其间隙的上方,这使该表面呈现中等黏附的超疏水特性.在μ-ICM过程中,涂覆在模板上的二氧化硅纳米粒子(SNPs)被转移到熔体中,并牢牢附着于微结构表层,赋予其表面亚微米或微米粗糙度,形成多层次微结构.在附着有亲水SNPs的微结构上,高表面自由能使水滴完全浸润微锥体之间的间隙,表面的水接触角为161.9°、滚动角大于90°,呈现极高黏附的超疏水特性(花瓣效应);在附着有疏水SNPs的微结构上,水滴受疏水SNPs的排斥而减弱与表面之间的黏附作用,表面的水接触角为163.5°、滚动角为3.5°,呈现极低黏附的超疏水特性(荷叶效应).     

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.     

胶带表面优异防覆冰性能

通过在普通胶带表面黏结聚甲基丙烯酸甲酯(PMMA)微米球,再通过水热法在微米球表面制备规则的ZnO纳米棒结构,经氟化处理后得到了具有柔性、大面积、低温超疏水和防冰性能的薄膜.低温环境中,液滴在这种复合的微纳米结构表面可以实现结冰延迟.经历结冰-融化循环后,液滴的界面未发生明显变化,证明了该结构的可靠性.这种抗结冰的薄膜是建立在胶带和PMMA基础之上的,在风电、高压线缆以及冰箱制造工业中具有良好的应用前景.     

超声辅助制备超疏水聚丙烯表面花瓣状微纳结构

超疏水微纳结构表面广泛应用于自清洁、防冰、抗菌、柔性传感等领域,但其制备工艺仍面临一定的挑战.以阳极氧化铝(AAO)膜为模板,采用热压印在聚丙烯(PP)表面成型了规整的纳米结构阵列.对纳米结构阵列进行超声处理,在超声空化作用下,PP表面纳米结构转变为类花瓣状微纳结构.结果表明,经超声处理后的微纳结构PP表面的接触角从152.3°上升至160.0°,滚动角从11.5°降低至1.8°,表面黏附力从75μN降低至38μN,呈现典型的超疏水低黏附特性且其自清洁效应明显.采用模板法与超声辅助相结合的方法制备超疏水微纳表面具有方便快捷、成本低廉、效果显著的优点,有望应用于工业生产领域.     

超疏水低粘着铜表面制备及其防覆冰性能

用喷砂处理在铜片表面形成微米级丘陵状凹坑,再用表面氧化处理在铜片表面制备菊花花瓣状CuO纳米片.通过喷砂-表面氧化处理在铜片表面成功构建了微米-纳米复合结构,这种表面氟化后与水滴的接触角高达161°,滚动角低至1°,显示出优异的超疏水性和很低的粘着性.低温下,这种表面与水滴间的热量交换较小,水滴不易凝结,有效地提高了抗结霜性.抗结霜性良好的超疏水铜有望在热交换器或低温运行设备等领域获得应用,这种简便的超疏水铜表面的制备方法也给其它工程材料超疏水表面的工业化制备提供了一个思路.     

Novel strategy in enhancing stability and corrosion resistance for hydrophobic functional films on copper surfaces

A rod-like 1-dodecanethiol film assisted with the preferential adhesion of polydopamine was prepared on the non-etching copper surfaces by a simple dip-coating method. The formation and surface structure of the film were characterized by water contact angle measurement, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Once the 1-dodecanethiol film formed on the polydopamine-coated copper surface, the hydrophilic surface changed to hydrophobic. The corrosion behavior of the functional films was evaluated by the electrochemical impedance spectroscopy (EIS). The excellent corrosion resistance property could be ascribed to the compact film structure and good seawater stability for modified copper surface, especially in limiting the infiltration of Cl⁻.     

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.     

含氟/硅丙烯酸酯乳液的合成进展

含氟丙烯酸酯聚合物具有良好的成膜性、光泽性、柔韧性、耐污性及耐腐蚀性,广泛应用于防腐耐候涂料。但其对基体的附着性差,对颜料、填料的润湿性差,不耐低温,加之含氟丙烯酸酯单体价格昂贵,大量使用受到限制。含氟/硅丙烯酸酯共聚物不仅兼备了含氟聚合物的诸多优良性能,而且能有效地提高与基体的附着力并降低聚合物成本。本文综述了氟/硅改性丙烯酸酯乳液常用单体;核壳型乳胶粒的结构及影响因素;氟/硅丙烯酸酯共聚物合成路线。     

Inorganic–organic sol gel hybrid coatings for corrosion protection of metals

Inorganic–organic hybrid coatings by sol–gel process are very suitable for fighting corrosion. Inorganic sols in hybrid coatings not only increase adhesion by forming chemical bonds between metals and hybrid coatings, but also improve comprehensive performances of polymer in the coatings. Different organic polymers or organic functionalities are introduced into gel network to achieve tailored properties, such as hydrophobic properties, increasing cross-linking density, etc. As for corrosion protection of metals organic components of hybrid coatings are selected to repel water and form dense thick films and reduce coating porosity. The factors, such as the ratio of inorganic and organic components, cure temperature, pigments in hybrid coatings, need to be optimized for attaining hybrid films with the maximum corrosion resistance. Electro-deposition technique offers relatively thick homogeneous defect-free hybrid coatings in comparison to dip or spin coating techniques. Green cerium ions and non-ionizable organic inhibitors are more developed in hybrid coatings nowadays than other corrosion inhibitors. Long-term corrosion resistance techniques of inhibitors are discussed. The inhibitors entrapped in the nanocontainers are doped in hybrid films to prolong release of the inhibitors to damaged zones, which is discussed in detail. Among all the nanocontainers of corrosion inhibitors the prospective techniques which show superior corrosion protection are cyclodextrin/organic inhibitor inclusion complexes and layer by layer assembly of organic corrosion inhibitors in nanocontainers. Super-hydrophobic property of hybrid coatings derives from low surface tension and surface roughness of hybrid coatings, which endues the films with excellent corrosion protection for metals, but the durable property of super-hydrophobic coatings needs to be improved for industrial application. An ideal multiple model of hybrid coatings for superior anti-corrosion of metals proposed is a combination of super-hydrophobic hybrid coatings and underlying hybrid coatings doped with sustained release of corrosion inhibitors on metal substrates.     

Effect of surfactants on wetting of super-hydrophobic surfaces

The effect of surfactants on wetting behavior of super-hydrophobic surfaces was investigated. Super-hydrophobic surfaces were prepared of alkylketene dimer (AKD) by casting the AKD melt in a specially designed mold. Time-dependent studies were carried out, using the axisymmetric drop shape analysis method for contact angle measurement of pure water on AKD surfaces. The results show that both advancing and receding contact angles of water on the AKD surfaces increase over time ( approximately 3 days) and reach the values of about 164 and 147 degrees , respectively. The increase of contact angles is due to the development of a prickly structure on the surface (verified by scanning electron microscopy), which is responsible for its super-hydrophobicity. Aqueous solutions of sodium acetate, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used to investigate the wetting of AKD surfaces. Advancing and receding contact angles for various concentrations of different surfactant solutions were measured. The contact angle results were compared to those of a number of pure liquids with surface tensions similar to those of surfactant solutions. It was found that although the surface tensions of pure liquids and surfactant solutions at high concentrations are similar, the contact angles are very different. Furthermore, the usual behavior of super-hydrophobic surfaces that turn super-hydrophilic when the intrinsic contact angle of liquid on a smooth surface (of identical material) is below 90 degrees was not observed in the presence of surfactants. The difference in the results for pure liquids and surfactant solutions is explained using an adsorption hypothesis.     

仿花瓣表面多功能高分子纳米薄膜的制备

以红玫瑰花瓣为模板, 用纳米压印图案转移法进行仿生合成, 获得具有多功能性的高分子薄膜. 通过将薄膜进行染色, 制得了具有特殊花瓣颜色的人工薄膜, 并探讨了化学色与结构色之间的关系.     

Contact angle of polyethylene on copper and its effect on adhesion

To determine whether the large differences in adhesion for polyethylene coatings applied to different types of copper surface could be attributed to changes in work of adhesion or wettability, the variations of contact angle with time has been measured for molten polyethylene droplets on these surfaces. It is concluded from these measurements that the low peel strengths obtained on certain substrates cannot be accounted for by a low work of adhesion of poor wetting of the surface.     

Wetting characteristics of aqueous rhamnolipids solutions

The wetting properties of surfactants on solid surfaces form the basis of many industrial and biological processes. The preferential adsorption of the surfactants from aqueous solutions onto solid surfaces alter the adhesion tension of the surface and this behavior may cause partial to complete wetting of the surfaces by the aqueous surfactant solutions. However, different types of surfactants show different wetting characteristics. To study the wetting properties of biologically produced rhamnolipids (RL), advancing contact angles of the aqueous solutions of the RL mixture of R1 and R2 in a ratio of R2/R1=1.1 were measured as a function of surfactant concentration. For a comparison of the wetting performance, sodium dodecyl sulfate (SDS) was chosen as the reference surfactant. A hydrophilic glass surface, a hydrophobic polymer, polyethylene terephthalate (PET), and gold surface were used as the solid surfaces to determine the wetting characteristics of rhamnolipids. At low surfactant concentrations (RL concentration <3x10(-5)M, SDS concentration<3x10(-4)M) contact angle (Theta) varied in a certain range depending on the character of the surfactant interactions with the surface. This was followed by a decrease in contact angle. Parallel to this behavior, at low surfactant concentrations the adhesion tension decreased, then remained constant and an increase at higher surfactant concentrations was obtained on hydrophobic surfaces. On hydrophilic surfaces a steady decrease in adhesion tension was observed with both surfactant solutions.