金属表面有机疏水涂层的研究进展

金属表面涂覆有机涂层是防腐蚀、防氧化的重要途径,其疏水特性在制备自清洁表面等方面得到了广泛研究。综述了有机涂层在金属表面的应用以及金属表面的预处理方式,尤其是硅烷偶联剂的重要应用。同时介绍了材料表面的疏水性理论及疏水性研究的最新进展,并展望了有机涂层在金属表面的应用。     

铝基表面超疏水材料的制备工艺、效果及耐蚀性

超疏水表面在自清洁材料、腐蚀防护及微流体运输等领域有着广阔的应用前景,目前对金属超疏水表面的研究较少,且制备方法较复杂,不能大面积制备。分别采用喷砂、阳极氧化、喷砂-阳极氧化等方法在铝基体表面构造粗糙结构并对其进行修饰,制备了超疏水表面,通过SEM、接触角及滚动角测定、腐蚀速率测定等分析了超疏水表面的微观形貌、疏水性能和耐海水腐蚀性能。结果表明:喷砂-阳极氧化法制备的铝金属表面具有微米-纳米二级结构,经氟化处理后,与水的接触角达158°,滚动角为1.5°,疏水性能良好;超疏水表面材料的腐蚀速率比铝材低1个数量级。     

沉积熔融法制备超疏水微结构表面

传统超疏水表面制备技术都有着各自的缺点,如加工成本高、受加工设备精度影响大、形貌尺寸随机性大。为得到低成本、形貌尺寸相对可控的超疏水微结构表面,提出了新型制备技术——沉积熔融法。通过金属颗粒悬浊液的自然沉积使微纳尺寸的颗粒均匀分布在金属表面,经熔融、再结晶使其与金属表面结合,再采用低表面能高分子修饰,制备出超疏水微结构表面。通过此方法采用锡铅合金在以黄铜、45号钢、6063铝合金基底上制备了超疏水微结构表面,并发现了金属基底材质与微结构表面的疏水性能之间没有必然关系。当微米尺寸的颗粒直径越小,制备的微结构表面的疏水性就越大。此外,相较于传统超疏水表面加工方法,沉积熔融法可实现微米级形貌的制备,且具有加工效率高、工艺简单、成本低廉、不影响原工件强度等优点,但其难以在弧形表面上应用的问题需要进一步研究。     

超疏水涂层的制备及其在金属防腐领域的应用研究进展

由于超疏水材料表面的特殊结构和高疏水性，当其应用在金属表面时，能有效阻止金属基材与腐蚀介质的接触，从而大幅度地提高金属材料的耐腐蚀性能及使用寿命。首先对固体表面浸润理论以及超疏水材料的基础理论进行阐述；然后，介绍了在金属材料表面制备超疏水涂层的常用工艺技术；最后，总结并讨论了超疏水表面涂层在钢、铝和镁等金属材料上的近期发展与应用状况。     

超疏水表面防结冰结霜性能的研究进展

利用超疏水表面可以防止或减少金属表面结冰结霜,在制备防结冰结霜表面中得到了广泛深入地研究。超疏水表面一般是利用其自身表面的粗糙结构和低表面能来使得液滴无法在其表面长时间停留而获得超疏水性能,但是液滴在低温和大湿度以及液滴在高高度撞击超疏水表面条件下会使超疏水表面的抗结冰结霜性能明显降低。针对这种情况,综述了超疏水表面在这方面的进展来探讨提高其抗结冰结霜性能的可能途径和方法。     

超疏水表面的润湿性及其应用研究

润湿性是衡量超疏水表面疏水强弱的最重要特征之一,主要由表面化学组成和表面微观结构共同决定.简述了超疏水表面的润湿性理论,综述了超疏水表面的最新研究进展,包括制备方法、应用研究及理论分析,详细介绍了其在自清洁和减阻方面的应用,最后提出了现阶段超疏水表面研究所面临的问题,并展望了其诸多领域的发展前景.     

自然对流条件下疏水表面与普通金属表面霜生长的对比研究

结霜是一种在低温下普遍存在的现象,可对设备造成很多危害.本文通过在自然对流条件下,竖直冷平板上疏水表面与普通金属表面霜生长过程显微动态观察实验,证明疏水表面有利于延缓霜的生长并根据相变动力学理论,分析了原因.     

一种材料超疏水表面的制备方法及其应用

首先介绍了超疏水表面的重要应用,对超疏水表面结构进行了定义,并列举了几种制备超疏水表面的方法.详细介绍了利用复制模塑法制备超疏水表面的工艺过程,通过样品的扫描电镜照片分析了该工艺的优点以及工艺参数对样品表面微造型的影响.水滴在方形柱和平行光栅这两种PDMS微结构表面上的接触角分别为(154.6±0.7)°和(160.2±1.9)°,滚动角分别为6°和3°,达到超疏水标准.最后介绍了复制模塑法在制备超疏水表面、生物抗粘附研究及细胞分选过程中的应用,展望了其广阔的发展前景.     

超疏水表面微纳结构设计与制备及润湿行为调控(Ⅰ)

超疏水表面因其优异的自洁排水性能可望在高科技领域和日常生活等方面有美好的应用前景.目前通过对荷叶表面微纳结构仿生已达到在亲水材料上制备超疏水表面的准商业化水平.然而,超疏水表面现有制备方法一般都工艺复杂和费用高昂,同时其超疏水性与其他材料性能很难相容,限制了其实际应用.对此,特别需要深入理论研究,优化设计表面微纳结构.同时充分利用外界作用调控其润湿行为,实现其在某些高科技领域的率先应用.针对超疏水表面研究的这些关键问题,重点评述了当前超疏水表面理论研究特别是表面几何设计方面的最新进展,总结了目前国内外制备超疏水表面的流行技术方法,进而讨论了利用外界作用调控超疏水行为的可能性.     

金属表面均三嗪二硫醇纳米聚合薄膜研究进展

综述了均三嗪二硫醇类化合物纳米聚合薄膜在各种金属基底表面的光聚合、热聚合、蒸发聚合及电化学聚合制备方法及在金属防护、材料间粘接、润滑特性、介电特性、超疏水和作为重金属离子处理剂等方面的应用。对该类化合物在不同金属表面的吸附作用和聚合机理进行了归纳、讨论与分析。提出了通过对该类三嗪二硫醇化合物分子进行改性研究,可在金属表...     

Effect of hydrophobicity on in vitro streptococcal adhesion to dental alloys

Non-specific interactions such as electrostatic interactions, and surface free energy are of importance in bacterial adhesion to dental surfaces as they determine whether or not bacteria are attracted to the surface. The relationship between adherence of Streptococcus mitis, S. mutans, S. oralis and S. sanguinis on precious and non-precious dental alloys, and the bacterial and alloy surface hydrophobicities (a measure of the surface free energy) was studied. The number of adhering bacteria was determined by fluorescence microscopy counts. The hydrophobicity of the bacteria and alloy surfaces were evaluated by adhesion to hexadecane and water contact angles, respectively. Our results showed that (i) the surfaces of the tested alloys were hydrophobic, (ii) S. sanguinis, S. mutans and S. oralis were hydrophobic, and (iii) S. mitis was hydrophilic. S. oralis, the more hydrophobic strain, demonstrated the highest adherence on the tested materials, whereas S. mitis adhered least on the hydrophobic surfaces. For the tested alloys, bacterial adherence was highest for the high gold content alloy, and lowest for the non-precious alloy. Our results showed that for the tested bacterial strains, there was a significant correlation between bacterial adhesion and substratum hydrophobicity: hydrophobic metal surfaces favor adhesion of hydrophobic bacteria.     

隔热疏水功能涂料研究进展

目的 归纳隔热疏水涂料的功能实现方法,分析疏水隔热功能涂料在包装中的潜在的应用价值,为新型多功能涂料的制备及其在纸包装领域的应用提供参考和借鉴。方法 梳理并归纳阻隔型、反射型、辐射型等3种类型隔热涂料的工作原理及实现方式,系统介绍几种常见的疏水表面形成机理模型以及制备方法,综述疏水隔热功能涂料的应用研究进展。结果 涂料的制备以及涂布技术已经成熟,疏水隔热功能涂料可涂布于瓦楞纸箱、白卡纸等表面用于食品保温包装。结论 将隔热疏水功能涂料用于纸包装箱,用来保护温敏食品品质和节约冷链运输成本,具有巨大的潜力和广阔的发展前景。     

Patterning Hydrophobic Surfaces by Negative Microcontact Printing and Its Applications

Here, a negative microcontact printing method is developed to form hydrophilic polydopamine (PDA) patterns with micrometer resolution on hydrophobic including perfluorinated surfaces. In the process of the negative microcontact printing, a uniform PDA thin film is first formed on the hydrophobic surface. An activated polydimethylsiloxane (PDMS) stamp is then placed in contact with the PDA‐coated hydrophobic surface. Taking advantage of the difference in the surface energy between the hydrophobic surface and the stamp, PDA is removed from the contact area after the stamp release. As a result, a PDA pattern complementary to the stamp is obtained on the hydrophobic surface. By using the negative microcontact printing, arrays of liquid droplets and single cells are reliably formed on perfluorinated surfaces. Microlens array with tunable focal length for imaging studies is further created based on the droplet array. The negative microcontact printing method is expected to be widely applicable in high‐throughput chemical and biological screening and analysis.     

DNA Hairpin Stabilization on a Hydrophobic Surface

DNA hybridization in the vicinity of surfaces is a fundamental process for self‐assembled nanoarrays, nanocrystal superlattices, and biosensors. It is widely recognized that solid surfaces alter molecular forces governing hybridization relative to a bulk solution, and these effects can either favor or disfavor the hybridized state depending on the specific sequence and surface. Results presented here provide new insights into the dynamics of DNA hairpin‐coil conformational transitions in the vicinity of hydrophilic oligo(ethylene glycol) (OEG) and hydrophobic trimethylsilane (TMS) surfaces. Single‐molecule methods are used to observe the forward and reverse hybridization hairpin‐coil transition of adsorbed species while simultaneously measuring molecular surface diffusion in order to gain insight into surface interactions with individual DNA bases. At least 35 000 individual molecular trajectories are observed on each type of surface. It is found that unfolding slows and the folding rate increases on TMS relative to OEG, despite stronger attractions between TMS and unpaired nucleobases. These rate differences lead to near‐complete hairpin formation on hydrophobic TMS and significant unfolding on hydrophilic OEG, resulting in the surprising conclusion that hydrophobic surface coatings are preferable for nanotechnology applications that rely on DNA hybridization near surfaces.     

Controlled effect of ultrasonic cavitation on hydrophobic/hydrophilic surfaces

Controlling cavitation at the solid surface is of increasing interest, as it plays a major role in many physical and chemical processes related to the modification of solid surfaces and formation of multicomponent nanoparticles. Here, we show a selective control of ultrasonic cavitation on metal surfaces with different hydrophobicity. By applying a microcontact printing technique we successfully formed hydrophobic/hydrophilic alternating well-defined microstructures on aluminium surfaces. Fabrication of patterned surfaces provides the unique opportunity to verify a model of heterogeneous nucleation of cavitation bubbles near the solid/water interface by varying the wettability of the surface, temperature and ultrasonic power. At the initial stage of sonication (up to 30 min), microjets and shock waves resulting from the collapsing bubbles preferably impact the hydrophobic surface, whereas the hydrophilic areas of the patterned Al remain unchanged. Longer sonication periods affect both surfaces. These findings confirm the expectation that higher contact angle causes a lower energy barrier, thus cavitation dominates at the hydrophobic surfaces. Experimental results are in good agreement with expectations from nucleation theory. This paper illustrates a new approach to ultrasound induced modification of solid surfaces resulting in the formation of foam-structured metal surfaces.     

Hydrophobic treatment enabling analysis of wettable surfaces using a liquid microjunction surface sampling probe/electrospray ionization-mass spectrometry system

An aerosol application procedure involving one or more commercially available silicone-based products was developed to create hydrophobic surfaces that enable analysis of otherwise wettable, absorbent surfaces using a liquid microjunction surface sampling probe/electrospray ionization mass spectrometry system. The treatment process resulted in a hydrophobic surface that enabled formation of the requisite probe-to-surface liquid microjunction for sampling and allowed efficient extraction of the analytes from the surface, but did not contribute significant chemical background in the mass spectra. The utility of this treatment process was demonstrated with the treatment of wettable high-performance thin layer chromatography plates, post-plate development, and their subsequent analysis with the sampling probe. The surface treatment process for different surface types was described and explained and the effectiveness of the treatment and subsequent analysis was illustrated using alkaloids from goldenseal (Hydrastis canadensis) root separated on a normal phase silica gel 60 F(254S) plate and peptides from protein tryptic digests separated on a ProteoChrom HPTLC Silica gel 60 F(254S) plate and a ProteoChrom HPTLC Cellulose sheet. This simple surface treatment process significantly expands the analytical surfaces that can be analyzed with the liquid microjunction surface sampling probe, and therefore, also expands the analytical utility of this liquid extraction based surface sampling approach.     

Superhydrophobic functionalized graphene aerogels

Carbon-based nanomaterials such as carbon nanotubes and graphene are excellent candidates for superhydrophobic surfaces because of their intrinsically high surface area and nonpolar carbon structure. This paper demonstrates that graphene aerogels with a silane surface modification can provide superhydrophobicity. Graphene aerogels of various concentrations were synthesized and the receding contact angle of a water droplet was measured. It is shown that graphene aerogels are hydrophobic and become superhydrophobic following the application of a fluorinated surfactant. The aerogels produced for this experiment outperform previous carbon nanomaterials in creating superhydrophobic surfaces and offer a more scalable synthetic procedure for production.     

Super‐Hydrophobic Surfaces: From Natural to Artificial

Super‐hydrophobic surfaces, with a water contact angle (CA) greater than 150°, have attracted much interest for both fundamental research and practical applications. Recent studies on lotus and rice leaves reveal that a super‐hydrophobic surface with both a large CA and small sliding angle (α) needs the cooperation of micro‐ and nanostructures, and the arrangement of the microstructures on this surface can influence the way a water droplet tends to move. These results from the natural world provide a guide for constructing artificial super‐hydrophobic surfaces and designing surfaces with controllable wettability. Accordingly, super‐hydrophobic surfaces of polymer nanofibers and differently patterned aligned carbon nanotube (ACNT) films have been fabricated.     

Surface wettability of plasma SiOx:H nanocoating-induced endothelial cells' migration and the associated FAK-Rho GTPases signalling pathways

Vascular endothelial cell (EC) adhesion and migration are essential processes in re-endothelialization of implanted biomaterials. There is no clear relationship and mechanism between EC adhesion and migration behaviour on surfaces with varying wettabilities. As model substrates, plasma SiO_x:H nanocoatings with well-controlled surface wettability (with water contact angles in the range of 98.5 ± 2.3° to 26.3 ± 4.0°) were used in this study to investigate the effects of surface wettability on cell adhesion/migration and associated protein expressions in FAK-Rho GTPases signalling pathways. It was found that EC adhesion/migration showed opposite behaviour on the hydrophilic and hydrophobic surfaces (i.e. hydrophobic surfaces promoted EC migration but were anti-adhesions). The number of adherent ECs showed a maximum on hydrophilic surfaces, while cells adhered to hydrophobic surfaces exhibited a tendency for cell migration. The focal adhesion kinase (FAK) inhibitor targeting the Y-397 site of FAK could significantly inhibit cell adhesion/migration, suggesting that EC adhesion and migration on surfaces with different wettabilities involve (p)FAK and its downstream signalling pathways. Western blot results suggested that the FAK-Rho GTPases signalling pathways were correlative to EC migration on hydrophobic plasma SiO_x:H surfaces, but uncertain to hydrophilic surfaces. This work demonstrated that surface wettability could induce cellular behaviours that were associated with different cellular signalling events.     

The microscopic structure of adsorbed water on hydrophobic surfaces under ambient conditions

The interaction of water vapor with hydrophobic surfaces is poorly understood. We utilize graphene templating to preserve and visualize the microscopic structures of adsorbed water on hydrophobic surfaces. Three well-defined surfaces [H-Si(111), graphite, and functionalized mica] were investigated, and water was found to adsorb as nanodroplets (～10-100 nm in size) on all three surfaces under ambient conditions. The adsorbed nanodroplets were closely associated with atomic-scale surface defects and step-edges and wetted all the hydrophobic substrates with contact angles<～10°, resulting in total water adsorption that was similar to what is found for hydrophilic surfaces. These results point to the significant differences between surface processes at the atomic/nanometer scales and in the macroscopic world.