Photo-responsive droplet manipulation slippery lubricant-infused porous surface with ultra-high durability

Photo-responsive slippery lubricant-infused porous surface(SLIPS) for droplet manipulation is flexible, noncontact and non-destructive in droplet manipulation, which has promising applications in flexible robotics, microfluidics,biomedicine, and chemical analysis. However, the repeated manipulations for droplets of SLIPSs are quite limited in the works reported so far, the poor durability of droplet manipulation severely limits the practical application of the surfaces. In this paper, an Fe3O4-doped polydimethylsiloxane(PDMS)-based SLIPS is proposed and implemented to achieve ultra-high repeated droplet manipulation numbers under near-infrared ray(NIR) laser irradiation. Firstly, a micron columnar array structure with micro-pits on the top side, as well as, a wall structure out of the array is designed on SLIPS to reserve the lubricant. Secondly, the prototype of the SLIPS is fabricated by a 3-step ultraviolet(UV) lithography, and subsequently immersed in silicone oil for more than 96 h to obtain the ultra-high durability slippery lubricant-infused porous surface(UD-SLIPS). With a power of 25 m W–85 m W NIR laser, the repeated manipulation of microdroplets(≤ 5 μL) in the scale of 1 cm can exceed more than 3000 times which is far beyond that in previous reports. Finally, the droplet manipulation performance of this photo-responsive UD-SLIPS and the influence of infusion time on durability are investigated. The mechanism of the PDMS swelling effect is found to be the key factor in improving the droplet manipulation durability of SLIPS. The findings of this work would be of great significance for the development of highly durable photo-responsive functional surfaces for droplet manipulation.

Triboelectric‘electrostatic tweezers'for manipulating droplets on lubricated slippery surfaces prepared by femtosecond laser processing

The use of‘Electrostatic tweezers'is a promising tool for droplet manipulation,but it faces many limitations in manipulating droplets on superhydrophobic surfaces.Here,we achieve noncontact and multifunctional droplet manipulation on Nepenthes-inspired lubricated slippery surfaces via triboelectric electrostatic tweezers(TETs).The TET manipulation of droplets on a slippery surface has many advantages over electrostatic droplet manipulation on a superhydrophobic surface.The electrostatic field induces the redistribution of the charges inside the neutral droplet,which causes the triboelectric charged rod to drive the droplet to move forward under the electrostatic force.Positively or negatively charged droplets can also be driven by TET based on electrostatic attraction and repulsion.TET enables us to manipulate droplets under diverse conditions,including anti-gravity climb,suspended droplets,corrosive liquids,low-surface-tension liquids(e.g.ethanol with a surface tension of 22.3 mN·m^(-1)),different droplet volumes(from 100 nl to 0.5 ml),passing through narrow slits,sliding over damaged areas,on various solid substrates,and even droplets in an enclosed system.Various droplet-related applications,such as motion guidance,motion switching,droplet-based microreactions,surface cleaning,surface defogging,liquid sorting,and cell labeling,can be easily achieved with TETs.

Carnivorous plants inspired shape-morphing slippery surfaces

Carnivorous plants,for instance,Dionaea muscipula and Nepenthes pitcher plant,inspired the innovation of advanced stimuli-responsive actuators and lubricant-infused slippery surfaces,respectively.However,hybrid bionic devices that combine the active and passive prey trapping capabilities of the two kinds of carnivorous plants remain a challenge.Herein,we report a moisture responsive shape-morphing slippery surface that enables both moisture responsive shapemorphing and oil-lubricated water repellency for simultaneous active-and passive-droplet manipulation.The moisture deformable slippery surface is prepared by creating biomimetic microstructures on graphene oxide(GO)membrane via femtosecond laser direct writing and subsequent lubricating with a thin layer of oil on the laser structured reduced GO(LRGO)surface.The integration of a lubricant-infused slippery surface with an LRGO/GO bilayer actuator endows the actuator with droplet sliding ability and promotes the moisture deformation performance due to oil-enhanced water repellency of the inert layer(LRGO).Based on the shape-morphing slippery surface,we prepared a series of proof-of-concept actuators,including a moisture-response Dionaea muscipula actuator,a smart frog tongue,and a smart flower,demonstrating their versatility for active/passive trapping,droplet manipulation,and sensing.

Recent advances in slippery liquid-infused surfaces with unique properties inspired by nature

The slippery liquid-infused porous surface(s)(SLIPS)that imitates the Nepenthes pitcher plant has proven to be highly versatile and can be combined with various surface characteristics such as dynamic response,antifouling,selective adhesion,and optical/mechanical tunability.In addition,the introduction of a lubricating fluid layer also gives it extremely low contact angle hysteresis and self-repairing properties,which further expands its application range.Currently,SLIPS has been proven to be suitable for many frontier fields such as aerospace,communications,biomedicine,and microfluidic manipulation.In this review,we explain the theoretical background of SLIPS and the preparation methods currently available,including the choice of substrate materials and lubricants,and we discuss the design parameters of the liquid injection surface and how to deal with the consumption of lubricants in practical applications.In addition,the paper focuses on current and potential applications,such as preventing pathogen contamination of and blood adhesion of medical equipment,manipulation of tiny droplets,and directional transportation of liquids.Finally,some weaknesses that appear when SLIPS is used in these applications are pointed out,which provides a new perspective for the development of SLIPS in the future.

Smart Manipulation of Gas Bubbles in Harsh Environments Via a Fluorinert-Infused Shape-Gradient Slippery Surface

Fundamental research and practical applications have examined the manipulation of gas bubbles on open surfaces in lowsurface-tension,high-pressure,and high-acidity,-alkalinity,or-salinity environments.However,to the best of our knowledge,effi cient and general approaches to achieve the smart manipulation of gas bubbles in these harsh environments are limited.Herein,a Fluorinert-infused shape-gradient slippery surface(FSSS)that could eff ectively regulate the behavior of gas bubbles in harsh environments was successfully fabricated.The unique capability of FSSS was mainly attributed to the properties of Fluorinert,which include chemical inertness and incompressibility.The shape-gradient morphology of FSSS could induce asymmetric driving forces to move gas bubbles directionally on open surfaces.Factors infl uencing gas bubble transport on FSSS,such as the apex angle of the slippery surface and the surface tension of the aqueous environment,were carefully investigated,and large apex angles were found to result in large initial transport velocities and short transport distances.Lowering the surface tension of the aqueous environment is unfavorable to bubble transport.Nevertheless,FSSS could transport gas bubbles in aqueous environments with surface tensions as low as 28.5±0.1 mN/m,which is lower than that of many organic solvents(e.g.,formamide,ethylene glycol,and dimethylformamide).In addition,FSSS could also realize the facile manipulation of gas bubbles in various aqueous environments,e.g.,high pressure(~6.8 atm),high acidity(1 mol/L H 2 SO 4),high alkalinity(1 mol/L NaOH),and high salinity(1 mol/L NaCl).The current fi ndings provide a source of knowledge and inspiration for studies on bubble-related interfacial phenomena and contribute to scientifi c and technological developments for controllable bubble manipulation in harsh environments.

Anti⁃icing/De⁃icing Mechanism and Application Progress of Bio⁃inspired Surface for Aircraft

Icing on the surface of aircraft will not only aggravate its quality and affect flight control,but even cause safety accidents,which is one of the important factors restricting all-weather flight.Bio-inspired anti-icing surfaces have gained great attention recently due to their low-hysteresis,non-stick properties,slow nucleation rate and low ice adhesion strength.These bio-inspired anti-icing surfaces,such as superhydrophobic surfaces,slippery liquid-infused porous surfaces and quasi-liquid film surfaces,have realized excellent anti-icing performance at various stages of icing.However,for harsh environment,there are still many problems and challenges.From the perspective of bioinspiration,the mechanism of icing nucleation,liquid bounce and ice adhesion has been reviewed together with the application progress and bottleneck issues about anti-icing in view of the process of icing.Subsequently,the reliability and development prospect of active,passive and active-passive integrated anti-icing technology are discussed,respectively.

受猪笼草启发的仿生超滑表面研究进展

自然界中猪笼草的袋状叶片内壁呈多孔结构,能锁住其分泌的蜡状物质,受此启发,向粗糙基底灌注低表面能液体以形成稳定的润滑油层,进而制备出注液超滑表面,其比超疏水表面具有更耐久的疏液、自清洁、防附着等性能,成为当前研究的热点。基于此,该文介绍了仿生超滑表面的润湿理论及作用机制,综述了超滑表面构建技术策略,包括粗糙基底成形-润滑油灌注与粗糙基底成形-基底化学修饰-润滑油灌注2种典型的路径;全面总结了粗糙基底的制备方法,包括刻蚀法、溶胶-凝胶法、呼吸图法、水热法,并介绍了仿生超滑表面在油水分离、水雾收集、防腐蚀、液滴操控、防覆冰领域的应用进展;最后,对仿生超滑表面的发展前景进行了展望。

超滑表面的抑霜与融霜特性

为解决低温高湿环境中超疏水表面防霜失效问题,通过超疏水表面粗糙基底灌注润滑油方法制作了超滑表面,并对其润湿特性和微观形貌进行了表征.设计并搭建了防冰霜系统和竖直融霜试验测试平台,对超滑表面、超疏水表面和纯铜表面的动态结霜和融霜过程进行了研究.结果表明:超滑表面可在基底多孔的粗糙结构中形成动态油膜层,能够有效减少霜晶形核吸附,防止“冰桥”形成,霜波传递速度与结霜质量均显著低于超疏水表面和纯铜表面,展现了优异的抑霜性能;在竖直融霜排液过程中,测试表面融霜效率与结霜质量呈正相关,超滑表面融霜水残留质量及表面覆盖率略高于超疏水表面,但远低于纯铜表面,具有良好的融霜排液效果.

液体润滑浸渍表面(SLIPS)船舶防污涂层最新研究进展

综述了近3年来关于液体润滑浸渍表面(SLIPS)船舶防污涂层的研究进展,特别是润滑液的选择与涂层的结构设计,以及这些因素如何影响涂层的整体性能,以期为未来的研究提供最新思路及研究方法。

公路岩质边坡工程的开挖稳定性分析

针对闽清县X127线省璜镇省璜至谷洋段公路改建工程某处边坡,对其进行开挖的稳定性分析。通过FLAC3D软件,进行“层-面-层”模型的构建并对其进行分析,同时设定3个监测桩对特征点的位移以及水平应力进行分析,以得到滑面,进行开挖稳定性的模拟。依据推力以及稳定参数,进行相应的锚固设计,同时经过验证,方案实际可行,能够保证开挖边坡坡体稳定。

Development of Slippery Liquid-Infused Porous Surface on AZ31 Mg Alloys for Corrosion Protection

The relatively poor corrosion resistance remarkably limits the wide applications of Mg alloys in practice,although they possess many attractive properties,like low density,high specific strength,and good biocompatibility.The formation of a protective coating can effectively suppress the corrosion.In this work,a slippery liquid-infused porous surface(SLIPS),with good surface hydrophobicity,stability,and self-healing property,was formed on AZ31 Mg alloys.The development of SLIPS requires suitable porous micro/nanostructures.Layered double hydroxide(LDH),with effective corrosion resistance for Mg alloys,was a good candidate to accommodate the liquid lubricant.Especially,different temperatures were applied to in situ form MgAl-LDH on AZ31 Mg alloys.The results showed that the temperature of 120℃was the best condition for the SLIPS to provide good corrosion protection for Mg alloys,with the lowest corrosion current density of 3.19×10^(-9)A cm^(−2).In addition,the SLIPS performed well in the long-term immersion test and abrasion test.The AZ31 Mg alloys with superior corrosion resistance and good mechanical and chemical stability can be extensively applied in areas of automotive,electronics,and aerospace.

Long-term deterioration of lubricant-infused nanoporous anodic aluminium oxide surface immersed in NaCl solution

This study investigated the deterioration of a lubricant-infused anodic aluminium oxide surface in a 1M NaCl solution for~200 days.Direct observation by cryo-SEM and quantitative analyses by UV spectroscopy and EIS revealed that the long-term deterioration of the lubricant-infused surface was divided into two stages:the surface-adhered lubricant layer gradually dissolved at a constant rate until the substrate was exposed;afterwards the lubricant infused in the nanochannels began to diffuse and was depleted after~200 days.The EIS results also revealed that the defects reduced the corrosion resistance of the lubricant-infused surface considerably.

Anti-attachment Function and Biomimetic Application of Slippery Zone in Nepenthes Pitcher

Carnivorous plants of Nepenthes species have evolved particular organs named pitchers at the tips of their conspicuous leaves, allowing slippery trapping and effective digesting prey to acquire sufficient growing nutrients. Nepenthes pitchers are generally distinguished by several morphological regions exhibiting distinct functions in prey capturing, and combined effect of the several zones results in great trapping efficiency. Depending on specific micro-structures, slippery zone performs an important role in efficiently preying arthropods, and this prey ability inspires an idea for biomimetic development of slippery trapping plate used in controlling agricultural pests. In this paper, combined with our latest results, the authors introduced the recent studies of the slippery zone, including surface structures and anti-attachment functions. They also highlighted the biomimetic application of slippery zone in developing slippery trapping plate for controlling agricultural pest.

含硅氧烷超滑表面的制备及其性能

文中利用端氨基聚硅氧烷(APT-PDMS)和顺丁烯二酸酐酯化β-环糊精(β-CD-MAH)进行反应,再通过金属配位反应引入铁离子,制备了聚硅氧烷-顺丁烯二酸酐酯化β-环糊精(APT-PDMS-co-β-CD-MAH)。分别通过红外光谱、核磁共振、紫外分光光度计检验了聚合物的组成与结构。采用操作简单、低成本的呼吸图法创新性地制备了特殊多层次孔结构膜,通过静态接触角测试仪测试了多孔结构膜的疏水性能,通过场发射扫描电子显微镜观察了多孔结构膜的表面形貌。结果表明,当APT-PDMS相对分子质量为3504、APT-PDMS与β-CDMAH的摩尔比为3∶1、聚合物浓度为25 mg/mL时制备的多孔基底及SLIPS性能最佳,该多孔基材结构中的大孔包含2~3个小孔,且小孔内还包含多个纳米级孔洞,静态接触角大于150°。灌入硅油后,滑动角小于10°,且该超滑表面(SLIPS)具有良好的稳定性、自清洁性、防冰抗冻及抗细菌黏附性。

形状记忆磁性润滑表面的制备及对超顺磁液滴的滑动操控

将磁性粒子与形状记忆聚合物复合,通过设计渐变式构型构筑了梯度形状磁性材料,并与润滑涂层相结合,制备了一种磁性润滑表面.在磁性梯度的作用下,超顺磁液滴在表面上能够自发定向运动.借助于材料形状记忆效应对表面区域形态进行可逆调控,进一步展示了超顺磁液滴自发定向运动过程中的启停开关式控制,实现了将液滴定向自发运输与启停控制相结合.考察了磁性粒子含量对材料形状记忆性能的影响,以及区域形态调控尺寸与液滴滑动性能间的相互关系.机理分析进一步阐明磁场梯度提供的定向驱动力促使液滴定向自发输运,表面区域形态控制的可逆调控则可以在液滴运动过程中增加/消除黏滞阻力,基于两种因素的协同作用,可以实现对超顺磁液滴运动的智能操控.

316L不锈钢超滑表面的制备及抗生物粘附性能研究

采用两步阳极氧化法在316L不锈钢表面制备了双层纳米多孔结构,然后采用十三氟辛基硅烷/乙醇溶液对其进行改性。最后将4种不同黏度的全氟聚醚注入改性后的双层纳米多孔结构中,形成4种不同黏度的超滑表面。对比研究了全氟聚醚的黏度对超滑表面润湿性、微观形貌和防污性能的影响。结果表明,相比于低黏度超滑表面和高黏度超滑表面,中黏度超滑表面同时具有稳定的润滑油层和低的水滑动角。与灌注全氟聚醚前的316L不锈钢表面相比,超滑表面的抗小球藻粘附性能大幅提高。在静态培养条件下,除了灌注高黏度全氟聚醚的超滑表面因润滑油层流动性差而导致抗小球藻粘附性较差之外,其他黏度的超滑表面的抗小球藻附着性能都良好。在动态培养条件下,由于水流的剪切作用,高黏度超滑表面的抗小球藻粘附性能明显提高,但较低黏度超滑表面的抗小球藻粘附性能有所下降。

电解液pH值对镁合金表面灌注液体型光滑多孔表面耐腐蚀性能的影响

在AZ31镁合金表面制备灌注液体型光滑多孔表面(SLIPS),从而为镁合金提供腐蚀防护。将粗糙多孔的层状双金属氢氧化物(LDH)作为纳米容器,用以盛放液体润滑液。通过调节电解液的pH值,获得用于构筑SLIPS的最佳LDH膜层。研究不同pH值对SLIPS表面形貌、表面润湿性和电化学行为的影响规律。结果表明,当pH值为10.5时,所制备的MgAl-LDH膜层厚度最大,为3.51μm,其可盛放最多的硅油,质量高达0.22mg/mm^(2),使得该MgAl-LDH膜层所构筑的SLIPS可为镁合金提供最优的腐蚀防护性能,腐蚀电流密度最低,为3.72×10^(-9)A/cm^(2)。另一方面,与超疏水表面相比,无论在电化学测试还是在长期浸泡试验中,SLIPS均可为AZ31镁合金基体提供更好的腐蚀防护。镁合金耐腐蚀性能的提高将进一步促进其在实践中的广泛应用。

MWCNTs光热相变超滑表面的制备及防/除冰性能研究

目的制备光热相变超滑表面,并研究不同含量的多壁碳纳米管(MWCNTs)和固体石蜡对防冰/除冰性能的影响。方法首先在纯Al表面刻蚀出微米结构,然后将MWCNTs、固体石蜡以及环氧树脂均匀混合后刮涂在处理后的Al基材表面,制备光热相变超滑表面,并对其润湿性、结冰/除冰性、机械稳定性以及自修复性进行表征。结果通过扫描电镜对涂层截面表征发现MWCNTs已经完全均匀分布在涂层内部。当用波长为808 nm、功率密度为0.5 W/cm2的近红外光(NIR)照射涂层,表层的固体石蜡融化成液体后水滴滑动角可由40°下降到5°,表现出极佳的滑动性能。在–20℃时,与纯Al基底相比,相变超滑表面可将水滴的结冰时长从27s延长至239s,其冰黏附强度降也只有34.9k Pa。得益于MWCNTs优异的光热性能,在NIR照射下,表面温度迅速升高,可在92s内实现快速除冰。此外,涂层在100次的循环摩擦后依然保持极低的冰黏附强度,并在NIR照射下可实现快速自修复。结论光热相变超滑表面相比于纯Al表面具有更加优异的防冰性,MWCNTs的加入,使表面具有快速除冰性。环氧树脂和固体石蜡则极大地提高了表面耐磨性以及自修复性,为长久的防冰/除冰提供了保障。

Slippery Surface of Nepenthes alata Pitcher： The Role of Lunate Cell and Wax Crystal in Restricting Attachment Ability of Ant Camponotus japonicus Mayr

This study attempts to investigate how the slippery surface of Nepenthes alata pitchers restricts the attachment ability of ant Camponotus japonicus Mayr, via climbing behavior observation and friction force measurement. Ants exhibited ineffective climbing behaviors and rather small friction forces when attached to upward-oriented slippery surfaces, but opposite phenomena were shown when on inverted surfaces. Friction forces of intact, claw tip-removed and pad-destroyed ants were measured on intact and de-waxed slippery surfaces, exploring the roles of wax crystals and lunate cells in restricting ant＇s attachment. On downward-directed slippery surfaces, greater forces were exhibited by intact and pad-destroyed ants; on the two slippery sur- faces, pad-destroyed ants presented slightly smaller forces and clawless ants generated considerably smaller forces. Somewhat different force was provided by clawless ants on upward and downward oriented slippery surfaces, and slightly higher force was shown when ants climbed on wax-removed surface. Results indicate that the lunate cells contribute greatly to decrease the friction force, whereas the wax crystals perform a supplementary role. Mechanical analysis suggests that the directionally growing lunate cells possess a sloped structure that effectively prevents the claw＇s mechanical interlock, reducing the ant＇s attachment ability considerably. Our conclusion supports a further interpretation of slippery surface＇s anti-attachment mecha- nism, also provides theoretical reference to develop biomimetic slippery plate to trap agricultural insect.

纳秒激光诱导黄铜超疏水光滑涂层的抗盐腐蚀性能研究

黄铜是工业产品的重要基础性材料之一,其抗盐腐蚀性能的提升问题,近年来受到工业界和科研界的广泛关注。本文提出一种制备黄铜抗盐腐蚀涂层方法。首先,利用纳秒激光诱导出了具有微纳织构的黄铜超疏水表面,并用氟硅烷进行修饰增强其稳定性;然后在制备的超疏水性基体中注入硅油,获得超疏水光滑涂层表面;最后,浸入35wt%NaCl溶液中进行PDP和EIS测试,结果表明光滑表面的抗盐腐蚀性能优于普通超疏水表面,更优于原始黄铜表面。本研究可对金属防腐涂层发展起到一定的促进作用,对于激光诱导制备超疏水光滑表面具有重要意义,为工业领域的金属防腐蚀途径提供了方便和有效的手段。