SLIPS功能表面的制备及应用

仿猪笼草唇叶结构的滑移功能表面(SLIPS)是通过将全氟液体、硅油或离子液体等润滑油注入到提前构建好的含有多孔或分级粗糙结构基底制备得到。由于毛细作用力和范德华力,动态油膜能够稳定锁定在粗糙基底中。所得到SLIPS的化学均相表面和特殊的液-固结合界使其展现出优异的液体排斥性、自修复性和高压稳定性等,并在近十年内成为表界面领域内研究热点。其应用领域主要包含防冻、防腐、防海洋污染和实现高透明性材料等,并在液体运输,太阳能电池表面和深海防污等领域展现出巨大应用前景。本文介绍了近五年来SLIPS主要制备与调控方法,还对其在防覆冰,防海洋生物污染与防菌,防腐和透明性等领域新的研究进展进行了阐述。最后,对滑移表面在未来的制备与应用所面临的挑战进行了展望。     

Biomimetic Self-Cleaning Anisotropic Solid Slippery Surface with Excellent Stability and Restoration

Anisotropic slippery surfaces are widely used in anti-fouling, smart control of liquid movement and directional liquid transportation. However, anisotropic slippery liquid-infused porous surfaces (SLIPS) cannot meet the need of practical applications owing to loss and contamination of liquid lubricants. Inspired by solid epicuticular wax on the surface of land plant leaves, we herein report a type of biomimetic anisotropic solid slippery surface (ASSS) based on paraffin wax-incorporated paper with directional micro-grooves. This ASSS material shows anisotropic sliding behavior for liquid droplets with different surface tensions. It is demonstrated to be of excellent stability compared with SLIPS as the solid lubricant cannot be lost and stain the contacting surfaces. It also exhibits outstanding acid and alkali corrosion resistance and restoration capability upon physical damage. Both hydrophilic and hydrophobic contaminants on our ASSS can be self-cleaned by using only water droplets. Our ASSS extends the fabrication of new slippery materials and overcomes some drawbacks of SLIPS.     

On the application of electrochemical impedance spectroscopy to study the self-healing properties of protective coatings

Active corrosion protection based on self-healing of defects in coatings is a vital issue for development of new advanced corrosion protection systems. However, there is a significant lack of experimental protocols, which can be routinely used to reveal the self-healing ability and to study the active corrosion protection properties of organic and hybrid coatings.The present work demonstrates the possibility to use EIS (electrochemical impedance spectroscopy) for investigation of the self-healing properties of protective coatings applied on a metal surface. The model EIS experiments supported by SVET (scanning vibrating electrode technique) measurements show that an increase of low frequency impedance during immersion in the corrosive medium is related to the suppression of active corrosion processes and healing of the corroded areas. Thus, EIS can effectively be employed as a routine method to study the self-repair properties of different protective systems. The 2024 aluminium alloy coated with hybrid sol–gel film was used as a model system to study the healing of artificial defects by an organic inhibitor (8-hydroxyquinoline).     

EIS investigation of a Ce-based posttreatment step on the corrosion behaviour of Alclad AA2024 anodized in TSA

In the aircraft industry, anodizing and posttreatment steps use Cr (VI) compounds, which, despite offering good corrosion resistance and self-healing properties, are highly toxic and carcinogenic. Ce compounds are recognized as efficient corrosion inhibitors for Al alloys, and several works report self-healing ability for these chemicals. In this investigation, the corrosion resistance of Alclad AA2024-T3 alloy anodized in tartaric-sulphuric acid (TSA) bath and posttreated in a solution comprising cerium nitrate without and with hydrogen peroxide was evaluated. The purpose is to investigate the potentiality of using hydrothermal treatment in Ce nitrate solution as candidate to replace Cr (VI) posttreatment. The aim is to provide a posttreatment step which, while improving the corrosion resistance, does not plug the mouths of the pores maintaining the adhesion properties of the porous anodic layer. Microstructural characterization was carried out by SEM-EDS whereas corrosion resistance was evaluated by EIS. The surface analysis showed that the posttreatments, all performed at 50°C, kept the open structure of the pores. EIS analysis showed that the posttreatments performed in the H₂O₂ solution for short immersion times were the most effective in improving the corrosion resistance of the samples, whereas electrical equivalent circuit (EEC) fitting of the data indicated sealing of the porous layer during the immersion of the different samples in the test solution. SEM-EDS analysis of the samples posttreated in the H₂O₂ containing solution, prior and after the corrosion test, showed the presence of Ce oxy-hydroxide randomly deposited on the sample surface, indicating that Ce could be incorporated/stored in the anodic layer.     

SECM and SKPFM Studies of the Local Corrosion Mechanism of Al Alloys – A Pathway to an Integrated SKP‐SECM System

Scanning Kelvin Probe Force Microscopy and Scanning Electrochemical Microscopy were applied for the investigation of localized corrosion on heterogeneous aiming on the investigation of the possible correlation between the local surface potential differences, measured by the Kelvin probe technique in ambient conditions, and corrosion during immersion in a corrosive electrolyte. A model sample mimicking the interaction of Al and Cu in Al alloys was chosen to demonstrate the complementary nature of the information received from SKPFM and SECM. The necessary prerequisites for a future integration of SKP and SECM into a single set‐up are discussed.     

XPS and AES surface analysis of WC-Co-(Cr) cemented carbide after immersion in neutral solution

The binder phase Co in WC-Co cemented carbide is dissolved easily in corrosive media (even in neutral solution), which has limited its application in a wider range. In this paper, the influence of Cr on corrosion resistance of WC-Co immersed in neutral solution was studied, with a focus on the surface chemistry of the corrosion product. The results show that in neutral solution, the corrosion is mainly caused by the selective dissolution of Co and the dominant surface corrosion product after immersion is Co (OH)₂. The corrosion resistance of WC-Co cemented carbide can be improved by the addition of Cr. This can be explained by the formation of more protective chromium containing oxide on the binder phase of WC-Co-Cr alloy, leading to reduced corrosion rate.     

Polystyrene‐grafted Al surface with excellent superhydrophobicity and corrosion resistance

A superhydrophobic Al surface was successfully fabricated by a facile and environmentally friendly method as the boiling water treatment and 3‐glycidoxypropyl trimethoxysilane (GPS) as well as carboxyl‐terminated polystyrene (PS‐COOH) modification. The fabrication procedure, morphology, composition, and corrosion resistance of the superhydrophobic Al surface were investigated. Results show that the treatment in the boiling water endows the Al surface with the porous and roughened structure, while the modification with GPS as well as PS‐COOH grafts the long PS chains onto the micro‐scale and nano‐scale hierarchical structure. Consequently, a superhydrophobic Al surface with a contact angle of 153.6° and a rolling angle of 3° is obtained. Additionally, a vast majority of surface area is covered by the air in the solid–liquid contact area for the superhydrophobic Al surface, and which can prevent the corrosive ions entering into the Al surface. As a result, the corrosion resistance is improved greatly. Copyright © 2015 John Wiley & Sons, Ltd.     

有机涂层失效过程的电化学阻抗和电位分布响应特征

结合使用电化学阻抗谱(EIS)和扫描Kelvin探针(SKP)技术研究了在质量分数为3.5%的NaCl溶液中的铁基有机涂层劣化过程特征. 结果表明, 根据EIS和SKP的响应特征, 可将涂层劣化过程分为3个主要阶段: (Ⅰ) 涂层渗水阶段. 此时, 涂层渗水阶段的EIS阻抗持续减小, 但保持单容抗弧特征, SKP特征是电位持续降低, 但分布保持均匀; (Ⅱ) 基底金属腐蚀发生阶段. 此时, EIS阻抗快速下降, 并产生第二时间常数; SKP特征为表面电位差增大; (Ⅲ) 基底金属腐蚀发展与涂层失效阶段. 此时, EIS出现扩散尾, SKP电位差保持较大数值. 实验结果表明, 在研究有机涂层劣化过程中, EIS和SKP的结合使用能够互相补充完善, 获得涂层劣化过程中更为准确\, 可靠的变化信息.     

Reinforcement of phosphorylated graphene oxide on the anticorrosive properties of waterborne acrylate-epoxy resin coatings

Abstract

Phosphorylated graphene oxide (PedGO) was synthesized through the in-situ phosphate esterification method with urea as catalyst and then embed into waterborne acrylate-epoxy resin emulsion (AE) coating to modify the coating. The TEM and AFM indicated that phosphate was uniformly decorated on GO sheets, forming a large phosphorylated graphene oxide sheets. The PedGO improved the water vapor permeability and the coating adhesion strength after 30?days of immersion in 3.5% NaCl of AE coatings, respectively. Electrochemical impedance spectroscopy measurements (EIS) revealed that the PedGO-modified AE (PedGO/AE) was an outstanding barrier against corrosive media compared with AE or GO-modified AE (GO/AE). Scratch tests also showed that the corrosion-promotion effect of PedGO in AE was inhibited. The enhanced corrosion protection performance was observed because on the one hand the PedGO can greatly prolonged the diffusion pathway of corrosive media in the coating matrix; on the other hand the organic phosphate on the PedGO formed the passivation membrane with metal ions by chelation in the corrosion region, which can prevented the contact of corrosive medium and metal.     

From the solvothermally treated poly(vinylidenefluoride) colloidal suspension to sticky hydrophobic coating

Solvothermally treating an as-prepared poly(vinylidenefluoride) (PVDF) colloidal suspension leads to a significant impact on the surface properties of the resulting topcoat on a pertinent prime coating. The coating, possessing a fibrous porous matrix, exhibits a water contact angle in the range of 115–136^°. However, the coating possesses droplets sticking ability that can be attributed to the pseudo-hydrogen bonding effect of the polarized C–H bonds in each repeating unit of PVDF polymer chains. The hydrophobicity of the topcoat is affected by the formulation of colloidal suspension, which is carried out by introducing a solution of PVDF in dimethylforamide into an excess of methanol. The colloidal suspension formed is subjected to solvothermal treatment subsequently. By thermodynamics, the treatment enhances chain packing density and growth of crystallites inside the colloidal particles of PVDF in the methanol-dominant dispersion medium. Furthermore, the realized chain packing states are retained during the drying of coating through chain affixation role of a small number of poly(divinylbenzene) nodules generated in situ. As a result, a fibrous porous matrix composed of the PVDF submicron knots is attained. The coexistence of the polarized CH₂ group and the fibrous porous structure prompts a sticky hydrophobic surface.     

Stimuli-responsive self-healing anticorrosion coatings: from single triggering behavior to synergetic multiple protections

As a notorious and ubiquitous destructive phenomenon, metal corrosion can cause huge economic losses, infrastructure failures, and even industrial disasters. Tremendous efforts have been dedicated to intelligent self-healing coatings for corrosion inhibition at damaged sites, targeting for enhanced longevity, extensive adaptability of metallic materials. Anticorrosion coating performing self-healing activities, by either healing coating defects or forming protective layer on corrosive parts, is quite attractive in metal-relevant applications. In this review, we mainly focus on stimuli-feedback anticorrosion coatings (SFACs), based on different triggering mechanisms to initiate self-healing behaviors. Stimuli-responsive smart systems, from single stimulus-response to synergetic multistimuli-response, act as a core concept both in controllable healing agent diffusion and increased availability of payloads for corroded area. Multifunctional stimuli-responsive self-healing coatings integrating with non-wettable property are also explored, which provide synergistic and diversified metal protections that are hard to actualize with a single action. Not only research progress of SFACs over the past few decades is reviewed in this article, but also perspectives on future development of this field are presented.     

钼酸盐封闭后处理的热镀锌钢板硅烷膜的耐蚀性

为进一步增强硅烷膜的耐蚀性, 将硅烷化热镀锌钢板用钼酸盐溶液进行封闭后处理, 并采用扫描电子显微镜(SEM)、中性盐雾(NSS)实验、盐水全浸实验和电化学技术研究了所得复合膜层的表面形貌和耐蚀性能. 结果表明: 经钼酸盐溶液封闭处理后, 硅烷膜的孔隙被填充, 在锌层表面形成了由硅烷膜和钼酸盐转化膜构成的连续完整致密的复合膜; 复合膜的耐蚀性能明显提高, 且与钼酸盐溶液的封闭时间有关, 封闭60 s时所形成的复合膜的耐蚀性最佳. 在5%(w, 质量分数)NaCl溶液中的电化学测量结果表明: 硅烷化热镀锌钢板经钼酸盐溶液封闭处理后, 同时抑制了腐蚀过程中的阳极和阴极反应, 但主要是抑制阴极反应, 导致腐蚀电流密度明显减小, 发挥了单一硅烷膜和单一钼酸盐转化膜腐蚀防护的协同效应, 腐蚀防护效率高达99.1%; 随浸泡时间延长, 试样低频扩散阻抗先增大后减小, 表明膜层具有一定的“自愈”能力, 其耐蚀性优于常规铬酸盐钝化膜.     

Versatility of hydrophilic and antifouling PVDF ultrafiltration membranes tailored with polyhexanide coated copper oxide nanoparticles

Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm⁻²h⁻¹ and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability.     

Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings

Stainless steel ISO 5832–9 type is often used to perform implants which operate in protein-containing physiological environments. The interaction between proteins and surface of the implant may affect its corrosive properties. The aim of this work was to study the effect of selected serum proteins (albumin and γ-globulins) on the corrosion of ISO 5832–9 alloy (trade name M30NW) which surface was modified by titania coatings. These coatings were obtained by sol–gel method and heated at temperatures of 400 and 800 °C. To evaluate the effect of the proteins, the corrosion tests were performed with and without the addition of proteins with concentration of 1 g L^?1 to the physiological saline solution (0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out within 7 days. The following electrochemical methods were used: open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy. In addition, surface analysis by optical microscopy and X-ray photoelectron spectroscopy (XPS) method was done at the end of weekly corrosion tests. The results of corrosion tests showed that M30NW alloy both uncoated and modified with titania coatings exhibits a very good corrosion resistance during weekly exposition to corrosion medium. The best corrosion resistance in 0.9 % NaCl solution is shown by alloy samples modified by titania coating annealed at 400 °C. The serum proteins have no significant effect onto corrosion of investigated biomedical steel. The XPS results confirmed the presence of proteins on the alloy surface after 7 days of immersion in protein-containing solutions.     

PVDF and HYFLON AD membranes: Ideal interfaces for contactor applications

Super-hydrophobic fluorinated membranes were tailored by combining traditional dry-wet phase inversion and wet chemical treatment techniques. PVDF and HYFLON AD 60X were selected as raw polymers for their chemical and mechanical resistance as well as hydrophobic and solvophobic properties. Membranes with modulated pore size, narrow distribution and high overall porosity were manufactured without using additional additives or modifiers. High resistance to liquid water entry pressure (LEPw), high mass transfer and low surface free energy of the membrane surfaces were fully achieved. The combination of these two fluorinated polymers improved dramatically the mechanical resistance and the water repellence of the PVDF membranes. Well-controlled structure combined with aimed supra-molecular chemistry makes these porous layers ideal interfaces to be processed in membrane contactor devices.     

Improved self-healing performance of polymeric nanocomposites reinforced with talc nanoparticles (TNPs) and urea-formaldehyde microcapsules (UFMCs)

The present work reports the self-healing performance of the epoxy based polymeric nanocomposite coatings containing different concentrations (1 and 3 wt%) of talc nanoparticles (TNPs) modified with sodium nitrate (NaNO₃), and a fixed amount (5 wt%) of urea-formaldehyde microcapsules (UFMCs) encapsulated with linseed oil (LO). The polymeric nanocomposites were developed, coated on polished steel substrates, and their structural, thermal, and self-healing characteristics were investigated using various techniques. The successful loading (~wt 10%) of NaNO₃ into TNPs, which can be ascribed to the involvement of physio-chemical adsorption mechanism, is validated and proceeds without altering the TNPs parent lamellae structure. The performed tests elucidated that the self-release of the corrosion inhibitor (NaNO₃) from TNPs is sensitive to the pH of the solution and immersion time. In addition, the release of the linseed oil (self-healing agent) from UFMCs in response to the external damage was found to be a time-dependent process. The superior self-healing and corrosion inhibition performance of the protective polymeric nanocomposites coatings containing 3 wt% TNPs and UFMCs/LO are proven using the electrochemical impedance spectroscopy (EIS) studies. A careful selection of smart carriers, inhibitor, and self-healing agent compatible with polymeric matrix has enabled to attain decent self-healing and convincing corrosion inhibition efficiency of 99.9% and 99.5%, respectively, for polymeric nanocomposites coatings containing 3 and 1 wt% TNPs, making them attractive for many industrial applications.     

Surface treatment of zinc by Schiff’s bases and its corrosion study

The zinc metal surface is chemically modified by newly synthesized Schiff’s bases and its corrosion protection is investigated. The influence of concentration of Schiff’s bases on modification of zinc surface and immersion time in treatment bath are investigated and optimized for maximum corrosion protection efficiency. The electrochemical studies of treated zinc specimens are performed in aqueous acid solution using galvanostatic polarization technique. The treated zinc samples show good corrosion resistance. The recorded electrochemical data of chemically treated samples indicate a basic modification of the zinc surface. The protection efficiency of organic layer formed on zinc surface is tested by varying the acid concentration and temperature of the corrosive medium. The corrosion protection efficiency increases with the concentration of Schiff’s bases and immersion time. This is due to a strong interaction between zinc and the organic molecules, which results in the formation of a protective layer. This layer prevents the contact of aggressive medium with the zinc surface. The surface modification is confirmed by the scanning electron microscopy images. The interaction between metal atoms and Schiff’s bases is also established by IR studies. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 886–892. The text was submitted by the authors in English.     

Sol–gel derived hybrid coatings as an environment friendly surface treatment for corrosion protection of metals and their alloys

Sol?Cgel derived organic inorganic hybrid coatings are effective corrosion protective systems for metals. They offer an excellent adhesion to metal as well as to the subsequent coat via strong covalent bond and a three dimensional network of ?CSi?CO?CSi?C linkages which helps to retard the penetration of corrosive medium through the coating. Unlike conventional surface protection methodology, silane based pre-treatment is an environment friendly technology with number of advantages like room temperature synthesis, chemical inertness, high oxidation and abrasion resistance, excellent thermal stability, very low health hazard etc. Further, the hybrid silane provides required flexibility and an increased compatibility with the subsequent coating in multicoat systems. The performance properties of hybrid systems depend on number of parameters like type of silane (mono or bis), degree of hydrolysis, type and dosage of inhibitive/barrier pigments (in case of pigmented system), application techniques, curing temperature and curing schedule, need to be optimized. A guideline formulation for maximum corrosion resistance with low environmental impact consist of a superprimer (a bis-silane with conventional resins, chrome free inhibitive pigments and additives) followed by epoxy or polyurethane top coat as per the exposure conditions.     

Improving hydrophilicity and protein resistance of poly(vinylidene fluoride) membranes by blending with amphiphilic hyperbranched-star polymer

To endow hydrophobic poly(vinylidene fluoride) (PVDF) membranes with reliable hydrophilicity and protein resistance, an amphiphilic hyperbranched-star polymer (HPE-g-MPEG) with about 12 hydrophilic arms in each molecule was synthesized by grafting methoxy poly(ethylene glycol) (MPEG) to the hyperbranched polyester (HPE) molecule using terephthaloyl chloride (TPC) as the coupling agent and blended with PVDF to fabricate porous membranes via phase inversion process. The chemical composition changes of the membrane surface were confirmed by X-ray photoelectron spectroscopy (XPS), and the membrane morphologies were measured by scanning electron microscopy (SEM). Water contact angle, static protein adsorption, and filtration experiments were used to evaluate the hydrophilicity and anti-fouling properties of the membranes. It was found that MPEG segments of HPE-g-MPEG enriched at the membrane surface substantially, while the water contact angle decreased as low as 49 degrees for the membrane with a HPE-g-MPEG/PVDF ratio of 3/10. More importantly, the water contact angle of the blend membrane changed little after being leached continuously in water at 60 degrees C for 30 days, indicating a quite stable presence of HPE-g-MPEG in the blend membranes. Furthermore, the blend membranes showed lower static protein adsorption, higher water and protein solution fluxes, and better water flux recovery after cleaning than the pure PVDF membrane.     

Ellipsometric analysis of corrosion behavior of 3C magnesium alloy surface touched by simulated sweat

As an optimum shell material, AZ80 magnesium alloys are widely applied in the 3C (computers, communications and consumer electronics) industries. The case of 3C products corroded by a sweaty hand has been simulated and the corrosion characters have been investigated by ellipsometric technology. Thickness variation of corrosive medium film on a Mg alloy surface was monitored. Surface structure of a corrosion layer was described with a three‐layer optical model (substrate—EMA—Cauchy) and thickness of each layer for different soaking time was obtained by fitting experimental data with the model. The corrosion product films with a refractive index of 1.45–1.62, loose corrosion product layer, can only provide limited protection to the substrate when a Mg alloy surface is corroded by sweat again. Copyright © 2010 John Wiley & Sons, Ltd.