含氟硅丙烯酸酯乳液超疏水膜中疏水基团的梯度分布与表面微观结构研究

利用含氟疏水基团的梯度分布,结合草莓形纳米SiO2粒子提供的双重粗糙表面,制备了具有类"荷叶效应"的超疏水涂膜,水接触角达(174.2±2)°,滞后角几乎接近0°.通过原子力显微镜、扫描电镜和水接触角的测试对膜表面形貌及疏水性能进行了表征;探讨了其表面微观结构与表面疏水性能的关系.草莓形复合粒子在膜表面的无规则排列赋予涂膜表面不同等级的粗糙度,使水滴与涂膜表面接触时能够形成高的空气捕捉率,这种微观结构与疏水基团的梯度分布相结合,赋予了含氟硅丙烯酸酯乳液涂膜表面超疏水性能.     

Direct catalytic route to superhydrophobic polyethylene films

Polyethylene films grow on a flat silica surface modified by the bis(imino)pyridyl iron(II) catalyst during ethylene polymerization in toluene solvent. The resulting films show superhydrophobic properties. Advancing water contact angle as high as 169 degrees and sliding angles as low as 2 degrees are obtained on these films. SEM images reveal special surface structures of these films containing micrometer-sized islands, submicrometer particles on the islands, and stress nanofibers between the islands, which render superhydrophobicity to the polyethylene surfaces. After the submicrometer particles and stress nanofibers are removed by annealing, the superhydrophobic properties of the polymer films disappear.     

Biomimetic superhydrophobic and highly oleophobic cotton textiles

We report a biomimetic procedure to prepare superhydrophobic cotton textiles. By in situ introducing silica particles to cotton fibers to generate a dual-size surface roughness, followed by hydrophobization with polydimethylsiloxane (PDMS), normally hydrophilic cotton has been easily turned superhydrophobic, which exhibits a static water contact angle of 155 degrees for a 10 microL droplet. The roll-off angle of water droplets depends on the droplet volume, ranging from 7 degrees for a droplet of 50 microL to 20 degrees for a 7 microL droplet. When a perfluoroalkyl chain is introduced to the silica particle surface, the superhydrophobic textile also becomes highly oleophobic, as demonstrated by a static contact angle of 140 degrees and a roll-off angle of 24 degrees for a 15 microL sunflower oil droplet.     

Superhydrophobic films of electrospun fibers with multiple-scale surface morphology

Superhydrophobic nanofiber films were created from electrospun nanofibers with undulated surfaces at multiple scales in micrometers and nanometers. The electrospun nanofibers were produced out of aqueous solutions which contained water-soluble polymers and different colloids: monodisperse silica or polystyrene microspheres for larger particles and monodisperse silica nanoparticles for smaller particles. Various types of fibrous films were produced depending on the properties of the dispersing medium, the effects of additives, and the compositions of the bidisperse colloids. When polystyrene microspheres were used as sacrificial templates, macropores were left behind in the nanofibers during the removal of polystyrene microspheres by calcination. The nonwoven films of electrospun nanofibers, which were decorated with silica microspheres or macropores, could be continuously produced with considerable ease under a relatively wide range of operating conditions. The surface properties of the films were characterized by contact angle measurement and an X-ray photoelectron spectrometer. Through the surface modification of the electrospun nanofibers with fluorinated silane coupling agents, superhydrophobic surfaces with low sliding angles were successfully prepared.     

Fabrication of hydrophobic surfaces by coupling of Langmuir-Blodgett deposition and a self-assembled monolayer

A novel method coupling the Langmuir-Blodgett (LB) deposition of silica particles and the formation of a self-assembled monolayer (SAM) of alkylsilane is proposed for fabricating hydrophobic surfaces. The LB deposition and the SAM are supposed to confer the substrate surface roughness and low surface energy, respectively. By controlling the hydrophobic-hydrophilic balance of the silica particle surface through the adsorption of surfactant molecules, deposition of monolayers consisting of hexagonally close-packed arrays of particles on a glass substrate can then be successfully conducted in a Langmuir trough. LB particulate films with a particle layer number up to 5 were thereby prepared. A sintered and hydrophobically finished particulate film with roughness factor of 1.9 was finally fabricated by sintering and surface silanization. Effects of particle size and particle layer number on the wetting behavior of the particulate films were systematically studied by measuring static and dynamic water contact angles. The experimental results revealed that a static contact angle of about 130 degrees resulted from the particulate films regardless of the particle size and particle layer number. This is consistent with the predictions of both the Wenzel model and the Cassie and Baxter model in that roughness of a hydrophobic surface can increase its hydrophobicity and a switching of the dominant mode from Wenzel's to Cassie and Baxter's. In general, an advancing contact angle of about 150 degrees , a receding contact angle of about 110 degrees , and a contact angle hysteresis of about 40 degrees were exhibited by the particulate films fabricated.     

Superhydrophobic polyimide films with a hierarchical topography: combined replica molding and layer-by-layer assembly

Artificial superhydrophobic surfaces with a hierarchical topography were fabricated by using layer-by-layer assembly of polyelectrolytes and silica nanoparticles on microsphere-patterned polyimide precursor substrates followed with thermal and fluoroalkylsilane treatment. In this special hierarchical topography, micrometer-scale structures were provided by replica molding of polyamic acid using two-dimensional arrays of polystyrene latex spheres as templates, and nanosized silica particles were then assembled on these microspheres to construct finer structures at the nanoscale. Heat treatment was conducted to induce chemical cross-linking between polyelectrolytes and simultaneously convert polyamic acid to polyimide. After surface modification with fluoroalkylsilane, the as-prepared highly hydrophilic surface was endowed with superhydrophobicity due to the bioinspired combination of low surface energy materials and hierarchical surface structures. A superhydrophobic surface with a static water contact angle of 160 degrees and sliding angle of less than 10 degrees was obtained. Notably, the polyimide microspheres were integrated with the substrate and were mechanically stable. In addition, the chemical and mechanical stability of the polyelectrolyte/silica nanoparticle multilayers could be increased by heat-induced cross-linking between polyelectrolytes to form nylon-like films, as well as the formation of interfacial chemical bonds.     

Fabrication and characterization of superhydrophobic silica nanotrees

Superhydrophobic silica nanotrees were obtained by sol–gel method with hybrid silica sol and jelly-like resorcinol formaldehyde resin. Rough surfaces were obtained by removing the organic polymer at high temperature. After the films with rough surface were modified by trimethylchlorosilane (TMCS), the wettability of the film changed from superhydrophilic to superhydrophobic. The surface roughness of the silica nanotrees film is about 20 nm, and it is transparent and superhydrophobic with a water contact angle higher than 150°.     

Preparation of superhydrophobic silica films with honeycomb-like structure by emulsion method

Silica films with honeycomb-like structure were successfully obtained by emulsion method. Emulsion films prepared by the Dip-Withdrawing method were dried at 180 °C for 2 h and sintered at 500 °C, the films turned from superhydrophilic to superhydrophobic after being modified by octyltrimethoxysilane (OTMS) to form a self-assembled monolayer (SAM) with low surface energy. The surface structures and the thickness of the silica emulsion films were observed by scanning electron microscopy (SEM), and the results showed that the emulsion method had a similar effect to the phase separation one on producing the honeycomb-like structure that highly influenced the wettability of solid surface.     

CaCO_3颗粒模板法制备聚合物超亲水/超疏水表面

以碳酸钙(CaCO3)颗粒层为模板,运用简单的热压和酸蚀刻相结合的方法制备聚合物超亲水/超疏水表面.首先在玻璃基底上均匀铺撒一层CaCO3颗粒,以此作为模板,通过热压线性低密度聚乙烯(LLDPE)使CaCO3颗粒均匀镶嵌在聚合物表面,获得了超亲水性质;进一步经酸蚀得到了具有微米和亚微米多孔结构的表面,其水滴静态接触角(WCA)可达(152.7±0.8)°,滚动角小于3°,具备超疏水性质.表面浸润性能和耐水压冲击性能研究表明该超疏水表面具有良好的稳定性和持久性.用同样工艺微模塑/酸蚀刻其它疏水性聚合物,得到类似结果.     

以多孔CaCO3微球为模板制备聚乙烯超疏水表面

以聚苯乙烯磺酸钠（PSS）掺杂的多孔碳酸钙（CaCO3）微球层为模板,通过热压低密度聚乙烯（LDPE）并结合酸蚀刻的方法制得了具有多层粘联微球结构、而非常见蜂窝状多孔结构的LDPE稳定超疏水表面（接触角152.8±2.5°,滚动角约6°）。元素分析表明,表面粘联微球为纯LDPE而非LDPE包覆的CaCO3。将多孔CaCO3微球稀疏地撒在LDPE表面并加热熔融,发现微球会自发沉降到熔体内部,酸蚀刻后形成了类似莲蓬的表面微结构,即坑内包含小球。结合CaCO3微球生成原理和多孔结构,认为粘联微球结构和莲蓬结构均是由于LDPE熔融大分子自发沉积到多孔CaCO3微球内部,“反模”形成了LDPE微球所致。本发现为多孔CaCO3微球的应用开辟了新方向。     

聚酰亚胺/二氧化硅/银杂化薄膜的制备及其结构与性能研究

采用溶胶-凝胶和原位自金属化相结合方法制备聚酰亚胺(PI)/二氧化硅(SiO2)/银(Ag)三元复合薄膜,通过红外(FTIR)、透射电镜(TEM)、动态粘弹谱仪(DMTA)等系统地考察了热处理过程中杂化薄膜结构形态变化以及SiO2含量对金属银向基体表面迁移情况和杂化薄膜各种性能的影响.实验结果表明,在热处理过程中可以同时完成聚酰胺酸的亚胺化、SiO2粒子的形成及银的还原,并且可以通过改变热处理温度和时间或改变SiO2含量来控制银粒子向聚合物基体表面的迁移.     

Transparent superhydrophobic films based on silica nanoparticles

We demonstrate a layer-by-layer processing scheme that can be utilized to create transparent superhydrophobic films from SiO2 nanoparticles of various sizes. By controlling the placement and level of aggregation of differently sized nanoparticles within the resultant multilayer thin film, it is possible to optimize the level of surface roughness to achieve superhydrophobic behavior with limited light scattering. Transparent superhydrophobic films were created by the sequential adsorption of silica nanoparticles and poly(allylamine hydrochloride). The final assembly was rendered superhydrophobic with silane treatment. Optical transmission levels above 90% throughout most of the visible region of the spectrum were realized in optimized coatings. Advancing water droplet contact angles as high as 160 degrees with low contact angle hysteresis (<10 degrees ) were obtained for the optimized multilayer thin films. Because of the low refractive index of the resultant porous multilayer films, they also exhibited antireflection properties.     

Super-liquid-repellent surfaces prepared by colloidal silica nanoparticles covered with fluoroalkyl groups

A simple and easy method to prepare super-liquid-repellent surfaces is proposed. Sol-gel films were prepared by hydrolysis and condensation of alkoxysilane compounds. Both surface energy and roughness were controlled using colloidal silica particles and fluoroalkylsilane. When the fractional amounts of both colloidal silica and fluoroalkylsilane were optimized in the films, the film surface exhibited repellency to both water and oil. Finally, it was shown that the method proposed here would be applied to a simple one-pot coating for a uniform large area, and be useful for practical use.     

喷涂法制备功能性超疏水复合涂层及其性能研究

以常用工程材料硅树脂BP与St(o)ber法合成的二氧化硅(SiO2)分散液为原料,运用喷涂法(spray-coating)制备出了功能性微/纳粗糙(MNR)结构的超疏水涂层,其接触角可以达到146.5°,滚动角小于1°(测试液滴量为15μL).通过分析喷涂法制备复合涂层所需的条件,得出喷涂液pH＝7.7-8.0时,在...     

溶胶凝胶法制备超疏水二氧化硅涂膜及其表面润湿行为

采用溶胶-凝胶法以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为前驱体制备超疏水SiO2涂层。红外光谱(FTIR)和热重分析(TGA)表征合成SiO2的化学组成,通过透射电镜(TEM)和扫描电镜(TEM)观察制备SiO2的结构形貌,扫描电镜(SEM)和原子力显微镜(AFM)观察SiO2涂膜的表面形貌,通过测试水接触角(WCA)讨论SiO2涂层的表面微观结构与其表面疏水性能的关系。结果表明以TEOS和MTES为共前驱体可以制备得到表面带-CH3基团的SiO2溶胶,SiO2溶胶在老化过程中纳米SiO2粒子由于自组装作用形成草莓状微米-纳米双微观结构,这种结构赋予SiO2涂膜表面不同等级的粗糙度,使得水滴与涂膜表面接触时能够形成高的空气捕捉率和较小的粗糙度因子,与SiO2表面疏水性的-CH3基团共同作用形成类荷叶超疏水结构。     

Facile fabrication of a superhydrophobic surface from natural Eucommia rubber

In this study, we introduce a fabrication method for a superhydrophobic surface made from natural Eucommia rubber. Based on the Eucommia rubber extract solution, we prepared a type of superhydrophobic material using the simple phase separation method and the addition of a low‐surface‐energy substance method, thus developing a new approach for the application of natural Eucommia rubber. The experimental results showed that a superhydrophobic film could be obtained by both the addition of acetone and induction by water vapor. Additionally, the film exhibited properties closely related to the crystalline Eucommia rubber spherical particles with a hierarchical structure. The addition of hydrophobic silica also increased the hydrophobic property of the Eucommia rubber film. When the content of the silica was 4% (wt%), the contact angle of the composite film reached 160.7°, which could be attributed to the properties of the nano‐silica and the micro‐nano structure of the composites. Copyright © 2017 John Wiley & Sons, Ltd.     

Characterization of Plasma Polymerized Hexamethyldisiloxane Films Prepared by Arc Discharge

Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface characterization was performed using scanning electron microscopy and atomic force microscopy. The growth process of the pp-HMDSO films was investigated as a function of deposition time from 30 to 300 s. The non-wetting characteristics of the pp-HMDSO films were evaluated by means of contact angle (CA) measurements and correlated with the morphological characteristics, as obtained from microscopy measurements. The deposited films were found to be nano-structured and exhibited dual-scale roughness with the static CA values close to 170°. Fourier transform infrared spectroscopy analysis was carried out to investigate chemical and functional properties of these films. Methyl groups were identified spectroscopically to be present within the pp-HMDSO films and were proposed to result in the low surface energy of material. The synergy between the dual-scale roughness and low surface energy resulted in the superhydrophobic characteristics of the pp-HMDSO films. A possible mechanism for the pp-HMDSO film formation is proposed.     

Investigating the interface of superhydrophobic surfaces in contact with water

Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface.     

Novel inorganic morphologies formed in polyimide/silica hybrid films

2-(4-Aminophenyl)-5-aminobenzimidazole was used to prepare polyimide/silica hybrid films via sol-gel process. At 40 wt.% silica content, hybrid films were still translucent. No noticeable silica particle has been observed. Unexpectedly, after treating at 800 °C, novel morphologies of silica were observed on the surface of inorganic films, which changed from homogeneous to sea-island and to co-continuous structure with increasing silica content in the matrix. Hydrogen bonding between NH in imidazole and silanol group results that silica tends to linear structures, which is considered as the main reason for this morphological change.     

Stable superhydrophobic organic-inorganic hybrid films by electrostatic self-assembly

Organic-inorganic hybrid films were prepared through layer-by-layer (LBL) deposition of poly(allylamine hydrochloride) (PAH) and ZrO(2) nanoparticles coated with poly(acrylic acid) (PAA), allowing facile control of surface roughness and hydrophobicity. Superhydrophobic behavior was observed after deposition of silica nanoparticles and a simple fluorination of the surface. The structure of films was controlled by the number of deposition cycles using PAA-coated 100 nm ZrO(2) nanoparticles, the particle size, and the prelayer with PAH and PAA. The change in the apparent water contact angle of (PAH/PAA-coated ZrO(2)n surfaces without fluorination of the surface agrees with Cassie and Baxter's model for nonwetted surfaces even though the outermost surface itself is hydrophilic. Superhydrophobic surfaces were then successfully developed by the deposition of hydrophilic silica nanoparticles on a 10 bilayer surface of PAH/PAA-coated ZrO(2), and a simple fluorination. Moreover, the chemical stability of the film was greatly increased by heat-induced cross-linking of the film. The incorporation of ZrO(2) nanoparticles in superhydrophobic films promises better mechanical properties than the organic film.