倾斜微结构疏水表面液滴的滞后特性

倾斜微结构疏水表面液滴的滞后特性包括接触角滞后和滚动角。目前,具有较高精度的微结构疏水表面滚动角模型是以理想液滴形状为计算基础,忽略了重力、接触角滞后以及能垒引起的变形。本文以聚二甲基硅氧烷（PDMS）为基底,制备了方柱状微结构疏水表面,考虑疏水表面微观结构以及液滴大小两方面的因素,研究了倾斜微结构疏水表面液滴的滞后特性。从力和能量的角度对其影响机理进行了分析,通过滚动角理论值与实际值的比较发现,微方柱间距较大时,接触角滞后和能垒对滚动角影响显著,证实了该分析的合理性,为研究更加精确的滚动角模型奠定了理论基础。     

置换反应制备锌表面超疏水薄膜

利用硫酸铜与锌的置换反应,在锌片表面生成具有微纳米结构的铜,制备锌表面超疏水薄膜。研究了硫酸的加入、硫酸铜浓度和反应时间对微纳米结构及疏水性能的影响。使用扫描电子显微镜(SEM)对表面结构进行了表征。使用接触角测量仪测量了疏水性。结果显示,在最优条件下接触角可达到154°,滚动角可达到6°。该超疏水薄膜具有一定的防腐蚀性。     

硅烷偶联剂KH-570对硅藻土表面疏水改性研究

采用硅烷偶联剂KH-570对硅藻土进行表面疏水改性以增强其在油性体系中的应用效果。应用接触角测定仪、红外光谱仪(FT-IR)、热重分析仪(TG)等实验分析手段对表面疏水改性前后的硅藻土进行表征,考察了改性剂KH-570用量对硅藻土表面疏水性能的影响,分析了KH-570作用于硅藻土表面疏水改性机理。结果表明,KH-570用量是影响硅藻土表面疏水性能的主要因素,当KH-570质量达到硅藻土质量的5%后,接触角达125.4°~147.3°,吸湿率为0.6%~0.8%,表现出良好的疏水性;红外光谱和热重分析均表明KH-570在硅藻土表面形成了疏水的有机包覆层。     

化学刻蚀法制备黄铜基超疏水表面

采用含有三氯化铁和盐酸的水溶液刻蚀金属黄铜表面，在黄铜表面上得到了一层由不规则块状结构和更细小的乳突状结构相结合的具有双重粗糙度的阶层结构。该表面经氟化处理后表现出超疏水性，水在该表面上的接触角达到了157°，接触角滞后为5°。考察了不同刻蚀时间对表面疏水性的影响，结果表明，刻蚀时间对表面上这种阶层结构的形成和水滴在表面上的接触角数据都有十分重要的影响。随着刻蚀时间的增加，表面上逐渐开始形成粗糙结构，接触角数据也不断增加，增加到一定数值后，接触角变化开始不明显。接触角滞后随着接触角的增加而减小。初步分析了这种阶层结构的形成机制，并用Cassie理论对表面的润湿性进行了分析。     

盐酸刻蚀制备铝合金超疏水表面的工艺及自清洁性研究

采用盐酸刻蚀法制备超疏水铝合金表面。用接触角仪、粗糙度仪和扫描电镜对疏水性、表面粗糙度(Ra)和微观形貌进行分析。研究了盐酸浓度、刻蚀时间、刻蚀温度以及长链烷烃酸对疏水性能的影响。结果表明,随着盐酸浓度、刻蚀时间、刻蚀温度的增加,铝合金表面粗糙度增加,而接触角先增大后减小。当刻蚀酸浓度为3 mol/L,刻蚀时间为20 min,刻蚀温度为25℃时,效果最佳,经过0.01 mol/L硬脂酸溶液改性后,接触角高达156°。采用长链烷烃酸对表面进行改性,随着烷烃酸碳链的增加,接触角略有增加。超疏水铝合金表面具有较好的自清洁性能。     

盐酸刻蚀制备铝合金超疏水表面的工艺及自清洁性研究

采用盐酸刻蚀法制备超疏水铝合金表面。用接触角仪、粗糙度仪和扫描电镜对疏水性、表面粗糙度(Ra)和微观形貌进行分析。研究了盐酸浓度、刻蚀时间、刻蚀温度以及长链烷烃酸对疏水性能的影响。结果表明,随着盐酸浓度、刻蚀时间、刻蚀温度的增加,铝合金表面粗糙度增加,而接触角先增大后减小。当刻蚀酸浓度为3 mol/L,刻蚀时间为20 min,刻蚀温度为25℃时,效果最佳,经过0.01 mol/L硬脂酸溶液改性后,接触角高达156°。采用长链烷烃酸对表面进行改性,随着烷烃酸碳链的增加,接触角略有增加。超疏水铝合金表面具有较好的自清洁性能。     

微纳米结构对聚合物超疏水表面润湿性的影响

对聚合物超疏水表面疏水原因的理论分析及其超疏水表面常用的制备方法进行了总结,并从热力学角度评述了关于超疏水状态的两种理论模型:Wenzel模型和Cassie模型,分析了微纳米结构对聚合物超疏水表面表观接触角的影响.     

含硅化合物改性聚酯的合成与性能研究

为制备疏水性聚酯,在缩聚阶段将含硅化合物双羟甲基硅油加入聚酯反应体系进行缩聚反应,合成含硅改性聚酯。利用傅里叶红外光谱(FT-IR)对改性聚酯结构进行表征,采用接触角测量仪测定水的静态接触角,分析双羟甲基硅油的添加量与改性聚酯表面疏水性的关系。采用差示扫描量热仪(DSC)和热重分析仪(TGA)对改性聚酯的结晶性能和热稳定性进行了测试。结果表明,双羟甲基硅油的加入量为2%时可使聚酯表面接触角提高33°,随着双羟甲基硅油添加,改性聚酯结晶速率变慢,热稳定性略有提升。     

共水解法制备透明超疏水表面

利用硅烷偶联剂与正硅酸乙酯共水解法对SiO2纳米颗粒进行原位疏水化处理,并采用共水解后的溶胶在玻璃基底上浸渍提拉成膜,两次成膜后即可以使玻璃表面呈现良好的超疏水性并保持较好的透明度。论文通过扫描电镜、原子力显微镜、傅立叶变换红外光谱、接触角仪进一步对超疏水表面进行了表征。实验结果显示制备的超疏水表面不仅具有较大的表观接触角（≥150°）,而且该表面有着较小的接触角滞后。通过该方法制备的超疏水表面不需要使用昂贵的全氟烷进行后续疏水化处理,从而简化了超疏水表面的制备工艺。     

绿孢链霉菌对不同煤阶煤的降解转化

以褐煤、肥煤和无烟煤为研究对象,进行降解时间、粒径和煤阶为因素的降解正交试验及绿孢链霉菌降解固定粒径各煤阶煤的实验;通过COD测定、元素分析和接触角测试,分析比较降解前后溶液有机物含量、煤的组成及亲水性,进而分析绿孢链霉菌对各煤阶煤降解转化的影响因素。结果表明:影响绿孢链霉菌对煤降解效果的主要因素是煤阶;绿孢链霉菌最容易利用降解褐煤生成的有机小分子物质,其次是利用降解肥煤与无烟煤生成的有机小分子物质;各煤阶煤经绿孢链霉菌降解后C元素和N元素含量相对升高,O元素和S元素含量及n(H)∶n(C)和n(O)∶n(C)值均降低;煤样经绿孢链霉菌降解后,褐煤的固液接触角变大,疏水性增强,而肥煤与无烟煤的固液接触角变小,亲水性增强,与各煤阶煤样的固液接触角由大到小的三种溶液依次为蒸馏水、矿井水和KO溶液。     

煤与纯水间平衡接触角的测量与分析

接触角对于研究固体的润湿性、液体在固体孔隙中的渗透性有重要意义，但接触角的测量难度比较大。笔者用快速照相法测定了来自我国七个不同矿区的煤的粉煤成形体压光表面与纯水间的平衡接触角，并分析了接触角的影响因素，初步得到了规律性认识。     

Theoretical and experimental analysis of droplet evaporation on solid surfaces

The evaporation of sessile drops is central to a number of important processes, including printing, washing and coating. In this paper, the evaporation of water sessile droplets on hydrophobised silicon wafers and Teflon was analysed from theoretical and experimental perspectives. The contact angle, volume and base radius of the water droplets as a function of time were determined using tensiometry. The theoretical analysis showed different evaporative flux phenomena for acute and obtuse contact angles. The non-linear evolution of residual droplet volume, contact angle and base radius are solved and depend on the hydrophobicity of the solid surface and droplet dimension. Good agreement between the theoretical and experimental results was observed during pinning and depinning stages of evaporation. It was shown that the surface roughness, hydrophobicity and the contact angle hysteresis significantly influenced the evaporation of sessile drops and need to be considered when quantifying the evaporation process.     

硅烷偶联剂表面改性二氧化钛粒子超疏水性能研究

针对无机二氧化钛（TiO2）粒子在有机体系中的分散性问题,采用硅烷偶联剂KH-570对无机填料钛白粉（二氧化钛,TiO2）的表面进行有机化改性;并通过红外光谱（FT-IR）、接触角测试、沉降实验、扫描电子显微镜（SEM）等手段表征表面改性TiO2粒子的结构,测试其超疏水性能,分析超疏水表面形成的机理。结果表明,经KH-570表面改性的TiO2粒子的疏水性和分散性得到明显改善,当KH-570质量分数达到15%时,表面改性的TiO2涂层与水的静态接触角达152.5˚,表现出良好的超疏水性能。     

Surface and mechanical properties of an organic-inorganic super- hydrophobic coating using modified nano-SiO2 and mixing polyurethane emulsion as raw materials

A series of organic-inorganic super-hydrophobic coatings were prepared using nano-SiO₂ particles modified by fluorine and silicone coupling agents, and a mixing polyurethane emulsion as main raw materials. The mixing polyurethane emulsion was consisted of the polyurethane emulsion end-terminated by double bond (WPUD) and polyurethane emulsion modified by silicone (WPUS). The influence of content of modified nano-SiO₂ particles and the weight ratio of WPUS to WPUD on microstructure and hydrophobicity of the coating surface were studied. The morphologies of coating surface were examined using SEM and AFM, hydrophobicity of the coating was researched by examining static water contact angle and so on. It was found that modified nano-SiO₂ particle was an indispensable factor during the preparation of super-hydrophobic coating. The roughness and hydrophobicity of the coating surface were enhanced obviously with an increase of the content of the modified nano-SiO₂ particles. When the content of the modified nano-SiO₂ particles increased up to 1.5%, the surface of coating possessed good super-hydrophobicity, and static water contact angle reached 169.1°. It was also noticed that the weight ratio of WPUS to WPUD in the base layer has also an important influence on the hydrophobicity and mechanical property of coating surface. With an increase of the ratio of WPUS to WPUD the hydrophobicity of the coating was enhanced, the tensile strength and peel strength reduced, but the elongation at break increased. When the weight ratio of WPUS to WPUD reaches up to 9/100, the static water contact angle reaches the maximum value of 169.1°.     

热处理对粉煤灰酸渣基二氧化硅气凝胶结构和疏水性的影响

粉煤灰酸渣是粉煤灰经酸溶提铝后的副产品,主要化学成分为无定形二氧化硅,其资源化利用不仅解决了粉煤灰酸渣堆存带来的环境问题,还能获得附加值较高的二氧化硅气凝胶。以粉煤灰酸渣制备的水玻璃为原料,通过溶胶-凝胶—溶剂交换/表面改性—常压干燥工艺成功制备了低密度（0.083 g/cm³）、高比表面积（708 m²/g）、高疏水性（接触角为143°）的多孔二氧化硅气凝胶。通过热重-差热分析、红外光谱分析、接触角测试、扫描电镜分析、氮气吸附-脱附测试等手段对热处理前后二氧化硅气凝胶的结构和疏水性进行了表征。结果表明,随着热处理温度升高,二氧化硅气凝胶的比表面积增大、疏水性逐渐减弱直至消失。300 ℃热处理后,二氧化硅气凝胶仍具有较强的疏水性（接触角约为128°）,密度为0.080 g/cm³。当热处温度为400~600 ℃时,二氧化硅气凝胶仍具有中孔结构,由疏水性变为亲水性,密度从0.073 g/cm³增加到0.078 g/cm³。     

Overlimiting mass transfer through cation-exchange membranes modified by Nafion film and carbon nanotubes

Eight cation-exchange membranes different in the surface morphology and the degree of hydrophobicity were studied by contact angle, voltammetry and mass transfer rate measurements. One series of membranes was prepared starting from heterogeneous MK-40 membranes, and another, from homogeneous Nafion? 117 membranes. Coating a membrane with a thin film of Nafion resulted in increasing surface hydrophobicity, while the doping of the Nafion surface film with carbon nanotubes (CNT) led to an unexpected decrease in hydrophobicity. It was found however that after 100 h operation of a Nafion? 117 membrane coated with a Nafion film doped with CNT, the contact angle increased from 51 to 81°. This increase in the surface hydrophobicity was accompanied by a significant rise in overlimiting transfer rate, more than 1.5 times, under the same voltage. High correlation between the overlimiting mass transfer rate and the degree of hydrophobicity was observed also in all studied cases: more hydrophobic surface leads to a higher mass transfer rate. The effect is explained by increasing electroconvection occurring as electroosmosis of the second kind: the slip of water over a hydrophobic surface enhances the tangential velocity of electroconvective vortex having its maximum at a distance of several hundreds of nm from the surface.     

Hydrophobic properties of films grown by torch-type atmospheric pressure plasma in Ar ambient containing C6 hydrocarbon precursor

The direct deposition of polymeric films with a torch-type atmospheric pressure plasma using benzene, n-hexane and cyclohexane in Ar was performed on several substrates. The surface morphologies of the films deposited with n-hexane and cyclohexane were uniformly smooth for all deposition thicknesses, and the typical water contact angle on the films indicating the degree of hydrophobicity was about 85o. However, the films deposited using benzene had a micro-coarse surface morphology and showed a superhydrophobic property with a water contact angle exceeding 150°. Some trace of oxygen incorporation was shown in all films due to the plasma deposition process in an air ambient. The small amount of oxygenated species did not lead to a decrease of hydrophobicity of the films.     

Improving the dewetability characteristics of hydrophobic fine particles by air bubble entrapments

The present study deals with the role of surface hydrophobicity and air bubble entrapment on filtration / dewatering of fine coal particles (− 0.5 mm). The experimental results showed that hydrophobizing reagents increased the contact angle (or hydrophobicity) and decreased the filtrate surface tension, cake formation time and moisture content of the fine particles. In addition to these, when the air bubbles were introduced to the hydrophobic fine coal particles in water, the cake formation time and moisture content of the filter cake were further reduced, which may be attributed to the fact that micro/nano size air bubbles were entrapped on the surface of the fine particles in a slurry and increased the dewetting characteristics of the fine particles. As a result, this process may lower the amount of moisture trapped during the dewatering fine particles and increase the efficiency of the filters.     

Preparation of transparent ultrahydrophobic silica film by sol�Cgel process

Transparent ultrahydrophobic films were synthesized by sol–gel process with organic silicones modified into silica sol and cured under UV irradiation. The effects of hydrolysis temperature, hydrolysis time, molar ratio of organic silicone to silica sol, and surface morphology on the hydrophobicity of the films were discussed in detail using FTIR spectroscopy, scanning electron microscopy (SEM), AFM, optical transmission, and contact angle measurement, respectively. The AFM and SEM images indicated that the surface roughness enhanced the hydrophobicity of the films. The results revealed that methyl-trimethoxysilane (MTMS)-modified silica film prepared at 50°C for 2 h with an MTMS/silica sol molar ratio of 1:10 had a very high contact angle (130°). However, the higher hydrolysis temperature and longer reaction time might have accelerated the self-condensation of silanol and decreased the contact angle of the films.     

煤与粘结剂的相互作用和型煤抗压强度的关系

煤的润湿性与型煤抗压强度相关。用于表征煤的润湿性方法有煤与淀粉粘结剂的接触角、粘合功、煤的润湿临界表面张力等。研究证明,随着煤化程度的升高,煤与淀粉粘结剂接触角变小,粘合功增加,粉煤的润湿性改善,型煤抗压强度得以提高。另外,煤的润湿临界表面张力越大,煤的润湿性越好,型煤抗压强度也就越高。