Hydrophobic mechanism and criterion of lotus-leaf-like micro-convex-concave surface

According to the principle that the contact angle of liquid droplet always increases on a limited liquid-solid interface,it is suggested that the integration of many small-size limited liquid-solid interfaces results in the increase of the hydrophobicity of lotus-leaf-like micro-convex-concave surfaces.Mathematical equations of the stability of liquid-droplets on the surface of lotus-leaf-like structure were established.The relationship between the theoretical critical-radius of the void of micro-convex-concave surface and the nature of the solid and the liquid was drawn.The three conditions of realizing hydrophobicity were described.The result of computation has shown that when the radius of the void of micro-concave-convex surface is less than the theoretical critical-radius r c,the droplets may always be in a stable state on the solid surface with the contact angle greater than 90°.Theminimum area of the liquid-solid interface and low surface energy of solids are important factors in realizing hydrophobicity.The effective work of adhesion W a ’ was proposed as a criterion for measuring the hydrophobic ability of the solid surface.     

工业化超疏水TiO2涂层的简易制备和性能研究

为探究适合工业化生产用超疏水纳米TiO₂的绿色改性工艺,以饱和脂肪酸A、硅烷B、纳米TiO₂（P25）等为原料制备超疏水TiO₂粉末,与环氧树脂混合后利用喷涂法制备出超疏水涂层。采用扫描电子显微镜、X射线衍射仪、傅里叶变换红外光谱仪和接触角分析仪对超疏水粉末和超疏水涂层表面的形貌和疏水性进行了表征。结果表明：超疏水TiO₂粒子表面具有疏水性基团和微-纳米双重粗糙结构,粒子表面的静态水接触角为158°,滚动角为3°;当超疏水TiO₂与环氧树脂的质量比在3.2～3.5时,超疏水涂层既保持超疏水性,又与基底稳固结合,同时具有自清洁性和可修复性。该工艺操作简单方便,成本低,疏水性好,无需特殊设备,工艺环保,适应工业化生产,可用来大面积制备超疏水涂层,拥有较高的商业价值。     

KH550的水解工艺及其对SiO2表面改性的研究

用电导率在线测量法和红外光谱法研究了硅烷偶联剂3-氨丙基三乙氧基硅烷(KH550)的水解工艺。采用共沸蒸馏和溶剂置换方式置换出湿凝胶中物理吸附水,并用KH550水解液对SiO2湿凝胶进行了改性。通过红外光谱（FT-IR）、邻苯二甲酸二丁酯（DBP）吸油值、粒度分析仪和接触角测定仪等方式对改性效果进行了表征。结果表明,采用KH550对SiO2湿凝胶进行改性后,产品的接触角显著提高,吸油值增大70%以上,孔容为未改性样品的2倍,有机相中的分散性显著提高。同时,对比共沸蒸馏和溶剂置换两种方式,共沸蒸馏得到疏水性更好的超细SiO2,改性后样品的接触角可以达到140°以上。共沸蒸馏过程中,当改性剂KH550用量为超细SiO2绝干粉重的17.5%（质量分数）时,改性效果最好。     

白炭黑的表面改性和性能研究

为提高白炭黑对有机高分子的亲和性,利用偶联剂同时拥有亲油基和亲水基的结构特性,对白炭黑颗粒表面进行改性.考察了改性时间、温度、pH和偶联剂与白炭黑的质量比对白炭黑表面改性情况的影响.通过红外光谱、热失重、氮气吸脱附、接触角、活化度及沉降体积测试等手段对改性前后白炭黑结构及改性效果进行表征.结果表明,γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)的改性效果明显优于γ-巯丙基乙氧基双(丙烷基-六乙氧基-硅氧烷)(Si747)和双-(γ-三乙氧基硅基丙基)四硫化物(Si69).以无水乙醇为改性剂,当KH570与白炭黑的质量比为14%、改性温度为50℃、pH为7、改性反应6 h时,活化度达到最大.改性后偶联剂接枝在白炭黑表面,亲水性降低、分散性提高,表面浸润性得到明显改善,拓宽了白炭黑在工业中的应用范围.     

改性气相SiO2和膨润土稳定环氧树脂水基乳液的研制

采用物理方法对SiO2粒子进行表面改性,并用改性纳米粉体气相SiO2和膨润土分别作乳化稳定剂,通过转相乳化法制备环氧树脂水基乳液,结果表明:通过对气相SiO2表面改性或向膨润土中添加亲水性微粒均能促成乳状液的转相跃迁.气相SiO2的表面润湿性对这种水基乳液的稳定性产生影响的主要原因体现在两个方面:一是用做改性剂的阳离子...     

木素磺酸盐在纸浆纤维表面的层层自组装及其疏水改性功能

利用木素磺酸盐 (LS) 与Cu2+层层自组装的方式对纸浆纤维进行了表面修饰，并研究了表面润湿性的变化。X射线光电子能谱证明了纤维表面S和Cu的含量随着LS与Cu2+ 的交替组装而增加，这说明LS和Cu2+在纤维表面的层层自组装是可行的。原子力显微镜对纤维表面的研究表明，随着层层自组装的进行，纤维表面的微细纤维逐渐被木素致密覆盖；表面木素的增加致使相图的平均相位逐渐增大，说明了表面疏水性的提高。通过测定动态接触角发现，纤维的初始接触角随着自组装层数的增加而增大，且一定时间(0.08s)内接触角的下降速率在减小。当组装5层木素后，纤维表面的初始接触角由0°提高至104.8°，0.08s 后下降至78.9°，表面由高度亲水性变为具有一定疏水性。通过控制SL自组装的层数可以有效且可控地实现纸浆纤维的疏水改性。     

超疏水泡沫吸油材料的制备及性能研究

采用十二烷基三甲氧基硅烷(DTMS)对氧化锌颗粒表面进行处理,得到改性氧化锌颗粒,将改性氧化锌颗粒涂覆在聚氨酯泡沫表面,制备得到泡沫吸油材料.采用傅立叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)和扫描电镜(SEM)对泡沫吸油材料的表面进行表征,利用接触角测试仪(CA)对其表面性能进行分析,并对其吸油性能和重复利用率进行了研究.结果表明:(1)该泡沫的表面水接触角为153°,具有超疏水特性;(2)该泡沫可以吸收多种油,最高吸油倍率为9.55g/g,吸水倍率为0.58g/g,重复利用率高.此种泡沫是一种综合性能优良的吸油材料.     

泡沫铝合金孔隙率对泡沫铝合金/聚甲醛互穿复合材料的影响

使用硅烷偶联剂KH570对孔隙率不同的泡沫铝合金进行表面改性后,通过注塑成型法制备了聚甲醛/泡沫铝合金互穿复合材料。研究了改性后泡沫铝合金表面的红外结构、泡沫铝合金/聚甲醛互穿复合材料的力学性能和摩擦学性能以及泡沫铝合金/聚甲醛互穿复合材料的磨损表面。研究结果表明,硅烷偶联剂KH570成功接枝到了泡沫铝合金的表面;复合材料的弯曲强度和压缩强度随着泡沫铝合金孔隙率的降低而升高;而复合材料的摩擦学性能随着泡沫铝合金孔隙率的增加而降低。     

乙醇超临界技术制备疏水性白炭黑粉体

以硅酸钠为硅源,浓硫酸为酸化剂,在超重力旋转床中制备出二氧化硅,经处理后置于高压釜内,在分别改变溶液体积与高压釜容积比值、滤饼质量或氮气预加压条件下进行乙醇超临界干燥,制得白炭黑粉体。用接触角测定仪、透射电镜、FT-IR红外光谱、氮气吸附容量法、DBP吸油值来表征所得样品。结果表明：所得样品具有极强的疏水性,接触角大都在130°以上,当溶液体积与高压釜容积比值增大时,接触角大体呈增大趋势;当滤饼质量增加时,接触角亦增大;当氮气预加压力增大时,接触角变化规律不明显;所得样品除粒径变化不大外,分散性、比表面积、吸油值等均有规律变化。     

多孔介质内泡沫稳定性定量评价实验

为了克服常规泡沫稳定性评价方法难以模拟高温高压多孔介质环境的不足,基于激光探测技术,根据激光透过不同衰变阶段泡沫时的透射性能差异,首次提出了一种高温高压条件下定量评价多孔介质内泡沫稳定性的实验方法。此外,为验证激光法评价结果的准确性,同时开展了泡沫粒径微观可视化实验,研究了压力、温度、多孔介质对泡沫稳定性的影响及其机理。研究发现,相同条件下,较无多孔介质,泡沫在多孔介质中的稳定性更好,且在高压条件下,多孔介质更有利于稳泡。原因是压力升高,孔隙受压缩其水力半径减小,空气与表活剂疏水链的分子间作用力增强,二者均会导致泡沫粒径减小,稳定性增强;升高同样温度,多孔介质中泡沫稳定性下降的幅度更大。是由于多孔介质中的固态颗粒导热系数比纯泡沫更高,单位时间内辐射出的热量更多,加剧了气泡膨胀及液膜排液,使泡沫粒径增大,稳定性降低。     

Bioinspired and hydrophobic alkyl-silanized protective polymer coating for Mg alloy

The modification of silica coating surfaces by trimethylsilylation has contributed to enhanced hydrophobicity(θ_w~o90°)against fluid permeation and corrosion in Na Cl.These alkyl-silanized coatings were deployed to protect Mg alloy after reinforcing their internal structures with nanosilica powder.The reduced wetness of coating surfaces is attributed to their chemically-modified surface morphology,and this has been compared to the reticulate leaf structures of lotus plant.The optimum amount of silylating additive(hexamethyldisilazane)required to prepare a hydrophobic coating with minimum water adhesion has been established.Barrier performance of coatings were examined by electrochemical and surface analyses in 5 wt%Na Cl.The corrosion resistance of these coatings is a result of the direct contribution of their bulk stability and surface hydrophobicity,and this is expressed in terms of the variation of electrochemical parameters with exposure time.These coatings may have emerging industrial applications,including a future in metal surface treatments and anticorrosion paints.     

改性微粒硅溶胶的研制及应用机理研究

The preparation and their application in papermaking of aluminium modified silica sol (AMS) and boron modified silica sol (BMS) were first investigated in China. At the same time the structures and configurations of AMS and BMS were first time authenticated. The modified silica sol microparticle system was detailedly and systemically studied with colloid charge titration. On the research of flocculation mechanism the laser sizer was also first time used to determine the floc size. Results showed that sodium silicate was treated and acidification was carried out by means of strongly acid cation exchange resins and obtained almost sodium free acid sols. The acid sol obtained after acidification was then made alkaline.     

Preparation of Cu-SiO<Subscript>2</Subscript> composite aerogel by ambient drying and the influence of synthesizing conditions on the structure of the aerogel

A copper-doped silica composite aerogel with high specific surface area was prepared using a sol-gel method at ambient pressure. A drying control chemical additive (DCCA) N,N-dimethylformamide (DMF) was introduced to the composite sol of tetraethyl orthosilicate (TEOS) and copper nitrate (Cu(NO3)2·3H2O) during the synthesizing process. The influence of the preparation conditions including Cu loading, catalyst concentration and heat treatment on the structure of copper-doped silica was investigated. The results showed that the obtained aerogel particles were uniformly distributed. The pore diameter was in a range of 2 to 15 nm. Heavier Cu loading benefited the formation of CuO crystalline, and reduced the specific surface area and pore diameter. When the catalyst concentration was high, the aggregation of Si-O network was reduced with the increase of it. The composite aerogel exhibited a good thermal stability after the heat treatment at high temperature.     

羟基化及硅烷化二氧化硅表面润湿行为的分子模拟

采用分子动力学模拟方法研究水团簇在羟基化及不同链长硅烷化二氧化硅表面的微观润湿行为,通过相互作用能、径向分布函数及扩散系数等参量对微观润湿机制进行分析。结果表明:羟基化二氧化硅表面具有极强亲水性,而硅烷化表面疏水性较强,且疏水性随烷基链增加呈增强趋势;羟基化二氧化硅表面与水分子存在强相互作用,使团簇底部水分子优先向表面移动,并带动其余水分子向表面迁移,促进水团簇在表面铺展,表现出强亲水性;硅烷化二氧化硅表面与水之间主要为范德华作用,不足以克服团簇内部相互作用而破坏水滴结构,表现出强疏水性,随着烷基链增长,表面与水分子的相互作用强度逐渐减弱,疏水性增强。     

Synthesis of MgO-Modified mesoporous silica and its adsorption performance toward CO2

The mesoporous silica modifed with magnesium ox- ide （MgO） was syntbesized by one step method and impregnating method, respectively. The samples were characterized by small angle X-Ray diffraction （XRD）, N2 adsorption-desorption and transmission electron microscopy （TEM）, and the carbon dioxide adsorption capacity was analyzed by thermal gravimetric analysis （TGA）. Compared with the original mesoporous silica （20.7 mg/g）, the CO2 adsorption capacity of MgO-modified mesoporous silica processed by one step method increases to 32.9 mg/g. Although its surface area greatly decreases compared with that of the original mesoporous silica, the MgO-modified mesoporous silica prepared by impregnating reaches an adsorptive value of 31.1 mg/g because the number of basic sites increases on the surface of the mesoporous silica.     

Magnetic properties and thermal stability of sintered Nd-Fe-B magnet with Dy-Ni additive

A sintered(Nd_(0.8)Pr_(0.2))_(30.7)FebalB_(0.98)Cu_(0.2) magnet with 3% intergranular Dy_(85)Ni_(15) additive is prepared to study the magnetic properties and thermal stability of the Nd-Fe-B magnet. The results show that the magnet with or without additive obtains its optimum comprehensive magnetic properties at the sintering temperature of 1 030 ℃ and 1 040 ℃, respectively. The maximum coercivity of the magnet with additive reaches 15.16 k Oe, while that of the magnet without additive is just 11.88 k Oe. Further investigation on microstructure indicates that the grains of the magnet with additive form a modified "core shell" structure. Adding Dy_(85)Ni_(15) can significantly enhance the coercivity of Nd-Fe-B magnet and thus decrease its coercivity temperature coefficient.     

Preparation and characterization of CoFe2O4/SiO2 nanocomposites

Recent years see an increasing interest in nanocomposites synthesized by a sol-gel procedure consisting of magnetic nanosized particles embedded in a silica matrix. due to their specific physical and chemical properties[1―4]. Sol-gel derived amorphous si…     

Laboratory study of improving petroleum recovery by changing the wettability between the solid/liquid interface

The wettability of the solid powders (silica gel or Kaolin) was measured with the modified Washburn equation indicated as contact angles. The wettability changes for SDBS aqueous solutions on the surface of a silica gel or Kaolin powder were studied. The average aggregation number of the micelle in SDBS aqueous solution was measured by the fluorescence quenching method. Then the oil recovery of n-dodecane on the silica gel or the Kaolin surface was tested. The relationship between the wettability of the powder surface, the critical micelle concentration (CMC) of SDBS aqueous solution, and the mimic oil recovery of the resident oil on the powder surface has been explored. It has been found that the minimum contact angle (most hydrophilic condition) and the maximum oil recovery occurred near the critical micelle concentration (CMC) of SDBS while the interfacial tension between the SDBS solution and n-dodecane was far from ultra-low condition (≤10^-3 mN·m^-1).     

压缩空气泡沫析液过程分析

利用压缩空气泡沫灭火系统和析液装置,对典型的蛋白型A类泡沫灭火剂在压缩空气泡沫产生方式下的泡沫析液(泡沫溶液的质量分数取0.3%~2.4%)过程进行了实验研究,同时通过建立分析模型来反映析液过程.研究发现泡沫在析液之前存在延迟现象,析液速率并非从一开始就递减,而是先有一个峰值,峰值过后其值逐步降低并趋近于0,此时析液质量趋于平稳.实验表明:最大析液速率、析液速率常数、50%析液时间都与溶液质量分数相关,增大溶液质量分数则最大析液速率、析液速率常数都会呈指数衰减而50%析液时间则呈指数上升.模型和实验结果的对比很吻合,能恰当地反映压缩空气泡沫的析液过程.     

十二烷基硫酸钠-长链醇体系泡沫性能与表面参数关系研究

使用德国KRSS公司生产的DSA100界面扩张流变仪,采用小幅周期振荡法在室温下考察十二烷基硫酸钠(SDS)和十二烷基硫酸钠/长链醇体系的泡沫性能(起泡性和稳定性)与表面参数(表面张力和表面扩张流变性)之间的关系。结果表明:向SDS溶液中分别加入十二醇、十四醇、十六醇和十八醇,体系的起泡体积和析液半衰期会随着醇的链长的增加先增大后减小,表面张力会先减小后增大,而体系的扩张模量、弹性模量和表面黏度都会先增大后减小;体系的起泡性由表面张力和表面黏弹性共同决定;体系的析液半衰期随着扩张模量、弹性模量和黏性模量增大而增大,并且析液半衰期与弹性模量具有较为明显的线性关系。