固液界面上表面活性剂吸附膜的组成与状态

根据表面活性剂在固液界面上的二阶段吸附模型,导出了各个别(包括单个吸附分子、表面胶团和表面空位的)等温线公式。计算结果表明单个分子的吸附量一般随浓度的增大先升后降,有最大值。表面胶团的量随浓度的增大呈S型地单调上升,最后趋极限值。表面空位数则随浓度的增大单调下降,但下降的方式与二阶段吸附的平衡常数有关。将由二阶段吸附模型导出的吸附等温线通用公式与Gibbs公式的积分式结合,可导出吸附膜的π-C关系,并可得出π-A曲线。结果表明表面活性剂在固液界面上的π-C曲线常显示有二阶段的性质,这在水面上可溶物的吸附膜中一般是没有的。另一方面,与水面上不溶物膜的结果相似,表面活性剂在固液界面上的π-A曲线显示有相变发生,这与表面胶团形成的观点是一致的。     

磷酸盐在赤泥中加藤石表面的吸附行为研究

赤泥对磷酸根离子具有吸附亲和力，可用于处理含磷废水，但单独使用时的除磷效果不理想，因此研究磷酸盐在赤泥表面润湿环境下的吸附动力学对研究赤泥吸附磷酸盐的机理具有重要意义。对赤泥的物相和晶体结构进行了定性和定量分析以及X射线能谱分析，发现赤泥中加藤石占比为39.11%。为了研究3种含磷酸盐水团簇在加藤石表面的吸附分布特征，基于密度泛函理论优化了加藤石的原始晶胞，并使用分子动力学模拟研究了含磷酸根离子水团簇在加藤石表面的吸附动力学。在含磷酸根离子水团簇吸附过程中，含磷酸根离子水团簇与加藤石表面之间的润湿膜逐渐变薄直至破裂，导致磷酸根离子均匀地吸附在加藤石表面，表明加藤石表面具有较好的润湿性。分析了不同含磷酸根离子水团簇在加藤石表面的吸附平衡构象以及加藤石中氧原子与含磷酸根离子水团簇中不同成分之间的径向分布函数，发现磷酸根离子在加藤石表面的稳定吸附受范德华力和氢键的共同影响。本研究成果有助于更好地解释磷酸盐在赤泥表面的吸附行为。     

表面活性剂界面吸附的研究

综述了4种主要表面活性剂的界面吸附模型,有Langmuir吸附模型、Frumkin吸附模型、重排吸附模型和严格重排吸附模型;讨论了这4种吸附模型的特点和相互间的联系,并且介绍了这些吸附模型在表面活性剂界面吸附研究中的应用,旨在为吸附模型在表面活性剂界面吸附的研究提供系统的理论基础和理论指导。最后提出了这4种吸附模型在表面活性剂界面吸附研究中的应用前景。     

电解质、聚合物或蛋白质诱导下在固液界面处形成的表面活性剂自组装结构和多层结构（待续)

对近年来在固液界面处形成的表面活性剂自组装结构和多层的研究进展进行了综述。重点介绍了从浓溶液或在电解质存在下的稀溶液形成的表面结构。对更复杂的聚合物-表面活性剂混合物中形成的表面结构进行了总结。对于表面活性剂自组装的吸附，以及已经很成熟的按顺序吸附法（例如逐层法“layer-by-layer”，很适合用于聚电解质及其相关混合物）进行了综述。讨论了调控润湿性能和提高润湿性能的方法，并突出强调了相应的潜在应用、润湿行为的改变、提高活性成分传递的效率和持久性，以及开发一系列智能功能化表面。     

负载型钯团簇上氢分子吸附和解离吸附的密度泛函理论

基于密度泛函理论考察勃姆石（AlOOH）和氧化锆（ZrO₂）负载的钯团簇表面氢分子吸附和解离吸附过程，通过分析一系列不同尺寸的钯团簇上氢吸附能以及氢分子-钯团簇-载体三者之间的电荷转移系统地研究了粒径效应和载体效应。结果表明，顶点位和面位分别是分子吸附和解离吸附的最佳吸附位置。随着钯团簇粒径的上升，氢分子吸附能和解离吸附能都下降，载体-钯团簇-被吸附氢三者之间的电荷转移量和方向也改变。氧化锆载体负载的钯团簇上分子吸附能和解离吸附能均大于勃姆石载体负载的钯团簇，说明载体对氢分子吸附过程有重要影响。     

冻结液滴融化过程中的表面及界面演化特性分析

液滴在血浆储存、航空航天等技术领域广泛存在,而其机理研究主要集中在冻结阶段,对融化阶段的研究则相对较少。故此,本文通过液滴可视化实验,发现并归纳了冻结液滴在不同材料表面、不同基底温度下融化过程的动态表面及界面演化模式,总结了液滴表面扩散系数、高度系数、相界面偏离度等形态演化参数与相变时间之间的变化规律并对其展开分析。结果表明：冻结液滴存在3种不同的表界面演化模式;在熔融中后阶段,金属材料（纯铝板、镀锌板）表面冻结液滴的冰相区以颗粒群状分布态融化,冰晶结合度低,而高分子聚合物材料[有机玻璃（PMMA）及聚氯乙烯（PVC）试板]表面冻结液滴的冰相区呈块状分布态融化,冰晶结合度高;金属类材料表面冻结液滴的相变速率高于聚合物类材料表面冻结液滴的相变速率,金属表面相变时间在100s以内,而聚合物表面冻结液滴的相变时间在300s以内;金属表面最大扩散系数分布区间为0.950~1.021,聚合物表面最大扩散系数分布区间为1.000~1.076,温度高,则各类材料表面液滴的微观前驱膜移动受阻,液滴的表面润湿过程受阻;金属表面冻结液滴的高度系数及冰相高度变化率受冰相区变化影响,聚合物表面则主要受温度影响;温度升高会使热量传递过程不稳定,加剧聚合物表面冻结液滴偏离度位移的波动性。     

直链型非离子表面活性剂在油水界面吸附的动态Monte Carlo模拟

用动态Monte Carlo方法模拟了对称性和非对称性直链非离子表面活性剂在油水界面的吸附过程,得到了关于系统达到平衡所需要的时间、界面上吸附的表面活性剂分子数、界面层厚度、系统链节密度分布、油水界面张力等动态和静态信息,讨论了表面活性剂分子的结构和浓度对它们的影响;系统达到平衡所需要的时间与表面活性剂分子的结构和浓度有关,表面活性剂分子结构一定时,系统处于临界胶束浓度（CMC）以下时,平衡时间随浓度增加而增加;表面活性剂分子数目一定,平衡时间与表面活性剂的链长和结构有关;达到平衡以后,系统的链节密度分布关于油水分界面的对称性与表面活性剂分子的对称性有关;直链型非离子表面活性剂的表面活性主要由其结构决定,对于对称性的非离子表面活性剂,链越长表面活性越高,而对于非对称非离子表面活性剂,其对称性越高,表面活性越高;在链长一定的情况下,油水界面张力随着表面活性剂分子浓度的增加而增加,在达到一个稳定值后,不再随着浓度改变而改变.     

用亚甲基蓝吸附法测量油层岩石的润湿性

储层岩石润湿性影响油、水在储层中的分布，对原油开采过程均具有至关重要的作用。测量储层岩石润湿性的标准方法（Amott and US-BM法）属于经验方法，包括在润湿相和非润湿相共存时让油、水两相相互驱替。测量结果可能与流体的饱和度和实验过程有关，而产生某些不确定性。本文提出根据亚甲基蓝在储层岩石表面的吸附面积分数，测量固体表面的润湿性。该法具有一定的理依据，测量结果不受流体的饱和度和实验过程的影响。     

80#石蜡/膨胀石墨定形复合相变材料的特性表征与分析

以80^#石蜡为相变材料,利用不同粒径膨胀石墨的多孔隙结构,以多层吸附、模压法压制方式制备了80^#石蜡/膨胀石墨定形复合相变材料。通过循环融冻实验分析了80^#石蜡的热稳定性和循环稳定性,滴定滤纸渗漏实验确定了不同组分复合相变材料的渗漏率。采用差示扫描量热仪(DSC)、扫描电子显微镜（SEM）、Hot Disk热常数分析仪等仪器对所制备复合相变材料的相变潜热、多孔基吸附结构、热导率、渗漏率等特性进行了分析。结果表明：当膨胀石墨的添加质量分数达到整体组分的8%时,复合定形相变材料的相变温度为80.86℃（吸热）和76.08℃（放热）,相变潜热为130.12kJ/kg,且渗漏率小于0.3%。制备的复合定形相变材料具有形状稳定、渗漏率低、蓄热密度高的特点,且具有较长的使用寿命。     

阴离子表面活性剂与阳离子表面活性剂的相互作用(Ⅰ)--表面活性

通过临界胶束浓度(cmc)、最低表面张力(γcmc)、表面吸附(Γ)、表面膜强度和表面润湿等,介绍了阴/阳离子表面活性剂混合溶液的表面活性。阴/阳离子表面活性剂混合溶液,消除了同电荷之间的斥力,形成了正、负电荷间的引力,十分有利于两种表面活性剂离子间的缔合,同时还增加了疏水性。因此,在适宜条件下,可以使胶团更容易形成,表面(或界面)上吸附量增加,使得复配溶液具有很低的表面和界面张力,提高表面活性。不仅等摩尔比的混合溶液的cmc和γcmc显著下降,非等摩尔混合也使cmc减小、γcmc降低。等摩尔混合溶液表面吸附层分子摩尔比近于1∶1,其他不同比例时,表(界)面层摩尔比在大多数情形中仍接近1∶1。吸咐层呈等比组成时达到最大电性吸引,表(界)面吸附量趋于饱和。与此同时,由于吸附层中分子间静电吸引力的较强相互作用,还使得表面膜机械强度增加,并表现出良好的润湿性能。     

Modeling of gas phase nucleation during silicon carbide chemical vapor deposition

An advanced model taking into account silicon cluster formation in the gas phase is suggested. 2D simulation is carried out at the growth parameters typical for chemical vapor deposition (CVD) of SiC in a vertical reactor. It is found that two main parameters have a significant effect on the nucleation and transport of the clusters in the gas phase: the input flow rate of silane and the thermophoretic force. Using a special criterion, the growth conditions favorable for parasitic graphite and silicon phases formation are determined. The obtained results are in good agreement with experimental data.     

A Comparison of the Work of Adhesion Obtained from Wetting and Vapor Adsorption Measurements

Some of the limitations to determining experimental values of the work of adhesion are discussed. Wetting measurements appear to provide the most direct means of assessing the work of adhesion for a solid-liquid system, but they require the formation of a finite contact angle by the liquid against the solid of interest, and the need for independent knowledge of the equilibrium spreading pressure of the liquid's vapor on the solid further limits their applicability. Vapor adsorption measurement using the technique of inverse gas chromatoraphy (IGC) provides a promising alternative means of determining the work of adhesion not subject to these limitations. The measurements are, furthermore, amenable to solids which are difficult to use with wetting measurements, e.g., those which are porous or granular. An attempt is made here to compare values of the work of adhesion determined using both wetting and vapor adsorption measurements. Good agreement is attained between the two methods for diiodomethane in contact with poly (vinyl chloride), poly (methyl methacrylate), and chemi-thermo-mechanical wood pulp fibers, suggesting that the technique of IGC is particularly well-suited for rapid determination of the work of adhesion.     

A Comparison of the Work of Adhesion Obtained from Wetting and Vapor Adsorption Measurements

Some of the limitations to determining experimental values of the work of adhesion are discussed. Wetting measurements appear to provide the most direct means of assessing the work of adhesion for a solid-liquid system, but they require the formation of a finite contact angle by the liquid against the solid of interest, and the need for independent knowledge of the equilibrium spreading pressure of the liquid's vapor on the solid further limits their applicability. Vapor adsorption measurement using the technique of inverse gas chromatoraphy (IGC) provides a promising alternative means of determining the work of adhesion not subject to these limitations. The measurements are, furthermore, amenable to solids which are difficult to use with wetting measurements, e.g., those which are porous or granular. An attempt is made here to compare values of the work of adhesion determined using both wetting and vapor adsorption measurements. Good agreement is attained between the two methods for diiodomethane in contact with poly (vinyl chloride), poly (methyl methacrylate), and chemi-thermo-mechanical wood pulp fibers, suggesting that the technique of IGC is particularly well-suited for rapid determination of the work of adhesion.     

蒸发-凝结流动的边界层现象及热短路效应

热管是一种高效传热元件,为了降低理论研究的复杂性,对其做出简化是必要的。针对一些基本假设的适用性,本文建立了一维蒸发-凝结流动传热模型。通过初积分,对控制方程进行了化简和数值计算。结果表明,温度、流速以及压力场,在蒸发和凝结相界面上明显存在着边界层,其中蒸发侧尤为明显,速度、压力梯度较大;在雷诺数很大的情况下,温度梯度也较大。由边界层现象推出了蒸发-凝结流动传热的热短路效应：汽相工质的最终趋势是达到均匀的温度场和饱和状态,汽相热阻为零。     

Use of novel polyetheralkanolamine comb polymers as pigment dispersants for aqueous coating systems

The adsorption of a series of polyetheralkanolamine comb polymers characterized by a different length of the hydrophilic tail has been investigated at the carbon black/water interface by measuring adsorption isotherm, contact angle, wetting rate, zeta potential, and particle size distribution. Zeta potential measurements and adsorption layer thickness results suggest that polyetheralkanolamines with high ethylene oxide (EO) content provide only steric stabilization and they adsorb at the interface with the ethylene oxide chains in a coil conformation. The thickness of the adsorbed layer increases with increasing EO units; however, the surface tension and interfacial tension decrease with increasing EO content. Adsorption isotherms show that most of the added polyetheralkanolamine adsorbs onto the carbon black and only a small amount stays in the water phase. When treated with a polyetheralkanolamine, carbon black dispersions show uniform (unimodal) and narrow particle size distribution with very small median sizes of about 0.10 μm. The pigment concentrates containing the polyetheralkanolamine show excellent color compatibility in various decorative commercial white paints containing a wide range of resins and exhibit low viscosity with nearly Newtonian flow behavior. Presented at the 2006 FutureCoat! Conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

阳-阴离子表面活性剂复配对褐煤疏水改性效果的研究

对不同配比下阳离子表面活性剂十二烷基三甲基溴化铵(DTAB)和阴离子表面活性剂十二烷基磺酸钠(SDS)复配溶液的性质进行了测量与计算,并测定了褐煤吸附复配表面活性剂后的润湿热值、水分复吸率值、红外光谱和Zeta电位值。结果表明:复配表面活性剂在降低表面张力的效能和效率方面均表现出协同作用,且通过润湿热值和水分复吸率值可以看出,对比单一表面活性剂,褐煤吸附复配表面活性剂后润湿热值与水分复吸率值都有明显的降低;通过红外光谱和Zeta电位值证明了复配表面活性剂对褐煤的作用效果和方式。表面活性剂复配体系相比相应的单一表面活性剂对于褐煤的疏水改性效果表现出明显的协同作用。     

Synthesis and Properties of Quaternary Ammonium Surfactants Based on Alkylamine,Propylene Oxide,and 2‐Chloroethanol

New quaternary ammonium salts are synthesized by octylamine, nonylamine, dodecylamine, and hexadecylamine reacting with propylene oxide at a mole ratio of 1:2, followed by reaction with 2‐chloroethanol. By tensiometric measurements of aqueous solutions, their surface activity has been determined. Using the results of these measurements and electroconductometric studies, important parameters such as critical micelle concentration (CMC), efficiency of surfactant adsorption, surface pressure at the CMC, changes of Gibbs free energies for micelle formation, and adsorption were estimated. By application of the Gibbs adsorption isotherm, indices such as maximum surface excess concentration and minimum surface area/molecule at the air–water interface were also calculated. Petroleum‐collecting properties of these surfactants were investigated. Among these quaternary ammonium surfactants, the surfactant based on dodecylamine, propylene oxide, and 2‐chloroethanol exhibits the highest petroleum‐collecting capacity.     

Investigation into adsorption equilibrium and thermodynamics for water vapor on montmorillonite clay

The isothermal adsorption curves for water vapor on montmorillonite were measured by a gravimetric adsorption system. Dent's model was employed to estimate the adsorption behaviors of water vapor on primary adsorption sites and secondary adsorption sites. The thermodynamics analysis of water vapor adsorption was performed. At low vapor pressure region, primary adsorption predominates, and with increasing vapor pressure, secondary adsorption becomes notable. Primary adsorption sites have an evidently stronger adsorption affinity than secondary adsorption sites. With increasing vapor pressure, Gibbs free energy variation rapidly increases and then reduces slowly. Although increasing vapor pressure raises adsorption spontaneity on primary adsorption sites, the enhancement in vapor pressure decreases the spontaneity of water vapor adsorption on secondary adsorption sites. As adsorbed loading increases, isosteric heat of adsorption and entropy loss decrease first and then increase quickly. The gradually growing water clusters are responsible for the increase of entropy loss at late stage.     

A comparison of nitrogen adsorption and thermogravimetric methods in the assessment of the pore size distribution of mesoporous silica gels

The pore dimensions are determined by using adsorption and thermogravimetry methods for unmodified silica gel Si-100 and silanized silica gel Lichrosorb RP-18. Thermal desorption measurements for various liquids were performed under quasi-isothermal conditions. Methanol, acetone, benzene and n-hexane were used as a wetting liquids. Pore size distributions and total pore volumes derived from thermal desorption compare reasonably well with results obtained from the analysis of adsorption isotherms of nitrogen. For different types of adsorbates the effects connected with the presence of the surface liquid film are discussed. The presence of long alkyl chains on the silica surface strongly influences the pore diameter calculated from thermogravimetric data.     

Characterization and adsorption behaviors of a novel synthesized mesoporous silica coated carbon composite

A novel mesoporous silica coated carbon composite(denoted SEG) with hierarchical pore structure has been successfully prepared in an aqueous solution that contains triblock copolymer template, aluminum chloride, siliceous source and expanded graphite. Textural property and morphology of the SEG composite were characterized by the combination of X-ray diffraction, N_2 adsorption–desorption, scanning electron microscopy,transmission electron microscopy and Fourier transform infrared measurements. Results show that mesoporous silica is steadily and uniformly grown on the surface of the graphite slices and the thickness of the silica layer can be finely tuned according to the silica/C molar ratio in the initial reaction solution. This newly synthesized SEG composite shows greatly increased adsorption capacity to methylene blue than the pristine expanded graphite in the batch tests. Both Langmuir and Frendlich models were further used to evaluate the adsorption isotherms of methylene blue over expanded graphite and SEG samples with different silica contents. Finally, pseudosecond-order model was used to describe the kinetics of methylene blue over expanded graphite and the silica-carbon composites.