不同液膜体系中Marangoni效应对活性剂液滴铺展的影响

针对含可溶性表面活性剂的液滴在预置液膜上的铺展过程,应用润滑理论建立液滴厚度、活性剂表面浓度及内部浓度演化过程的控制方程组,采用PDECOL程序模拟液滴的演化特征,探讨不同液膜体系下Marangoni效应的作用机理,并基于瞬态增长法分析负体系下液滴演化的不稳定性.研究表明,正体系下Marangoni效应可促进活性剂分子扩散,有利于活性剂液滴的稳定铺展;负体系下Marangoni效应则抑制液滴铺展,使液滴在中心区域产生振荡现象,呈现不稳定性特征,且该特征随负效应增强而愈加明显.在正负两种体系下,Marangoni作用力均是促使液滴横向演化的主要驱动力.     

Surfactant sputtering

Sputter erosion of materials is among the most important techniques for fabricating advanced thin film coatings. Sputter processes are also of considerable relevance for surface polishing down to an atomic scale, nano-structuring of surfaces as dot and ripple patterns and micro-machining of materials using focused ion beams or reactive ion etching. We present a new, versatile sputter technique utilizing the steady state coverage of a substrate surface with up to 10¹⁶ cm⁻² of foreign or self atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These surfactant atoms (surface active agents) strongly modify the substrate sputter yield on atomic to macroscopic length scales. Depending on the surfactant–substrate combination, the novel technique allows enhanced smoothing of surfaces, the generation of novel surface patterns and nanostructures and the controlled shaping of surfaces on the nanometer scale. We present selected examples of surface morphology evolution, smoothing of surfaces and shaping of surfaces to demonstrate the capabilities of the new surfactant sputtering technique.     

Effect of Surfactant Type and Concentration on Surfactant Migration,Surface Tension,and Adhesion of Latex Films

The effect of surfactant type and concentration on the migration behavior of surfactant in a latex film was investigated. Two types of surfactant, including an anionic (sodium lauryl sulfate, SLS) and a non-ionic (nonylphenol ethoxylate, average number of ethylene oxide units = 40, NP-40) surfactant, were used in an emulsion polymerization of methyl methacrylate butyl acrylate copolymer (MMA–BA). The total amount of surfactant was varied in three levels, i.e., 1.5, 3, and 4.5 wt%, and the surfactants were used both pure and in a mixture state. The surfactant migration to the film–air (F–A) and film–substrate (F–S) interfaces of the latex films was determined by using an attenuated total reflection-Fourier transform infrared (ATR-FTIR) method. In addition, the adhesion of the latex films to glass substrates was measured by a pull-off test. The results showed that the migration of anionic surfactant to the interfaces was greater than the non-ionic one. It was also found that the use of non-ionic surfactant along with anionic surfactant could decrease the migration of the anionic surfactant to the interfaces.     

CTAC表面活性剂水溶液的流变特性

在25℃条件下,测量了质量分数w=0.007%～0.15%范围内表面活性剂水溶液的流变特性。实验结果表明,表面活性剂稀溶液在剪切作用下出现剪切增稠转变,随着溶液浓度的增加,剪切增稠转变越来越弱。当浓度达到某一临界饱和浓度时,不再有剪切增稠转变发生,该浓度所对应的流变曲线称为最大黏度线;对于表面活性剂稀溶液,剪切诱导时间和剪切平衡时间均是剪切速率的幂函数,幂指数为-1.0;剪切增稠转变结束后,表面活性剂稀溶液的稳态黏度随浓度增大而增大,当w>0.05%时,稳态黏度逼近最大黏度线,继续增大浓度,稳态黏度几乎保持不变。     

Surfactant Effects of Au on Polar ZnO Surfaces

The electronic properties of one monolayer of Au atoms on polar ZnO surfaces are examined by first-principles slab calculations. It is found that an Au ad-layer on top of the surface is energetically more favourable than other gold diffused cases, and Au capping layer on the ZnO polar surfaces may modify the growing properties of ZnO nanostructures by enhancing the binding energy.     

表面活性剂增敏光度法测定锌

在弱酸性(pH=4.5)介质中,非离子表面活性剂Tween-80存在下,7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸(BTAQS)与锌形成2:1的紫色配合物,最大吸收波长位于580nm处,表观摩尔吸光系数为7.4×104L·mol-1·cm-1,锌含量在0-6μg/25mL范围内符合比耳定律。测定矿样中的锌,结果满意。     

Surfactant assisted surface studies of zinc sulfide nanoparticles

We report a simple soft chemical method for the synthesis of ZnS nanoparticles using varying concentration of cationic surfactant CTAB and examine its surface properties. Powder X-ray diffraction, UV-vis spectroscopy, photoluminescence spectroscopy, selective area electron diffraction, and transmission electron microscopy are used to characterize the as prepared ZnS nanoparticles. XRD and TEM measurements show the size of polydispersed ZnS nanoparticles is in the range of 2-5 nm with cubic phase structure. The photoluminescence spectrum of ZnS nanoparticles exhibits four fluorescence emission peaks centered at 387 nm, 412 nm, 489 nm and 528 nm showing the application potential for the optical devices. In Raman spectra of ZnS nanoparticles, the modes around 320, 615 and 700 cm⁻¹ are observed.     

活性剂浓度分布对液膜排液过程的影响

针对含不溶性活性剂的垂直液膜排液过程,考虑分离压和表面黏度的作用,应用润滑理论建立液膜厚度、活性剂浓度和表面速度的控制方程组,分析初始活性剂浓度及梯度对排液过程的影响.结果表明：当液膜表面不含活性剂时,其排液历程很短,很快发生破断.当液膜表面添加活性剂时,可以延长液膜存续时间.而当液膜表面活性剂浓度较低时,其诱发的Marangoni效应不足以克服重力的排液作用,其形成的"黑膜"不能稳定存在.随活性剂浓度增大,液膜表面流动速度减小,液膜表面更加"坚固",所形成的"黑膜"非常稳定.当考虑初始活性剂浓度梯度时,其影响主要体现在减缓排液初期的表面速度.     

Surfactant fluorescence in the study of aggregation and clouding

The intrinsic fluorescence of Triton X-114 and Igepal CO-630 was used to monitor the aggregation behavior of micellar solutions of these surfactants. The response to changes in surfactant concentration, increases in temperature up to and beyond the cloud point, and addition of an ionic surfactant (SDS) was monitored. The intrinsic fluorescence was used to measure aggregate anisotropy as a function of SDS concentration and temperature. Relative aggregate abundance showed a minimum at the CMC, confirming the existence of premicellar assemblies. Structural differences in the hydrophobic portions of the two nonionic surfactants led to vastly different packing in their aggregates. The addition of SDS produced smaller, more closely packed micelles.     

表面活性剂修饰多孔硅的光致发光光谱

分别利用4种不同的表面活性剂对多孔硅进行表面修饰,结果表明油酸钠溶液、CPB溶液和乳化剂OP溶液修饰的多孔硅样品发光减弱,SDS溶液修饰的多孔硅样品发光增强,不同浓度的SDS溶液的增强倍数也不同。这种现象不仅可以为研究多孔硅的发光机制提供新的依据,还为提高多孔硅的发光效率提供了一个新的有效途径。     

表面活性剂对合成碘化亚铜晶体微观结构的影响

利用液相沉淀法,以粗碘为碘源合成了碘化亚铜晶体。采用XRD和SEM分析技术考察了表面活性剂种类对合成碘化亚铜产品晶相组成和微观形貌的影响。结果表明,表面活性剂对合成碘化亚铜产品晶相组成影响较小,但对晶体微观形貌具有较大的影响。分别以柠檬酸、十二烷基磺酸钠、十六烷基三甲基溴化铵、聚乙二醇-6000为表面活性剂制得碘化亚铜晶体尺寸较大、易团聚。以聚乙二醇-6000和1%水合肼为表面活性剂可制备出尺寸均匀(50—100nm),分散较好的纳米球形γ-CuI晶体。     

可溶性活性剂驱动的液滴铺展稳定性

对含可溶性活性剂的液滴在预置液膜上的非均匀铺展过程,基于润滑理论建立基态和扰动态下的液滴厚度、表面活性剂浓度和内部浓度的演化模型,应用非模态理论分析演化过程的稳定性,探讨活性剂溶解特性及典型参数对液滴演化特征的影响.研究表明:扰动波的引入有利于增强液滴演化的稳定性,且稳定程度与扰动波的波数呈正相关性;然而随扰动波数的持续增大,液滴演化的稳定性逐渐下降,直至失稳;相对于非溶性活性剂,可溶性活性剂减缓了液滴的铺展程度,增强了演化过程的稳定性;预置液膜厚度、Marangoni数、毛细力数及吸附系数的增大,均有利于液滴稳定演化,其中Marangoni效应和毛细力的影响较大,预置液膜厚度则主要增强液滴厚度演化的稳定性.     

含表面活性剂液膜去湿过程的数值模拟

对存在壁面滑移的含非溶性表面活性剂薄液膜在固体表面的去湿过程,采用PDECOL程序对描述其演化过程的液膜厚度和表面活性剂浓度方程组进行数值求解.基于液膜表面扰动波形的变化,分析各参数对去湿特性及液膜稳定性的影响规律.研究指出:Marangoni数M较小时其效应使液膜失稳区缩短,而M较大时液膜失稳区间无限延伸,稳定性降低;毛细力数减小使液膜失稳区间缩短,减至一定程度后可有效抑制去湿现象的发生;滑移效应对演化过程的影响与M有关,M较小时滑移使液膜失稳区间缩减,使扰动增长率增大,M较大时这一影响并不显著;随平衡液膜厚度增大,液膜表面的扰动程度减小,但扰动区间显著增大.相对于外源性表面活性剂而言,内源性情形的失稳区间更小,液膜稳定性更强.     

表面活性剂热致液晶性质的拉曼光谱研究

表面活性剂热致液晶性质的拉曼光谱研究徐蔚青吴立新１，２（１吉林大学超分子结构与谱学开放实验室长春１３００２３２中科院长春物理研究所）ＲａｍａｎＳｐｅｃｔｒａｏｆａＳｕｒｆａｃｔａｎｔｏｎＴｈｅｒｍａｌｔｒｏｐｉｃＬｉｑｕｉｄＣｒｙｓｔａｌＰｒｏｐｅｒ...     

表面活性剂增敏分光光度法测定微量锡研究

建立了表面活性剂增敏分光光度法测定水样中微量锡的新方法.锡与二甲酚橙形成络合物,在pH 9.5时吸光度A最大,加入聚乙二醇辛基苯基醚(Triton X-100)胶束后,络合物的稳定性好,灵敏度大大增加.实验条件下显色络合物的最大吸收峰位于431 nm处,线性范围为Sn 2.0-20.0 μg/mL,回收率为98.9%-104.2%.此方法选择性好、灵敏度高、操作简单,用于分析水样中的微量锡,结果令人满意.