光敏型阴离子表面活性剂的合成及表面性能

本文制备了一种含有偶氮苯基团的阴离子表面活性剂,其表面活性及对方解石矿物的润湿性能,可以用紫外光照射进行调控。在紫外光照射后,表面活性剂的临界胶束浓度(cmc)、最低表面张力(γcmc)、分子极限占有面积(Amin)增大,饱和吸附量(Гmax)和降低表面张力的效率(pC20)降低,对方解石的润湿能力增强。     

仿生表面液固界面摩擦力的动态调控

仿生超疏水材料在自清洁、防雾抗冰、油水分离、集水等领域有着重要应用;而在不同疏水状态之间的转换将大大促进仿生超疏水材料在智能技术领域的应用.利用软印刷技术将玫瑰花表面微观结构转印到聚氨酯弹性体PU膜表面,利用机械应力实现表面微结构的动态实时调控,实现了表面微观结构在各向同性与各向异性之间的可逆转换;利用毛细管投影传感技...     

液滴撞击等温固体平壁的数值模拟

建立了液滴撞击等温固体平壁的物理和数学模型,数值模拟了撞击后液滴的变形和反弹过程,将模拟结果与文献中的实验结果做了比较,两者吻合较好,表明所采用的模型可以模拟液滴在水平壁面上的运动形态.通过比较不同条件下铺展因素随时间的变化规律,分析了液滴碰撞速度、初始接触角对变形过程的影响.     

聚乙酰亚胺涂敷单晶硅表面上全氟亏酸单层膜

Ultra-thin film of perfluorodecanoic acid expected to be excellent lubricant for micro-machines was prepared successfully on single crystal silicon substrate.The film was characterized by means of X-ray photoelectron spectroscopy (XPS) and contact-angle meter.The chemical reaction involved in the preparation of the ultra-thin film was discussed as well.After being immersed in a dilute aqueous solution of polyethyleneimine (PEI) for 15 minutes and rinsed with distilled water,the silicon substrate was coated with a thin film of PEI,which was then put into a dilute solution (1× 10－ 3 mol· L－ 1) of perfluorodecanoic acid in hexadecane.Subsequently the steady perfluorodecanoic acid ultra-thin film was developed on PEI coating in the presence of a covalent amide bond between carboxylic group and the primary or secondary amine groups of PEI.This process was accompanied by the contact angle changes of water droplet on the Si surface (see Table 1).Moreover,the reaction between perfluorodecanoic acid and PEI was significantly influenced by N,N′ -dicyclohexylcarbodiimide (DCCD).The contact angle on the ultra-thin film of perfluorodecanoic acid is only 66.3° in the absence of DCCD in the reacting solution; it rises to 89.4° in the presence of DCCD.This indicates that the reaction between perfluorodecanoic acid and PEI was accelerated by DCCD,and the quality of perfluorodecanoic acid ultra-thin film thus improved.XPS analysis of the ultra-thin film indicates that the derivatization of PEI with perfluorodecanoic acid was accompanied by several changes.First,a large and highly symmetrical F 1s peak appeared at 688.3 eV (C－ F*).Secondly,a new peak of N 1s appeared at 400.7 eV (chemical shift 1.4 eV),which was attributed to the N atom attached to the carbonyl group (O=C－ N*).Thirdly,three new peaks of C 1s appeared at 286.1 eV (chemical shift 1.5 eV),288.1 eV (chemical shift 3.5 eV),and 291.0 eV (chemical shift 5.4 eV),respectively.These C 1s peaks were attributed to the C atom attached to the O=C－ N group (O=C－ N－ C*),the carboxyl C atom (O=C*－ N),and the C atom in － CF3 group (C*－ F),respectively.Therefore it can be concluded that perfluorodecanoic acid has been chemically adsorbed onto the surface of PEI and perfluorodecanoic acid ultra-thin film prepared successfully.     

玻璃基底上平衡态液滴接触角特性

为了了解玻璃基底上平衡态液滴接触角特性,采用实验和理论相结合的方法分析了玻璃基底表面水滴平衡时应满足的热力学条件,得到了液滴汽-液界面形状以及平衡态接触角大小。分析发现,玻璃基底上平衡态液滴接触角是与三相接触线压力相关的热力学参数,当三相接触线曲率一定时,平衡态液滴接触角随三相接触线处压比的增加而增大.同时,考虑到固-液界面吸附特性,根据平衡态时系统亥姆霍兹自由能最小这一热力学判据可以预测出液滴平衡接触角大小,结果和实验值吻合。     

乙醇液滴撞击高温壁面蒸发过程的模拟预测研究北大核心CSCD

采用CLSVOF方法,引入描述壁面润湿特性的动态接触角,建立了乙醇液滴撞击高温壁面的数值模型,对乙醇液滴撞击高温壁面后的沸腾蒸发过程展开了研究,并与实验数据进行了对比验证.研究表明:在相同液滴温度下,壁面温度越高,亲水性越强,乙醇液滴的撞击速度越快,液滴的沸腾时间越早,蒸发完成所用时间也越短.在此研究基础上,基于机器学习算法,建立了液滴蒸发预测模型,对乙醇液滴撞击高温壁面后蒸发剩余量随时间的变化进行了预测研究,并通过将不同机器学习算法的预测结果与模拟结果对比,选出最优预测模型.     

润湿性判据的直接推导

采用物理图象鲜明,而数学处理简捷、严格的方法导出用内聚力场和附着力场分布来表示的表面张力、附着层张力和固-液接触角公式,并指出传统的润湿性判据的错误根源.     

动态接触角的初步分析

应用经典的Moffatt解,通过引入接触线特征参数λ给出接触线上的粘性剪切应力,导出动态接触角和接触线移动速度的关系,尝试解释文献中两种不同测量方法所得静态接触角不一致的现象,理论所揭示的动态接触角和接触线移动速度的关系曲线和以往文献中的曲线形式基本一致,通过和Hoffman试验数据的比较发现,λ与流体性质无关,是表征固壁性质的特征参数,并初步探讨了λ的数理意义。     

PANI 在玻璃基体表面的生长成膜过程

采用分散聚合法,在玻璃基体表面原位生长聚苯胺制得高电导率(10-3S/cm)、微纳米级的聚苯胺薄膜.通过扫描电镜、原子力显微镜以及接触角分析研究聚苯胺在玻璃基体表面成膜的驱动力和过程.结果表明:成膜的驱动力是聚合过程中产生的活性中间体与基体间的强吸附力.活性中间体主要是苯胺的二聚体、三聚体等短链小分子,它们与基体问的作用为分子间力作用,属物理吸附.聚苯胺在玻璃基体表面成膜的过程符合吸附生长模式,膜的厚度存在饱和值.     

MICROWAVE-ASSISTED SURFACE MODIFICATION OF CALCIUM BICARBONATE

Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious superiority to those of powder samples treated by traditional surface modification method and of untreated calcium bicarbonate in suspension turbidity, suction potential, contact angle with water, and mechanical properties of their composites with PVC resin.