梯度接触角表面的构建与应用

梯度接触角是梯度表面张力的反映,固体表面的润湿性由表面化学组成和表面微观形貌共同决定。通过表面化学组成和表面微观形貌的梯度化,可制备接触角变化范围不同的梯度接触角表面。本文综述了梯度接触角表面在液滴移动、微流体流动和生物吸附等领域中的应用。梯度接触角表面具有的不平衡杨氏力是促进液滴移动的主要原因,而表面所产生的接触角滞后则阻碍液滴移动;在生物学领域,梯度接触角表面会造成蛋白质和细胞选择性吸附或黏附。最后,简要探讨了梯度接触角表面存在的问题和发展方向。     

基于超声振动的微液滴生成装置设计与实验研究

设计了一种基于V型直线超声电机驱动的微液滴生成装置用于制备具有微米级尺寸的微液滴.此装置由基于V型直线超声电机驱动的微液滴生成部件、基于V型直线超声电机的三维位移控制平台和基于压电振子的微液滴分离部件组成.其中,生成部件包含超声电机、医用注射器、硅胶软管和自制的玻璃基微喷嘴.利用控制器驱动直线超声电机高精度地移动,由滑台推动注射器,在玻璃基喷嘴尖端产生附着的微小液滴;再利用压电振子激发杆状喷嘴的固有振型,使得附着的液滴克服粘性力从微喷嘴尖端分离,落在一定的范围内, 并计算生成的球形微液滴的半径.以蒸馏水作为初始液体,探究此装置生成的微液滴的特性.研究结果表明,蒸馏水在直线电机的精密驱动下,在微喷嘴尖端形成附着的球冠状液滴.通过分离部件的振动,附着的液滴克服自身的粘性力从喷嘴尖端分离, 形成球形液滴,通过测量得出此装置生成的球形液滴的半径小于40 μm.     

基于各向异性表面的液滴驱动

驱动液滴实现各种动态行为在生物医学、微流控、痕量检测等领域具有重要应用。液滴的驱动主要依赖于对液滴不同位置受力的调节。具有浸润性差异或结构差异的各向异性表面,在对液滴进行驱动时具有操作简便、节约能源等优势,逐渐成为液滴操控领域的研究热点之一。本文结合本课题组的研究工作,对近年来利用各向异性表面驱动液滴的相关研究进行了综述。首先,分析了各向异性表面驱动液滴的基本原理。依据制备方法的不同,将各向异性表面分为浸润性各向异性表面、结构各向异性表面和协同各向异性表面三类,分别归纳了其常见制备方法和在液滴驱动领域的主要应用。最后,本文对各向异性表面驱动液滴的局限性和发展方向进行了总结和展望。     

离子液体微乳液体系的应用研究

室温离子液体具有诸多优异的物理化学性质及功能,是一类备受关注的新型介质和材料,应用于诸多领域。特别是近年来,由离子液体参与形成的微乳液因其在生物、医药、催化以及材料制备等领域具有潜在的应用前景而备受关注。本文综述了近年来咪唑类离子液体作为极性、非极性和表面活性剂组分,分别取代微乳液体系中的水相、油相和表面活性剂相,形成的一系列新型的微乳液体系的研究进展,归纳了水、有机溶剂、高聚物、助表面活性剂、温度等因素对离子液体微乳液性质的影响。重点介绍了离子液体微乳液的热点应用,包括以离子液体微乳液液滴为模板合成纳米材料,离子液体微乳液作为酶反应的介质及其在有机反应等方面的研究进展。     

基于微流体脉冲驱动控制技术的电化学微流控芯片制备方法

基于微流体脉冲驱动控制技术搭建了电化学微流控芯片的制备系统.首先将纳米银墨水和甘油溶液分别微喷射到玻璃基底表面形成微电极图形和微流道液体阳模图形;然后分别进行烧结和聚二甲基硅氧烷(PDMS)模塑工艺制得微电极和微流道;最后将微电极和微流道键合形成电化学微流控芯片.研究了系统参量对液滴产生的影响以及液滴直径和重叠率对液滴成线的影响,制得的微电极最小线宽为45 μm、厚度为2.2 μm、电阻率为5.2 μΩ·cm,制得的微流道最小线宽为35 μm,流道表面光滑.采用制得的电化学微流控芯片进行了葡萄糖浓度的电化学流动检测.结果表明,葡萄糖溶液的浓度与响应电流具有较高的线性关系,可对一定浓度范围内的葡萄糖溶液进行定量检测.基于微流体脉冲驱动控制技术的电化学微流控芯片制备方法具有微喷射精度高、重复性好,制备系统结构简单、成本低廉等优点,可用于生化分析、生物传感器等领域的芯片制备.     

浸润性梯度表面研究与应用

浸润性梯度表面是指表面浸润性随着表面位置的变化而连续变化的一种特殊梯度表面.在过去的20年间,由于浸润性梯度表面在智能涂料、微流体器件和液体自输送等方面具有广阔的应用前景,因此人们研发并制备了各种类型的浸润性梯度表面,总体而言,可分为三类:(1)化学组成类浸润性梯度表面;(2)表面形貌类浸润性梯度表面;(3)化学组成-表面形貌复合型浸润性梯度表面.重点介绍了这三大类浸润性梯度表面的分类与区别,以及近些年来这些新型浸润性梯度表面的主要制备方法,如扩散法、浸泡法、刻蚀与打印、机械拉伸法、半月板沉积法和温度梯度法等,并归纳总结了这些方法的各自优缺点.在目前的材料科学领域,虽然关于浸润性梯度的研究还属婴儿期.可是利用梯度表面研究生物蛋白或细胞吸附,液体自输送等,已经发展成为一门成熟的学科.最后综述了近期关于浸润性梯度表面在研究生物蛋白或细胞吸附,液体自输送等方面的应用进展,并展望了该课题的未来发展.     

多尺度柔性结构的防覆冰性能

通过软复型和晶体生长的方法制备了具有柔性微米锯齿和纳米棒结构的微纳米复合表面,其具有低温低黏附的特性,达到了优异的防覆冰效果.柔性微纳米结构表面的形变,可以在低温条件下有效去除液滴.研究结果表明,微米结构的弯曲作用改变了液滴在表面的三相线,凹面增大了气/液/固三相线长度,增加了驱动液滴的难度;凸面减小了气/液/固三相线长度,有利于减少液滴与表面之间黏附力,使液滴在重力作用下快速脱除.     

电控液滴移动的研究进展

电控液滴移动是一种利用电场作用驱动液滴移动的策略, 因其液滴具有响应速度快、 运动速度快及路径可控等优点而备受关注, 在外场刺激驱动液滴移动等基础研究和智能微流体器件等实际应用中具有重要意义. 本文概述了传统电润湿驱动液滴移动的基本原理和研究进展, 介绍了新型电控液滴移动的代表性成果, 展望了相关研究和应用的发展前景.     

具有纳升级精度的手持式数字移液器研制成功

正中国科学技术大学工程科学学院微纳米工程研究室副教授李保庆与美国加州大学戴维斯分校教授潘挺睿合作,提出并实现了一种具有纳升级精度的液体移取技术。该技术结合普通移液器技术与微流控打印技术,利用微流控芯片可控产生纳升体积的液滴,以单个液滴为最小单元,     

流化床气化炉带出细粉非机械返料机构研究

对非机械返料机构（流动密封阀式）在流化床气化炉上的应用进行了研究。结果表明，流动密封阀式返料机构同样可以在流化床气化炉上应用；在返料室截面积、供料室截面积、水平孔口面积比为1∶1∶0.5时，通过流化风、松动风或侧吹风的组合充气获得了良好的开启、运行及调节性能；同时考察了压力对返料机构运行的影响；最后得到了适合流化床气化炉非机械返料机构操作的经验公式，试验值和计算值符合较好。对改进流化床气化炉循环返料系统和提高气化炉碳转化率提供了理论指导和设计参考。     

杯芳烃的超分子化学研究(Ⅰ)-对-叔丁基杯[n]芳烃对K+和Na+离子的液膜传输规律

杯芳烃的液膜传输作用是其典型的超分子化学特征之一［１］．在探索杯芳烃及其衍生物作为流动载体传输金属离子的能力及传输作用的规律性,以及模仿细胞壁两边金属离子的传递过程及其控制方式方面有潜在应用前景．Ｉｚａｔ［２］等认为,只有当源相处于强碱性条件（ｐＨ＞...     

液相控制沉淀法制备纳米级Co3O4微粉

报道了一种液相控制沉淀与分解制备Co₃O₄超微粉的方法.研究表明,采用液相沉淀控制技术,无需引入高分子保护剂,同样可以制备出晶粒细小、粒度分布均匀、无团聚的高质量Co₃O₄超微粉.该法工艺简单、成本低、产率高.     

Large Continuous Mechanical Gradient Formation via Metal–Ligand Interactions

Mechanical gradients are often employed in nature to prevent biological materials from damage by creating a smooth transition from strong to weak that dissipates large forces. Synthetic mimics of these natural structures are highly desired to improve distribution of stresses at interfaces and reduce contact deformation in manmade materials. Current synthetic gradient materials commonly suffer from non‐continuous transitions, relatively small gradients in mechanical properties, and difficult syntheses. Inspired by the polychaete worm jaw, we report a novel approach to generate stiffness gradients in polymeric materials via incorporation of dynamic monodentate metal–ligand crosslinks. Through spatial control of metal ion content, we created a continuous mechanical gradient that spans over a 200‐fold difference in stiffness, approaching the mechanical contrast observed in biological gradient materials.     

Thermokinetic characteristics of lithium chloride

The characterisation of the ionic compound of lithium chloride, LiCl, through XRD, SEM, DSC, TG, DTG and TG-MS analysis is reported. The results show that nominally anhydrous LiCl particles can readily absorb water from the ambient atmosphere to form a surface layer of lithium chloride mono-hydrate, LiCl·H₂O. Solid surface-hydrated LiCl is de-dehydrated via a two-stage mechanism at low heating rates and via a single-stage mechanism at high heating rates. Molten LiCl exhibits substantial evaporation at temperatures below its nominal boiling point, with the rate of evaporation increasing significantly before complete evaporation occurs. The melting process of de-hydrated LiCl is marginally affected by the heating rate; whilst the evaporation process is strongly affected by the heating rate and also dependent on the quantity of material used and the flow rate of the gas passed over it. Heating of surface-hydrated LiCl up to the point of evaporation under a flow of argon and under a flow of ambient air gives identical results, proposing the possibility of performing LiCl-based processes in an air environment. The enthalpies and activation energies for the processes of surface de-hydration, melting, and high-temperature evaporation are determined. The results are consistent with the following thermal phase evolution:

$ [{\text{LiCl + LiCl}} \cdot {\text{H}}_{{\text{2}}} {\text{O}}]_{{{\text{solid}}}} \to [{\text{LiCl}}]_{{{\text{solid}}}} \to [{\text{LiCl}}]_{{{\text{liquid}}}} \mathop\rightarrow\limits^{{{{\text{H}}_{{\text{2}}} {\text{O}} \downarrow {\text{ HCl}} \uparrow}}}[{\text{LiCl-LiOH}}]_{{{\text{liquid}}}} \mathop\rightarrow\limits^{{{{\text{H}}_{{\text{2}}} {\text{O}} \uparrow}}}[{\text{LiCl-Li}}_{{\text{2}}} {\text{O}}]_{{{\text{liquid}}}} \to {\text{Gas}} $

     

Directional and path-finding motion of polymer hydrogels driven by liquid mixing

The spreading of a miscible liquid with a low surface tension on a water surface generates the directional motion of submerged polymer hydrogels, which could be attributed to convective flows resulting from the gradient of surface tension along the surface (Marangoni effect). The direction and velocity of this motion can be well controlled by altering the driving conditions. Furthermore, a spherical hydrogel can smartly find the path to walk through a microfluidic maze when liquid mixing occurs near the maze exit. This convenient chemical driving approach to transporting submerged objects in a desired way may be useful in microfluidics, micromechanics, and other applications.     

Polymeric film formation in spin coating

The results of numerical modeling of polymeric film formation under mass force action are presented. The instability of non‐Newtonian liquid front edge at the initial stage of flow over a disk is studied. The quasi‐stationary shape of the liquid film (in front edge vicinity) speading over the surface is determined for certain rheology laws. At the modeling of the second stage of coating flow, the special attention was paid to the effects connected with the two‐dimensional character of the flow. The impact of rheological properties of a liquid on the free surface shape was studied using codes that calculate the two‐dimensional non‐stationary flow of non‐Newtonian liquid. The factors that determine the final shape of polymeric coating free surface are discussed.     

The rupture of a liquid layer by solutocapillary flow

The development of a strong deformation of the surface of a thin viscous liquid layer on a horizontal wettable substrate is experimentally studied. The deformation develops owing to a concentration-induced surface tension gradient that appears as a result of the deposition of a droplet of a soluble surface-active liquid onto the free surface of the layer. The conditions under which the viscous liquid layer is ruptured and the place beneath which the spreading droplet becomes partly uncovered are studied. For different pairs of liquids, the dependences of the radius of the dry spot on time, on the volume of a deposited droplet, on the horizontal sizes and thickness of the layer, and on the difference between the surface tensions of the droplet and the layer are obtained. It is shown that the rupture occurs at an appreciably larger initial thickness of the liquid layer than in the case of thermocapillarity. The critical thickness of the layer, at which its deformation reaches the substrate, is virtually independent of the amount of the deposited surfactant and is determined mainly by the surface tension gradient on the surface.     

Highly Stereoselective Synthesis of New Aziridines via Baldwin Rearrangement and Their Potential Biological Activities

An atom‐economical conversion of N‐ substituted isoxazoline derivatives to new N‐ substituted aziridines has been described using microwave irradiation through Baldwin rearrangement. N‐ substituted isoxazoline derivatives have been synthesized using a variety of nitrones and alkynes via 1,3‐dipolar cycloaddition reactions in ionic liquid. Simple react\ion methodology, greener approaches, non involvent of catalysts, good to excellent yields, and cis diastereoselectivities are the important features noticed in this synthesis. Potential biological activity of the new aziridine derivatives made this protocol more attractive.     

Effect of charge density gradient on characteristics of electric double layer for salt melts

The equilibrium conditions are analyzed for a spatially inhomogeneous ionic liquid using the density functional theory with allowance made for the second order gradient corrections. Solutions for the distribution of potential and charge density in the electric double layer at the ionic liquid/vapor interface are obtained using a parameterized total density profile normal to the surface. It is shown that taking into account the effects of the charge density gradient in the theory results in the appearance of damped oscillations of the charge density near the surface, while the double layer localized on the surface is reduced.