基于空间调制电场的聚合物微纳米结构成形机理及控制

发布时间：2018-04-20 00:26

本文选题：空间调制电场 + 聚合物微纳米结构　；参考：《西安交通大学》2017年博士论文

【摘要】：聚合物微纳米结构由于独特的物理和化学功能而受到越来越多的关注,可以广泛应用于微流控、有机光电子、生物检测等方面。在聚合物微纳米结构制造方法中,空间调制电场诱导聚合物流变成形技术由于在材料普适性、结构均匀性等方面的独特优势,获得了学术界的关注。“空间调制电场诱导聚合物流变成形”工艺采用结构化导电模板与涂覆有聚合物薄膜的导电衬底作为对电极,形成诱导模板/空气/聚合物/导电衬底的多层结构。电极对之间施加电压后,因模板结构的调制,在空气-聚合物界面处形成随空间位置变化的电场。这种“空间调制电场”产生的Maxwell应力张量驱动聚合物朝向诱导模板运动,形成具有一定形貌或尺寸的聚合物微纳米结构。本文围绕空间调制电场诱导聚合物流变成形工艺的机理和控制方法展开了研究,其出发点和研究结果如下:1)空间调制电场诱导成形中,聚合物的形貌完全由调制电场控制,不存在其它任何几何约束,因此,正确理解聚合物在空间调制电场作用下的流变机理是实现微纳米结构高保真复形的关键。但是,基于流体润滑理论的线性稳定分析方法,忽略了微纳米尺度效应的影响,不能准确描述空间调制电场作用下聚合物的流变行为,尤其不适用于低粘度聚合物电场诱导的快速成形。为此,本文基于电流体动力学,兼顾微纳尺度效应,建立了非线性两相流动力学模型,从力学行为状态分析出发,研究了聚合物在空间调制电场作用下的流变成形机理,将整个诱导过程分为三个阶段:成形阶段、准静态阶段以及融合阶段。只有在准静态阶段固化聚合物才能得到与模板图案一致的复形结构。(1)2)目前空间调制电场诱导聚合物流变成形研究中,都是直接展示与模板图案一致的复形结构,忽略了工艺参数不合理导致聚合物结构与诱导模板图案的不一致性。为此,本文提出了强/弱调制概念以描述聚合物复形结构与诱导模板图案的异同,定义聚合物复形结构与模板图案一致为强调制,反之为弱调制。仿真分析和实验观察表明:聚合物气液界面处电场分布中的平均分量是导致聚合物复形结构与模板图案不一致的根本原因。进而提出了调制强度以表征调制状态,分析了工艺参数对调制强度的影响,研究了通过调整工艺参数实现强调制复形的途径。3)归结于聚合物高保真复形与结构大深宽比之间的矛盾,即大深宽比结构复形意味着诱导过程中的大空气间隙,然而大空气间隙会导致电场力不足以驱动聚合物克服表面张力和黏滞阻力形成与模板图案一致的结构,因此,空间调制电场诱导聚合物流变成形技术仅能实现小深宽比结构(一般小于1)。为此,本文从聚合物材料特性和工艺方法出发,分别提出了导电聚合物空间调制电场诱导成形和预结构聚合物空间调制电场诱导成形两种变种工艺,从调制强度概念出发比较了变种工艺与传统工艺的差异性,从仿真分析角度阐述了变种工艺实现大深宽比微纳米结构的合理性和可行性,从实验手段出发制备了传统工艺所没有实现的结构深宽比。4)现阶段空间调制电场诱导聚合物流变成形技术着眼的微纳米结构都是单一尺寸或相近尺寸,忽略了其在变尺寸复形方面的可行性。但是此类变尺寸微纳米结构在微流系统、生物检测等方面同样具有广泛的应用。因此,将空间调制电场诱导聚合物流变成形技术扩展至变尺寸复形结构,是亟待解决的问题之一。为此,本文从强/弱调制概念出发,讨论了空间调制电场诱导聚合物流变成形技术在变尺寸结构复形方面的可行性,定义了三种细化的强/弱调制状态,即欠调制、强调制和过调制,提出了区分三种调制状态的判定准则,探索了不同工艺参数对强/弱调制区域的影响,并从实验角度实现了变尺寸结构复形。5)基于空间调制电场诱导聚合物流变成形强/弱调制的规律,本文从应用出发,探索了电场诱导成形方法在仿生超疏水多级结构和微透镜阵列制造中的应用:(a)利用平膜聚合物的弱调制状态和预结构聚合物的强调制状态实现了聚合物多级结构的制备,该结构表现出接触角大于150°,滑动角小于10°的超疏水特性;(b)利用大间距特征的诱导模板,在强调制状态下实现了填充比高达98.8%的聚合物微透镜阵列。
[Abstract]:Polymer micro nanostructures have attracted more and more attention due to their unique physical and chemical functions. They can be widely used in microfluidic, organic optoelectronics and biological detection. In the manufacturing methods of polymer microstructures, the spatial modulated electric field induced polymer rheological formation technology is due to the universality of materials, structure uniformity, and so on. The "space modulated electric field induced polymer rheological forming" process uses a structured conductive template and a conductive substrate coated with polymer film as the pair of electrodes to form the multilayer structure of the induced template / air / polymer / conductive substrate. The modulation of the structure at the air polymer interface forms an electric field that changes with the space position. The Maxwell stress tensor produced by the "space modulated electric field" drives the polymer to move towards the induced template and forms a polymer micro nanostructure with a certain morphology or size. The mechanism and control method of art are studied. The starting point and the research results are as follows: 1) in the space modulated electric field induced forming, the morphology of the polymer is completely controlled by the modulated electric field, and there is no other geometric constraint. Therefore, the correct understanding of the rheological mechanism of the polymer under the action of the space modulated electric field is to realize the high fidelity of the micro nano structure. However, the linear stability analysis method based on the theory of fluid lubrication neglects the influence of the micro nano scale effect and can not accurately describe the rheological behavior of the polymer under the action of the space modulated electric field, especially it is not suitable for the rapid formation of the low viscosity polymer electric field induced by the electric field. The dynamic model of nonlinear two-phase flow is established by the scale effect. From the analysis of mechanical behavior state, the rheological forming mechanism of polymer under the action of space modulated electric field is studied. The whole induction process is divided into three stages: forming stage, quasi static stage and fusion stage. Only the polymer can be cured at the quasi-static stage. The conformable structure consistent with the template pattern. (1) 2) in the current study of polymer rheological formation induced by space modulated electric field, the complex structure which is consistent with the template pattern is directly displayed, and the inconsistency between the polymer structure and the induced template pattern is ignored. Therefore, the concept of strong / weak modulation is proposed to describe the polymerization. The complex structure of the compound is similar to that of the induced template pattern. It is defined that the polymer complex structure is consistent with the template pattern as strong modulation, and vice versa. The simulation analysis and experimental observation show that the average component of the electric field distribution at the polymer gas liquid interface is the root cause of the disagreement between the polymer complex structure and the template pattern. The modulation strength is characterized, and the influence of the process parameters on the modulation strength is analyzed. The contradiction between the high fidelity complex of the polymer and the ratio of the large width to width by adjusting the process parameters,.3, is studied. That is, the large depth width ratio structure means the large air gap in the induction process, but the large air gap in the induction process is large. The air gap will lead to the electric field force not enough to drive the polymer to overcome the surface tension and the viscous drag to form the same structure with the template pattern. Therefore, the space modulated electric field induced polymer rheological forming technology can only achieve a small depth to width ratio structure (generally less than 1). Two varieties of electric field induced electric field induced and prestructured polymer space modulated electric field induced forming process were used. From the concept of modulation strength, the difference between the variety and the traditional process was compared. The rationality and feasibility of the variety process to realize the large depth and width ratio micro nano structure were expounded from the angle of simulation analysis. On the basis of the experimental method, the structure depth width ratio (.4) which is not realized by the traditional process is prepared. The micro nanostructures with the focus on the space modulated electric field induced polymer rheological forming technology at the present stage are both single size or similar size, ignoring the feasibility of the variable dimension complex. However, this kind of variable size micro nano structure is produced in the microfluidic system. Therefore, it is one of the problems to be solved to extend the space modulated electric field induced polymer rheological forming technology to the variable size complex structure. Therefore, this paper, starting with the concept of strong / weak modulation, discusses the space modulated electric field induced polymer rheological forming technology in the variable size structure complex square. Three strong / weak modulation states, namely under modulation, emphasis system and over modulation, are defined, and the criterion for distinguishing three kinds of modulation states is proposed. The influence of different process parameters on strong / weak modulation regions is explored, and the variable size structure complex.5 is realized from the experimental point of view. The application of the electric field induced forming method in the fabrication of the bionic superhydrophobic multistage structure and microlens array is explored from the application of the strong / weak modulation. (a) the preparation of the multistage structure of the polymer is realized by using the weak modulation state of the flat film polymer and the stress state of the prestructured polymer. The structure shows the contact angle. The super hydrophobicity of more than 150 degrees and a sliding angle less than 10 degrees; (b) a polymer microlens array with a high filling ratio of 98.8% is realized by using the induced template with large spacing characteristics.

【学位授予单位】：西安交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ317;TB383.1

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