【作者】 姚晰；

【导师】 江雷；

【作者基本信息】 吉林大学 ， 物理化学， 2014， 博士

【摘要】 向自然学习是人类获得科技进步，提高生活质量的起点。科研工作者通过对自然界生物的细致观察和研究，揭示了生命能够适应环境生存繁衍的深刻道理。巧妙的生存本领为科研工作者们提供了无穷无尽的灵感，促成了各种智能仿生材料的开发以及在生产生活领域的应用。凝胶材料作为人工材料中十分重要的一个领域，每天都影响着人们的生活和科技的发展进步。受生物体内的细胞生长分化启发的仿生干细胞培植分化，以及水下鱼鳞超疏油对仿生抗油污、抗生物粘附的水下涂层的启发，人们已经从自然中学习了很多巧妙的材料设计理念，用以发明各种在科研和生产生活领域产生广泛应用的凝胶材料。然而到目前为止，一方面由于对油相凝胶材料的表面特殊浸润性的研究方兴未艾，另一方面对于水凝胶材料表面浸润性的调控不存在类似固体表面修饰方法这样普适的方法。导致对于多数水凝胶体系而言，后处理水凝胶界面浸润性质，或者说对多数水凝胶体系普遍适用的表面改性策略仍然是一个挑战。本文在这样的背景下，从水下鱼鳞的水凝胶层以及细胞膜疏水机制出发，道法自然，对具有特殊浸润性的智能响应凝胶材料进行了研究。尤其是针对不同的潜在应用需求，分别深入地探索了凝胶材料在单个液滴的可逆性操控、石油管道防结蜡性能和溶剂的动力学扩散进程的影响等方向的研究，具体开展了如下工作：(1)受鱼鳞表面水凝胶的启发，我们制备了能够实现通过温度控制的对于水滴粘附的可逆开关控制的油凝胶材料。我们通过将高温熔化的石蜡液体溶胀聚二甲基硅氧烷(PDMS)交联网络当中，制备出了具有熔点特性的油凝胶材料。这种材料的熔点特性体现在当温度低于石蜡熔点时，油凝胶材料呈现出不透明的乳白色固体状态，此时材料的表面对于水滴的粘附呈现Wenzel高粘附态。而当温度升高时油凝胶的石蜡成分彻底熔化，使材料展现液态性质，材料对水滴产生了润滑效果的低粘附状态。研究还显示这种对水滴粘附的转变能实现多次可逆控制。在本文中我们还研究了如何通过调节石蜡碳原子数目来调节产生粘附可逆性变化的临界温度。另外材料透明性的温控特性也为实现温控光学开关和窗体材料提供了新的思路。(2)从(1)中的油凝胶材料出发，我们将用于溶胀聚二甲基硅氧烷(PDMS)的有机溶剂进行了拓展研究。发现，在溶胀了小分子量的各种烷烃、芳烃混合物(包括汽油、柴油、甚至原油)以后，我们发现油凝胶材料表面具有对于发生相变过程的石蜡产生极低的粘附作用。我们首先通过系统的研究获得了油凝胶材料的溶胀率同各种因素，如溶剂成分、温度、交联度等的关系。通过石蜡的超低粘附行为我们分析并提出了油凝胶材料对于相变过程中石蜡的超低粘附的形成机理。其核心的概念是石蜡在有油膜包覆的油凝胶材料表面由于良溶剂中的自由结晶而全程被避免了的同固体表面的直接接触。进一步的研究证实这种特殊的油凝胶材料能够在相对低温的条件下起到十分显著的防止石油管道内表面石蜡沉积的作用。通过测试我们证明该材料比目前主流的石油管道内衬材料的防石蜡沉积性能高两个数量级以上。(3)我们受细胞膜的启发疏水层的选择透过性启发，我们还研究了通过水/油界面化学反应对水凝胶的表面进行疏水的改性。向常规的水凝胶成胶体系中引入含有二甲氨基团的功能单体，进而通过季胺化反应，将含有不同碳链长度的烷基链以及溴代对家苯乙烯聚合物化学键联到水凝胶的表面。藉此我们将水/油界面季胺化改性水凝胶表面的方法进行了普适性的研究。通过实验我们发现，经过表面改性的水凝胶一方面在空气中能够呈现出稳定疏水性质，另一方面表面改性的水凝胶表面展现出了明显的水下亲油和油下疏水的性质，这一性质与水凝胶原本的液相下的浸润性恰好相反。因此我们成功地得到了理想的水凝胶表面改性材料。在此基础上，我们结合模板冲孔和牺牲模板法制备了具有高长径比的水凝胶表面锥状阵列。与季胺化疏水处理相结合，我们成功地构筑了水凝胶超疏水表面。接下来我们通过三明治法制备了玻璃管中的水凝胶夹层。并通过荧光标记的水体系监测了表面改性对于水凝胶界面的水扩散动力学影响。通过实验我们发现，一方面疏水层的存在能够延迟水向水凝胶材料内部扩散的进程，另一方面从较长时间尺度上观察，疏水层的存在能够维持水凝胶材料内外部分的浓度差，这为水凝胶材料内部水的均匀扩散赢得了时间。水凝胶材料的表面改性研究，为指导我们将这类常规材料在油/水分离和生物医药控释等方面的应用打下坚实的基础。更多还原

【Abstract】 Nature is a necessary path that promotes the developing of modern technology and thequality of life. Through insightful observation into the natural organisms, researchers havebeen able to explain the mysterious ways of living organisms adapting their respectiveecological environments. Inspired by these amazing surviving skills, researchers haveinvented many bio-mimicking materials which have been implemented in industrial areas anddaily life. As for the vast developing area of gel materials, a great deal has been achievedsince the last century. Inspired by fish scales, coating technology targeting at anti-oil andanti-biofouling functions has found broad market in the past. Besides, researchers havelearned the biological hydrogel environments for the differentiation of stem cells in livingbodies and base on which developed versatile tools to make artificial hydrogel environment inspecial patterns and arrangements to greatly benefit both the surviving and differentiation ofstem cells in desirable ways in vitro conditions. However to date, the research on organogel,which mainly contains a big amount of oil phase in its constitution, The consideration of the special interfacial wettability is only beginning. And unlike a ubiquitous wettability renderingmethod for common solid surfaces, there is in lack of a general idea in how to render analready made hydrogel material surface. In other words, it is still a challenge to invent aubiquitous methodology in post modulation of the surface wettability on a regular hydrogelsurface. In this thesis, learning from fish scale and hydrophobic lipid bilayer in cells, weprepared smart-responsive gel materials with special wettability. Especially, we investigatethe feasibility of smart-responsive gel materials in application in reversible manipulation ofsessile drops, oil/water separation and prevention of wax deposition in crude oil pipeline, etc.The main contents are as follows:(1) Inspired by fish scales, we prepared n-paraffin swollen organogel material withthermally switchable water adhesion property on its surface. The organogel materials wasprepared by swelling n-paraffin with different carbon numbers at high temperature into thecross-linking network of poly(dimethyl siloxane)(PDMS). The organogel exhibitsmelting-point feature, which is at temperature lower than melting point of the n-paraffin used,organogel exhibits solid property, opaque in milky-white; whereas at temperature higher thanmelting point, organogel is complete transparent. At temperature lower than the melting pointof the n-paraffin, the gel surface exhibits Wenzel high-adhesion state towards water drops;whereas at temperature higher than melting point, water drops are lubricated and inlow-adhesion state. Moreover, this wetting state transition is in-situ reversible. And the alsoreversible switching of transparency on organogel might provide new ideas in thermallycontrollable optical switches and windows.(2) Originated from the organogel in (1), we extend the types of solvent used forpreparing organogel. It is found that gasoline, diesel oil and even crude oil could impartorganogel with extremely low adhesion towards paraffin wax. We first investigated the factorsthat pose influence to the swelling ratio of organogel, such as the composition of solvents,temperature, cross-linking density, etc. Then we proposed a possible mechanism of theformation of ultra-low adhesion of solidifying paraffin wax to organogel surface, which isrelated to the free crystallization of paraffin wax at a miscible liquid layer, which largely prevents the direct contact of paraffin wax to the solid surface of organogel material. Furtherexperiment showed that the special organogel material is able to prevent wax deposition eventin crude oil pipeline at low temperature. From the experiment we verified that the ability ofanti-waxing on organogel surface is two orders higher than conventional pipeline materials.(3) Inspired by the selective permeability of the hydrophobic lipid bilayer on cellmembrane, we developed a general method of post-modifying hydrogel surface viaquarternization reaction at water/oil interface. We conduct this strategy by introducingfunctional groups including dimethylamino groups into the cross-linking gelation of regularhydrogel system. We successfully grafted short alkyl chains with different carbon numbers aswell as polymer chains onto hydrogel surface and found that the surface was renderedhydrophobic. We also found that the wettability of normal hydrogel under liquids wascompletely reversed. That is, the modified hydrogel exhibited both oleophilicity underwaterand superhydrophobicity underoil. Based on the aforementioned results, we successfullyobtained superhydrophobic hydrogel surface by combining the punching hole and modelscarification techniques in preparing cone arrays on hydrogel surface. Later, we investigatedthe influence of surface modification on water diffusion dynamics to the hydrogel interface.In the experiment, we fabricated the hydrogel section in a glass tube through the so called“sandwich” technique. From the experiment, we found that the existence of hydrophobic layeron hydrogel surface delayed the diffusion process from water to hydrogel. And we also foundthat in a longer time span, the hydrophobic layer could keep a difference in waterconcentration between inside and outside of hydrogel interface, which enable the inside ofhydrogel to have time to reach distribution equilibrium of the out coming solvents. Theresearch of hydrogel post-modulation strategy will benefit the potential application in areas ofoil/water separation and bio-medicine control release.更多还原