剪切诱导双连续相界面拥挤乳液凝胶（bijels）的形成及机理

Bicontinuous interfacially jammed emulsion gels (bijels) are tortuous, interconnected structures of two immiscible liquids, kinetically trapped by interfacially jammed colloidal particles. Developing the method to produce the bijels with uniform domain structures is of great significance for the basic study and holds significant promise in interfacial catalysis, mass transferred separation, energy storage. Deep understanding the morphology development during the procedure, yet, is prerequisite for controlling the uniformity of the bicontinuous structures. .In this project, we will firstly synthesize functionalized polymers, and prepare the bijels under shearing field where the functionalized polymers manipulate the line contact angle of nanoparticle at the interfaces and thereby stabilize the bicontinuous curvatures. The characteristics of the component dictating the morphology, including the molecular weight, concentration and type of functionalized polymers, nanoparticle size, concentration and functional density, the ratio between the two immiscible fluids and the shearing rate, will be systematically studied mainly via small angle neutron scattering (SANS). The dependence of interfacially assembly element and preparation parameters on the uniformity of the domains will be illustrated, such that a valid method to construct bijels with uniform domains is expected. And, real time SANS will be used to investigate the kinetics associated the formation of bijels. As such, the morphology evolution from two macro-phases to the interconnected structures will be uncovered. This proposal could guide the preparation of uniform structured bijels, and provide protocol for other soft matter systems to monitor the kinetics associated with the morphology evolution.

Bijels是胶体粒子界面拥挤而稳定的双连续相液体。发展结构均一bijels的制备方法对其基础研究和在界面催化、传质分离、能源存储等领域具有重要意义。而深入理解制备过程中相结构演化机理是控制双连续相结构均一性的前提。.本项目首先合成官能化聚合物，在剪切场中，利用其调节纳米粒子界面接触角以稳定双连续相曲面，制备 bijels；拟主要以小角中子散射为手段，系统地探讨官能化聚合物分子量、浓度、种类，纳米粒子尺寸、浓度，两相体积比和剪切速率等影响因素对bijels形貌的影响规律；揭示界面组装基元、制备参数与bijels结构均一性之间的关系，发展制备结构均一bijels的有效方法；并拟采用原位在线小角中子散射研究剪切诱导bijels的形成动力学过程，揭示宏观两相向双连续相结构转变的相演化机制。本项目的顺利实施将为结构均一bijels的制备和其它软物质体系的相演化机理研究提供理论指导和实验依据。

深入理解双连续结构乳液凝胶（bijels）制备过程中相态演化、界面调控机理对发展新型bijels材料具有重要意义。本项目以活性阴离子和开环聚合合成了不同分子量的官能化聚合物。建立了聚合物分子量与其在纳米粒子表面构象行为和性质的内在关系。研究了聚合物分子量、浓度对两液相相态行为的调控规律。基于官能化聚合物与纳米粒子在两液相界面协同组装，采用原位中子散射研究了剪切动态过程中相态演化和界面调控机制。进而，明晰了剪切诱导制备bijels的聚合物/纳米粒子界面组装的关键参数。取得如下进展：1）采用活性阴离子和开环聚合，调控引发剂/单体比等聚合条件，得到了不同分子量的氨基化聚苯乙烯和聚二甲基硅氧烷。2）阐明了聚合物链在纳米粒子表面的构象特征，为两者调控液相界面结构奠定了基础。聚合物在纳米粒子表面高密度接枝时，靠近纳米粒子表面的聚合物链段运动受限、构象熵急剧下降，表现出玻璃化转变温度增加等异常性质；远离纳米粒子表面的聚合物链段则呈现与本体链类似的高斯链行为。3）在静态下，揭示了聚合物分子量和浓度对两液相相态行为的影响规律。调控聚合物分子量或浓度可获得曲率值可控的正、负曲率液相界面。4）在剪切场中，利用原位小角中子散射阐明了两液相相态演化动力学过程和双连续相结构的形成机制。与传统旋节分解机理不一样，剪切诱导法中两液相首先以分散乳液方式存在，然后相尺寸逐步降低，并伴随着相态的桥联、贯通，最后形成双连续结构，无经典的成核、生长过程。5）进一步地发现，聚合物与纳米粒子协同组装调节两液相界面微曲率时，纳米粒子的浓度对相态尺寸起决定因素，而高、低分子量聚合物同时与纳米粒子协同组装是形成双连续负高斯曲率的关键。综上，发展了剪切诱导制备bijels的方法并建立了原位研究相态、界面演化的方法，为新型软物质体系的设计提供了实验基础。发表相关论文4篇，申请中国发明专利5项（其中2项已授权），培养硕士生1名。