分子凝胶中的寡聚效应研究

Molecular gels, which are mainly composed of liquids, and possess controlled and reversible phase transition properties, are a typical class of stimulus-responsive soft materials. It is well known that the emergence and development of molecular gels have boosted the fabrication of functional systems, the development of molecular materials, and the conduct of chemical transformation due to its superiors in various aspects. For these reasons, molecular gels have drawn increasing attention during the last few years. On the basis of above consideration, our accumulation in studies of molecular gels, and careful analysis of the strong and weak points of chemical gels, physical gels, as well as molecular gels, a project relevant to the studies of oligomerization effect in molecular gels is proposed. The main purpose of the project is to find out a way to significantly enhance the mechanical strength of molecular gels and at the same time to maintain their super-smart stimulus-responsive properties, and the pure solvent-like viscosity when they exist in liquid state. It is believed that these gels are the ones to be developed, of which the gel networks are formed and maintained by synergistic action of the supramolecular association, a dominate interaction mainly found in conventional molecular gels, and covalent bonding, an interaction found in chemical and polymer gels. Therefore, synergistic action of supramolecular association and covalent bonding is a key issue in the studies of present project. Accordingly, a series of oligomers with cholesterol, cholic acid, aromatics, ferrocene, and ligands for transition metal ions as key structural units will be designed under the guidance of supramolecular principles, and prepared by using the synthetic techniques established in conventional molecular chemistry. Their solubility in relevant solvents and their self-assembly behavior in solution state and at air/liquid interfaces will be studied. On the basis of these studies, the gelation behavior of the oligomers, and the properties, in particular the mechanical properties of the gels as obtained will be investigated systematically. Furthermore, studies on the tentative application of the gels of superior stability as new medium for electrophoresis will be also conducted. It is believed that a number of new gelators and new molecular gels possessing both the advantages of chemical gels and those of conventional molecular gels will be developed via implementation of the present project. No doubt, conduction of the research briefly described must be helpful for the understanding of the structure-property relationship of molecular gels and for extending their real-life applications.

分子凝胶是一类典型的以液体为主要成分的刺激响应性软物质。分子凝胶的发展为构建功能体系、发展分子材料、进行化学转化提供了常规溶剂和化学凝胶无法比拟的介质优势。因此，近年来分子凝胶研究受到了人们日益广泛的关注。本项目立足已有工作基础，围绕力学强度难以提高这一制约分子凝胶发展与应用的突出问题，在比较化学凝胶、高分子凝胶和小分子物理凝胶固有特点、局限性和结构差异的基础上，提出以典型超分子单元为核心结构，按照超分子化学原理，利用化学合成技术设计、制备具有不同拓扑结构，包含有限结构单元的系列寡聚物，通过对以共价键合与超分子作用协同为特征的寡聚效应的深入研究，获得一批结构新颖、性能优异的新型胶凝剂，构建兼具分子凝胶和化学凝胶优势，液态粘度接近纯溶剂的刺激响应性超强凝胶，探索显著改善分子凝胶力学性能的有效途径。毫无疑问，此类研究必将有助于加深人们对分子凝胶结构-性能关系的认识，拓展分子凝胶的实际应用。

在国家自然科学基金委员会的支持下，在过去的四年里，房喻教授领导的研究小组按照“分子凝胶研究中的寡聚效应”项目申请书所提出的研究任务，主要开展了以下几个方面的研究工作：（1）以胆固醇、苝酐、萘酐、芘、八羟基喹啉、NBD等为基本结构单元，设计制备了三十余种具有不同聚合度、不同片段组成，且性能优异的小分子胶凝剂；（2）通过溶剂筛选和条件优化，得到了一系列分子凝胶和凝胶乳液；（3）利用凝胶乳液的模板作用，合成制备了十余种具有不同内相结构，对甲醛、甲醇、甲苯、苯等易挥发性有机物（VOCs）具有高效，乃至选择性吸附作用的多孔低密度材料；（4）针对稳定剂泄漏问题，设计合成了多种可聚合小分子胶凝剂，从而使其得以在发挥稳定凝胶乳液作用之后，经由聚合进入多孔材料，由此规避泄漏问题；（5）通过凝胶介导和胶凝剂的荧光功能化，得到了有序或部分有序，且富含分子通道的新型荧光薄膜材料，实现了对肺癌标识物苯胺等重要化学物质的高灵敏、高选择性检测；（6）搭建多孔低密度材料吸附VOCs原位在线研究装置五套，荧光凝胶薄膜传感性能评价系统一套。. 项目执行期间，申报发明专利7件，获批发明专利3件，发表研究论文43篇，荣获陕西省科技成果一等奖1项，应邀为中国化学会《科学通报》、美国化学会Langmuir和英国皇家化学会Molecular Systems Design & Engineering撰写了综述文章，系统介绍了作者实验室在过去几年里在分子凝胶和荧光传感领域的研究工作。培养博士4名（其中1人获陕西省优秀博士论文奖励）、硕士14名（4名硕博连读，5名赴国外攻读博士学位），此外，正在学习的博士后1人，预期2017年年内出站。