基于Marangoni效应的智能运动中超两亲分子作用机制的研究

Self-propulsive device based on Marangoni effect is meaningful in various aspects of fundamental and application fields. Especially, most research in this field used the approach of releasing surfactant at interface to form surface tension gradient, which acts as the driving force for Marangoni effect. Related systems have drawn wide attention for insight investigations. However, currently this research field is facing a bottleneck problem and great challenge: the released surfactant reaches its critical micelle concentration rapidly, resulting that the interface becomes inert, the surface tension gradient disappears and the smart motions stopped. To handle this issue, for the first time this project introduces the new concept of supra-amphiphiles to smart motions based on Marangoni effect. By using the characteristics of supra-amphiphiles formed through non-covalent bonds, we can adjust the adsorption status and assembly forms of surfactants through dissolving surfactants with host molecules in solution or decomposing the supra-amphiphiles with stimulus-responsive systems in a controlled way. In this way, the over-aggregation of surfactants at interface could be eliminated and thus to maintain surface tension gradient for sustainable smart motions. With tracking dyes and systematic analyses of surface tension, we will investigate the influences of the assembly/disassembly behaviors of supra-amphiphiles on the sustainable smart motions, thus providing novel ideas and solutions to the development of self-propulsive smart devices.

基于马兰格尼（Marangoni）效应的自驱动器件在诸多基础和应用领域具有重要研究意义。特别地，大多数相关研究采用在界面释放表面活性物质的方式，以产生表面张力梯度作为驱动力，相应的体系得到了广泛关注和深入研究。然而，该领域目前面临着表面活性物质到达临界胶束浓度过快而导致表面张力梯度消失、运动停滞的瓶颈问题和重要挑战。为此，本项目首次将超两亲分子这一新兴概念引入到基于马兰格尼效应的智能运动中，利用超两亲分子非共价键结合的特点，通过溶液体系中的主体分子将传统表面活性剂溶解，或者通过刺激-响应体系实现超两亲性分子的可控分解，调控表面活性物质在界面的吸附形态，消除其在界面的过度聚集，从而维持表面张力梯度，实现可持续的智能运动。借助示踪观察和体系表面张力的系统分析，我们将分别从定性和定量角度研究超两亲分子组装/解组装行为对持续性智能运动的影响，从而为推进自驱动智能器件的发展提供新思路和新方案。

Marangoni 效应是一种由溶液浓度或温度差异而引起界面传质的现象，它因意大利物理学家Carlo Marangoni对“红酒之泪（tears of wine）”现象的系统化研究和论述而被命名。随着新型智能材料的迅速发展，Marangoni效应由于其响应速度快、作用力程长、适用范围广等特点，在自驱动器件的研究中受到了广泛关注和深入研究。利用表面活性剂作为驱动物质，通过其可控释放来产生表面张力梯度，进而形成Marangoni效应驱使器件运动的方式具有诸多优点。然而，其问题与挑战在于，随着表面活性剂的释放，界面会由于其临界胶束浓度限制被快速钝化，表面张力梯度消失，运动过程难以持续。本项目将将负载有具有表面活性物质的载体与具有减阻效果的超疏水船体相结合制备功能协同器件，通过具有表面活性物质的释放，实现由Marangoni效应驱动的快速运动，进而通过调节外界环境刺激，基于超分子组装策略和超两亲分子策略，去除水面上富集的表面活性物质，维持表面张力梯度，实现器件的持续运动。进一步将上述长效Marangoni运动作为宏观构筑基元的驱动力，发展了一种基于组装动力学调控的精准组装方法，提高了精准宏观超分子组装的效率。本项目为表面活性剂不能持久维持Marangoni效应以驱使器件运动的难题提供了解决方案，分别从动态超分子组装消除界面的表面活性剂分子聚集和基于动态共价键的超两亲分子的可逆分解两个方面，解决界面钝化和表面张力梯度消失的问题，从而实现器件的持续运动，进而推进自驱动智能器件的研究并探索其在宏观组装等领域的应用。