Mesoscale Photomechanical Coupling in Photoactive Liquid Crystal Elastomers

该奖项将支持基础研究，以研究光活性液晶弹性体中光，机械和化学之间的耦合。这项研究将在纳米尺度分子和宏观尺度材料之间架起一座桥梁。光敏液晶弹性体是由液晶分子组成的橡胶材料，其响应于光而经历大的变形。然而，与单个光活性分子相比，现有的宏观光活性材料表现不佳。本研究将联合收割机理论与实验相结合，填补单分子行为与宏观性能之间的差距。该项目将通过创造新的机会从光中获取能源来满足经济和社会需求。潜在的新应用包括用于极端环境的光驱动机器人系统。此外，该项目将对研究生和本科生的教育和培训产生更广泛的影响。他们将在PI的实验室进行研究培训，并参加软活性材料的新课程。还将支持几项组织良好的外联活动。这些活动包括高中夏令营和科学实地考察，重点关注参与STEM的代表性不足的人群。本研究的目的是了解介观尺度光机械耦合的基本机制，通过建立一个微力学理论框架和一个多物理实验平台，光敏液晶弹性体受到光照和机械载荷。微观力学理论将从单分子光反应和许多相互作用的液晶分子的统计物理中提取信息，并将其整合到连续介质力学模型中。为了评估理论模型，将在实验中制造具有不同组合物的光敏液晶弹性体样品，其中将表征它们在规定的光照、温度和机械应力下的宏观行为。与这些因素相关的基本机制将被研究，以优化材料的光驱动功输出，并通过调整液晶分子的介观分子排列来开发光机械致动的新方法。通过利用材料相变和机械不稳定性，宏观变形和工作输出将进一步增强。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award will support fundamental research to investigate the coupling between light, mechanics, and chemistry in photoactive liquid crystal elastomers. This research will bridge the length scales between a nanoscale molecule and a macroscale material. Photoactive liquid crystal elastomers are rubbery materials composed of liquid crystal molecules that undergo large deformation in response to light. However, compared to an individual photoactive molecule, existing macroscopic photoactive materials do not perform as well. This research will combine theoretical and experimental approaches to fill the gap in understanding between single molecule behavior and macroscopic performance. This project will benefit the economic and societal needs by enabling new opportunities to harvest energy from light. Potential new applications include light-driven robotic systems for extreme environments. In addition, the project will have broader impacts in the education and training of graduate and undergraduate students. They will be engaged in research training in the PI’s lab and a new course on soft active materials. Several well-organized outreach activities will also be supported. These include high school summer camps and science field trips with a strong focus on engaging underrepresented populations in STEM.The objective of this research is to understand the fundamental mechanics of mesoscale photomechanical coupling, by building a micromechanical theoretical framework and a multiphysics experimental platform for photoactive liquid crystal elastomers subjected to both light illumination and mechanical load. The micromechanical theory will extract information from the single-molecule photoreaction and the statistical physics of many interacting liquid crystal molecules and integrate it into a continuum mechanics model. To assess the theoretical model, samples of photoactive liquid crystal elastomer will be fabricated with different compositions in experiments, where their macroscopic behaviors subjected to prescribed light illumination, temperature, and mechanical stress will be characterized. The fundamental mechanisms related to these factors will be investigated to optimize the light-driven work output by the material and develop new ways of photomechanical actuation through tuning the mesoscale molecular alignment of liquid crystal molecules. The macroscopic deformation and work output will be further enhanced by harnessing material phase transformation and mechanical instability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.