CAREER: Controlling Chain Conformation in Amorphous Polymers through Soft Nanoscale Confinement

非技术：聚合物在我们的日常生活中发挥着核心作用，特别是那些在技术、能源和生物医学应用中广泛使用的具有固有结晶性的聚合物。然而，一些最广泛使用的聚合物缺乏任何形式的结晶度，这阻碍了它们在这些高级应用中的使用。这项研究提出了一种独特的方法，通过探索液晶的使用，模板结晶性，液晶显示器(LCD)中常见的材料，在创造聚合物材料。这项研究旨在了解和控制这些新型结晶聚合物的特性，潜在地开启它们在软机器人、锂离子电池和太阳能电池等高级应用中的用途。此外，从这项研究中获得的关于液晶如何影响这些聚合物的性能的知识将使聚合物科学和液晶研究界大大受益。该项目的一个重要方面还包括各种综合教育和外联活动。这项研究将为研究生和本科生提供软物质方面的研究培训，为高中生提供实验室经验，扩大参与范围，并通过各种教育计划提高公众对软材料的认识。技术：聚合物链构象的控制显著影响聚合物的物理化学性质。虽然已经采用了各种技术来对准结晶聚合物中的高分子链，例如通过原位聚合、外场对准或硬几何纳米限制，但对准本质上无定形的聚合物，如聚甲基丙烯酸甲酯、聚苯乙烯和聚丙烯酸丁酯尤其具有挑战性。无定形聚合物在受热时倾向于迅速和不可逆地采用无规卷曲构象，并且缺乏必要的结构特征来保持可逆链构象变化所需的取向，这是形状记忆材料的关键特征。在这项研究中，提出了一种新的方法，利用非反应性热致液晶(LCS)的各向异性流体性质，在本质上无定形聚合物的聚合过程中实现纳米级的软限制。主要目标是通过利用LCS中的取向顺序来对齐聚合物链。这项研究将集中在三个关键目标上：(1)研究LC相和聚合温度对LC溶剂中生成的链构象的影响；(2)研究去除LC的溶剂的选择如何影响LC提取后聚合物链的构象；(3)表征生成的聚合物网络的相行为和物理化学性质。深入了解软纳米尺度限制对聚合物链构象、相行为和性质的影响，可能会使聚合物性能的优化和先进功能的引入成为可能，包括形状改变，与软致动器和软机器人以及具有增强的定向离子传导性的聚合物电解质的未来发展相关。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL:Polymers play a central role in our everyday lives, particularly those with inherent crystallinity that are widely used in technological, energy, and biomedical applications. However, some of the most widely used polymers lack any sort of crystallinity, which prevents their use in these advanced applications. This research proposes a unique approach to template crystallinity by exploring the use of liquid crystals, common materials found in liquid crystal displays (LCDs), during the creation of polymeric materials. This research aims to understand and control the characteristics of these newly crystalline polymers, potentially unlocking their use in advanced applications such as soft robotics, Li-ion batteries, and solar cells. In addition, the knowledge gained from this research regarding how liquid crystals affect the properties of these polymers will significantly benefit both the polymer-science and liquid-crystal research communities. A significant aspect of this project also incorporates various integrated educational and outreach activities. This research will provide research training in soft matter for graduate and undergraduate students, will offer laboratory experience for high school students, will broaden participation, and will raise public awareness of soft materials through various educational programs.TECHNICAL:The control of polymer chain conformation significantly influences the physicochemical properties of polymers. While various techniques have been employed to align polymer chains in crystalline polymers, such as through in-situ polymerization, external field alignment, or hard geometrical nanoconfinement, aligning intrinsically amorphous polymers such as poly(methyl methacrylate), polystyrene, and poly(butyl acrylate) is particularly challenging. The amorphous polymers tend to rapidly and irreversibly adopt a random coil conformation when heated and lack the necessary structural features to maintain aligned orientations required for reversible chain conformational changes, a key feature for shape memory materials. In this research, a novel approach is proposed, which employs non-reactive thermotropic liquid crystals (LCs), characterized by their anisotropic fluid properties, to achieve “soft” nanoscale confinement during the polymerization of intrinsically amorphous polymers. The primary objective is to align polymer chains by leveraging the orientational order within the LCs. The research will focus on three key goals: (1) Investigation of the influence of LC phase and polymerization temperature on the resulting chain conformations within the LC solvent; (2) Study of how the choice of solvent for LC removal impacts the conformation of polymer chains post-LC extraction; (3) Characterization of the phase behavior and physicochemical properties of the resulting polymeric network. A deep understanding of the effects of soft nanoscale confinement on polymer chain conformation, phase behavior, and properties may enable the optimization of polymer properties and the introduction of advanced functionalities, including for shape-change, relevant to future developments in soft actuators and soft robotics and in polymer electrolytes with enhanced directional ion conductivity..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.