DMREF: Design Rules for Flexible Conductors: Predicting Chain Conformations, Entanglements, and Liquid Crystalline Phases of Conjugated Polymers

摘要：柔性电子设备具有改变我们社会的潜力，如分布式电源、固态照明、个人电子和生物医学设备。该计划的目标是加速用于柔性电子的共轭聚合物的发展。该项目将生成工具来预测共轭聚合物的基本性质，如链骨架的刚度，它们形成液晶的能力，以及链缠绕的可能性，所有这些都来自化学结构。因此，理论、模拟和实验的结合将为改进共轭聚合物的设计概念提供机会，从而为学术和工业努力创建一个加速材料设计框架。除了柔性电子产品，开发半柔性聚合物的理论描述将在生物聚合物、工程热塑性塑料和液晶的许多应用中具有变革性。此外，该计划将创建一个试点项目，旨在提高STEM领域学生的保留率。宾夕法尼亚州立大学将利用其独特的结构，即一个大型的中央校区与较小的联邦校区紧密相连，探索将远程研究活动作为招聘和留住人才的工具。技术摘要：该计划包括三种计算工具的开发。pi最近的工作提出了一种计算成本低廉的方法来预测共轭聚合物的持续长度。本计划的工作将验证这一方法，通过在熔融体中使用中子散射或在稀溶液中使用光散射对合成聚合物进行实验测量。此外，模拟和实验的结合将产生对社区感兴趣的各种共轭聚合物的持续长度值。pi还将利用他们开发的一种结合MD模拟和SCFT的新方法来预测向列耦合参数和向列到各向同性的转变温度。对不同硬度共轭聚合物相行为的预测将与流变学、光学显微镜和去偏振光散射的结果进行比较。最后，该工作将测试缠结长度与堆积长度的缩放关系，从分子结构预测任何共轭聚合物的缠结长度，并通过流变学测量来测试这些预测。理论、模拟和实验的结合为改进共轭聚合物的设计概念提供了机会。初步研究表明，硬链排列在界面附近，可能会增强依赖于介电界面附近输运的薄膜晶体管等器件中的电荷输运。

Non-technical Abstract:Flexible electronic devices have the potential to transform our society, such as in distributed power, solid-state lighting, personal electronics, and biomedical devices. The objective of this program is to accelerate the development of conjugated polymers for flexible electronics. The project will generate tools to predict fundamental properties of conjugated polymers, such as the stiffness of the chain backbones, their ability to form liquid crystals, and the likelihood that chains will entangle, all from the chemical structure. As such, the combination of theory, simulation, and experiment will provide opportunities to refine design concepts in conjugated polymers and therefore create an accelerated materials design framework useful for both academic and industrial efforts. Beyond flexible electronics, developing a theoretical description for semiflexible polymers will be transformative across many applications of biopolymers, engineering thermoplastics, and liquid crystals. Furthermore, this program will create a pilot program aimed at improving the retention of students in STEM fields. Penn State's unique structure will be leveraged, where a large central campus is closely linked to smaller commonwealth campuses, to explore the use of remote research activities as a recruiting and retention tool. Technical Abstract: This program encompasses the development of three computational tools. Recent work by the PIs suggests a computationally inexpensive approach to predict the persistence length of conjugated polymers. The work of this program will validate this approach, with experimental measurements on synthesized polymers using neutron scattering in the melt or light scattering in dilute solution. Furthermore, the combination of simulations and experiments will generate values of the persistence length for various conjugated polymers that are of interest to the community. The PIs will also leverage their development of a new approach combining MD simulations and SCFT to predict the nematic coupling parameter and the nematic-to-isotropic transition temperature. Predictions of the phase behavior of various conjugated polymers that vary in stiffness will be compared with results from rheology, light microscopy and depolarized light scattering. Finally, the work will test scaling relationships for the entanglement length versus packing length, to predict the entanglement length of any conjugated polymer from the molecular structure, and test these predictions with rheological measurements. The combination of theory, simulation and experiment provides an opportunity to refine design concepts for conjugated polymers. Preliminary studies suggest that stiff chains align near interfaces, potentially enhancing charge transport in devices such as thin-film transistors that rely on transport near dielectric interfaces.