Controlled symmetry breaking in semicrystalline polymer crystalsomes

非技术总结：半结晶聚合物构成了目前使用的绝大多数聚合物材料。虽然聚合物晶体的基本对称性与它们的小分子对偶物没有什么不同，但聚合物的长链性质确实显著影响它们的结晶行为。了解半晶聚合物的结构和形态对提高其性能和扩大其应用范围至关重要。本项目涉及聚合物晶体的结构控制。本研究的首要目标是通过控制结晶条件和/或聚合物分子结构来获得独特的球形聚合物晶体，并阐明这种弯曲晶体生长的形态和基本分子水平过程。预计这些控制良好的球形晶体将在药物输送和免疫治疗领域得到应用。建议的教育部分包括：1)指导研究生和本科生。2)通过开发将用于德雷塞尔大学研究生课程的两个课程模块来解决现代聚合物科学教育的需求。3)将高中学生和教师，特别是代表性不足的人群，纳入拟议的研究活动。技术概述：聚合物的长链特性给它们的结晶行为带来了最有趣的特征：结晶材料中复杂的非晶畴。结晶体和非晶态相互交织的分层形态决定了半晶聚合物的一些独特性质。基于晶体形态与平动对称性的相关性，将聚合物晶体分为形状对称相称晶体和形状对称不相称晶体。在后一种情况下，晶体形态决定了沿至少一个单元胞轴的平移对称性被破坏。本项目旨在系统地研究一类聚合物球形晶体在ssic中的应用。本文将采用自顶向下的模板技术和自底向上的分子工程方法来打破聚合物晶体的平移对称性。最近发现的球形晶体将被用作模型系统。因此，提出的工作的具体目标是：1)了解曲率依赖的结晶和熔融聚合物晶体体。2)通过形态控制形成复杂的结晶体。3)利用自发平移对称破缺制备晶体体。该项目将推动聚合物结晶领域的发展，并形成一个晶体体库，作为量身定制的聚合物纳米颗粒。这些潜在的应用包括药物输送和免疫治疗。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。

NON-TECHNICAL SUMMARY:Semicrystalline polymers constitute the large majority of polymeric materials in use today. While the basic symmetries of polymer crystals are not different from their small molecular counterparts, the long-chain nature of polymers does significantly affect their crystallization behavior. Understanding the structure and morphology of semicrystalline polymers is crucial to improving their properties and broadening their applications. This project concerns the structural control of polymer crystals. The overarching goal of this research is to achieve unique spherical polymer crystals by controlling the crystallization conditions and/or the polymer molecular structure and to elucidate the morphology and the fundamental molecular-level processes involved in such curved-crystal growth. It is anticipated that these well-controlled spherical crystals may find applications in the fields of drug delivery and immunotherapy. The educational component of the proposal includes: 1) Mentoring graduate and undergraduate students. 2) Addressing the need for the education of modern polymer science by developing two class modules that will be used in graduate courses at Drexel University. 3) Involving high school students and teachers, particularly under-represented populations, in the proposed research activities.TECHNICAL SUMMARY: The long-chain nature of polymers brings the most interesting feature to their crystallization behavior: the intricate amorphous domains in a crystalline material. The hierarchical morphology of the intertwining crystalline and amorphous phases accounts for some unique properties of semicrystalline polymers. Based on the correlation between crystal morphology and translational symmetry, polymer crystals are divided into shape-symmetry commensurate crystals and shape-symmetry incommensurate crystals (SSICs). In the latter, crystal morphology dictates broken translational symmetry along at least one unit-cell axis. This project aims to systematically investigate a class of polymer spherical crystals in the context of SSICs. Two approaches, namely a top-down templating technique and a bottom-up molecular engineering method, will be employed to break the translational symmetry in polymer crystals. The recently discovered spherical crystalsomes will be used as the model system. Accordingly, the specific aims of the proposed work are: 1) Understanding curvature-dependent crystallization and melting in polymer crystalsomes. 2) Developing complex crystalsomes via morphological control. 3) Fabricating crystalsomes using spontaneous translational symmetry breaking. This project will advance the field of polymer crystallization and lead to a library of crystalsomes as tailor-designed polymeric nanoparticles. Potential applications for these include drug delivery and immunotherapy..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.