Controlled symmetry breaking in semicrystalline polymer crystalsomes

非技术概述：半结晶聚合物构成了当今使用的大多数聚合物材料。虽然聚合物晶体的基本对称性与小分子晶体没有什么不同，但聚合物的长链性质对其结晶行为有很大的影响。了解半结晶聚合物的结构和形态对于改善其性能和扩大其应用具有重要意义。该项目涉及聚合物晶体的结构控制。这项研究的主要目标是通过控制结晶条件和/或聚合物的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所涉及的形态和基本的分子水平过程。预计这些控制良好的球形晶体可能会在药物输送和免疫治疗领域得到应用。该提案的教育部分包括：1)指导研究生和本科生。2)通过开发两个课程模块来满足现代聚合物科学教育的需求，这些模块将用于德雷克塞尔大学的研究生课程。3)让高中生和教师参与拟议的研究活动，特别是代表不足的人群。技术摘要：聚合物的长链性质为其结晶行为带来了最有趣的特征：晶体材料中复杂的无定形结构域。缠绕在一起的晶相和非晶相的层次化形态解释了半结晶聚合物的一些独特性质。根据晶体形态与平移对称性的关系，将聚合物晶体分为形状对称的公度晶体和形状对称的非公度晶体。在后者中，晶体形态决定了沿至少一个单位晶胞轴的平移对称性的破坏。本项目旨在系统地研究一类SSICs背景下的聚合物球晶。两种方法，即自上而下的模板技术和自下而上的分子工程方法，将被用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，建议的工作的具体目标是：1)了解聚合物晶状体中依赖曲率的结晶和熔融。2)通过形态控制形成复杂的结晶体。3)利用自发平移对称性破缺制备晶体小体。该项目将推动聚合物结晶领域的发展，并产生一个作为定制设计的聚合物纳米颗粒的结晶体资料库。这一裁决反映了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 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.