Confined and Directed Polymer Crystallization at Curved Liquid/Liquid Interface

非技术性总结：雪花和钻石等常见晶体的迷人几何形状是由规则的分子堆积决定的。晶体的最小单元，晶胞，在三维空间中以直线重复自己，以生长这些令人惊叹的物体。 但是，如果晶体形成的可用空间是不平坦的，即弯曲的呢？ 如何容纳单位细胞，结构将如何扭曲？ 当分子进入晶格时，它们必须进行转弯，并且所得晶体的形状和性质将变化。该项目关注这样的场景，旨在了解聚合物晶体如何在非常小和弯曲的空间中形成的基本原理。 PI最近表明，可以通过在液滴表面上结晶聚合物来形成中空晶体胶囊。这些独特的胶囊被称为“晶体体”。在本项目中，溶液结晶将在小液滴中进行。结晶条件和聚合物的分子结构将系统地变化，以控制晶体体的形状和大小，其结构将使用许多先进的仪器技术进行研究。 可以预见，良好控制的晶体体可能会在纳米马达、药物递送和基因治疗等领域中找到应用。该提案的教育部分包括：（1）开发两个将用于高级聚合物表征课程的课程模块;（2）指导研究生和本科生;（3）让高中学生和教师，特别是来自代表性不足的人群的学生和教师参与拟议的研究活动;以及（4）参与当地推广活动，以提高对科学和技术的更广泛兴趣。 技术总结：结晶是自然界中普遍存在的自组装过程。根据定义，结晶意味着单位晶胞在三维（3D）晶格中遵循平移对称性进行自我重复。另一方面，弯曲空间本质上与3D平移对称不相称。最近，PI的小组在细乳液系统中观察到一种独特的结晶形态。发现聚合物结晶被限制在弯曲的液/液界面内并由弯曲的液/液界面引导。 聚合物单晶状胶囊获得和结构模仿熟悉的聚合物囊泡。术语“晶体体”被创造出来描述这种独特的结构，而拟议工作的目标是系统地研究这些奇特晶体体的结构和结晶行为。该提案的具体目的是了解1）微乳液-溶液结晶系统中的单晶生长机制，以及2）这些弯曲晶体体中的晶体结构和链堆积。在这个项目中，各种定制设计的晶体将使用新的细乳液溶液结晶方法制造。这些晶体体的结晶形态和结构将使用X-射线散射，差示扫描量热法，电子显微镜和扫描探针显微镜进行系统研究。 预计该项目将导致更清楚地了解聚合物结晶在纳米级和弯曲的液/液界面的机制。

NON-TECHNICAL SUMMARY:The intriguing geometrical shapes of familiar crystals such as snowflakes and diamond are dictated by regular molecular packing. The smallest unit of the crystal, the unit cell, repeats itself in straight lines across three dimensions to grow these stunning objects. But what if the available space for the crystals to form is non-flat, i.e. curved? How could the unit cells be accommodated and how will the structure be distorted? The molecules have to make turns as they pack into the crystalline lattice, and the shape and properties of the resultant crystals will vary. This project is concerned with such a scenario, and aims to understand the fundamentals on how polymer crystals are formed in a very small and curved space. The PI has recently shown that hollow crystal capsules can be formed by crystallizing polymers on the surface of liquid droplets. These unique capsules are termed "crystalsomes". In this project, crystallization from solution will be conducted in small liquid droplets. Crystallization conditions and the molecular structure of the polymers will be systematically varied to control the shape and size of the crystalsomes, whose structure will be studied using a number of advanced instrumental techniques. It is anticipated that well-controlled crystalsomes may find applications in the fields of nanomotors, drug delivery and gene therapeutics. The educational component of the proposal includes: (1) Developing two class modules which will be used in an Advanced Polymer Characterization course; (2) Mentoring graduate and undergraduate students; (3) Involving high school students and teachers, particularly from under-represented populations, in the proposed research activities; and (4) Engaging in local outreach activities to enhance broader interest in science and technology. TECHNICAL SUMMARY: Crystallization is a ubiquitous self-assembly process in nature. By definition, crystallization implies that a unit cell self-repeats in a three-dimensional (3D) lattice following translational symmetry. A curved space, on the other hand, is intrinsically incommensurate with 3D translational symmetry. Recently, the PI's group observed a unique type of crystalline morphology in a miniemulsion system. Polymer crystallization was found to be confined within and directed by the curved liquid/liquid interface. Polymer single crystal-like capsules were obtained and the structure mimics the familiar polymersomes. The term "crystalsome" was coined to describe this unique structure, and the goal of the proposed work is to systematically investigate the structure and crystallization behavior of these peculiar crystalsomes. The specific aims of the proposal are to understand 1) the single-crystal growth mechanism in miniemulsion-solution crystallization systems, and 2) the crystal structure and chain packing in these curved crystalsomes. In this project, a variety of tailor-designed crystalsomes will be fabricated using the novel miniemulsion solution crystallization method. The crystalline morphology and structure of these crystalsomes will be systematically investigated using X-ray scattering, differential scanning calorimetry, electron microscopy, and scanning probe microscopy. It is anticipated that this project will lead to clearer understanding of the mechanism of polymer crystallization at nanosized and curved liquid/liquid interfaces.