Molecular Manipulation on Crystal Orientation, Phase Transformation and Stability in Nano-Confined Environments using Block Co-polymers and Blends as Templates

本提案的目标是使用嵌段共聚物和共混物作为模板，获得具有不同几何形状和尺寸的纳米环境中的聚合物，以实现对聚合物在这些纳米受限空间中的相变行为的基本理解。主要研究包括几个重要的目标。首先，将设计和合成一系列新的非晶嵌段共聚物和共混物（与阿克伦大学的合成教授合作）。构建这些纳米密闭环境的基本思路是，利用不同的化学结构、分子量和形状，操纵相形态的有序-无序转变温度、非晶态块体的玻璃化转变温度和可结晶块体的结晶温度之间的关系。这些受限的几何形状可以从相对简单的层状、圆柱形和球形几何到复杂的六边形穿孔层、双陀螺仪和逆相。其次，在不同的结晶温度下，在不同的限制几何形状和尺寸下，系统地研究薄膜和块状样品中可结晶块的相取向和结构变化。通过将这些约束样品的结果与相应的无约束聚合物的结果进行比较，可以阐明尺寸和几何形状对相取向和结构的影响。本研究的第三个目标将集中在基于相尺寸的相稳定性反演的概念上。为此，所设计的非晶嵌段共聚物需要具有具有多晶性的可结晶嵌段。通过这种方法，可以定量地了解相的大小和相稳定性之间的关系。本提案中提出的方法不仅通过加强对聚合物相结构和转变的尺寸效应的科学理解而具有价值，而且还将为设计在不同纳米技术中具有所需机械，电气和光学性能的新型纳米材料提供门户。

The goal of this proposal is to obtain polymers confined in nano-environments with different geometric shapes and sizes using block copolymers and blends as templates to achieve a fundamental understanding of how polymers behave during phase transformations in these nano-confined spaces. The main research includes several important objectives. First, a series of new amorphous-crystalline block copolymers and blends will be designed and synthesized (by collaborating with the synthetic professors at Univ. of Akron). The basic idea in constructing these nano-confined environments involves manipulating the relationships among the order-disorder transition temperature of the phase morphology, the glass transition temperature of the amorphous blocks, and the crystallization temperatures of the crystallizable blocks using different chemical structures, molecular weights, and shapes. These confined geometric shapes may range from relatively simple lamellar, cylindrical, and spherical geometries to complex hexagonal perforated layers, double gyroids, and inverse phases. Second, systematic studies of the phase orientation and structural changes of the crystallizable blocks in thin film and bulk samples will be carried out at different crystallization temperatures within various confined geometric shapes and sizes. By comparing the results from these confined samples with those of their corresponding unconfined polymers, the size and geometry effects on the phase orientations and structures can be elucidated. The third objective of this research will concentrate on the concept of phase stability inversion based on the phase size. For this purpose, the designed amorphous-crystalline block copolymers will need to have crystallizable blocks which exhibit polymorphism. With this approach, a quantitative understanding of the relationship between the size of the phase and the phase stability will be attained.The approach presented in this proposal will not only be valuable by enhancing the scientific understanding of the size effect on polymer phase structures and transformations, it will also provide a gateway in designing novel nano-materials that possess desired mechanical, electrical, and optical properties in different nano-technologies.