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

University Of Akron, Akron OH

Investigators

Abstract

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.