Semiconducting polymers are a special class of macromolecules that can conduct electrical currents and absorb or emit light. These polymers are used in a wide range of electronic devices, including light-emitting diodes, solar cells, transistors, and many others. This CAREER project is concerned with melt-processable semiconducting polymers, a departure from the current focus of solution-processed polymers (which usually involve toxic and environmentally harmful solvents for processing). Specifically, the proposal research is to explore, understand, and optimize flow-induced orientation in melt-processed semiconducting polymer blends and its impact on mechanical and electronic properties. Successful execution of this project could lead to a greener and more sustainable future for organic electronics. The educational objective of the CAREER plan is to build a dynamic polymer program at Purdue University for educating next generation polymer chemists, as well as for raising the public awareness about polymer science and engineering. Specifically, the PI will integrate polymer chemistry and laboratory into undergraduate and graduate curricula, and organize the Notre Dame - Purdue Annual Symposium on Soft Matter and Polymers in collaboration with local high schools. Further, the PI plans to adapt new technological tools (i.e. interactive online Apps that K-12 students and the general public nowadays prefer to interact with) for outreach activities.
The CAREER proposal seeks to understand the nature of flow-induced chain alignment and the resulting morphology and its impact on optical, electronic and mechanical properties in melt-processed complementary semiconducting polymer blends (c-SPBs). Flow-induced crystallization has long been an important subject in conventional (insulating) polymer processing, but little is known in a semiconducting polymer melt. In this project, the PI will make melt-processable c-SPBs and study flow-induced structure formation in order to establish the structure-property-processing relationship. In phase I of the project, the PI will synthesize a wide range of semiconducting polymers that can be melted at desired temperatures. Phase II is concerned with elucidating the nature of flow-induced oriented structures and thin-film morphologies in polymer melts by in-situ rheo-optical and rheo-X-ray techniques, among other morphological tools. Phase III is aimed to correlate flow-induced morphologies with their electronic and mechanical properties in aligned fibers or thin films of polymer blends. This project aims to: 1) rationalize the molecular design principles for melt-processable semiconducting polymers, 2) reveal the role of flow-induced crystallization in polymer thin-film morphology development, and 3) offer a fundamental correlation between flow-induced morphologies and important materials properties. The long-term goal of this project is to develop high-performance melt-processable c-SPBs and enable melt-processing of semiconducting polymers for future organic electronics, complementary to or advantageous over current solution-processed approaches.
