PhD Oral Exam - Twinkalben Patel, Chemistry

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

In recent years healable electronics have garnered significant attention for its scope in next-generation electronic devices. In particular, triboelectric nanogenerators (TENGs) which are capable of harvesting energies from mechanical motions have been explored as a promising power source for self-powered devices. TENGs possess the benefits of high performance, convenience, eco-friendliness, and low cost and require great strength and functionality to perform. The incorporation of self-healability into the design of TENG systems could improve their lifetime and durability as well as their energy harvesting capabilities. Dynamic covalent chemistries have been utilized extensively for the development of covalent adaptive networks exhibiting self-healability and reprocessability. However, most approaches require the use of external stimuli to establish the reversibility of broken networks. Therefore, the development of a new strategy for the synthesis of robust networks with the balanced properties of void-filling and mechanical strength is required for value-added applications such as flexible electronics.

Hindered urea bond (urea with a bulky substituent, attached to its nitrogen atom) is a promising dynamic covalent chemistry which undergoes dynamic exchange reaction at mild temperature, with no catalysts. The reaction of a bulky amine with isocyanate allows for a simple design of polyurea self-healing network, further broadening the scope of applications for these materials.

My PhD research has aimed to study self-healing mechanisms of hindered urea chemistry and to design and synthesize new materials that can undergo catalyst-free dynamic exchange reaction and thus autonomously repair cracks and starches at lower temperatures as well as exhibit reprocessability. Furthermore, the developed networks were evaluated for TENG performances to better understand the design principles of self-healable TENGs.