Design of nitroxide-based radical polymer materials for electronic applications

Martha E Hay, Purdue University

Abstract

Radical polymers represent a new class of organic electronic materials that rely on an oxidation-reduction (redox) reaction to transport charge. That is, stable radical sites pendant to the polymer backbone communicate electronically through a rapid oxidation-reduction reaction. This redox mechanism has previously been established as effective for charge-storage applications (e.g., secondary batteries). When applied in the solid state, radical polymers demonstrate electrical conductivity on par with that of first-generation conjugated polymer electronic materials. This initial success has prompted interest in developing design rules for radical polymers. Specifically, this thesis explores the impact of radical density in a polymer blend system of poly(2,3-bis(2’,2’,6’,6’-tetramethylpiperidinyl- N-oxyl-4’-oxycarbonyl)-5-norbornene) (PTNB) and its non-functional counterpart on electrical conductivity. An exponential decay of electrical conductivity is established as a function of decreasing radical density, which also corresponds to decreased proximity of radical sites. It is proposed that quantum tunneling would support this exponential relationship, as well as the observed temperature-independence of electrical conductivity in the radical polymer system. Moving forward, we propose exploring the handles known to be critical in the quantum tunneling system, and thus anticipate elucidating the impact of these handles to allow for improved design of next generation radical polymer materials.

Degree

M.S.Ch.E.

Advisors

Boudouris, Purdue University.

Subject Area

Chemical engineering|Materials science|Plastics

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