Date of Award
Summer 7-2022
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
School
Polymer Science and Engineering
Committee Chair
Derek L. Patton
Committee Chair School
Polymer Science and Engineering
Committee Member 2
Sarah E. Morgan
Committee Member 2 School
Polymer Science and Engineering
Committee Member 3
Yoan C. Simon
Committee Member 3 School
Polymer Science and Engineering
Committee Member 4
Sergei Nazarenko
Committee Member 4 School
Polymer Science and Engineering
Committee Member 5
James W. Rawlins
Committee Member 5 School
Polymer Science and Engineering
Abstract
With plastic production poised to increase in coming years, there arises a need to develop new polymeric materials designed to combat the global pollution crisis. A commonly utilized approach in addressing this challenge is to employ a responsive functional moiety into the polymer architecture. Thiol-X reactions, a commonly utilized class of “click” reactions, have garnered broad implementation in new stimuli-responsive materials. This work specifically focuses on utilizing radical-mediated thiol-ene coupling and base-catalyzed thiol-isocyanate reactions to develop a library of ternary thiol-ene/thiourethane covalent adaptable networks (CANs) and hydrolytically labile poly(thioether ketal) thermoplastics. CANs are a class of network materials capable of undergoing dynamic exchange, rendering the material reprocessable while maintaining the high-performance properties traditionally associated with thermosets. Herein, the thiourethane moiety, formed via the thiol-isocyanate reaction, is employed as the dynamic covalent chemistry (DCC) utilized in our approach to CANs. Additionally, linear thiol-ene photopolymerizations are employed to develop a series of poly(thioether ketal) thermoplastics. The ketal moiety incorporated into the polymer backbone of these materials render the resulting material hydrolytically labile – allowing the material to readily degrade at its end-of-lifetime. The work presented herein should provide a framework by which new environmentally friendly materials can be developed.
Chapter I of this dissertation focuses on the various utility of thiol-X reactions within the realm of polymeric materials – with specific interest on implementation within CANs and thermoplastic synthesis. Chapter II outlines the methods by which the thiol-X based materials, described herein, were developed and studied. Chapter III focuses on understanding the specific structure-property relationship of ternary thiol-ene/thiourethane CANs affecting vitrimeric relaxation behaviors and material property retention throughout reprocessing. Chapter IV elaborates on the stoichiometric effects of ternary thiol-ene/thiourethane on the dynamic exchange equilibrium – ultimately dictating thermal relaxation behaviors. Finally, Chapter V utilizes linear thiol-ene photopolymerizations to develop a library of poly(thioether ketals) capable of undergo hydrolysis within an acidic environment while remaining stable in basic and neutral conditions.
Recommended Citation
Sloan, Reese, "DESIGNING DYNAMIC AND DEGRADABLE POLYMERIC MATERIALS WITH THIOL-X CHEMISTRIES" (2022). Dissertations. 2063.
https://aquila.usm.edu/dissertations/2063
Included in
Materials Chemistry Commons, Organic Chemistry Commons, Physical Chemistry Commons, Polymer Chemistry Commons