Using Piezoelectricity to Develop Syntheses to Access Polymeric Materials via Force

Abstract

Mechanochemistry provides a promising way to make polymer and materials synthesis more sustainable and applicable to diverse systems, allowing for the use of many force sources and the incorporation of various monomers. Particularly, mechanoredox catalysis, utilizing piezoelectricity to do redox catalysis, presents an avenue to develop reactions that mimic traditional redox mechanisms but occur when force is applied. In polymer chemistry, mechanoredox catalysis has been rapidly developed in the last five years, utilizing different force sources and being applied to many polymerizations and materials syntheses. Detailed within this thesis are our reports of BaTiO3-mediated mechanoredox polymerizations utilizing primarily aryl iodonium salts, readily accessible and functionalizable radical initiators; the required force can be generated within ultrasound baths, ball mills, and vortexers. Mechanoredox polymerizations can require very little solvent, allowing for less waste and incorporation of immiscible monomers. Both free and reversible deactivation radical polymerizations are demonstrated, and while much of the work presented focuses on industrially-relevant polyacrylates and polymethacrylates, it is established that more challenging monomers can be incorporated into polymer systems. Block copolymers can be made with traditionally compatible and incompatible monomer systems, some with unique self-assembly properties useful for the development of electronic devices. Additionally, composite materials with acrylates and BaTiO¬3 nanoparticles are made via free radical mechanoredox polymerization, both with and without the incorporation of crosslinkers. The methods developed throughout these thesis projects also show less energy consumption than traditional stimulus, increasing the sustainability profile of mechanoredox catalysis.