Date of Award
Doctor of Philosophy (PhD)
Conducting polymers are organic semiconductors characterized by conjugated backbones (alternating single-double bonds) that enable mixed ionic-electronic conductivity. Their polymeric nature, tunable band structure and reversible redox capability have demonstrated fundamental advances in the fields ranging from electrochemical energy storage, sensing, to electro/photo catalysis and neuromorphic engineering. Conjugated backbones, the origin of all the unique physical and chemical properties associated with conducting polymers, prevent their solubility due to high lattice energy which hinders processing. Current solution utilizes a long-chain polymer (PSS) as dopants to render conducting polymer water dispersible (PEDOT:PSS). Nonetheless, PSS is highly acidic and hydrophilic limiting applicability with acid-incompatible or hydrophobic materials and surfaces. An attractive alternative of liquid solution is a liquid dispersion of submicron particles that overcomes insolubility restrictions associated with conducting polymers. However, compared to thin films, conducting polymer submicron particles with high electrical conductivity is far less established.This thesis focuses on developing and optimizing synthesis of highly conductive PEDOT submicron particles and subsequently demonstrates advanced processability in non-aqueous solvents where PEDOT:PSS phases separates preventing processing. Synthetic technique developed in this work is named as aerosol vapor polymerization where oxidant solution is aerosolized and liquid EDOT monomer is vaporized; resulted PEDOT particles have a spherical shape templated by the air-suspended droplets and possess the highest reported electrical conductivity. PEDOT particles readily form colloidal dispersions in organic solvents enabling developing of pH sensitive thermoplastics and temperature sensitive sulfur concrete. An organic ink is developed to conformally coat 3D prints and particle nature enable engineering of strain sensor and high efficiency NIR photothermal coating promising for light induced surface sanitization. Moreover, mixed ionic-electronic conductivity leads to development of an ion-exchange membrane proofing the concept of particle-based ion conduction mechanism. Another part of this dissertation focuses on building scientific instruments using “Do it yourself” (DIY) concept. A 3D printed four-point probe systems reduces the instrumental cost from $ 5000 down to less than $100.
Julio M. D'Arcy
Pratim Biswas, Alexandra L. Rutz, Bryce Sadtler, Srikanth Singamaneni,