Theses and Dissertations
ORCID
https://orcid.org/0000-0002-0347-0353
Advisor
Scott, Colleen N.
Committee Member
Wipf, David O.
Committee Member
Mlsna, Todd
Committee Member
Montiel-Palma, Vicky
Committee Member
Santanu, Kundu,
Date of Degree
12-12-2025
Original embargo terms
Embargo 2 years
Document Type
Dissertation - Open Access
Major
Chemistry
Degree Name
Doctor of Philosophy (Ph.D.)
College
College of Arts and Sciences
Department
Department of Chemistry
Abstract
The design and synthesis of intrinsically conductive polymers (ICPs) require a fundamental understanding of how structural modifications influence material performance. Polyaniline (PANI), as a prototypical ICP, is well known for its versatile redox chemistry, environmental stability, and wide range of applications. However, translating its intrinsic molecular properties into advanced functional materials requires precise control over structure-property relationships. Specifically, backbone modifications, side-chain substituents, and morphology all affect the processability, conductivity, electrochemical behavior, and thermal stability. This dissertation systematically explores these relationships through backbone engineering, side-chain functionalization, and processing as thin films and electrospun fibers. Chapter I provides an overview of the historical development of conjugated polymers, with a specific focus on PANI and its derivatives, emphasizing the role of dopants, structural modifications, and applications. Chapter II describes the synthesis and analysis of nine phenothiazine-based PANI (PTZ-PANI) derivatives prepared. via the Buchwald-Hartwig coupling reaction. These derivatives incorporate various alkyl and aryl side chains on the phenothiazine core and methyl groups on the aryl backbone. The steric effects of the pendant groups significantly influence packing and conductivity, as bulky substituents disrupt π-π interactions, while rigid groups facilitate charge transport. Chapter III reports on the electrospinning processing of PTZ-PANI derivatives into uniaxial and coaxial fibers, revealing that coaxial architectures exhibit better chain alignment, higher glass-transition temperatures, and improved electrochemical activity. Chapter IV examines six biphenyl-phenothiazine-bridged PANI derivatives (PB-PANI), designed with various steric and electronic substituents around the biphenyl group. Substituent-dependent changes were identified using UV-Vis-NIR, CV, PXRD, and DSC analyses, establishing a strong link between electronic effects and functional performance. Selected derivatives also demonstrate promising activity in electrochemical sensing of biological analytes. Chapter V presents the synthesis of a fluorene-based PANI derivative (FL-PANI) and compares it with other fused-ring analogues containing carbazole, phenothiazine, and phenoxazine units. Incorporation of the fluorene core leads to the highest molecular weight, improved electrochemical and thermal stability, and highly reversible redox behavior. Chapter VI covers future perspectives, including expanding the substituent library, employing computational modeling and machine learning for predictive design, and pursuing device-level integration. Overall, this study demonstrates that systematic backbone and side-chain engineering, in conjunction with precise morphological control, enables the establishment of robust structure-property relationships that advance intrinsically conducting polymers toward practical applications in optoelectronic, sensing, and energy-related devices.
Sponsorship (Optional)
NSF Career (CHE-1945503)
Recommended Citation
Giri, Hari, "Structure-property relationships of phenothiazine-based polyaniline derivatives" (2025). Theses and Dissertations. 6777.
https://scholarsjunction.msstate.edu/td/6777
