Chain-end functionalized regioregular poly(3-hexylthiophene): Synthesis, characterization, and application as chemical sensors

There exists a synergy between molecular structure and intermolecular organization that leads to the overall properties of a material. It is this combinatory effort that leads to the high conductivity in regioregular poly(3-alkylthiophene) (PAT). In order to fully utilize PAT as a viable conducting material, we must gain an understanding of how both molecular and macromolecular structure manifest in the overall material properties.;We attempt to understand the relationship between molecular and macromolecular structure by investigating the effect of chain-end functional groups on the physical and electrical properties of poly(3-hexylthiophene) (PHT). From X-ray studies, the addition of aromatic functional groups effect the polymer packing and is evident in a change in nanofibril width. By extending the end-groups to polymer chains and synthesizing PMMA-PHT-PMMA triblock copolymers, we wish to interfere with intra-chain charge transfer and can observe the extent of inter-chain charge transfer. Even with 50 mol% insulating material, the triblock copolymer demonstrates some conductivity and transistor action. The pi-pi stacking of the PHT is persistent which is evident in the formation of nanofibrils as well as bulk electrical properties. The nanofibril width increases with length of PMMA indicating an induced alignment of the PMMA. The annealing of triblock copolymer samples disrupts extended pi-pi stacking resulting in a granular morphology and insulator bulk properties. Also, an alternated synthesis of polythiophene triblock copolymer is explored.;Due to polythiophenes excellent electrical properties, PATs have found application in a number of electronic devices. We investigate the use of PATs as the sensing layer in a chemical sensor. Principal component analysis (PCA), a data analysis tool, is utilized in studying the relationship between polythiophene structure and its interaction to a number of analytes. Functional groups on the chain-end add selectivity to the sensing properties of PATs.