Synthesis of Stable Open-shell Moieties and Polymers for Charge Transfer Applications
Open-shell small molecules and non-conjugated polymers containing open-shell moieties as pendant groups have been of significant interest lately with regards to liquid crystalline materials, polymerization initiators, and in electrical conductivity applications. The research presented in this thesis focuses on the latter application and especially on tuning the optoelectronic properties of a novel class of small molecules viz. the 6-oxoverdazyl radicals and, as a result, is broadly divided into two parts. The former part consists of designing a low glass transition temperature polymer for attainment of high electrical conductivity values not reported previously for non-conjugated pendant radical polymers. The high conductivity value results from the low glass transition temperature of the polymer, which allows for thermal annealing. In turn, this causes the formation of a percolation network of pendant nitroxyl moieties. The alignment that occurs on annealing at a temperature higher than its glass transition temperature leads to the formation of a redox-active site network thus facilitating the charge transfer. The latter part of the thesis deals with the design and functional group modification of the 6-oxoverdazyl species. The modification aims at tuning the opto-electronic properties of the radical small molecule species and also to induce stacking amongst the molecules thereby reducing the effective distance between them. The latter half of the thesis also encompasses miscellaneous projects involving synthesis of an open-shell ligand species for the construction of a radical perovskite structure and fabrication of a poly(3-alkyl thiophene)-b-poly(2,2,6,6-tetramethylpiperidinyl-N-oxyl methacrylate) [P3AT-b-PTMA] di-block polymer.
Boudouris, Purdue University.
Organic chemistry|Polymer chemistry
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