Interest in the memristor has grown in recent years as it shows great promise for a variety of applications such as modelling synaptic response and new computing concepts. The memristor is a passive circuit element that is capable of having multiple conductivity states based on the electrical current that has been previously applied to the device. Traditionally, polymeric memristors have been dominated by bistable devices that only show a high conductivity 'on' state and a low conductivity 'off' state. Poly(2-(9H-carbazol-9-yl)ethyl methacrylate) (PMAK) is a polymer that has been demonstrated to show bistabilty through the conformation changes of the attached carbazole groups. However, in this polymer, the carbazole groups are constrained. Therefore, this work focuses on altering the flexibility of the carbazole groups allowing the polymer to achieve more conductivity states. This is achieved by the lengthening of the alkyl chains connecting the pendant carbazole moieties with the polymer backbone, which allows control over the electrical properties of the device. Carbazole polymers were prepared by two different polymerizations - free radical and reversible addition-fragmentation chain transfer (RAFT), while varying the length of the side chain attaching the carbazole group. These polymers were characterized using nuclear magnetic resonance (NMR) for structure and gel permeation chromatography (GPC) for molecular weight. These polymers were thermally and optically characterized before the polymers where used in the fabrication of two-terminal devices. The voltage-current characteristics of these devices were then studied. These polymers were successfully synthesized, and it was found that the length of the alkyl chains influences the electric properties; however, all these polymers exhibit memristive behaviour of varying degrees.

Polymer synthesis and characterization of methacrylate polymers with pendant carbazole groups

254th National Meeting (2017)

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