Conductive Polymer Nanosheets Generated from the Crystal Surface of an Organic Oxidant

Abstract

Morphology control of conductive polymers contributes to improvinge lectrochemical properties based on their redox-active nature.I ng eneral, it is not easy to achieves imultaneous synthesis and morphologyc ontrol of conductive polymers because of their low solubility and processability.H ere the crystal surfaceo fa no rganic oxidativea gent is used for simultaneous synthesis and morphogenesis of the conductive polymerp olypyrrole (PPy) under mild conditions. The oxidant crystal plays multiple roles, serving as the reactionfield to supply the oxidative agent, the template forcontrol of hierarchical morphology, and the source of dopant, with diffusion of the monomer vapor under low temperature and ambientp ressure. Ah ollow plate-like morphologyc onsisting of the PPy nanosheets was obtained from crystalso fq uinone derivatives through oxidative polymerization in high yield. The resultant PPy nanosheets showedi mproved conductivity without furtherd oping and enhanced electrochemical properties as an active materialo f redox capacitors. The present approach using the crystal surface can be applied to avariety of polymerizationsystems.The designa nd synthesiso fp olymers and macromolecules have been studied on the molecular scale for the development of functional materials. [1] On al arger scale, the morphologyo f functional materials contributes to enhancing their properties. [2] Conductive polymers with a p-conjugated backbone have av ariety of applications based on their photochemical, electronic,a nd electrochemical properties. [3] When conductive polymers are applied to charge-storage devices owing to their redox-active nature, the morphologies from the nanometer to the micrometer scale affect the electrochemical properties. [4] The nanoscale morphologies contribute to an increase in the specific surfacea rea. In addition, sufficient interspace on the sub-micrometer scale is necessary for the diffusion of electrolytes. However,i ti sn ot easy to control the hierarchical morphologies of conductive polymers because of their low solubility and processability,o riginating from the rigid p-conjugated chain. New rational and versatile approaches are required to achieve the simultaneous synthesis and morphogenesis. In the presentw ork, the surface of an organic oxidant crystal induced formation of ah ollow plate consisting of the PPy nanosheets upon diffusion of the monomer vapor.T he organic oxidant crystal plays an important role for the simultaneous synthesis and morphogenesis throughas olvent-and metal-free route under mild conditions. Chemical oxidative polymerization in the liquid phase is used to for morphology control of conductive polymers. [5] Improvede lectrochemical properties can be achieved by morphologyc ontrolu sing templates and additive molecules. [6] For example, PPy nanowires and hollow nanorods were synthesized by using surfactant templates. The resultant PPy showed enhanced electrochemical properties as an active material of redox capacitors. [4a-c, 6] PPy nanosheets were synthesized in the...

Polythiophene Doping of the Cu-Based Metal–Organic Framework (MOF) HKUST-1 Using Innate MOF-Initiated Oxidative Polymerization

“…From Figure , we expect the rate of polymerization of PEDOT to be particularly rapid, always outstripping that of unsubstituted thiophenes. In a hypothetical limiting case where polymer growth is extremely rapid compared to the rate of diffusion into the MOF, the polymer will be deposited exclusively on the crystal surface, similar to reactions reported with solid (nonporous) organic oxidizing agents . This simple analysis implies that, in general, monomers comprised of easily oxidized single arene units such as EDOT will tend to form surface coatings of polymer rather than host–guest structures in redox-active MOFs.…”

“…In a hypothetical limiting case where polymer growth is extremely rapid compared to the rate of diffusion into the MOF, the polymer will be deposited exclusively on the crystal surface, similar to reactions reported with solid (nonporous) organic oxidizing agents. 59 This simple analysis implies that, in general, monomers comprised of easily oxidized single arene units such as EDOT will tend to form surface coatings of polymer rather than host−guest structures in redox-active MOFs. The analysis also implies that it may be possible to switch a monomer from surface-initiated polymerization to interior polymerization by absorbing the monomer into the MOF at a low temperature, followed by a temperature jump to induce polymerization, if the energy of adsorption of the monomer on the MOF is significantly lower than the barrier to the excitation represented in Figure 17.…”

Influence of Postsynthesis Heat Treatment on Vapor-Phase-Polymerized Conductive Polymers

“…All samples exhibited a drop in conductivity during postpolymerization heat treatment, accompanied by an increase in film thickness. Thicker films are most likely the result of residual monomer being present within the oxidant (and/or polymer) layers , as the substrates are removed from the VPP chamber. While exposed to the heat treatment, the polymerization process is able to continue.…”

Experiment‐Oriented Materials Informatics for Efficient Exploration of Design Strategy and New Compounds for High‐Performance Organic Anode

“…Molecular structures and morphologies have impact on electrochemical properties of organic electrodes. In our previous works, electrochemical properties of conjugated polymers and redox‐active molecules were improved by the morphology control from nanometer to micrometer scales . Nanoscale morphologies play important roles for diffusion behavior of charge carriers .…”