Radical polymer-wrapped SWNTs at a molecular level: high-rate redox mediation through a percolation network for a transparent charge-storage material

6-Oxoverdazyl radical polymers with tunable electrochemical properties

6-Oxoverdazyl radical polymers were synthesized and their tunable redox properties studied in solution and the solid-state.

Organic n-type materials for charge transport and charge storage applications

Conjugated materials have attracted much attention toward applications in organic electronics in recent years. These organic species offer many advantages as potential replacement for conventional materials (i.e., silicon and metals) in terms of cheap fabrication and environmentally benign devices. While p-type (electron-donating or hole-conducting) materials have been extensively reviewed and researched, their counterpart n-type (electron-accepting or electron-conducting) materials have seen much less popularity despite the greater need for improvement. In addition to developing efficient charge transport materials, it is equally important to provide a means of charge storage, where energy can be used on an on-demand basis. This perspective is focused on discussing a selection of representative n-type materials and the efforts toward improving their charge-transport efficiencies. Additionally, this perspective will also highlight recent organic materials for battery components and the efforts that have been made to improve their environmental appeal.

Highly-Tunable Polymer/Carbon Nanotubes Systems: Preserving Dispersion Architecture in Solid Composites via Rapid Microfiltration

This research presents a new fabrication method for tailoring polymer/carbon nanotube (CNT) nanostructures with controlled architecture and composition. The CNTs are finely dispersed in polymeric latex, that is, polyacrylate, via ultrasonication, followed by a microfiltration process. The latter step allows preserving the homogeneous dispersion structure in the resulting solid nanocomposite. The combination of microfiltration and proper choice of the polymer latex, particle size, and composition allows the design of complex nanostructures with tunable properties, for example, porosity and mechanical properties. An important attribute of this methodology is the ability to tailor any desired composition of polymer-CNT systems, that is, nanotube content can practically vary anywhere between 0 to 100 wt %. Thus, for the first time, a given polymer/CNT system is studied over the entire CNTs composition, resembling two-phase polymer blends. The polyacrylate in these systems exhibits a structural transition from a continuous matrix (nanocomposite) to segregated domains dispersed within a porous CNTs network. An analogy of this structural transition to phase inversion phenomena in two-phase polymer blends is suggested. The resulting polyacrylate/CNT layers exhibit a percolation threshold as low as 0.04 wt %. Additionally, these nanomaterials show low total reflectance values throughout the visible, NIR and SWIR spectrum at a CNT content as low as 1 wt %, demonstrating their potential applicability for optical devices.

Aqueous electrochemistry of poly(vinylanthraquinone) for anode-active materials in high-density and rechargeable polymer/air batteries

A layer of poly(2-vinylanthraquinone) on current collectors underwent reversible electrode reaction at -0.82 V vs Ag/AgCl in an aqueous electrolyte. A repeatable charging/discharging cycles with a redox capacity comparable to the formula weight-based theoretical density at the negative potential suggested that all of the anthraquinone pendants in the layer was redox-active, that electroneutralization by an electrolyte cation was accomplished throughout the polymer layer, and that the layer stayed on the current collector without exfoliation or dissolution into the electrolyte during the electrolysis. The charging/discharging behavior of the polymer layer in the aqueous electrolyte revealed the capability of undergoing electrochemistry even in the nonsolvent of the pendant group, which offered insight into the nature of the anthraquinone pendants populated on the aliphatic chain. Charging/discharging capability of air batteries was accomplished by using the polymer layer as an organic anode-active material. A test cell fabricated using the conventional MnO(2)/C cathode catalyst exhibited a discharging voltage at 0.63 V corresponding to their potential gap and a charging/discharging cycle of more than 500 cycles without loss of the capacity.