Jared F. Mike

Oxidatively stable polyaniline:polyacid electrodes for electrochemical energy storage

Conjugated polymers, such as polyaniline, have been widely explored as sensors, electrodes, and conductive fillers. As an electrode material in electrochemical energy storage systems, polyaniline can be subject to irreversible oxidation that reduces cycle life and electrode capacity, thus, limiting its widespread application. Here we present a simple route to produce and prepare polyaniline-based electrodes that are oxidatively stable up to 4.5 V vs. Li/Li(+). The route uses a polyacid to stabilize the fully oxidized pernigraniline salt form of polyaniline, which is normally highly unstable as a homopolymer. The result is an organic electrode of exceptionally high capacity, energy density, power density, and cycle life. We demonstrate that the polyaniline:polyacid electrode stores 230 mA h g(-1) of polyaniline for over 800 cycles, far surpassing homopolymer polyaniline under equivalent conditions. This approach provides a highly stable, electrochemically reversible replacement for conventional polyaniline.

An Efficient Synthesis of 2,6-Disubstituted Benzobisoxazoles: New Building Blocks for Organic Semiconductors

2,6-Disubstituted benzobisoxazoles have been synthesized by a highly efficient reaction of diaminobenzene diols with various orthoesters. The scope of this new reaction for the synthesis of substituted benzobisoxazoles has been investigated using four different orthoesters. The utility of these compounds as building blocks for the synthesis of conjugated polymers is demonstrated.

Facile synthesis of 2,6-disubstituted benzobisthiazoles: functional monomers for the design of organic semiconductors.

The synthesis of several synthetically useful 2,6-disubstituted benzobisthiazoles is described. The method is based on the Lewis acid-catalyzed ring-closing reaction between substituted orthoesters and diamino benzene dithiol. The resulting benzobisthiazoles are obtained cleanly and in good yields. These materials are of interest for the development of new organic semiconductors.

Efficient synthesis of benzobisazole terpolymers containing thiophene and fluorene

We report the synthesis and lumuminescence properties of three novel polymers composed of 9,9-dioctylfluorene and a donor–acceptor-donor (D–A-D) triad of a benzobisazole moiety sandwiched between two octylthiophenes. The requiste monomers, 2,6-bis(5-bromo-3-octylthiophen-2-yl)-benzobisazoles were obtained efficiently via the Lewis acid catalyzed cyclization of 2-bromo-3-octyl-5-(triethoxymethyl)thiophene and the corresponding diamino diols or dithiols. The polymers were synthesized in excellent yield by the Suzuki coupling reaction between the D–A-D benzobisazole monomers and 9,9-dioctylfluorene bisboronic acid. Alkyl side chains provided the polymers with solubility in common organic solvents, enabling characterization using gel permeation chromatography, 1H NMR, UV-Vis and fluorescence spectroscopy. The polymers have optical bandgaps of 2.43–2.63 eV and HOMO levels at −5.54 to −5.65 eV relative to vacuum as determined by UV visible and photoelectron spectroscopy respectively. Light-emitting diodes using blends of the copolymers in a poly(N-vinyl carbazole) matrix yielded blue-green emission with luminous efficiencies of 0.86 Cd/A at ∼505 nm. This efficient and high-yielding route is a promising approach for the synthesis of polymers containing benzobisazole moieties.

Highly Flexible Self-Assembled V2O5 Cathodes Enabled by Conducting Diblock Copolymers.

Mechanically robust battery electrodes are desired for applications in wearable devices, flexible displays, and structural energy and power. In this regard, the challenge is to balance mechanical and electrochemical properties in materials that are inherently brittle. Here, we demonstrate a unique water-based self-assembly approach that incorporates a diblock copolymer bearing electron- and ion-conducting blocks, poly(3-hexylthiophene)-block-poly(ethyleneoxide) (P3HT-b-PEO), with V2O5 to form a flexible, tough, carbon-free hybrid battery cathode. V2O5 is a promising lithium intercalation material, but it remains limited by its poor conductivity and mechanical properties. Our approach leads to a unique electrode structure consisting of interlocking V2O5 layers glued together with micellar aggregates of P3HT-b-PEO, which results in robust mechanical properties, far exceeding the those obtained from conventional fluoropolymer binders. Only 5 wt % polymer is required to triple the flexibility of V2O5, and electrodes comprised of 10 wt % polymer have unusually high toughness (293 kJ/m3) and specific energy (530 Wh/kg), both higher than reduced graphene oxide paper electrodes. Furthermore, addition of P3HT-b-PEO enhances lithium-ion diffusion, eliminates cracking during cycling, and boosts cyclability relative to V2O5 alone. These results highlight the importance of tradeoffs between mechanical and electrochemical performance, where polymer content can be used to tune both aspects.