Guoqiang Ding

Non-volatile polymer electrolyte based on poly(propylene carbonate), ionic liquid, and lithium perchlorate for electrochromic devices.

A series of solvent-free ionic liquid (IL)-based polymer electrolytes composed of amorphous and biodegradable poly(propylene carbonate) (PPC) host, LiClO4, and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)) were prepared and characterized for the first time. FTIR studies reveal that the interaction between PPC chains and imidazolium cations weakens the complexation between PPC chains and Li(+) ions. Thermal analysis (DSC and TGA) results show that the incorporation of BMIM(+)BF4(-) into PPC/LiClO4 remarkably decreases the glass transition temperature and improves the thermal stability of the electrolytes. AC impedance results show that the ionic conductivities of the electrolytes are significantly increased with the increase of BMIM(+)BF4(-) amount, the ambient ionic conductivity of the electrolyte at a PPC/LiClO4/BMIM(+)BF4(-) weight ratio of 1/0.2/3 is 1.5 mS/cm, and the ionic transport behavior follows the Arrhenius equation. Both PPC/LiClO4/BMIM(+)BF4(-) and PPC/BMIM(+)BF4(-) electrolytes were applied in electrochromic devices with polyaniline as the electrochromic layer. The PPC/LiClO4/BMIM(+)BF4(-)-based device exhibits much better electrochromic performance in terms of optical contrast and switching time due to the presence of much smaller cations.

Layer-by-layer assembled sulfonated-graphene/polyaniline nanocomposite films: enhanced electrical and ionic conductivities, and electrochromic properties

In this article, we report the facile synthesis of sulfonic acid-grafted reduced graphene oxide (S-rGO) using a one-pot method under mild conditions, and layer-by-layer (LbL) assembly and electrochromic properties of S-rGO/polyaniline (S-rGO/PANI) nanocomposite thin films. It was found that the multilayer films of S-rGO/PANI exhibit much faster electrochromic switching kinetics than that of corresponding spin-coated PANI thin films. The enhancement can be attributed to the drastically increased electrical and ionic conductivities of the S-rGO/PANI films brought by the graphitic structure of the S-rGO sheets and the sulfonic acid groups attached to S-rGO, which lead to non-diffusion-controlled redox processes of PANI.

Electrofluorochromic detection of cyanide anions using a benzothiadiazole-containing conjugated copolymer

Selective detection of cyanide anions is realized via electrofluorochromism of a benzothiadiazole-containing conjugated copolymer because oxidative fluorescence quenching induced by positive potentials can be significantly weakened by interaction between nucleophilic cyanide and electron-deficient benzothiadiazole.

Near-infrared responsive conjugated polymers to 1.5 μm and beyond: synthesis and electrochromic switching application.

Azulene-containing conjugated polymers with near-infrared absorption up to 1.5 μm and beyond are achieved by treating with trifluoroacetic acid (TFA). Density functional theory calculations reveal that the near-infrared absorption arises from a strong intramolecular charge transfer transition on the polymer backbone, and the near-infrared absorption can be tuned by the degree of protonation. Furthermore, TFA treated polymers show a ten-fold enhancement in electrochromic contrast and significantly improved switching stability, suggesting that these polymers are promising candidates for fabrication of the first generation organic near-infrared devices.

Supercritical Carbon Dioxide-Treated Electrospun Poly(vinylidene fluoride) Nanofibrous Membranes: Morphology, Structures and Properties as an Ionic-Liquid Host

A reverse-barrier technique is used to enable the treatment of electrospun poly(vinylidene fluoride) nanofibrous membranes with supercritical carbon dioxide. The treatment induces the formation of nanopores and extended-chain β crystallites of small lateral dimensions in the nanofibers. It also creates interfiber junctions, resulting in a remarkable improvement in mechanical properties of the membranes. The treated membranes are able to retain their shape very well after loading with an ionic liquid (IL). The ionic conductivity of the IL-loaded membrane is very close to that of the neat IL.

Nacre-like composite films based on mussel-inspired ‘glue’ and nanoclay

Inspired by the brick-and-mortar structure of nacre and catechol–ferric ion complexes in marine mussel adhesive fibers, we utilized polydopamine (PDA) as “super glue” and clay nanosheets as “bricks” to fabricate nacre-like polydopamine-coated clay (D-clay) films using a simple vacuum filtration-assisted assembly method. The D-clay films were subsequently immersed in an aqueous solution of Fe3+ ions, allowing Fe3+ ions to diffuse in and cross-link the nanosheets. The morphologies and structures of D-clay and D-clay/Fe3+ films were characterized using field emission scanning electron microscopy, energy dispersive X-ray element mapping and two-dimensional X-ray diffraction. The results show that the diffusion of Fe3+ ions into the D-clay films induces morphological rearrangement of the D-clay platelets, leading to improved alignment and denser packing of the platelets in the films. Synergic combination of the improved packing structure and strong cross-linking coordination bonds result in significantly enhanced mechanical properties for the D-clay/Fe3+ films. Moreover, the nacre-like nanocomposite films exhibit excellent fire-shielding properties upon exposure to open flame as PDA can be easily carbonized in the combustion process.

Electrofluorochromic Detection of Cyanide Anions Using a Nanoporous Polymer Electrode and the Detection Mechanism

An electrofluorochromic (EFC) conjugated copolymer (PEFC) containing carbazole and benzothiadiazole (BTD) moieties is synthesized through Suzuki coupling followed by electrochemical polymerization, resulting in a nanoporous EFC polymer electrode. The electrode exhibits high sensitivity and selectivity in the EFC detection of cyanide anions (CN(-)) in largely aqueous electrolyte (67 vol % water) because electrochemical oxidation of PEFC leads to significant fluorescence quenching, and the presence of different concentrations (1 to 100 μM) of CN(-) in the electrolyte can weaken the oxidative quenching to substantially different extents. Although PEFC is hydrophobic in the neutral state, it is converted to radical cation/dication states upon oxidation, rendering the PEFC some hydrophilicity. Moreover, its nanoporous morphology provides a large surface area and short diffusion distance, facilitating the movement of CN(-) in the electrolyte into the PEFC film to interact with receptors. Density functional theory calculations show that the noncovalent interaction between electron-deficient BTD and nucleophilic CN(-) is energy favorable in the oxidized states in both aqueous and organic media, suggesting that the specific π(-)-π(+) interaction plays the main role in the CN(-) detection.