Tingyang Dai

Controlled growth of polypyrrole nanotubule/wire in the presence of a cationic surfactant

We describe herein a new facile approach to control the size and morphology of polypyrrole (PPy) nanotubular/wire structures in the presence of a cationic surfactant. The fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self-degraded template for the formation of polypyrrole nanotubules, was modified by cetyltrimethylammonium bromide (CTAB), which plays a dual role of adjusting the size of the seed template and providing an expanded region for the growth of polypyrrole. The modified template itself reacted oxidatively with pyrrole monomers to effectively construct nanotubular/wire structures with high yield. The effect of the concentration of CTAB on the initial template and subsequent polymerization process of pyrrole was investigated systematically. In the case of introducing anionic surfactant sodium dodecyl sulfate (SDS) into the system, the MO–FeCl3 template was etched, resulting in a congregation of polypyrrole nanotubes and granules.

Facile fabrication of conducting polymer hydrogels via supramolecular self-assembly

We describe a simple and versatile method to fabricate conducting polymer hydrogels via supramolecular self-assembly between polymers and multivalent cations; the as-prepared hydrogels are potentially applicable in the fields of electrosensors, chemical release and artificial muscles.

Capacitance performances of supramolecular hydrogels based on conducting polymers

The capacitance performances of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) supramolecular hydrogels have been investigated systematically. The materials show a specific capacitance of 67 F/g and display excellent rate capability at the scan rate as high as 5000 mV/s in the cyclic voltammogram measurements, accompanied by good cycle stability. On the basis of the measurements of the microscale morphologies, specific areas and electrical conductivities, the mechanisms for the improvement of the electrochemical properties are discussed and ascribed to the novel porous microstructures of the hydrogels and the synergetic effect of the rigid PEDOT and soft PSS components. Furthermore, polyaniline (PAn) is compounded with the PEDOT-PSS hydrogels through an interfacial polymerization process, endowing the hydrogel materials with a higher specific capacitance of 160 F/g at the scan rate of 5000 mV/s. The significance of this work lies in the demonstration of a novel method to solve the problems of conducting polymers in electrochemical applications.

Preparation, characterization and application of polyaniline/epoxide polysiloxane composite films

Composites of polyaniline (PAn) and epoxide polysiloxane (EPSi) are reported for the first time. EPSi is designed, synthesized and N-grafted onto the PAn backbone through covalent bonds. As-prepared EPSi-g-PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%–100% and the selectivity as high as 84%–98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.

Sequential Polymer Precipitation of Core–Shell Microstructured Composites with Giant Permittivity

Polymeric core-shell microstructures have been constructed through a new method, namely sequential precipitation, which is intrinsically a self-assembly and phase separation process. High-quality poly(vinyldene fluoride)-polycarbonate-lithium perchlorate composite films with spherical core-shell microstructures have been prepared and determined to consist of conducting cores and insulating shells. Because of the percolation effect, the resulting materials present a dielectric constant as high as 10(4) -10(7) at the threshold.

Poly(tetrafluoroethylene) composite membranes coated with urchin-like polyaniline hiberarchy: preparation and properties

Spiny polyaniline (PANI) spheres (urchin-like) were coated on a poly(tetrafluoroethylene) (PTFE) membrane via a counter-diffuse interfacial oxidation polymerization of aniline in an aqueous medium. The produced composite membrane has both unexpected superhydrophilicity and conductivity. The microstructure and morphology of the composite membrane were characterized by FTIR, UV-vis, XRD, TGA, and SEM. Effects of reagent concentrations and polymerization time on the membrane morphology and properties were studied systematically. A possible formation mechanism of the urchin-like polyaniline nanospheres on PTFE surface has been briefly discussed. The co-effect of both spherical micelles formed by Nafion and nanofibrous micelles formed by aniline/p-toluenesulfonic acid was considered to be a reason to produce the urchin-like PANI nanospheres. The PTFE/Nafion/PANI composite membrane showed a convertible hydrophilic/hydrophobic feature via adjusting acidity/alkalinity of an aqueous medium and also was able to adsorb heavy metal-ions from the medium.

Self-Assembled Core-Shell Polymer Dielectric Prepared by Solution Casting Process

ABSTRACT Giant permittivity at 1 MHz, which slightly changes with temperatures, is observed in a polymer composite. The dielectric spectroscopy demonstrates that the samples are electrically heterogeneous. The microstructure observation and the ingredient analysis evidence they self assemble the conducting cores surrounded by the insulating shells. The giant-dielectric phenomenon is therefore attributed to the percolation effect. The electrically heterogeneous microstructure with effective permittivity values about 10 000 can be fabricated by a simple solution casting process in air. The composite is an attractive option to the currently used printing dielectric and the future flexible electronics.