: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Progress in preparation, processing and applications of polyaniline

Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

A review of vapor grown carbon nanofiber/polymer conductive composites

A review of recent research on mechanics of multifunctional composite materials and structures

This paper summarizes and reviews the research on electromagnetic interference (EMI) shielding with intrinsically conducting polymers (ICPs), mainly polyaniline (PANI) and polypyrrole (PPY), and their composites in various frequency ranges. ICPs are new alternative candidates for EMI shielding applications due to their lightweight, corrosion resistance, ease of processing, and tunable conductivities as compared with typical metals. More importantly, the dominant shielding characteristic of absorption other than that of reflection for metals render ICPs more promising materials in applications requiring not only high EMI shielding effectiveness but also shielding by absorption, such as in stealth technology. Copyright © 2005 John Wiley & Sons, Ltd.

Intrinsically conducting polymers for electromagnetic interference shielding

Sonochemical synthesis of polyaniline nanofibers.

With unique structure and extraordinary electronic, thermal, and mechanical properties, graphene fascinates the scientific community. Due to its hydrophobic feature, preparation of a stable and highly concentrated graphene dispersion without the assistance of dispersing agents has generally been considered a challenge. Chemical reduction of graphene oxide (GO) is one of the most important methods for preparing a graphene dispersion. The aggregation of graphene sheets is a key reason to destabilize the resulting dispersion during conversion of aqueous GO dispersion to graphene. In this study, by replacing mechanical stirring with ultrasonic irradiation, the aggregation of various intermediates is effectively suppressed during the process of reduction of GO. Hence, a stable graphene dispersion with a high concentration of 1 mg·mL−1 and relatively pure graphene sheets are achieved, and the as-prepared graphene paper exhibits a high electric conductivity of 712 S·m−1. Ultraviolet−visible absorption spectrosco...

Preparation of a Stable Graphene Dispersion with High Concentration by Ultrasound

The thermal stability and pyrolysis mechanism of boron-containing phenolic resins: The effect of phenyl borates on the char formation

A superhydrophobic (SH) surface is usually constituted by a combination of low surface energy substances and micro- and nanometer scale roughness structures. The latter, however, always have poor mechanical strength and require complicated fabrication procedures, seriously hindering the large-scale preparation and industrial application of SH surfaces. In this study, by introducing fluoroalkyl silane modified silica nanoparticles into hydroxyl acrylic resin using a simple spray-coating method, an SH acrylic polyurethane (SAPU) coating with good abrasion resistance and stable adhesion was obtained after cross-linking with polyisocyanate at room temperature. By virtue of the reaction between the silanol groups in silica NPs and the isocyanate groups in the curing agent, the hydrophobic silica NPs were stably anchored into the SAPU resin matrix while constructing hierarchical micro- and nanometer scale roughness structures on the coating surface. The dual characters ensure that the SAPU coating has a static water contact angle (CA) of >160°, a sliding angle of ∼10° and good mechanical properties, which exhibits CAs of >150° after wearing with sandpaper and maintains strong adhesion even after cross-cutting or impacting tests. Moreover, the SAPU coating retains an excellent water-repellent property after 12 h of immersion in hydrochloric acid with pH = 1, and can recover its water-repellent property after 12 h of immersion in sodium hydroxide solution with pH = 14 through hot air blowing. The facile spray-coating method as well as a mild room temperature curing process make this kind of SH coating especially suitable for non-wetting protection or modification of large-scale parts, providing a novel pathway for the development of a high performance SH surface.

Xinli Jing

Papers

Intrinsically conducting polymers for electromagnetic interference shielding

Sonochemical synthesis of polyaniline nanofibers.

Preparation of a Stable Graphene Dispersion with High Concentration by Ultrasound

The thermal stability and pyrolysis mechanism of boron-containing phenolic resins: The effect of phenyl borates on the char formation

Facile preparation of a mechanically robust superhydrophobic acrylic polyurethane coating