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Yang D.,Beijing Institute of Petrochemical Technology | Yang D.,Beijing Key Laboratory of Special Elastomeric Composite Materials | Huang S.,Beijing Key Laboratory of Special Elastomeric Composite Materials | Huang S.,Beijing University of Chemical Technology | And 12 more authors.
RSC Advances | Year: 2015

In order to improve compatibility between the dielectric filler and polymeric matrix, we used bio-inspired polydopamine (PDA) to modify titanium dioxide (TiO2) nano-particles. The PDA coated TiO2 (TiO2-PDA) nano-particles were incorporated into nitrile-butadiene rubber (NBR) which contains a large amount polar groups to obtain a dielectric elastomer composite with a large actuated strain under a low electric field. The relatively soft insulating PDA layer on the TiO2 nano-particles led to the composites filled with TiO2-PDA nano-particles displaying better filler dispersion, much lower elastic modulus, lower dielectric loss, and higher electric breakdown field compared with the composites filled with pristine TiO2 nano-particles, resulting in a high electromechanical sensitivity (β). At last, an actuated strain of 5.2% at a relatively safe electric field of 12.5 kV mm-1 without any pre-strains was obtained by the 10 phr TiO2-PDA/NBR composite, a 140% increase in actuated strain compared with the actuated strain (0.69%) of pure NBR at 20 kV mm-1 without any pre-strains. This biomimetic method is simple, efficient, nontoxic, and easy to control, which can be used in other dielectric fillers to improve electromechanical properties of dielectric elastomers. © 2015 The Royal Society of Chemistry. Source


Yang D.,Beijing Institute of Petrochemical Technology | Yang D.,Beijing Key Laboratory of Special Elastomeric Composite Materials | Huang S.,Beijing Key Laboratory of Special Elastomeric Composite Materials | Huang S.,Beijing University of Chemical Technology | And 13 more authors.
RSC Advances | Year: 2015

Dielectric elastomers (DEs), which are capable of displaying considerable stress and strain in response to an applied electric field, have shown the closest similarity in performance to natural muscles. However, the high operating voltage of DEs limits their practical application. A reduction of the operating voltage can be achieved through increasing the dielectric constant and/or decreasing the elastic modulus. Here, an all-organic non-percolative dielectric composite with enhanced electromechanical actuating performance was prepared by introducing polyaniline (PANI) and epoxidized soybean oil (ESO) into a nitrile-butadiene rubber (NBR) matrix. A small amount of PANI was used to increase the dielectric constant through adding electron movement which is similar to dipole polarization, while ESO was used to decrease the elastic modulus of the composite through weakening intermolecular interactions in NBR and molecular interaction between NBR and PANI. Finally, an actuated strain of 2.5% was obtained at 4.5 V μm-1 by 4 phr PANI/NBR composite filled with 50 phr ESO, a 700% improvement in actuated strain compared with the actuated strain (0.31%) of pure NBR at 4.5 V μm-1 without any pre-strains. In comparison with other dielectric composites filled with conductive filler, the ESO/PANI/NBR composite also displays a relative advantage under conditions of no pre-strain and low electric field. © 2015 The Royal Society of Chemistry. Source


Wu Y.-B.,Beijing Institute of Petrochemical Technology | Wu Y.-B.,Beijing Key Laboratory of Special Elastomeric Composite Materials | Han L.,Beijing Institute of Petrochemical Technology | Han L.,Beijing Key Laboratory of Special Elastomeric Composite Materials | And 11 more authors.
Polymer Chemistry | Year: 2015

Cationic polymerization of isobutyl vinyl ether (IBVE) in an ionic liquid 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]) was thoroughly examined at 0°C. A variety of coinitiators were used in conjunction with the IBVE-HCl adduct acting as a cationogen. Compared with polymerization in organic solvents, the cationic polymerization of IBVE in [omim][BF4] proceeded in a milder exothermic manner, yielding polymers with higher molecular weight, and giving a higher monomer conversion. Although the polymerization reaction in [omim][BF4] could not be controlled due to the presence of β-proton elimination, the monomer addition experiments confirmed the existence of long-lived species. Introducing a small amount of 2,6-di-tert-butylpyridine (DTBP) into the system may lead to a controlled polymerization. The corresponding elementary reactions and stabilization mechanism of propagating the carbocation in [omim][BF4] were also proposed. This journal is © 2015 The Royal Society of Chemistry. Source

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