Dielectric elastomer generators (DEGs), which follow the physics of variable capacitors and harvest electric energy from mechanical work, have attracted intensive attention over the past decade. The lack of ideal dielectric elastomers, after nearly two decades of research, has become the bottleneck for DEGs' practical applications. Here, we fabricated a series of polyurethane-based ternary composites and estimated their potential as DEGs to harvest electric energy for the first time. Thermoplastic polyurethane (PU) with high relative permittivity (∼8) was chosen as the elastic matrix. Barium titanate (BT) nanoparticles and dibutyl phthalate (DBP) plasticizers, which were selected to improve the permittivity and mechanical properties, respectively, were blended into the PU matrix. As compared to pristine PU, the resultant ternary composite films fabricated through a solution casting approach showed enhanced permittivity, remarkably reduced elastic modulus, and relatively good electrical breakdown strength, dielectric loss, and strain at break. Most importantly, the harvested energy density of PU was significantly enhanced when blended with BT and DBP. A composite film containing 25 phr of BT and 60 phr of DBP with the harvested energy density of 1.71 mJ/cm was achieved, which is about 4 times greater than that of pure PU and 8 times greater than that of VHB adhesives. Remarkably improved conversion efficiency of mechano-electric energy was also obtained via cofilling BT and DBP into PU. The results shown in this work strongly suggest compositing is a very promising way to provide better dielectric elastomer candidates for forthcoming practical DEGs.

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Herein we report the highly improved electromechanical actuation of thermoplastic polyurethane (TPU) by blending with polydimethylsiloxane (PDMS) to construct a bicontinuous structure. TPU/PDMS blend films with various PDMS loadings were fabricated through a simple solution-assisted casting method. Infrared spectroscopy measurements confirmed that TPU and PDMS are thermodynamically incompatible with each other. For TPU 80 with 80 parts of PDMS, a bicontinuous phase structure was achieved. The TPU 80 film showed greatly decreased elastic modulus and improved elongation at break compared to pristine TPU. It also showed the highest dielectric constant among the TPU/PDMS blend films with various contents of PDMS due to strong interfacial polarization. Most importantly, the TPU 80 film exhibited a maximum areal strain of 2.3% under an electric field of 40 V mm À1 , which is about 60 times higher than that of pristine TPU. The results described in this work demonstrate that the construction of a bicontinuous interface structure at the micrometer scale is very effective to develop elastomers with superior electromechanical actuation performance.

In this article, four different plasticizers are blended in thermoplastic polyurethane (PU) to improve its electromechanical actuation performance. The selected plasticizers include dibutyl phthalate, triphenyl phosphate, polyethylene glycol (PEG), and an unsaturated polyester PMG. The plasticization effect of various plasticizers on the mechanical properties, dielectric properties, and the electromechanical actuation of PU films is carefully characterized and compared. Results demonstrate that the actuated strain under low electric fields and the electromechanical coupling efficiency of PU can be substantially improved by blending with appropriate type and amount of plasticizers. The oligomer‐type plasticizers, PEG and PMG, act more efficiently in the improvement of actuation. An actuated strain in thickness of 1.54%, 140 times higher than that of pure PU, along with an electromechanical coupling efficiency of 0.60 under a low electric field of 5 V/μm was achieved for the PU plasticized with PMG suggesting an attractive approach toward advanced dielectric elastomer actuators. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45123.

Herein a diaphragm type dielectric elastomer actuator by blending azobenzene dyes into a polyurethane matrix (Azo/PU) is described. The effects of azobenzene content on the dielectric, mechanical, and electromechanical properties of the Azo/PU blends are discussed. The resultant blends with azobenzene content ranging from 1 to 8 wt% were characterized. The dielectric permittivity of PU increased from 8.0 to 11.1 (increasing of 38.5%) at 1 wt% azo content and reached a maximum of 35.6 (increasing of 343%) at 4 wt% azo content. By blending with a small content of azo the dielectric breakdown strength reached 57 kV mm À1 , which is 86% higher than that of the neat PU. The 30 mm thick diaphragm of Azo/ PU blend with 1 wt% azo content exhibited the highest actuated displacement at the center around 700 mm. Meanwhile the neat PU gave a displacement of 25 mm. That is a 26-fold increase in actuation is obtained by blending only 1 wt% azo dyes into the PU matrix. Infrared spectroscopy was used to characterize the structure of the Azo/PU blends. The particular chemical structure the Azo/PU blend containing 1 wt% of azo dyes is proposed to be responsible for the improvement in electromechanical actuation.

Treatment of lithiated (η6-X n -substituted-arene)Cr(CO)3 complexes (X = OMe, n = 2, 3) with (η6-benzene)Mn(CO) x L3 - x PF6 complexes (L = P(OEt)3, x = 0, 1) gave rise to the formation of di-, tri-, and tetrapolymetallic complexes depending on the experimental conditions. A “one-pot” procedure was developed to obtain tetranuclear complexes directly from (η6-arene)Cr and -Mn mononuclear complexes. The molecular structures of the trinuclear complex 5b ((CO)3Cr[(μ-η6-1,3-(OCH3)2-C6H2:(η5-C6H6)2]Mn2[(CO)4(P(OEt)3)2] and of tetranuclear complex 9 ((CO)3Cr[μ-η6-1,3,5-(OCH3)3-C6:(η5-C6H6)3]Mn3[(CO)6(P(OEt)3)3] have been determined by X-ray crystallography.

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