We describe a straightforward production pathway of polymer matrix composites with increased dielectric constant for dielectric elastomer actuators (DEAs). Up to date, the approach of using composites made of high dielectric constant ceramics and insulating polymers has not evidenced any improvement in the performance of DEA devices, mainly as a consequence of the ferroelectric nature of the employed ceramics. We propose here an unexplored alternative to these traditional fillers, introducing calcium copper titanate (CCTO) CaCu 3 Ti 4 O 12 , which has a giant dielectric constant making it very suitable for capacitive applications. All CCTO-polydimethylsiloxane (PDMS) composites developed display an improved electro-mechanical performance. The largest actuation improvement was achieved for the composite with 5.1 vol% of CCTO, having an increment in the actuation strain of about 100% together with a reduction of 25% in the electric field compared to the raw PDMS matrix.

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Eutectic temperature and composition in the CuO-Ti0 2 pseudobinary system have been experimentally determined in air by means differential thermal analysis (DTA), thermogravimetry (TG) and hot-stage microscopy (HSM). Samples of the new eutectic composition treated at different temperatures have been characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structural spectroscopy (XANES) to identify phases and to determine the Cu valence state, respectively. The results show that the eutectic temperature in air is higher by 100 °C (~1000 °C) for a Ti-richer composition (X Ti02 = 25 mol%) than the one calculated in the literature. The reduction of Cu 2+ to Cu + takes places at about 1030 °C. The existence of Cu 2 Ti0 3 and Cu 3 Ti0 4 has been confirmed by XRD in the temperature range between 1045 and 1200 °C.

Influence of the pH and ageing time on the acid aluminum phosphate synthesized by precipitation

The extensive range of applications where synthetic nanomaterials are nowadays used is causing a huge commercial market. An incipient use of these nanomaterials arises from the need to generate alternative antimicrobial agents, anticipating the development of resistant microorganisms. Here, we show a nanostructured ZnO with antimicrobial properties and low-cytotoxicity based on a nanoparticles arrangement by controlling the formation of sintering-neck into nanoporous spheres. The antimicrobial effectiveness of ZnO spheres is tested in a broad-spectrum of microorganisms such as fungi, Gram-negative and Gram-positive bacteria. The hierarchical structures show highly effective antimicrobial activity at low concentrations and in relatively short action times (24-72h). We demonstrate that the enhanced antimicrobial properties against microorganisms are ascribed to a combining of both physical and chemical interactions between microorganism and ZnO. The approximation mechanism between microorganism and ZnO is provided through electrostatic forces (physical interaction) which, thanks to the ZnO-microorganism proximity, promote a rapid release of zinc cations and the reactive oxygen species penetration into microorganisms (chemical interaction). We believe that this work provides insights on the mechanisms underlying the interactions ZnOmicroorganism and possess a combined action mechanism for which nanostructured ZnO is so effective to combat microorganisms.