Nanocomposites based on vinyl alcohol-containing polymers and nanostructured gold have been efficiently prepared by a UV photo-reduction process. The very fast process provided dispersed gold nanoparticles with average diameters ranging from 3 to 20 nm depending on the host polymer matrix and the irradiation time. Uniaxial drawing of the irradiated Au/polymer nanocomposites favours the anisotropic distribution of packed assemblies of gold particles, providing oriented films with polarization-dependent tunable optical properties. These pronounced dichroic properties suggest that the nanocomposite films could find potential applications as colour polarizing filters, radiation responsive polymeric objects and smart flexible films in packaging application
The combination of memory and signal handling characteristics of a memristor makes it a promising candidate for adaptive bioinspired information processing systems. This poses stringent requirements on the basic device, such as stability and reproducibility over a large number of training/learning cycles, and a large anisotropy in the fundamental control material parameter, in our case the electrical conductivity. In this work we report results on the improved performance of electrochemically controlled polymeric memristors, where optimization of a conducting polymer polyaniline in the active channel and better environmental control of fabrication methods led to a large increase both in the absolute values of the conductivity in the partially oxydized state of polyaniline and of the on-off conductivity ratio. These improvements are crucial for the application of the organic memristor to adaptive complex signal handling networks
Polymer/metal nanocomposite containing intrinsically anisotropic metal nanostructures such as metal nanorods and nanowires appeared extremely more sensitive and responsive to mechanical stimuli than nanocomposites containing spherical nanoparticles. After uniaxial stretching of the supporting polymer matrix (poly(vinyl alcohol)), the elongated silver nanostructures embedded at low concentration into the polymer matrix (<1 wt % of Ag) assume the direction of the drawing, yielding materials with a strong dichroic response of the absorption behavior. Accordingly, the film changed its color when observed under linearly polarized light already at moderate drawings. The results obtained suggest that nanocomposite films have potential in applications such as color polarizing filters, radiation responsive polymeric objects and smart flexible films in packaging applications.
Nanocomposites based on poly(vinyl alcohol) and silver nanoparticles were efficiently prepared by sun- and thermal-promoted reduction processes. Uniaxial drawing of the Ag/PVA nanocomposites favoured the anisotropic distribution of silver particles, providing oriented films with polarisation-dependent tunable optical properties. These dichroic properties were more pronounced for nanocomposites produced by sun exposition, which provided more compact and interacting metal clusters. The results obtained suggest the nanocomposite films could find potential applications as colour polarising filters, radiation responsive polymeric objects and smart flexible films in packaging application
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