Preparation, structure and properties of uniaxially oriented polyethylene-silver nanocomposites

Uniaxially oriented composites of high-density polyethylene and silver nanoparticles were prepared using solution-casting, melt-extrusion and solid-state drawing techniques. The absorption spectrum in the visible wavelength range of the drawn nanocomposites was observed to strongly depend on the polarisation direction of the incident light. For instance, the nanocomposites appear bright yellow or red when the vibration direction of linearly polarised light is perpendicular or parallel, respectively, to the drawing axis. The optical anisotropy of the drawn nanocomposites originates from uniaxially oriented, pearl-necklace type of arrays of nanoparticles of high aspect ratios. The absorption spectrum of the nanocomposites can be shifted to higher wavelengths using appropriate annealing procedures. The annealing results in an increased size of the primary silver particles, due to Ostwald ripening, and consequently a range of polarisation-dependent colours can be generated in the drawn nanocomposites. (C) 1999 Kluwer Academic Publishers.