Plasticised polymer inclusion membrane as tunable host for stable gold nanoparticles

Stable Au nanopartieles (nps) were synthesised in matrix of the self-supported plasticised polymer inclusion anion-exchange membrane using the ion-exchange route for loading AuCl(4)(-) anions in membrane and their subsequent reduction with BH(4)(-) anions. The compositions of membrane was varied by changing concentration of the anion exchanger, and also using different plasticiser. X-ray diffraction patterns of the membrane samples embedded with Au nps were taken to study the parameters involved in the formation of Au nps in the plasticised polymer matrix. The content of Au nps in the membrane was increased by 1 repeating the sequential cycles of loading of AuCl(4)(-) ions followed by the reduction with BH(4)(-) in the membrane matrix 2 increasing the concentration of anion exchanger in the membrane matrix. It was observed in TEM images of cross section of membrane that spherical Au nps of 10 nm sizes were dispersed throughout the matrix of membrane. The increase in Au(0) content in the membrane did not alter the average size of Au nps significantly, but slightly increased the range of size distribution. The nanostructures like prism, rod, sphere, bipyramid and cuboid were also observed in the membrane matrix, but their number density was 5% of nanoparticles present in the membrane matrix. The analyses of isotopic-exchange rate profiles of iodide ions between the membrane sample and well-stirred equilibrating salt solution indicated that formation of Au nps lead to a significant increase in self-diffusion mobility of the anions in membrane. The surface plasmon band (SPB lambda(max) = 535 nm) of Au nps did not change on equilibration of the membrane samples with the solutions containing Cl(-), I(-), ClO(4)(-), and CH(3)COO(-) anions, but completely disappeared on equilibration with solution containing molecular iodine