Thin films of layered double hydroxide and silver-doped polystyrene particles

Abstract

Monodisperse polystyrene latex dispersions containing particles with 55nm (PS55) and 560nm (PS560) average diameters were synthesized by emulsion polymerization. The surface of the PS55 latices was modified with sodium styrene sulfonate as co-monomer and styrene (PS55–SO3−). The maximal adsorbed amount of the silver ion was 37.6mg/g (0.348mmol/g) on the surface of the PS55–SO3− spheres. Silver nanoparticles (NPs) were prepared on the surface of PS55–SO3− and PS560 by chemical reduction. TEM images verified the presence of silver NPs on the surface of the polymer latex particles as well as free in the dispersion. The mean particle size of the silver-dotted PS55–SO3− seed decreased with increasing silver content. The plasmon resonance peak of silver-modified latex particles shifted to smaller wavelengths with increasing silver content with 11nm in Ag0/PS560 and with 17nm in Ag0/PS55–SO3− dispersions. Thin films were prepared by the layer-by-layer (LbL) deposition from negatively charged PS55–SO3− or PS560 and positively charged lamellar colloidal particles of 2:1 MgAl-layered double hydroxide (LDH). Film formation was detected by optical methods. The absorbance maxima of LDH∣Ag0/PS55–SO3− thin films at 7.45⁎10−2 or 1.49⁎10−1 Ag/PS ratios appeared at 390nm. The wavelength of the absorbance maximum of the LDH∣Ag0–PS560 thin films shifted from 393nm to 382nm with increasing silver content. The film thicknesses of the LDH∣Ag0–PS55–SO3− films are in the 200–955nm range. The thickness varies from 183 to 417nm for the LDH∣Ag0–PS560 LbL films depending on the Ag content. The average roughness values of the LDH∣Ag0/PS560 films are 28 and 37nm, while 16 and 19nm for the LDH∣Ag0/PS55–SO3− films, respectively.