Silver-Polymer Nanohybrids Prepared by Microemulsion Polymerization
This work presents the preparation of some Ag°-polymer nanoparticles by emulsion polymerization of styrene (St), butyl acrylate (BuA) or methyl methacrylate (MMA), followed by the metal particles engendering. In order to increase the polymer-Ag° interaction, acrylic acid (AcrA), hydroxyethylmethacrylate (HEMA), sodium styrenesulfonate (StSO3Na) and vinyltriethoxysilane (VTES) coupled with tiopropyltrimethoxysilane (HSTMS) were subsequently used as comonomers when the polymeric latexes were prepared. Comparing the two surfactants used in this study – nonylphenol ethoxylated with 25 moles of ethylene oxide (NPEO25) and sodiumdodecylsulfate (SDS) - one can notice that particle size was larger and zeta potential value decreased when, instead of the ionic surfactant SDS, the nonionic surfactant NPEO25 was added to the formulation. The latexes UV-Vis spectra shows absorptions at ~400 nm due to plasmon resonance adsorption assigned to Ag° nanoparticles. The value of λ caused by this phenomenon decreases in the following order: PSt>PBuA>PMMA, because of the increase of polarity. The reactive comonomers, mentioned above, cause the decrease of the maximum value, due to the increase of the polymer-metal interaction. Thermal stability of PSt is higher when silver nanoparticles are present and is lower after copolymerization. For HEMA and StSO3Na copolymers, the XRD studies point out the existence of a cubic crystalline phase, generated because of the maximum (high) concentration of Ag°. The UV-Vis reflexion spectra show maximum values of reflectance for the same two copolymers, proving that the crystalline phase of Ag° has a mirror effect.
D. Donescu et al., "Silver-Polymer Nanohybrids Prepared by Microemulsion Polymerization", Journal of Nano Research, Vol. 6, pp. 147-156, 2009