Polymerization of benzylthiocyanate on silver nanoparticles and the formation of polymer coated nanoparticles

Polymerization of benzylthiocyanate on silver nanoparticles produces organic shell covered nanoparticles with controllable thickness in a one-pot process. Gram scale quantities of core-shell materials have been synthesized by this method. The methodology involves the addition of the precursor into Ag-citrate solution and the shell nucleates over a period of three weeks with complete precipitation of the core-shell material which can be dispersed subsequently in organic solvents. The material has been characterized using transmission electron microscopy, X-ray diffraction, FT-IR, laser desorption mass spectrometry, thermogravimetry, surface enhanced resonance Raman spectroscopy (SERRS) and Raman imaging. A typical composite material consists of a silver core of 40 nm diameter coated with a polymeric shell of 8 nm thickness. The polymer exhibits characteristic features in mass spectrometry and vibrational spectroscopy. The core-shell structure of nanoparticles is imaged for the first time using the Raman intensity of the shell. Proton assisted polymerization of benzylthiocyanate occurs on the silver surface, leading to a linear chain which subsequently deposits on the nanoparticle surface resulting in the core-shell structure.