Polymerization of benzyl thiocyanate 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.