One-step synthesis of organic-inorganic hybrid asymmetric dimer particles via miniemulsion polymerization and functionalization with silver

Organic-inorganic polystyrene (PSt)-silica (SiO2) hybrid asymmetric particles were prepared in one step by a miniemulsion polymerization technique. The organic and inorganic reagents were confined in miniemulsion microreactor droplets. After the formation of PSt and SiO2, internal phase separation inside the droplets was accelerated owing to the hydrophobicity of PSt and the hydrophilicity of SiO2. Therefore, PSt-SiO2 hybrid asymmetric particles could be synthesized in one step. Between each pair of asymmetric particles, silane couplers act as bridges connecting the PSt and SiO2 particles. The size of PSt particles in these asymmetric particles was easily tuned either by changing the weight ratio of St/TEOS or by varying the sonication power during the miniemulsion preparation. After functionalization of the as-prepared asymmetric dimers by surface decoration with Ag particles, enhanced surface-enhanced Raman scattering (SERS) properties were observed due to electromagnetic enhancement of the added Ag colloids.