Clay-Mediated Synthesis of Silver Nanoparticles Exhibiting Low-Temperature Melting

Nanohybrids of silver nanoparticles (AgNPs) supported on mica clay were synthesized by in situ reduction of silver nitrate in an aqueous solution: The required mica platelets of high aspect ratio were previously prepared by the exfoliation of mica clay stacks in a multilayered structure through an ionic exchange reaction with poly(oxypropylene)-amine-salt. The exfoliated nanoscale mica platelets (Mica) are polydispersed such that each platelet is 300-1000 nm in width and 1 nm in thickness. These platelets possess ionic charges in the form of SiO-Na+ at 120 mequiv/100 g and are suitable for supporting AgNPs in the process of in situ reduction of silver nitrate. Transmission electronic microscopy revealed the formation of-AgNPs with a narrow size distribution of ca. 8 nm in diameter on the rim of individual Mica platelets. However, the pristine layered Mica structure without exfoliation failed to produce a fine AgNP distribution but instead generated particles larger,than 30 nm and some precipitates Characterization 14: differential scanning calorimetry and field emission scanning electron microscopy revealed that the fine AgNPs on Mica platelets exhibited a low melting temperature of 110 degrees C. The AgNP/Mica nanohybrid not containing an organic dispersant is Considered to be a "naked" silver particle.