Fabrication and characterization of colloidal silver nanoparticle via photochemical synthesis

This study used polyvinylpyrrolidone (PVP) and 4-cyano-4′-pentylbiphenyl (5CB) as capping agents for batch and cyclic photochemical synthesis, respectively, to fabricate colloidal silver nanoparticles via ultraviolet irradiation of ethanol containing silver nitrate (AgNO3). The cyclic photochemical process offers colloidal silver particles with mean particle size (MPS) and particle-size distribution (PSD) that were reduced by approximately 14% and 49% versus a batch photochemical process. Relative to PVP, the MPS and PSD of as-prepared Ag capped with 5CB decreased from 4.2 ± 1.3 nm to 3.7 ± 0.8 nm. This infers that MPS and PSD of colloid Ag particle could be manipulated by different photochemical processes and capping agents. In addition, the transition temperature between anisotropic and isotropic phases of 5CB liquid crystal was reduced by only about 4% when the as-prepared silver nanoparticles capped with 5CB reached 1 wt%. This suggests that blending as-prepared colloidal Ag nanoparticle with liquid crystals of 5CB increases the sensitivity to electric field and the nematic phase remains a stable state