Microwave-Assisted Polyol Synthesis of Polymer-Protected Monometallic Nanoparticles Prepared in Batch and Continuous-Flow Processing

Microwave-assisted polyol synthesis of monometallic Pd, Rh, Ru, and Pt nanoparticles has been demonstrated by the use of ethylene glycol and glycerol as a reducing agent in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). The size and morphology of the synthesized nanoparticles have been investigated by means of high-resolution transmission electron microscopy (HRTEM) and extended X-ray absorption fine structure (EXAFS). A comparison between batch scale-up and continuous-flow processing for the microwave-assisted polyol synthesis has been also indicated in terms of the size and morphology of various nanoparticles. In the single-mode MW-assisted continuous-flow processing (10 mL processing volume), the well-dispersed colloidal nanoparticles with a metal concentration equal to similar to 10 mM were successfully produced in a sealed glass reactor at boiling temperature of the solvent at a flow rate of 1 mL/min. Furthermore, in the multimode MW-assisted batch processing, the colloidal nanoparticles appeared to have a narrower size distribution in ethylene glycol than in glycerol. The availability of the size regulation (i.e., particle size, size distribution) is discussed.