Properties of Nanocomposites Based on Platinum Nanoparticles Stabilized by Chitosan

Abstract

AbstractPlatinum nanoparticles were obtained chemically in acetic acid solutions of chitosan from the precursor H2PtCl6 using sodium borohydride as a reducing agent with simultaneous UV irradiation. The compositions were studied by SAXS, TEM, dynamic light scattering, FTIR‐spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and atomic force microscopy. Nanoparticles are characterized by a narrowly dispersed size distribution while the effect of the conformation of chitosan macromolecules on their characteristics is manifested. The SAXS method showed that in a chitosan solution with a semi‐flexible coil conformation of macromolecules, 96.8 % of the formed nanoparticles are characterized by an average radius of 1.4 nm. According to the TEM results, platinum nanoparticles are characterized by a crystal structure and a particle diameter of about 1.3–5.0 nm. A different picture is observed for platinum nanoparticles formed in chitosan with the rigid rod conformation of macromolecules – only 91 % of platinum nanoparticles had an average radius of 1.4 nm. The TEM method showed these nanoparticles turned out to be about 1 nm in size, and they did not crystallize, but remained amorphous. The introduction of platinum nanoparticles into the polysaccharide matrix significantly shifts the glass transition temperature of chitosan toward lower values by 20 and 10 °C respectively, and increases the tensile strength of the composites by 35 MPa.