Platinum nanoparticles were synthesized by reduction of K_2PtCl_4 with H_2 at room temperature. Effect of poly( yV-isopropylaciylamide) (PNIPA), poly( yV-vinylacetamide) (PNVA) and poly (vinylalcohol) (PVA) on the size of the nanoparticles and the stability of colloid was studied. Results of TEM and the stability of the colloid after addition of KCl electrolyte solution indicated that the smallest size of Pt nanoparticle and best stability of the Pt colloid had been achieved by using PNIPA as stabilizer. Higher PNIPA/Pt2+ molar ratio is beneficial to obtaining smaller Pt nanoparticles. No remarkable influence of the molecular weight of PNIPA was observed. The growth of Pt nanoparticles was relatively slow under H2 atmosphere, which has not completed until 6 h after stopping of H2, but the Pt colloid was still stable even after six months.

Key words: POLYMER, PLATINUM, NANOPHASE MATERIALS, TEM, GRAIN