Effect of polyvinyl alcohol (PVA) polymerization degree on solid-phase reduction of Pt nanoparticle-doped AgNO3/PVA layers

This study investigates the effect of the polymerization degree of polyvinyl alcohol (PVA) on the solid-phase reduction of AgNO3/PVA layers in an attempt to lower the fabrication temperature of Ag nanostructures. Spin-coated layers were prepared using PVA with low polymerization (LP, n = 1500) and high polymerization (HP, n = 1800), both doped with trace amounts of Pt nanoparticles. The reduction process was evaluated by monitoring electrical resistance variations during heating. Our findings reveal that a lower polymerization degree significantly accelerates the reduction process. Specifically, the minimum reduction temperatures were identified as 170 °C for LP specimens and 180 °C for HP specimens. LP specimens further demonstrated superior reproducibility and exhibited lower room-temperature resistances compared to HP specimens. Thermal analysis (TG-DTA) indicated that the thermal decomposition of LP-PVA begins at approximately 165 °C, whereas that of HP-PVA begins at 183 °C. These decomposition temperatures closely align with the observed minimum reduction temperatures, indicating that the thermal stability of the polymer matrix directly dictates the reaction kinetics. These results establish the PVA polymerization degree as a critical parameter for optimizing solid-phase reduction, providing a strategic approach for the low-temperature fabrication of functional Ag nanostructures.