In situ electrosynthesis, optimization and stability of AgNPs within chitosan: pullulan polymeric network

Abstract In this study, a systematic investigation to achieve a deeper understanding of the synergistic effect of chitosan (CS) and pullulan (PL) as a polymeric matrix on the in situ electrosynthesis AgNPs under applied voltage 1.5 V for 2 h. The process was applied using CS: PL blend with different ratio as electrolytic solution, reducing, and stabilizing agent avoiding using toxic reducing agent, byproduct of the reaction, controlling AgNPs size and stability. Investigation of the samples using UV–visible spectroscopy (UV–vis), Inductively coupled plasma optical emission spectroscopy (ICP), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TG) revealed that AgNPs successfully formed under controlling the size and stability. Across all ratios except using only PL as an electrolyte, the results revealed the occurrence [chitosan/pullulan] Ag+ complex band at around 250 nm and a localized peak at 420 nm attributed to the SPR of AgNPs. TEM confirmed AgNPs formation with decreasing in size and increasing in concentration as a function of increasing CS content. Findings obtained by quantifying the concentration of silver using ICP whereas the concentration of CS is raised, the concentration of silver liberated increases. Zeta potential revealed that AgNPs have a positive surface charge maximized with increasing CS content. Furthermore, stability against aging for 2 months at 4 °C revealed that the addition of PL to CS matrix works on increasing the stability of AgNPs against aging.