Mechanistic insight into improving strength and stability of hydrogels via nano-silica

In this investigation, the nanocomposite hydrogels were prepared by hydrophilic nanoscale silica secondary crosslinking hydrolytic polyacrylamide (HPAM) hydrogel to improve its strength and stability performance. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to study the composition and microstructure of nanocomposite hydrogel. In addition, it increases the viscosity of the gel solution by increasing the amount of nano-silica. According to Sydansk coding system, the maximum gel strength of P (HPAM/HMAM/SiO2) hydrogel increased from code “F” to codes “G” and “H”. The stability time of P(HPAM/HMAM/SiO2) hydrogel increased from 30 days to 90 days. The results of molecular dynamics simulation (MDS) and differential scanning calorimetry analyses (DSC) showed that SiO2 increases the interactions between the water molecules and colloidal phase, which is the main reason for improving the stability of the nanocomposite hydrogel. The dehydration rate of hydrogel decreased with the increase of nanoparticle content in terms of the dehydration tests. The dehydration rate of hydrogel increases with the increase of temperature. In addition, the kinetics of all nanocomposite hydrogels dehydration can be described by first-order kinetics at 35 °C, 45 °C, and 55 °C.