Fast and energy efficient crosslinking of PVA to make water resistant coating using glutaraldehyde

Glutaraldehyde has recently drawn attention as a crosslinking agent for PVA due to its ability to facilitate reactions under ambient conditions. The study focused on comparing the effects of glutaraldehyde, formaldehyde, and glyoxal as crosslinking agents for PVA under similar conditions, using different aldehyde-to-PVA ratios (0.2, 0.4, 0.6, 0.8, and 1.0). The crosslinking reaction was conducted at 50 °C for a duration of 5 min, to assess the efficiency of crosslinking agents at milder conditions. Initial evaluations focused on determining the water swelling degree, the degree of crosslinking, and moisture uptake of the prepared films under humid conditions. Results demonstrated a high degree of crosslinking: with glutaraldehyde at GA/PVA ratios of 0.6 and 0.8, crosslinking reached 99%. Formaldehyde achieved a crosslinking degree of 97% at an FA/PVA ratio of 0.8, while glyoxal reached 90% at a ratio of 0.2. Among the aldehydes tested, glutaraldehyde exhibited the highest crosslinking efficiency under similar conditions, making it the preferred crosslinker for further characterization studies. FTIR, TGA, and XRD spectra confirmed successful crosslinking between GA and PVA, evidenced by acetal bond formation and changes in the diffraction patterns correlating with increased amorphous character in the PVA films.