H-PVA Cross-Linking Mechanism Prepared By Freeze-Thaw And Annealing: Optimizing Gel Fraction And Swelling

PVA has attracted attention as a material in the formation of hydrogels for drug release media. Crosslinking is one of the keys to hydrogel formation. Gel fraction, swelling ratio, and degree of crystallinity are parameters used to determine the enhancement of crosslinking and the formation of mechanical properties of hydrogels. H-PVA was synthesized through freeze-thaw and annealing processes and optimized by Box- Behnken design. Analysis of the degree of crystallinity revealed that the freeze-thaw and annealing processes formed and increased crosslinking. This is supported by data from the gel fraction analysis, which indicates that the number of crosslinks increases and the swelling ratio decreases, indicating that the hydrogel structure is strong enough to withstand water absorption. The results of the design of the experiment (DOE) showed that simultaneously the model was able to explain the presence of crosslinks formed in H-PVA, as seen from the p-value <0.0001 and the statistical test results R² = 0.99 (close to 1). Optimal conditions were found at a PVA concentration of 18.972 (%w/v), a freeze-thaw cycle of three times, and an annealing temperature of 92 °C.