Stoichiometric optimization of biodegradable poly(vinyl alcohol)/starch/glycerol hydrogels for flexible wound dressings

Abstract Poly(vinyl alcohol) (PVA) hydrogels are attractive wound-dressing materials due to their hydrophilicity, flexibility, and biocompatibility; however, achieving both high tensile strength (TS) and elongation at break (EAB) remains a major challenge. In this study, biodegradable PVA/starch (ST)/glycerol (GL) hydrogels were fabricated through stoichiometric control of hydroxyl molar ratios, guided by central composite design and freeze–thaw processing at −80 °C, to enhance hydrogen bonding without chemical crosslinkers. Synergistic interactions among PVA, ST, and GL enabled the hydrogels to achieve dual benchmarks of durability and flexibility. At GL/PV A = 0.1, PVA 4–10 wt%, and ST/PV A = 0.03–0.06, the hydrogels exhibited TS 12.5–24.4 MPa and EAB 270%–397%, exceeding favorable thresholds (TS >11.5 MPa; EAB >180 %). Additional attributes included high swelling capacity (>260 %), appropriate water vapor transmission (2660–3000 g/m ² /day), favorable biodegradability (<32 % weight loss after 28 days), and intrinsic UV-shielding efficiency (>80 % UVA/UVB blocking). Representative formulations highlighted the tunability of the system: one optimized for flexibility (EAB 390 %, TS 17.2 MPa) and another for UV protection (UV blocking >95 %). Microstructural and dynamic mechanical analyses confirmed that GL acted as a plasticizer, enhancing chain mobility, while ST modulated phase separation and stabilized the network. Overall, the findings demonstrate that stoichiometric control of hydroxyl molar ratios enables multifunctional PVA/ST/GL hydrogels to achieve a balance of strength, flexibility, and barrier properties, underscoring their potential as next-generation wound dressings.