Functionalized nano SiO 2 reinforced gelatin–PVA hydrogels for sustainable wood adhesion

-APTES significantly reinforced the hydrogel network, increasing storage modulus and viscosity while maintaining pronounced shear-thinning behaviour suitable for adhesive applications. The strongest improvement was observed for the 5 : 1 gelatin : PVA formulation, where nanoparticle incorporation increased the storage modulus from ∼240 to ∼450 Pa. Lap-shear testing on wood substrates revealed a maximum adhesion strength of 735 ± 25 kPa, corresponding to a 71% increase compared with the unfilled gelatin/PVA adhesive and a 122% increase relative to gelatin alone. These improvements are attributed to a combination of proposed interactions, including hydrogen bonding, ionic interactions, and possible mechanical interlocking between the functionalized nanoparticles, polymer network, and wood surface. The results demonstrate that silica-reinforced gelatin/PVA hydrogels represent a promising formaldehyde-free, bio-based adhesive platform for sustainable wood bonding applications.