Enhanced mechanical and thermal properties of OH-BNNS reinforced SA/PAM double-network hydrogels

In this work, hydroxylated boron nitride nanosheets (OH-BNNS) reinforced sodium alginate/polyacrylamide (SA/PAM) double-network hydrogels were successfully prepared via free-radical polymerization and Ca2+ ionic crosslinking.The hydroxyl functionalization significantly improved the dispersibility of BN nanosheets in aqueous systems and promoted strong interfacial interactions with the polymer matrix. The incorporation of OH-BNNS and the formation of the SA/PAM double-network structure effectively enhanced the mechanical and thermal properties of the hydrogels. Compared with pure PAM hydrogel, the ternary composite hydrogel exhibited a tensile strength of 106.36 kPa and a Young's modulus of 33.6 kPa, corresponding to increases of 96.6% and 354%, respectively. In addition, the glass transition temperature and maximum decomposition temperature increased by 13 °C and 12 °C, respectively. The enhanced properties were mainly attributed to hydrogen bonding interactions and the increased crosslinking density within the hydrogel network. Furthermore, the equilibrium swelling degree decreased from 15.6 to 11.3 after incorporation of OH-BNNS and SA. The prepared composite hydrogels demonstrate potential applications in biomedical materials, adsorption, and flexible functional materials.