Preparation and Properties of P( <scp>DMDAAC</scp> ‐ <i>co</i> ‐ <scp>AA</scp> )/ <scp>BC</scp> Composite Hydrogel

ABSTRACT To meet the demands of complex environments such as the human body, it is essential to develop multifunctional hydrogels with integrated properties, including pH responsiveness, swelling capacity, conductivity, and mechanical performance. In this study, a semi‐interpenetrating network hydrogel was synthesized via aqueous solution polymerization using dimethyl diallyl ammonium chloride (DMDAAC) and acrylic acid (AA) as monomers, bacterial cellulose (BC) as a mechanical reinforcement, 2,2′‐azobis(2‐methylpropionamidine) dihydrochloride (V50) as the initiator, and triallylamine (TAA) as the crosslinker. The results demonstrated that when the molar ratio of DMDAAC to AA ( n (DMDAAC): n (AA)) was adjusted from 5:5 to 9:1, the maximum fracture stress of the hydrogel increased from 0.33 to 4.26 MPa, while the elastic modulus and toughness modulus improved by 521.24% and 74.55%, respectively. At 25.0°C, the maximum swelling ratio in pH 7 distilled water rose from 3.06 to 50.31 g/g. Notably, when the pH increased from 2 to 4, the P(DMDAAC‐ co ‐AA)/BC(9:1) composite hydrogel exhibited a maximum swelling ratio increase of up to 30.38 g/g, achieving rapid swelling response within 30 s (peak swelling ratio: 1.63 g/g). These findings provide an experimental foundation for potential applications in wound dressings, humidity monitoring, pH‐responsive systems, and flexible sensors.