Highly Tough Antibacterial Hydrogels Based on Chitosan/Poly(acrylic acid)/Nano-Silver

The chitosan (CS)/poly(acrylic acid) (PAA) hydrogel with a double network (DN) was prepared by photo-initiated copolymerization of acrylic acid (AA) and CS, using N,N′-methylenebisacrylamide (MBA) as crosslinker. CS/PAA/nano-silver composite hydrogel was subsequently obtained by incorporating silver nitrate into the hydrogel networks. The chemical structure of the CS/PAA hydrogel was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). The mechanical performance of the hydrogel was evaluated by the universal testing machine. The antibacterial properties of the composite hydrogel were also investigated. The experimental results show that the mechanical properties of the CS/PAA hydrogel reached at the highest level when the mass fraction of AA and CS are 20% and 5%, respectively. The high strength of CS/PAA DN hydrogel was mainly attributed to the hydrogen bonding between the two networks of the DN hydrogel and coordination interactions between the fragments of AA and MBA. Moreover, a further increase in mechanical strength as high as 5.2 MPa was observed for the CS/PAA/nano silver hydrogel which shows the antibacterial properties with zone of inhibition of 3.2 mm.