Preparation and properties of composite amphiphilic hydrogel anti-fouling materials

Amphiphilic hydrogel/organic substrate interfaces are commonly generated with a hydrophobic layer, which enhances underwater adhesion of the hydrogel via aggregation and assembly of the oleophilic structural units in the amphiphilic hydrogel. However, water absorption is considerably weakened by the hydrophobic interactions, which inhibits the formation of a stable hydration layer at the hydrogel/aqueous interface and leads to degradation of the anti-fouling ability of the amphiphilic hydrogel. Herein, composite amphiphilic hydrogel anti-fouling materials were prepared by mixing an amphiphilic hydrogel prepolymer and the pure aqueous structural units of a hydrogel prepolymer. In particular, adhesion of the hydrogels was strengthened by the oleophilic structural units of the amphiphilic hydrogel, and the hydrophilic structural units of the pure aqueous hydrogel formed a stable hydration layer at the hydrogel/aqueous interface; thus, the anti-fouling performance was strongly enhanced. As a result, superior adhesion of the composite amphiphilic hydrogel was maintained, and its resistance to shedding was clearly manifested in the experimental results obtained after immersion in static seawater (60 d) and rotating seawater (30 d); additionally, the water absorption capacity and anti-fouling effect were significantly better than those of the control amphiphilic hydrogel materials, e.g., the water uptake rate of the composite hydrogel BSH60T (S% = 324.2 %) was 6.7 times higher than that of the amphiphilic polymer hydrogel BS60T (S% = 48.3 %). Both proteins and Nitzschia closterium f. minutissima were very weakly attached to the surface of the composite amphiphilic hydrogel, and excellent anti-fouling performance was observed for the test panels in practical marine environments. This study provides a creative approach to optimizing the adhesion and anti-fouling properties of the hydrogel anti-fouling materials.