Preparation of salt-tolerant chitosan hydrogels and their anti-biofouling behavior study

The hydration of wettable materials can help to improve their anti-biofouling effect, but their hydration stability under high salinity conditions is a challenge considering the future applications in natural marine environments. Inspired by the self-cleaning properties of crustaceans, chitosan (CS)/Poly (vinyl alcohol) (PVA) hydrogels have been prepared, and their anti-biofouling and salt tolerant mechanism were deeply investigated using surface analysis and molecular dynamics simulation. Interestingly, it is found that CS/PVA hydrogels can be controllably triggered at a low pH, and they can self-adjust to enhance anti-biofouling performance following the changes of environmental conditions. The hydration of CS/PVA hydrogels is enhanced in seawater because of a low salt sensitivity factor (f) of these hydrogels with a value of less than 0. Super hydrophilicity of CS/PVA hydrogels makes water drop achieve super spreading within 66.5 ms. Compared to PVA hydrogels, almost no crude oil, protein and algae can adhere to the surface of the prepared CS/PVA (0.2:1) hydrogel. The field tests in the south sea of China also demonstrate that CS/PVA (0.2:1) hydrogel has an excellent anti-biofouling ability after 6 months of testing. The anti-biofouling mechanism is also discussed according to the experimental results and molecular dynamics simulation.