The Design And Application Of Anti-biofouling Hydrogels

Hydrogels are soft and elastic materials composed of three-dimensional hydrophilic network and the swollen water.High hydrophilicity and low interfacal free energy of hydrogels result in low adhesion to barnacles,algae,bacteria and proteins on the surfaces.A lot of literatures reported that hydrogels are well potential candidates for the marine anti-biofouling application.In this thesis,we designed and prepared high strength hydrogels,hydrogels loading silver nanoparticles and preparation of silicone hydrogel composite coating,studied the role of these hydrogels in inhibition of proteins,bacteria and algae adhesion,and explored the practical application of hydrogels in anti-biofouling field.A series of polyelectrolyte hydrogels were prepared by adjusting the molar ratio of 3-sulfopropylmethacrylate(SA)to methacryloyloxyethyltrimethyl-ammonium chloride(TMA),and their mechanical properties were significantly improved by introducing a flexible polyacrylamide network.The elastic moduli of the double-network hydrogels are 2-5 times higher than that of the corresponding single-network polyelectrolyte hydrogels.It was also found that the positively charged-hydrogel inhibited the adhesion of lysozyme(LYZ)and bovine serum albumin(BSA),the negatively charged-hydrogel resisted attachment of Chlorella(Ch)and Phaeodactylum tricornutum(PT),and the mixed amphoteric hydrogels show good antifouling performance for proteins and algae.Polymerizable multiquaternized nanoparticles(about 20 nm)were designed from hyperbranched polyethyleneimine(HPEI),and could be uniformly dispersed in water.Poly(hydroxyethacrylate)(PHEMA)hydrogel was prepared with this quaternized nanoparticles as crosslinking agents.The possible formation mechanism of hydrogels is that the initiators adsorbed on the HPEI nanoparticles triggered the chain growth and bridged between the HPEI nanoparticles.Mechanical property tests showed these hydrogels exhibit well tensile,torsion and compressive performance.These quaternized nanoparticle hydrogels effectively inhabited the adhesion of E.coli,Ch and PT.The “clawlike” monomers containing six thioether functional groups were synthesized and successfully incorporated into the thermosensitive poly(N-isopropylacrylamide)(PNIPAM)hydrogel system.The silver nanoparticles(AgNPs)loaded in hydrogel were prepared by chemical reduction of the silver ions absorbed into the hydrogel system.The size of the silver nanoparticles decreased from about 50 nm to 20 nm with increasing of thioether groups,but the loading silver nanoparticles increased 30-fold.Besides,the lower critical solution temperature(LCST)of hydrogel can be finely tuned by controlling the content and the oxidation degree of the thioether groups.The fitting korsmeyer-peppas release model showed that the durable release of AgNPs in hydrogels was controlled by Fick diffusion.These hydrogel showed much better antimicrobial property for Escherichia coli and anti-algae performance for Ch and PT.The self-repairing AgNPs hydrogels were constructed by chelation of silver nanoparticles with sulfur-containing polymer chains.Too high or too low ratio of Ag/S is not conducive to the formation of hydrogels and improvement of the mechanical properties,but could effectively improve self-repair performance.All these self-repairing hydrogels showed excellent anti-algae performance.The silicone hydrogel composite coatings were prepared by introducing this self-repairing AgNPs hydrogels into the silicone Elastomer.This mixed system can be cured at room temperature,suitable for large area application.The silicone hydrogel showed excellent resisted adhesion of algae and the attached algae was also easy to remove at 42 pa water shear pressure.After 6 months of marine plate testing,these coatings exhibited good anti-biofouling performance.