Research On Preparation And Antibiofouling Performance Of Nanocomposite Hydrogels Based On Cuprous Oxide-tannic Acid Submicroparticles

Marine biofouling refers to the attachment and accumulation of marine organisms on various surfaces of facilities in seawaer.Marine biofouling can cause different kinds of detriments,such as reduced ship speed and increased fuel consumption.After abandoning the antifoulant tributyltin globally,researchers stick to develop environmentally friendly and effective antifouling coating materials all along.Highly hydrophilic hydrogel could be used as a fouling-resistant coating to prevent fouling and adhering of organisms.Researchers have conducted a series of exploration and study on antifouling hydrogels.However,a series of problems,such as complicated preparation process,poor mechanical properties and long-term stability,limit the development and application of hydrogels as antifouling coatings.Thus,the simultaneous improvement of both mechanical properties and antifouling performance of hydrogels,which will lead to the realization of long-term and highl-efficency antifouling,has become an urgent issue.To this end,this thesis aims to prepare a kind of nanocomposite hydrogel with enhanced mechanical properties and synergistic antifouling properties（i.e.,the combination of toxic copper release and fouling-resistant coating）in a simple and low-cost way.The spherical Cu₂O-TA submicroparticles that are synthesized with the assistance of tannic acid（TA）can be incorporated into polyvinyl alcohol（PVA）or polyvinyl alcohol/sodium alginate（PVA/ALG）hydrogels through a freeze-thaw method to form PVA nanocomposite hydrogels and PVA/ALG double-network nanocomposite hydrogels.In the PVA/ALG hydrogels,PVA acts as the first network,while ALG is the second network.Both PVA and ALG are hydrophilic polymer materials,which work for the fouling-resistant effect.Cu₂O-TA particles can be oxidized to Cu²⁺in seawater during the release process and play a role in biocide-based antifouling.The intergatation of Cu₂O-TA particles also increases the mechanical properties of hydrogels.The structural characterization of prepared hydrogels indicates that all the nanocomposite hydrogels have a three-dimensional network structure.The tests of contact angles and slide angles performed by using different oil droplets show that all the nanocomposite hydrogels have the long-term stability of underwater superoleophobicity.The compressive strengthes and moduli of the hydrogels are enhanced due to the doping of Cu₂O-TA particles and the forming of double-network structure.Moreover,PVA nanocomposite hydrogels show the self-healing property,which should be beneficial to the long-term application of the hydrogels.In addition,compared with the hydrogels doped with Cu₂O,the doping of Cu₂O-TA particles can reduce the copper release rate and achieve the long-term sustained release effect.It should be beneficial to minimize the harm to the natural environment with effective antifouling ability.The results of the test of antifouling performance show that all the nanocomposite hydrogels can significantly inhibit the adhesion of Chlorella Vulgaris.Both the underwater superhydrophobic surface and the release of copper ions play an important role for effective antifouling,indicating the synergism of fouling-resistance approach and chemical biocidal antifouling.In summary,all the nanocomposite hydrogels show stable underwater superoleophobicity,enhanced mechanical properties,good self-healing ability,low copper release rate,and improved antifouling performance.The present nanocomposite hydrogels should pave a promising way to access robust fouling-resistant coatings on both dynamic and static conditions.