| Marine biofouling will cause harmful adhesion to the material surfaces of ships,infrastructure,etc.submerged in the ocean.Hydrogel can form a hydrated layer on the substrate surface,blocking the fouling phenomenon from the root.However,the critical problems of hydrogel materials,such as structural looseness after water absorption and swelling,reduced strength,easy to be destroyed by external forces and poor bonding adhesion with the substrate,need to be solved urgently.Meanwhile,silicone materials,due to their high hydrophobicity and low surface energy,can perfectly solve the related drawbacks of hydrogels.But these coatings have poor mechanical properties,low confinement,easy to break under external forces and difficult to repair,and have a single antifouling mechanism can not resist proteins adsorption in static environments.To solve the shortcomings of hydrogel and silicone in the field of marine antifouling,to obtain an efficient antifouling coating which has the application significance and value.In this thesis,microspheres with core-shell structure and polyethylene glycol-based hydrogels with controlled swelling degree were prepared,and the hydrogel/silicone coatings were prepared by physical blending method,the preparation process was optimized to obtain application-ready matching coatings.Their chemical structure,surface morphology,surfaceinterface properties,mechanical properties,corrosion resistance,and antifouling properties were tested and characterized,with the focus on the formation process of microgels,swelling mechanism,and antifouling mechanism of the hydrogels,and evaluating the long-lasting antifouling performance of hydrogel/silicone application-based coating in seawater.It has solved the problems of easy oxidation of traditional hydrogels,low structural strength,and poor adhesion after swollen,it enhanced the practicality of nanocomposite hydrogel,it also had efficient and long-lasting antifouling properties.(1)Poly(St@(HEMA/PEGMA))microspheres(PEAS)with St as the core and HEMA and PEGMA as the shell were prepared by soap-free emulsion polymerization by using HEMA and PEGMA as hydrophilic monomers,St as hydrophobic monomer and azo diisobutyl amidine hydrochloride(AIBA)as initiator.PEAS-PEG microgel polymer solutions were prepared by in-situ polymerization and solution polymerization with PEG2000 and HSH330 as the reactive monomers,IPDI as the cross-linking agent,and BDO as the chain extender.Then,PEAS-PEG hydrogel with different PEAS microsphere additions was prepared by wet-curing method.The chemical structures,morphology,and physical properties of the microspheres,microgels and hydrogels were characterized by FTIR,SEM,TEM,CLSM,XRD and DSC.The hydrogels physicochemical and mechanical properties were characterized by swelling properties,surface interface properties,compression properties,tensile properties and 400 % elastic recovery rate.The focus was on testing and evaluating the hydrogels antifouling performance by using marine bacteria adhesion test and benthic diatom adhesion test.The results showed that the controlled variable method was used to adjust the initiator content to construct PEAS microspheres with particle size ranging from 60 nm to 500 nm,and it decreased gradually with the increased of initiator content.The average particle size of microgel spheres was about 26 μm,and multiple microgel spheres aggregated to form microgel collapsed spheres with an average size of about290 μm.PEAS-PEG hydrogels have amphiphilic properties.With the increased addition of PEAS microspheres,the hydrogel surface free energy was gradually increased,but the solubility,mechanical properties and antifouling properties showed a trend of first increasing and then decreasing.The hydrogel had the best antifouling properties when the PEAS microsphere addition was 14.2 wt.%.PEAS-PEG hydrogels have achieved highly effective anti-bioadhesive behavior through three advantages: highly hydrated layer,unstable surface,and low roughness.(2)The hydrogels’ internal structures were fixed by freeze-drying method and liquid nitrogen deep-freezing method.The structure of the hydrogels was preserved by freeze-drying method after swelling by seawater.FTIR,SEM and CLSM were used to analyze and characterize the swelling behavior of PEAS-PEG hydrogels before and after swelling.The focus was on proposing the mechanism of its swelling in seawater through the parameter changes before and after swelling,and establishing the corresponding mechanism model.The results showed that seawater led the infrared absorption peaks to move to the low frequency region.With the increased addition of PEAS microspheres,the 3D network structure strength of the hydrogel increased,and the swelling degree showed a trend of first increased and then decreased.The roughness of the xerogel gradually increased before the swelling,while it showed an opposite trend after the swelling.The PEAS-PEG hydrogel went through three stages of ’wetting-rapid swelling-swelling equilibrium’ during the swelling process.The focus was on the controlled swelling degree in the range of 100 % ～ 800 % by changing the ratio of hydrophilic monomer polyethylene glycol to polyether terpol.(3)PEAS-PEG hydrogel/PDMS coatings with different PEAS-PEG hydrogel additions were prepared by physical co-blending method.The swelling properties,surface interface properties,mechanical properties,and antifouling properties of the coatings were tested and evaluated.Optimized process conditions and prepared ’primer coat + intermediate coat +surface coat’ application type coating.Focuing on the interlayer adhesion test to analyze the antispalling performance of the coating,and fluorescently labeled bovine serum albumin(BSA)adsorption efficiency test,anti-marine bacterial adhesion test,anti-benthic diatom adhesion test and anti-biological mucus adhesion test to analyze the antifouling performance of the coating.The results showed that the coatings with the increased addition of PEAS-PEG hydrogel,the mechanical properties,antispalling properties and antifouling properties of the coatings showed a trend of first increase and then decrease.When PEAS-PEG hydrogel was added at 20 wt.%,the coating had both amphiphilic and low surface energy properties,and it has optimal antifouling properties.The focus was on the formation of a highly hydrated layer,low surface energy properties,high matrix stability,and high interlayer adhesion of the coating to achieve efficient antifouling bioadhesion properties.(4)The long-lasting antifouling performance of the coating was tested by static seawater immersion experiment for up to one year.Different time points were selected to characterize the macroscopic morphology,roughness,surface interface properties,interlayer adhesion and mechanical tensile properties of the coatings with immersion time,increased characterization of corrosion resistance after two years of seawater immersion.Focusing on the changes in the antifouling properties of BSA fluorescent protein adsorption efficiency,anti-marine bacterial adhesion,and anti-benthic diatom adhesion for coatings with different hydrogel additions.The results showed that the coating with PEAS-PEG hydrogel added was always amphiphilic during the immersion process.With increasing seawater immersion time,the coating with added hydrogel showed better antispalling properties,mechanical properties,and long-lasting antifouling properties than the single PDMS coating,and the coating has excellent corrosion resistance.When the hydrogel was added at 20 wt.%,the coating also had low surface energy properties,and was minimally affected by seawater.After 365 days of immersion,the coating showed an increase of 329.95 % in antispalling rate,801.64 % in elastic modulus,178.37 % in BSA fluorescent protein adsorption efficiency,300.74 % in marine bacteria adhesion rate,and191.25 % in benthic diatom adhesion rate compared to PDMS coating. |
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