| Surface drag reduction and antifouling(biological fouling prevention)are of great significance for marine vehicles and medical devices.The classical methods of surface antifouling and drag reduction are biomimetic and coating methods.The surface self-assembly micro and nano morphology construction method is a dense method in recent years.However,there are many problems such as complex preparation process and poor stability of coatings.In this study,a hydrophilic microsphere bionic coating scheme is proposed,namely,constructing hydrophobic micro domains in hydrophobic coatings.First,the polystyrene micro and nanospheres with polyethylene glycol(PEG)(PS-PEG microspheres)were prepared;and aqueous suspension of the microspheres was then blended with an acrylic polymer emulsion to form a latex blend.Finally,the latex blend was coated on the material surface,costructing the acrylic polymer coating with hydrophilic micro area using hydrophilic microspheres.The aim of this study is to establish a bionic coating technology that improves the drag reduction and antifouling properties of the coating with good coating stability and easy to achieve large area coating.The main research work includes:1.Study on the design and preparation of PS-PEG microspheres.The microspheres with different PEG amount,chain length and particle size were obtained,and the surface of the microspheres had an open ring cross-linked epoxy group.Using styrene(St)as the main monomer,glycidyl methacrylate(GMA)as functional monomer and PEGMA as a reactive macromolecule emulsifier,microspheres with different particle sizes and PEG branched chains were obtained by emulsion polymerization,microsuspension polymerization and suspension polymerization.The results show that:the microspheres with controllable particle size and uniform distribution can be prepared by emulsion polymerization.The PS-PEG microspheres,using PEGMA(molecular weight of 2080)as the molecular emulsifiers,with amount of Owt%,6wt%,10wt%and 20wt%respectively,with a particle size range of 103.7 ± 2.1-173.5 ± 10.5nm,is obtained.By emulsion polymerization,microspheres with different PEG chain length were obtained by using PEGMA with a molecular weight of 500,2080 and 5000 respectively,and the particle size range was 103.7 ± 2.1-112.9 ± 7.8nm.When the amount of PEGMA(molecular weight 2080)was the same,microspheres with the size of 10Onm,500nm,1μ,m and 5μm were prepared by emulsion polymerization,microsuspension polymerization and suspension polymerization(adding a certain amount of DVB).2.The design and preparation of coating main material.In this study,acrylate polymer was used as the main coating material,which Tg was 35 ℃and can be crosslinked by epoxy open ring.Using methyl methacrylate(MMA)and n-butyl acrylate(BA)as copolymerized monomers and GMA as functional monomers,acrylate polymer emulsion was prepared by soap free emulsion polymerization.And the measured Tg of the polymer was 40 ℃.3.The preparation process of bionic coating and the surface morphology,hydrophilicity and stability of the coating were studied.The above microsphere emulsion was blended with acrylate polymer emulsion at a certain mass ratio,and the coating was obtained through coating and drying process.The crosslinking of polyvinyl amine(PEI)crosslinking agent on the coating was studied,and the suitable crosslinking conditions were determined to be crosslinking 5h under heating at 80 ℃.The effect of microsphere amount on the coating surface morphology was investigated by scanning electron microscope.The effect of the content of microspheres on the surface hydrophilicity was investigated by the static water contact angle test,and the effect of crosslinking within the coating layer on the stability of the coating layer was also studied.The results showed that:with the content of microspheres in the coating increased,the surface microspheres on surface were more compact,and the microspheres began to accumulate after 6wt%.The hydrophilicity of the coatings layer was increased with the increase of the amount of microspheres in the coating as indicated by the contact angle of water drop.When the microsphere content increases from Owt%to 15wt%,coatings contact angle can be reduced from 83.5 ± 1.8° to 67.5 ± 1.8°.The contact angle of the crosslinked coating is basically unchanged after shaking 30 days,and the stability of coating is good.4.Study on fluid resistance of coating and influencing factors.The influence of amount of microspheres in coatings,microspheres of different PEGMA amountt,microspheres of different size and microspheres of different PEG chain on fluid resistance of coatings were investigated by the torque method.The results show that as the content of microspheres in the coating increase,the drag reduction increased firstly and then tended to be stable.When the particle size is equal,the drag reduction rate of the coating increased with the increase of PEGMA content in the microspheres,and the maximum drag reduction rate of the coating is 21%with the content of PEGMA 20%.When the amount and the molecular weight of PEGMA in microspheres are at the same time,with the increase of the microspheres size in coatings,the maximum drag reduction first increased and then decreased,and when the size of the microspheres is 500nm,the maximum drag reduction rate is 34%.While the size of microspheres is equal and the PEGMA adding molar ratio is the same,the drag reduction efficiency of the coating increased with the increase of the PEG chain length,and the maximum drag reduction efficiency is 29%when the molecular weight of the PEGMA is 5000.5.Study on the anti protein adsorption properties of the coating.Using BSA-FITC as an adsorbent protein,the microspheres of different PEGMA content,the microspheres of different size and the microspheres of differentPEG chain on anti-protein adsorption of coatings were investigated.The results showed that the anti protein adsorption efficiency of the coating increased with the microsphere content increase in coatings,when the microsphere content was 15wt%,the maximum anti protein adsorption efficiency could reach 97%.When the microsphere content was 9wt%in coatings,the anti protein adsorption efficiency increased with the increase of PEGMA content in the microspheres.And the anti-protein adsorption efficiency of the coating with different size of microspheres was above 90%.The anti protein adsorption effect of the coating with different microspheres of different PEG chain length was good,and increased with the increase of PEG chain length.When the molecular weight of PEGMA was 5000,the anti protein adsorption efficiency reached 97%. |
