Preparation Of SiO_x/wpu Super-amphiphobic Coatings And Its Anti-biofilm Mechanism To Shewanella Putrefaciens

The SiO_x/waterborne polyurethane(WPU)super-amphiphobic coatings were prepared by dropping coating method based on the idea of "fluorination first,then constructing rough structure".SiO_x particles were prepared by the hydrolysis of tetraethyl silicate(TEOS)and the low surface energy modification was carried out in the same solvent system.The SiO_x/WPU coatings with different hydrophobic and oleophobic properties were obtained by modifying the process conditions using SiO_x particles to constructe the roughness.The SiO_x particles were characterized by XRD and FI-IR.The chemical properties of the coatings surface were characterized by XRD,FI-IR and XPS.The microstructures of the coatings were characterized by SEM,TEM and AFM.The thermal stability of the coatings was evaluated by TG/DSC.Taking the dominant spoilage bacteria of aquatic products,Shewanella putrefaciens as the object,the anti-bacterial adhesion properties and anti-biofilm mechanism of the SiO_x/WPU coatings were investigated.1.The effects of modification on the hydrophobic and oleophobic properties,chemical properties,microstructure and thermal stability of the SiO_x/WPU coatings were studied.The results show that,compared with the SiO_x/WPU coatings prepared with 1.2%(m/V)unmodified SiO_x particles,the hydrophobicity and thermal stability of the SiO_x/WPU coatings prepared with 4.0%(m/V)unmodified SiO_x particles is significantly enhanced,but the oil repellency becomes worse,the surface energy of the coatings is the increased,the particles size is uniform,and SiO_x particles agglomerate on the surface,which resulted in the presence of mesoporous structure of the coatings.After SiO_x particles were modified by PFOTS,the surface energy of the SiO_x/WPU coatings were decreased,the hydrophobic and oleophobic properties were improved,and the surface was rough with the appearance of fluorocarbon compounds,but the thermal stability was slightly reduced.Compared with the primarily modified SiO_x/WPU coatings,after the secondary modification of SiO_x particles,the oil repellent property of the SiO_x/WPU coatings were superior,the surface energies of the coatings were lower,and the surface fluorocarbon content were higher.Among them,the super-amphiphobic coatings was obtained by compounding WPU with secondary modified SiO_x micro-nano particles prepared by adding 4.0 m L concentrated ammonia in modification process.The surface energy of the coatings was the lowest,the surface was micro/nano composite structure and the content of fluorocarbon compounds was the highest.2.Taking Shewanella putrefaciens of aquatic products as the object,the anti-bacterial adhesion properties and the mechanism of anti-biofilm of SiO_x/WPU coatings with different hydrophobicity and oleophobicity were characterized.The results showed that,for the hydrophobic SiO_x/WPU coatings,the stronger the oleophobic property,the greater the ability of anti-bacterial adhesion,while the anti-bacterial adhesion ability of amphiphilic SiO_x/WPU coatings is stronger than that of hydrophobic and selectively oleophobic or super-hydrophobic and oleophobic SiO_x/WPU coatings.However,because the super-amphiphobic SiO_x/WPU coatings can be in the Cassie state with the bacterial solution for a long time,it can "capture" enough air to inhibit the irreversible adhesion of the bacteria.In addition,the coatings can also inhibit the metabolic activity,secretion of EPS,and activities of ATP enzyme and AKP of the adherent bacteria,so it has a better anti-biofilm property.3.The effects microstructure of SiO_x particles on hydrophobic and oleophobic properties,surface energy,microstructure and thermal stability of modified SiO_x/WPU coatings were studied.The results show that the modified C-SiO_x/WPU coatings prepared with CTAB modified SiO_x particle as the roughness construction factor has the highest fluorine content,but only shows hydrophobic and super-lipophilic properties,the highest surface energy,and the surface morphology is completely composed of SiO_x microspheres with a particle size of about 400 nm,and has the worst thermal stability.The thermal stability of the modified fumed nano-SiO_x/WPU coatings was the highest,but it only showed super-hydrophobic and selectively oleophobic properties,the surface energy of the coatings was lower,and the surface micrometer scale protrusion was completely caused by the stacking of SiO_x particle with particle sizes of 30 nm-50 nm.The surface of modified micro-scale SiO_x/WPU coatings showed super-amphiphobicity,the surface energy of the coatings was the lowest,and the surface was composed of micro/nano topology formed by the mutual stacking of nano-scale and micro-scale SiO_x particles,and the thermal stability was higher.4.The influence of microstructure of SiO_x particles on the formation of biofilm on the surface of the modified SiO_x/WPU coatings during the biofilm formation of aquatic Shewanella putrefaciens was investigated.The results showed that the performance of the modified C-SiO_x/WPU coatings on anti-bacterial adhesion was the worst,and the bacteria could adhere rapidly on the surface and undergo metabolism and then secrete EPS to form the biofilm.The modified C-SiO_x/WPU coatings could inhibit the adhesion of bacteria at the initial stage,but there was a long-range " hydrophobic interaction " between bacteria and the surface of the coatings,the number of adhered bacteria increased rapidly with the increase of incubation time,and microcolonies were formed.Due to the micro/nano topological structure formed by two different sizes of SiO_x particles on the surface of the modified micro-scale SiO_x/WPU coatings,the coating has super-amphiphobic,which can significantly inhibit the adhesion of bacteria,reduce the metabolic activity and the secretion of EPS of biofilm bacteria,and then prevent the formation of micro colonies.