Preparation And Properties Of Multifunctional Hydrophilic Coatings Inspired By Bioadhesion

Bioadhesion belongs to a kind of interface behavior,which is a special ability formed by organisms in the process of long-term survival and evolution.The adsorption of microorganisms on the material surface mainly includes specific adsorption and non-specific adsorption.The above process is usually completed under the action of van der Waals force,electrostatic force,hydrogen bond,hydrophobic force and covalent bond.However,the existence of bioadhesion has many adverse effects on human production and life.For example,the contamination of medical equipment by bacteria will threaten human life,the surface of underwater equipment will be corroded by organisms and will accelerate the loss,and the oil pipeline will be blocked by biological colonies reduce transmission efficiency.Therefore,the hazard of bioadhesion has become a basic and universal problem in the research fields of biochemistry,medical materials,and marine antifouling.It is inevitable that microorganisms tend to adhere to the surface of the material.If we can grasp certain laws and commonalities from the process of bioadhesion,we can scientifically transform the mode of action of poor adhesion into a controllable driving force for humans,so as to prepare with anti-bioadhesion and multifunctional surface,this will be of great significance.Because the microbial surface protein contains hydrophobic residues,this can make it adsorb to the hydrophobic surface under the drive of hydrophobic interaction.If the hydrophilic polyelectrolytes containing hydrophobic alkyl chains can be adsorbed on the surface of hydrophobic substrate by the same method,not only the surface can be hydrophilically modified,but also the surface can be functionalized by polyelectrolytes with different functions.Based on the above analysis and understanding,inspired by bioadhesion,this article explores the influence of different functional groups on the surface of polyelectrolytes about its adsorption behavior on hydrophobic surfaces,and is committed to establishing a theory of hydrophilic polymer adsorption on hydrophobic surfaces.On this basis,the surface physicochemical properties,stability,interface formation mechanism of polyelectrolyte coatings and their applications in the fields of oil-water separation,anti-bioadhesion,and antibacterial have been systematically and deeply studied.The specific contents are as follows:1.Inspired by the process of bioadhesion,we can make use of proteins with similar structure,that is,polyelectrolyte with hydrophobic hydrocarbon group as main chain and hydrophilic group as base material.Driven by the hydrophobic force,the hydrophobic groups on the polyelectrolyte surface can spontaneously adsorb to the hydrophobic surface in water,while the exposed hydrophilic groups can hydrophilically modify the model hydrophobic surface decorated by carbon and fluorine.By adjusting the pH value,ionic strength of the solution and the immersing time of the hydrophobic substrate,the effect on the adsorption of polyelectrolytes with different functional groups on the hydrophobic surface is studied.Among them,the polyelectrolyte with adjustable surface electrical properties has the best adsorption.By changing the solvent,changing the hydrophilicity and hydrophobicity of the substrate,and characterizing the wettability of the reverse side of the polyelectrolyte membrane.It is proved that the hydrophobic force is the main driving force for the adsorption of the polyelectrolyte on the hydrophobic surface.This method provides a theoretical and experimental basis for the adsorption of hydrophilic polymers on hydrophobic surfaces in solution.2.In the solution of pH=3 and 1.35 M NaCl,PAA with adjustable surface electrical properties can be uniformly and compactly adsorbed on the hydrophobic surface to form a hydrophilic coating.The surface carboxyl group packing density of the coating is as high as 4.8 nm^-2,which makes it superhydrophilic(CA°=6.5)and surface anti-aging properties.By calculating the distance Dp between the adjacent PAA molecular chains in the solution,the flory radius Rf,and the radius of gyration Rg,it is deduced that the hydrophilic modification of the hydrophobic surface is coordinated and controlled by the following two effects:the long-range hydrophobic interaction between a single PAA polymer chain and the hydrophobic surface and the short-range hydrogen bonding between adjacent PAA polymer chains.The superhydrophilic coating can not only be used for efficient oil-water separation(flux of 430 Lm²/S),but also exhibits excellent resistance to bovine serum albumin and fibrinogen after being grafted with methoxy polyethylene glycol amine.The amount of adhesion was 0 and6.7 ng/cm²,respectively.3.In order to prepare a hydrophilic coating that is stable in an alkaline environment,using the hydrophobic interaction between the polyacrylamine and the hydrophobic substrate in the pH=11,1.0 M NaCl solution as the driving force,polyacrylamide can be effectively adsorbed on the hydrophobic surface of the model(CA°=34.7°),and the surface of a variety of hydrophobic polymers can be hydrophilically modified.Polyacrylamide hydrophilic coatings exhibit excellent stability in strong acids,strong bases,high ionic strength solutions,and a variety of polar and non-polar organic solvents.The hydrophilic coating not only achieves effective oil-water separation,but also exhibits extremely low adhesion to Escherichia coli(1.8%)and Staphylococcus aureus(2.6%).In addition,after grafting polyethylene glycol onto the surface of the polypropylene amine coating,the adhesion of the surface to bovine serum albumin was7.6 ng/cm².After treatment with sodium hypochlorite solution,the chlorinated polyacrylamine coating(2 cm×2 cm)kills 99.9%of E.coli(10⁶ CFU/m L)in the solution.