Medical magnesium alloy surface antibacterial and corrosion-resistant coating and preparation method thereof

Abstract

The application discloses a kind of medical magnesium alloy surface antibacterial corrosion-resistant coating and preparation method thereof, the coating is double-layer composite coating, inner layer is inorganic porous coating, outer layer is flexible piezoelectric polymer coating;Inorganic porous coating raw materials include KF, KOH, K2CO3;Flexible piezoelectric polymer coating raw materials include piezoelectric polymer, inorganic filler, wetting aid and adhesion aid.The application utilizes improved non-solvent induced phase separation method (NIPS) to prepare porous piezoelectric polymer coating on the surface of porous inorganic coating.The coating of the application has porous structure, good hydrophilic performance, and uses electric stimulation strategy to exert bacteriostatic, antibacterial effect.

Description

TECHNICAL FIELD

[0001] The present application relates to a coating and a preparation method thereof, in particular to a medical magnesium alloy surface antibacterial and corrosion-resistant coating and a preparation method thereof, and belongs to the technical field of materials. BACKGROUND

[0002] Magnesium alloy is a kind of light metal material, which has good biocompatibility, mechanical compatibility and osteogenesis function. At the same time, magnesium alloy also has excellent biodegradability, which can be gradually dissolved and absorbed in the body environment. It is a new type of biodegradable medical material, especially suitable for manufacturing metal stents with certain mechanical strength. However, there are still many challenges and difficulties to be overcome in the clinical application of magnesium alloy. First, magnesium alloy has high chemical and electrochemical activity, which is easy to be corroded by body fluid, and degrades too fast in the use process, which cannot meet the requirements of material integrity. Second, how to inhibit and eliminate bacterial infection on the surface of the implanted body. It is very important to construct a coating with corrosion resistance and antibacterial function on the surface of magnesium alloy. Surface coating treatment technology can functionalize the material surface without affecting the overall performance of the material, so as to have corrosion resistance and antibacterial function.

[0003] The corrosion resistance function of magnesium alloy surface is usually realized by coating a corrosion-resistant polymer coating on its surface. The polymer coating can hinder the direct contact of medical magnesium alloy with body fluids, blood and other in-vivo substances, thereby reducing the degradation rate of magnesium alloy. However, the polymer coating generally has hydrophobicity, which is not conducive to the adsorption and proliferation of human cells. The antibacterial function of magnesium alloy surface is usually realized by doping antibacterial agents (including antibacterial drugs and metal elements with antibacterial effect) in the coating preparation liquid. The antibacterial mechanism of doping antibacterial drugs is easy to cause bacterial resistance; and the doping of inorganic antibacterial materials such as metal ions usually has certain toxicity, and the doping of metal particles inevitably forms a certain degree of galvanic corrosion between magnesium alloy, which is not conducive to the stability of corrosion resistance function. Therefore, it is very desirable to develop a simple and effective strategy to make magnesium alloy have hydrophilic corrosion resistance and corrosion resistance at the same time.

[0004] Piezoelectric catalytic antibacterial is a kind of remote control and non-invasive antibacterial method. The built-in electric field formed by piezoelectric material electrolyzes water to produce active oxygen, thereby destroying various metabolic pathways of bacteria and finally killing bacteria. This method can avoid the defects of drug resistance and the use of metal elements, and realize the antibacterial effect under external field control. Flexible piezoelectric material has excellent electroactive characteristics, however, there is no report on using flexible piezoelectric material to prepare magnesium alloy surface coating for medical use to improve its corrosion resistance and antibacterial performance at the same time.

[0005] The present technical scheme mainly has the following problems:

[0006] 1. The hydrophilicity of the polymer corrosion-resistant coating is poor, which is not conducive to cell adhesion, growth and proliferation;

[0007] 2. The antibacterial strategy only relies on the intrinsic chemical and physical properties of the antibacterial agent. The antibacterial mechanism of the antibacterial agent is easy to cause bacterial resistance; and the inorganic antibacterial material doped with metal ions usually has certain toxicity, and the doping of metal particles inevitably forms a certain degree of galvanic corrosion with the magnesium alloy, which is not conducive to the stability of the corrosion-resistant function. SUMMARY

[0008] The purpose of the present application is to provide a medical magnesium alloy surface antibacterial corrosion-resistant coating, which has a porous structure, good hydrophilicity, and uses an electric stimulation strategy to play an antibacterial and antibacterial effect. Another purpose of the present application is to provide a preparation method of a medical magnesium alloy surface antibacterial corrosion-resistant coating.

[0009] Technical scheme: The medical magnesium alloy surface antibacterial corrosion-resistant coating of the present application is a double-layer composite coating, the inner layer is an inorganic porous coating, and the outer layer is a flexible piezoelectric polymer coating. The raw materials of the inorganic porous coating include KF, KOH and K2CO3. The raw materials of the flexible piezoelectric polymer coating include piezoelectric polymer, inorganic filler, wetting aid and adhesion aid.

[0010] Preferably, the raw material of the inorganic porous coating is a mixed solution containing KF, KOH and K2CO3. In the mixed solution, the concentration of KF is 0-20 g / L, the concentration of KOH is 0-56 g / L, and the concentration of K2CO3 is 0-60 g / L.

[0011] More preferably, in the mixed solution, the concentration of KF is 2.5-8.5 g / L, the concentration of KOH is 8-12 g / L, and the concentration of K2CO3 is 25-35 g / L.

[0012] Preferably, the raw material of the flexible piezoelectric polymer coating is a piezoelectric polymer-based coating solution containing piezoelectric polymer, inorganic filler, wetting aid and adhesion aid. The piezoelectric polymer-based coating solution includes 2.5-17.5 wt% piezoelectric polymer, 0-5 wt% inorganic filler, 20-1000 ppm wetting aid and 20-1000 ppm adhesion aid, and the solvent of the piezoelectric polymer-based coating solution is a polar liquid.

[0013] More preferably, the piezoelectric polymer-based solution includes 5-15 wt% piezoelectric polymer, 1-3.75 wt% inorganic filler, 40-200 ppm wetting aid and 40-200 ppm adhesion aid, and the solvent of the piezoelectric polymer-based solution is a polar liquid.

[0014] Preferably, the piezoelectric polymer is one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a PVDF copolymer, polyvinyl chloride (PVC), PLGA, PLA, PCL, chitosan;

[0015] Preferably, the polar liquid is one or more of dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO);

[0016] Preferably, the inorganic filler includes one or more of zinc oxide (ZnO), metal oxides such as titanium oxide (TiO2), barium titanate (BaTiO3), potassium sodium niobate (Na 0.5 K 0.5 NbO3), and other piezoelectric ceramics.

[0017] Preferably, the wetting aid is selected from at least one of a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a non-ionic surfactant;

[0018] Preferably, the adhesion aid is selected from one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-methyl-γ-aminopropyltrimethoxysilane, N-(n-butyl)-γ-aminopropyltrimethoxysilane, N-(n-butyl)-γ-aminopropyltriethoxysilane, N,N-diethyl-γ-aminopropyltrimethoxysilane, 3-cyclohexyl-aminopropylmethyldimethoxysilane, anilinomethyltrimethoxysilane, anilinomethyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldiethoxysilane, aminoethylaminoisobutylmethyldimethoxysilane, 3-(2-hydroxyethylaminoethyl)-aminopropylmethyldimethoxysilane, diethylenetriaminylpropylmethyldimethoxysilane, bis[3-(trimethoxysilylpropyl)]amine, bis[3-(triethoxysilylpropyl)]amine, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

[0019] In another aspect, the present application is a method for preparing a medical magnesium alloy surface antibacterial and corrosion-resistant coating as described above, and the method comprises the following steps:

[0020] Step one, pretreating the magnesium alloy surface to obtain a pretreated surface;

[0021] Step two, preparing an inorganic porous membrane layer on the pretreated surface obtained in step one by using a hydrothermal method;

[0022] Step three, preparing a flexible piezoelectric polymer coating on the porous inorganic coating surface obtained in step two by using an improved non-solvent induced phase separation method;

[0023] The improved non-solvent induced phase separation method comprises adding piezoelectric polymer-based coating liquid droplets on the porous inorganic coating surface obtained in step two to cover the entire surface, and then preparing a flexible piezoelectric polymer coating on the porous inorganic coating surface to obtain a magnesium alloy sample;

[0024] Spraying water mist on the magnesium alloy sample for a period of time, and then soaking the magnesium alloy sample in water for a period of time to form a three-dimensional porous membrane on the surface of the magnesium alloy sample.

[0025] In the above technical solution, the entire magnesium alloy sample is immersed in deionized water for 10 min, a large amount of deionized water enters the PVDF solution through the porous PVDF surface layer and exchanges with the remaining organic solvent to form a three-dimensional porous membrane.

[0026] Preferably, in step one, the pretreated surface is prepared by mechanical grinding: cutting the magnesium alloy sample into a suitable size, mechanically grinding with water sandpaper to remove surface oxide scale and impurities, and then ultrasonic cleaning in acetone or anhydrous ethanol for 10 min and cold air drying.

[0027] Preferably, in step two, the conditions for preparing an inorganic porous membrane layer on the pretreated surface obtained in step one by using a hydrothermal method are as follows: the reaction solution is composed of KF, KOH and K2CO3, the concentration of KF is 0-20 g / L, the concentration of KOH is 0-56 g / L, the concentration of K2CO3 is 0-60 g / L, the pH value of the reaction solution is adjusted to 9-15 using KOH or HNO3, and the ratio of the volume of the reaction solution to the surface area of the sample is kept at 2.5-10 ml / cm 2 , the treatment temperature is 40-180℃, and the treatment time is 2-12 hours.

[0028] More preferably, the concentration of KF is 2.5-8.5 g / L, the concentration of KOH is 8-12 g / L, the concentration of K2CO3 is 25-35 g / L, the pH value of the reaction solution is adjusted to 10-12 using KOH or HNO3, and the ratio of the volume of the reaction solution to the surface area of the sample is kept at 4-6.5 ml / cm 2 , the treatment temperature is 80-140℃, and the treatment time is 6-10 hours.

[0029] Preferably, in step two, the piezoelectric polymer-based coating solution is prepared by first weighing 2.5-17.5 g of piezoelectric polymer powder, 80-97.5 g of polar organic solvent, 0-5 g of inorganic filler, 20-1000 ppm of wetting aid, and 20-1000 ppm of adhesion aid. Then, the above materials are poured into a ball mill tank, the ball milling speed is set to 200-450 rpm, and the ball milling time is 1-24 h to obtain a uniform piezoelectric polymer-based coating solution.

[0030] More preferably, the piezoelectric polymer powder is 5-15 g, the polar organic solvent is 85-95 g, the inorganic filler is 1-3.75 g, the wetting aid is 40-200 ppm, the adhesion aid is 40-200 ppm, the ball milling speed is 250-350 rpm, and the ball milling time is 8-16 h, and the sample is left to stand at room temperature for >2 h to fully remove air bubbles.

[0031] Preferably, in step three, the piezoelectric polymer-based coating solution is added dropwise to the magnesium alloy surface treated in step two to cover the entire surface, and left to stand for 30-300 s.

[0032] More preferably, the sample is left to stand for 60-120 s.

[0033] Preferably, in step three, the method for preparing a flexible piezoelectric polymer coating on the surface of the porous inorganic coating is coating, the coating speed is 300-3000 rpm, and the coating time is 30-600 s. The coating method is any one of spin coating, dip coating, or blade coating.

[0034] More preferably, the coating speed is 600-1500 rpm, and the coating time is 60-360 s.

[0035] Preferably, in step three, the water mist spraying conditions are as follows: the water mist spraying time is 20-1200 s, and the distance between the magnesium alloy sample and the water mist is 3-30 cm.

[0036] More preferably, the time is 60-180 s, and the distance is 5-15 cm.

[0037] Beneficial effects: Compared with the prior art, the present application has the following significant advantages: a corrosion-resistant coating is prepared on the surface of the magnesium alloy, the coating has a porous structure, good hydrophilic properties, and uses an electric stimulation strategy to exert antibacterial and antibacterial effects. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 SEM images of the surfaces of the hydrophilic and antibacterial composite coatings, wherein (a) is the surface morphology of Example 1, and (b) is the surface morphology of Example 2.

[0039] Figure 2Surface contact angle for different samples, wherein (a) is the original magnesium alloy, (b) is the general polymer coating described in Comparative Example 1, and (c) is the hydrophilic antibacterial composite coating described in Example 2;

[0040] Figure 3 Tafel polarization curves in SBF solution and the corrosion potential and corrosion current values obtained from the curves for different surface treatment samples, wherein the composite coating is the coating described in Example 1 and the inorganic coating is the coating described in Comparative Example 2;

[0041] Figure 4 Antibacterial effect of the magnesium alloy coated with the antibacterial composite coating on E. coli, and * indicates a significant difference. DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further described below with reference to the accompanying drawings.

[0043] Comparative Example 1: Preparation of a PLA film on the surface of a magnesium alloy

[0044] Step 1: Preparation of a pretreated surface by mechanical grinding

[0045] The magnesium alloy sample was cut into small pieces of 10x10x10mm, and mechanical grinding was performed using 400#, 800#, 1000#, and 1500# sandpaper, respectively, to remove the surface oxide scale and impurities. Subsequently, ultrasonic cleaning was performed in anhydrous ethanol for 2 times, each for 5min, and the sample was dried with cold air for standby;

[0046] Step 2: Preparation of an inorganic porous coating by hydrothermal method

[0047] An inorganic porous film layer was prepared on the pretreated surface obtained in Step 1 by hydrothermal method. The reaction solution was composed of KOH and KF, the concentration of KOH was 56g / L, the concentration of KF was 5.8g / L, the pH value of the reaction solution was adjusted to 14 using KOH, and the ratio of the reaction solution volume to the sample surface area was maintained at 5ml / cm 2 , the treatment temperature was 120℃, and the treatment time was 8 hours. After hydrothermal treatment, ultrasonic cleaning was performed in pure water for 2 times, each for 1min, and then ultrasonic cleaning was performed in anhydrous ethanol for 2 times, each for 1min, and the sample was dried with cold air for standby;

[0048] Step 3: Preparation of a PLA coating

[0049] (1) Preparation of a PLA coating solution

[0050] First, 10g of PLA polymer powder and 90g of hexafluoroisopropanol (C3H2F6O) were weighed, stirred and dissolved, the stirring speed was 500r / min, and the stirring time was 3h until complete dissolution. The coating solution was ultrasonically treated for 15min at room temperature to remove air bubbles.

[0051] (2) Preparation of PLA coating

[0052] First, the PLA polymer base coating solution described in step three (1) was added to the magnesium alloy surface treated in step two, covering the entire surface, and left to stand for 120 s. The coating was prepared using a spin coating method at a spin coating speed of 800 rpm and a spin coating time of 300 s. After spin coating, it was left to stand at room temperature for 3 minutes. The prepared sample was placed in a vacuum drying oven and dried at 40°C for 4 hours.

[0053] The hydrophilic property of the obtained composite coating was about 126°, showing hydrophobicity, as shown in Figure 2 .

[0054] The antibacterial effect of the obtained composite coating on E. coli was shown in Figure 4 , and there was no obvious antibacterial effect under standing and ultrasonic conditions. Under ultrasonic conditions, the survival rate of bacteria decreased to 87%, and a small amount of bacteria died due to physical damage caused by cavitation of ultrasonic.

[0055] Comparative Example 2: Preparation of a porous inorganic thin film on the surface of a magnesium alloy

[0056] Step one, preparation of a pretreated surface by mechanical grinding

[0057] The magnesium alloy sample was cut into small pieces of 10x10x10mm, and mechanical grinding was performed using 400#, 800#, 1000#, and 1500# sandpaper, respectively, to remove the surface oxide scale and impurities. Subsequently, ultrasonic cleaning was performed in anhydrous ethanol for 2 times, 5 min each time, and cold air was used for drying;

[0058] Step two, preparation of an inorganic porous coating by hydrothermal method

[0059] An inorganic porous film layer was prepared on the pretreated surface obtained in step one by a hydrothermal method. The reaction solution was composed of KOH and KF, the concentration of KOH was 56g / L, the concentration of KF was 5.8g / L, the pH value of the reaction solution was adjusted to 14 using KOH, and the ratio of the volume of the reaction solution to the surface area of the sample was kept at 5ml / cm 2 , the treatment temperature was 120°C, and the treatment time was 8 hours. After hydrothermal treatment, ultrasonic cleaning was performed in pure water for 2 times, 1 min each time, and then ultrasonic cleaning was performed in anhydrous ethanol for 2 times, 1 min each time, and cold air was used for drying;

[0060] The corrosion resistance of the obtained inorganic coating was shown in Figure 3 , compared with untreated magnesium alloy, the corrosion potential shifted positively, and the corrosion current decreased, indicating that the corrosion resistance was improved.

[0061] Example 1: A medical magnesium alloy surface antibacterial composite coating and its preparation method

[0062] Step one, preparation of a pretreated surface by mechanical grinding

[0063] The magnesium alloy sample was cut into 10x10x10mm pieces, and mechanically ground with 400#, 800#, 1000#, and 1500# sandpaper, respectively, to remove the surface oxide scale and impurities, and then ultrasonically cleaned in anhydrous ethanol for 2 times, 5min each time, and dried with cold air for standby;

[0064] Step two, hydrothermal method for preparing inorganic porous coating

[0065] An inorganic porous film layer was prepared on the pretreated surface obtained in step one by a hydrothermal method. The reaction solution was composed of KOH and KF, the concentration of KOH was 56g / L, the concentration of KF was 5.8g / L, the pH value of the reaction solution was adjusted to 14 using KOH, and the ratio of the reaction solution volume to the sample surface area was kept at 5ml / cm 2 , the treatment temperature was 120℃, and the treatment time was 8 hours.

[0066] Step three, preparation of a porous flexible piezoelectric polymer-based coating

[0067] 1) Preparation of piezoelectric polymer-based coating solution

[0068] First, 5g of PVDF-TrFE (70:30) polymer powder, 95g of DMF, 200ppm of sodium dodecyl sulfate, and 40ppm of γ-aminopropyltrimethoxysilane were weighed. Then the above materials were poured into a ball mill tank, the ball mill speed was set to 300rpm, and the ball mill time was 4h to obtain a uniform piezoelectric polymer-based coating solution. The coating solution was left to stand at room temperature for 4h to fully remove air bubbles.

[0069] 2) Preparation of a porous flexible piezoelectric polymer-based coating

[0070] A porous piezoelectric polymer coating was prepared on the porous inorganic coating surface obtained in step two by using a modified non-solvent induced phase separation method (NIPS).

[0071] First, the piezoelectric polymer-based coating solution described in step three (1) was added dropwise to the magnesium alloy surface treated in step two, covering the entire surface, and left to stand for 120s. A coating was prepared by spin coating at a speed of 800rpm for 300s. After spin coating, it was left to stand at room temperature for 3 minutes.

[0072] Then the thin film obtained by spin coating was transferred to a water mist generator, and the water mist device was turned on, and the water mist was sprayed for 30s. Deionized water was selected for the water mist, and the distance between the sample and the water mist was 0cm.

[0073] Next, the sample was immersed in deionized water at 25℃ for 10min to form a three-dimensional porous film. The prepared sample was cleaned with ethanol and then placed in a vacuum drying oven at 40℃ for 2 hours.

[0074] The obtained composite coating structure is as shown in Figure 1 (a) The surface is microporous structure.

[0075] The corrosion resistance of the obtained composite coating is as shown in Figure 3 The inorganic coating is the coating described in Comparative Example 2. Compared with the sample coated only with the inorganic coating, the composite coating has a positive shift in corrosion potential and a smaller corrosion current, and the corrosion resistance is further improved.

[0076] The antibacterial effect of the obtained composite coating on Escherichia coli is as shown in Figure 4 It has obvious antibacterial effect under the action of ultrasonic waves.

[0077] Example 2: A medical magnesium alloy surface antibacterial composite coating and a preparation method thereof

[0078] Step one, mechanical grinding to prepare a pretreated surface

[0079] Cut the magnesium alloy sample into small pieces of 10x10x10mm, and use 400#, 800#, 1000#, and 1500# sandpaper for mechanical grinding to remove the surface oxide skin and impurities. Then ultrasonically clean in anhydrous ethanol for 2 times, 5min each time, and dry with cold air for standby;

[0080] Step two, hydrothermal method to prepare an inorganic porous coating

[0081] The hydrothermal method is used to prepare an inorganic porous film layer on the pretreated surface obtained in step one. The reaction solution is composed of K2CO3 and KF, the concentration of K2CO3 is 60g / L, and the concentration of KF is 8.5g / L; use KOH to adjust the pH value of the reaction solution to 12, and the ratio of reaction solution volume to sample surface area is kept at 5ml / cm 2 , the treatment temperature is 120℃, and the treatment time is 8 hours.

[0082] Step three, preparation of a porous flexible piezoelectric polymer-based coating

[0083] 1) Preparation of piezoelectric polymer-based coating solution

[0084] First, weigh PVDF-TrFE(70:30) polymer powder 10g, polyvinyl alcohol(PVA) 5g, DMF 80g, nano-zinc oxide 1.0g, sodium dodecyl sulfate 40ppm, and γ-aminopropyl trimethoxysilane 200ppm. Then pour the above materials into a ball mill tank, set the ball mill speed to 300rpm, and ball mill for 4h to obtain a uniform piezoelectric polymer-based coating solution. The coating solution is left to stand at room temperature for 4h to fully remove the bubbles.

[0085] 2) Preparation of a porous flexible piezoelectric polymer-based coating

[0086] A porous piezoelectric polymer coating is prepared on the surface of the porous inorganic coating obtained in step two by using improved non-solvent induced phase separation (NIPS).

[0087] First, the piezoelectric polymer-based coating solution described in step three (1) is added to the magnesium alloy surface treated in step two, covering the entire surface, and left to stand for 120 s. A coating is prepared by spin coating at a speed of 800 rpm for 300 s. After spin coating, the sample is left to stand at room temperature for 3 min.

[0088] Subsequently, the spin-coated film is transferred to a water mist generator, and the water mist device is turned on, and the water mist is sprayed for 30 s. Deionized water is used for the water mist, and the distance between the sample and the water mist is 0 cm.

[0089] Then, the sample is immersed in deionized water at 25°C for 10 min to form a three-dimensional porous film. After cleaning with ethanol, the prepared sample is placed in a vacuum drying oven and dried at 40°C for 2 h.

[0090] The structure of the obtained composite coating is shown in Figure 1 (b), and the surface has a microporous structure. The nano-ZnO particles are embedded in the polymer porous framework.

[0091] The surface hydrophilicity of the obtained composite coating is shown in Figure 2 The surface water contact angle of the composite coating is significantly lower than that of the original magnesium alloy and the polymer film in the comparative example.

[0092] The antibacterial effect of the obtained composite coating on E. coli is shown in Figure 4 Under static conditions, the composite coating has a certain antibacterial effect, and the antibacterial effect is more obvious under the action of ultrasonic waves.

[0093] Example 3: A medical magnesium alloy surface antibacterial composite coating and a preparation method thereof

[0094] Step one: mechanical grinding to prepare a pretreated surface

[0095] The magnesium alloy sample is cut to the appropriate size, mechanically ground with water sandpaper to remove the surface oxide scale and impurities, and then ultrasonically cleaned in acetone or anhydrous ethanol for 10 min, and dried with cold air;

[0096] Step two: preparation of an inorganic porous coating by a hydrothermal method

[0097] An inorganic porous film layer is prepared on the pretreated surface obtained in step one by a hydrothermal method. The reaction solution is composed of KOH and K2CO3, the concentration of KOH is 8 g / L, the concentration of K2CO3 is 25 g / L, the pH value of the reaction solution is adjusted to 15 using KOH, and the ratio of the volume of the reaction solution to the surface area of the sample is kept at 4 ml / cm 2 The treatment temperature is 80°C, and the treatment time is 6 hours.

[0098] Step three, preparation of porous flexible piezoelectric polymer based coating

[0099] 1) Preparation of piezoelectric polymer based coating solution

[0100] Firstly, PVDF-TrFE (70:30) polymer powder 5g, DMF 95g, nano-zinc oxide 3.75g, sodium dodecyl sulfate 40ppm, γ-aminopropyl trimethoxysilane 40ppm were weighed. Then the above materials were poured into a ball mill tank, the ball milling speed was 250rpm, the ball milling time was 8h, and the uniform piezoelectric polymer based coating solution was obtained after standing at room temperature for >2h.

[0101] 2) Preparation of porous flexible piezoelectric polymer based coating

[0102] The porous piezoelectric polymer coating was prepared on the surface of the porous inorganic coating obtained in step two by using the improved non-solvent induced phase separation method (NIPS).

[0103] Firstly, the piezoelectric polymer based coating solution described in step three (1) was added dropwise to the surface of the magnesium alloy treated in step two, covering the entire surface, and standing for 60s. The coating was prepared by spin coating at a speed of 600rpm for 60s.

[0104] Then the thin film obtained by spin coating was placed under water mist for 60s. Deionized water was selected as the water mist, and the distance between the sample and the water mist was 5cm.

[0105] Next, the entire sample was immersed in deionized water for 10min, and a large amount of deionized water entered the PVDF solution through the porous PVDF surface layer and exchanged with the remaining organic solvent, forming a three-dimensional porous film.

[0106] The prepared sample was cleaned with ethanol and then placed in a vacuum oven and dried at 40C for 2h.

[0107] Example 4 A medical magnesium alloy surface antibacterial composite coating and a preparation method thereof

[0108] Step one, preparation of pretreated surface by mechanical grinding

[0109] The magnesium alloy sample was cut into appropriate size, mechanically ground with water sandpaper to remove surface oxide scale and impurities, and then ultrasonically cleaned in acetone or anhydrous ethanol for 10min, and dried by cold air;

[0110] Step two, preparation of inorganic porous coating by hydrothermal method

[0111] An inorganic porous membrane layer is prepared on the pretreated surface obtained in step one by hydrothermal method. The reaction solution is composed of KF and K2CO3, the concentration of KF is 20 g / L, the concentration of K2CO3 is 35 g / L, the pH value of the reaction solution is adjusted to 12 using KOH, and the ratio of the volume of the reaction solution to the surface area of the sample is kept at 6.5 ml / cm 2 , the treatment temperature is 140°C, and the treatment time is 10 hours.

[0112] Step three, preparation of a porous flexible piezoelectric polymer-based coating

[0113] 1) Preparation of a piezoelectric polymer-based coating solution

[0114] First, 15 g of PVDF-TrFE (70:30) polymer powder, 95 g of DMF, 3.75 g of nano-zinc oxide, 200 ppm of sodium dodecyl sulfate, and 200 ppm of γ-aminopropyltrimethoxysilane are weighed. Then, the above materials are poured into a ball mill tank, the ball milling speed is 350 rpm, the ball milling time is 16 h, and the uniform piezoelectric polymer-based coating solution is obtained after standing at room temperature for > 2 h.

[0115] 2) Preparation of a porous flexible piezoelectric polymer-based coating

[0116] A porous piezoelectric polymer coating is prepared on the surface of the porous inorganic coating obtained in step two by using a modified non-solvent induced phase separation method (NIPS).

[0117] First, the piezoelectric polymer-based coating solution described in step three (1) is added dropwise to the surface of the magnesium alloy after step two treatment, covering the entire surface, and standing for 120 s. The coating is prepared by spin coating at a speed of 1500 rpm for 360 s.

[0118] Then, the thin film obtained by spin coating is placed under water mist for 180 s. Deionized water is selected for the water mist, and the distance between the sample and the water mist is 15 cm.

[0119] Next, the entire sample is immersed in deionized water for 10 min, and a large amount of deionized water enters the PVDF solution through the porous PVDF surface layer and exchanges with the remaining organic solvent, forming a three-dimensional porous membrane.

[0120] The prepared sample is cleaned with ethanol and then placed in a vacuum oven for drying at 40°C for 2 hours.

[0121] Example 5: A medical magnesium alloy surface antibacterial composite coating and a method for preparing the same

[0122] Step one, preparation of a pretreated surface by mechanical grinding

[0123] The magnesium alloy sample was cut into the appropriate size, mechanically ground with water sandpaper to remove the surface oxide and impurities, and then ultrasonically cleaned in acetone or anhydrous ethanol for 10 min, and then blown dry with cold air;

[0124] Step two, preparation of inorganic porous coating by hydrothermal method

[0125] An inorganic porous film layer was prepared on the pretreated surface obtained in step one by a hydrothermal method. The reaction solution was composed of KF, KOH and K2CO3, the concentration of KF was 20 g / L, the concentration of KOH was 56 g / L, the concentration of K2CO3 was 60 g / L, the pH value of the reaction solution was adjusted to 12 using KOH, and the ratio of the volume of the reaction solution to the surface area of the sample was kept at 10 ml / cm 2 , the treatment temperature was 180°C, and the treatment time was 12 hours.

[0126] Step three, preparation of a porous flexible piezoelectric polymer-based coating

[0127] 1) Preparation of piezoelectric polymer-based coating solution

[0128] First, 17.5 g of PVDF-TrFE (70:30) polymer powder, 97.5 g of DMF, 5 g of nano-zinc oxide, 1000 ppm of sodium dodecyl sulfate, and 1000 ppm of γ-aminopropyltrimethoxysilane were weighed. Then, the above materials were poured into a ball mill tank, the ball milling speed was 450 rpm, the ball milling time was 24 h, and the uniform piezoelectric polymer-based coating solution was obtained after standing at room temperature for >2 h.

[0129] 2) Preparation of a porous flexible piezoelectric polymer-based coating

[0130] A porous piezoelectric polymer coating was prepared on the porous inorganic coating obtained in step two by using a modified non-solvent induced phase separation method (NIPS).

[0131] First, the piezoelectric polymer-based coating solution described in step three (1) was added dropwise to the magnesium alloy surface treated in step two, covering the entire surface, and standing for 300 s. The coating was prepared by spin coating at a speed of 3000 rpm for 600 s.

[0132] Then, the thin film obtained by spin coating was placed under water mist for 1200 s. Deionized water was used for the water mist, and the distance between the sample and the water mist was 30 cm.

[0133] Next, the entire sample was immersed in deionized water for 10 min, and a large amount of deionized water entered the PVDF solution through the porous PVDF surface layer and exchanged with the remaining organic solvent, forming a three-dimensional porous film.

[0134] The prepared sample was cleaned with ethanol and then placed in a vacuum oven for drying at 40°C for 2 hours.

[0135] Example 6 A medical magnesium alloy surface antibacterial composite coating and a preparation method thereof

[0136] Step one, mechanical grinding to prepare a pretreated surface

[0137] Cut the magnesium alloy sample into the appropriate size, mechanically grind with water sandpaper to remove the surface oxide scale and impurities, and then ultrasonically clean in acetone or anhydrous ethanol for 10 min, and dry with cold air;

[0138] Step two, hydrothermal method to prepare an inorganic porous coating

[0139] An inorganic porous film layer is prepared on the pretreated surface obtained in step one by a hydrothermal method. The reaction solution is composed of KF, KOH and K2CO3, the concentration of KF is 2.5 g / L, the concentration of KOH is 12 g / L, the concentration of K2CO3 is 60 g / L, HNO3 is used to adjust the pH value of the reaction solution to 9, and the ratio of the reaction solution volume to the sample surface area is kept at 2.5 ml / cm 2 , the treatment temperature is 40℃, and the treatment time is 2 hours.

[0140] Step three, preparation of a porous flexible piezoelectric polymer-based coating

[0141] 1) Preparation of a piezoelectric polymer-based coating solution

[0142] First, weigh 2.5 g of PVDF-TrFE (70:30) polymer powder, 80 g of DMF, 20 ppm of sodium dodecyl sulfate, and 20 ppm of γ-aminopropyltrimethoxysilane. Then pour the above materials into a ball mill tank, the ball milling speed is 200 rpm, the ball milling time is 1 h, and the uniform piezoelectric polymer-based coating solution is obtained after standing at room temperature for >2 h.

[0143] 2) Preparation of a porous flexible piezoelectric polymer-based coating

[0144] A porous piezoelectric polymer coating is prepared on the porous inorganic coating surface obtained in step two by using a modified non-solvent induced phase separation method (NIPS).

[0145] First, the piezoelectric polymer-based coating solution described in step three (1) is added dropwise to the magnesium alloy surface treated in step two, covering the entire surface, and standing for 30 s. The coating is prepared by spin coating at a speed of 300 rpm for 30 s.

[0146] Then, the thin film obtained by spin coating is placed under water mist for 20 s. Deionized water is selected for the water mist, and the distance between the sample and the water mist is 3 cm.

[0147] The whole sample was then immersed in deionized water for 10 minutes, and a large amount of deionized water entered the PVDF solution through the porous PVDF surface layer and exchanged with the remaining organic solvent, forming a three-dimensional porous membrane.

[0148] The prepared sample was cleaned with ethanol and then placed in a vacuum oven for drying at 40°C for 2 hours.

Claims

1. A medical magnesium alloy surface antibacterial corrosion resistant coating, characterized in that, The coating is a double-layer composite coating, the inner layer is an inorganic porous coating, and the outer layer is a flexible piezoelectric polymer coating; wherein the raw materials of the inorganic porous coating include KF, KOH, and K2CO3; the raw materials of the flexible piezoelectric polymer coating include a piezoelectric polymer, an inorganic filler, a wetting aid, and an adhesion aid; wherein the raw materials of the inorganic porous coating are a mixed solution containing KF, KOH, and K2CO3, in the mixed solution, the concentration of KF is 2.5-8.5 g / L, the concentration of KOH is 8-12 g / L, and the concentration of K2CO3 is 25-35 g / L; the raw materials of the flexible piezoelectric polymer coating are a piezoelectric polymer-based coating solution containing a piezoelectric polymer, an inorganic filler, a wetting aid, and an adhesion aid; the piezoelectric polymer-based coating solution includes 2.5-17.5 wt% of the piezoelectric polymer, 0-5 wt% of the inorganic filler, 20-1000 ppm of the wetting aid, and 20-1000 ppm of the adhesion aid, and the solvent of the piezoelectric polymer-based coating solution is a polar liquid; the piezoelectric polymer is a PVDF-TrFE polymer; the method for preparing the medical magnesium alloy surface antibacterial and corrosion-resistant coating comprises the following steps: Step one, pretreating the magnesium alloy surface to obtain a pretreated surface; Step two, preparing an inorganic porous film layer on the pretreated surface obtained in step one by using a hydrothermal method; Step three, preparing a flexible piezoelectric polymer coating on the surface of the inorganic porous coating obtained in step two by using an improved non-solvent induced phase separation method; The improved non-solvent induced phase separation method includes dropping the piezoelectric polymer-based coating solution on the surface of the inorganic porous coating obtained in step two to cover the entire surface, then preparing the flexible piezoelectric polymer coating on the surface of the inorganic porous coating to obtain a magnesium alloy sample; Spraying water mist on the magnesium alloy sample for a period of time, then soaking the magnesium alloy sample in water for a period of time, and forming a three-dimensional porous film on the surface of the magnesium alloy sample.

2. The medical magnesium alloy surface antibacterial and corrosion resistant coating according to claim 1, characterized in that, The piezoelectric polymer-based solution includes 5-15 wt% of the piezoelectric polymer, 1-3.75 wt% of the inorganic filler, 40-200 ppm of the wetting aid, and 40-200 ppm of the adhesion aid, and the solvent of the piezoelectric polymer-based solution is a polar liquid.

3. The medical magnesium alloy surface antibacterial and corrosion resistant coating according to claim 1, characterized in that, The raw materials of the flexible piezoelectric polymer coating satisfy the following conditions: The polar liquid is one or more of dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide; The inorganic filler is one or more of zinc oxide, titanium oxide, barium titanate, and potassium sodium niobate; The wetting aid is at least one surface active agent selected from a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a non-ionic surfactant; The adhesion aid is selected from one or more of gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, N-methyl-gamma-aminopropyltrimethoxysilane, N-(n-butyl)-gamma-aminopropyltrimethoxysilane, N-(n-butyl)-gamma-aminopropyltriethoxysilane, N,N-diethyl-gamma-aminopropyltrimethoxysilane, 3-cyclohexyl-aminopropylmethyldimethoxysilane, anilinomethyltrimethoxysilane, anilinomethyltriethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyltriethoxysilane, N-beta-(aminoethyl)-gamma-aminopropylmethyldimethoxysilane, N-beta-(aminoethyl)-gamma-aminopropylmethyldiethoxysilane, aminoethylaminoisobutylmethyldimethoxysilane, 3-(2-hydroxyethylaminoethyl)-aminopropylmethyldimethoxysilane, diethylenetriaminepropylmethyldimethoxysilane, bis[3-(trimethoxysilylpropyl)]amine, bis[3-(triethoxysilylpropyl)]amine, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, gamma-(2,3-epoxypropoxy)propylmethyldimethoxysilane, gamma-glycidoxypropyltriethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

4. A method for preparing the medical magnesium alloy surface antibacterial and corrosion resistant coating according to any one of claims 1-3, characterized in that, The preparation method comprises the following steps: Step 1: pretreating the surface of the magnesium alloy to obtain a pretreated surface; Step 2: preparing an inorganic porous film layer on the pretreated surface obtained in Step 1 by using a hydrothermal method; Step 3: preparing a flexible piezoelectric polymer coating on the surface of the porous inorganic coating obtained in Step 2 by using an improved non-solvent induced phase separation method; wherein the improved non-solvent induced phase separation method comprises adding a piezoelectric polymer-based coating solution drop on the surface of the porous inorganic coating obtained in Step 2 to cover the entire surface, and then preparing a flexible piezoelectric polymer coating on the surface of the porous inorganic coating to obtain a magnesium alloy sample; water mist is sprayed on the magnesium alloy sample for a period of time, and then the magnesium alloy sample is soaked in water for a period of time, and a three-dimensional porous film is formed on the surface of the magnesium alloy sample.

5. The method for preparing the antibacterial and corrosion-resistant coating on the surface of medical magnesium alloy according to claim 4, characterized in that, In step two, the conditions for preparing the inorganic porous membrane layer on the pretreated surface obtained in step one by hydrothermal method are as follows: the reaction solution is composed of KF, KOH and K2CO3, the concentration of KF is 2.5-8.5 g / L, the concentration of KOH is 8-12 g / L, the concentration of K2CO3 is 25-35 g / L, the pH value of the reaction solution is adjusted to 9-15 by using KOH or HNO3, and the ratio of the volume of the reaction solution to the surface area of the sample is kept at 2.5-10 ml / cm 2 , the treatment temperature is 40-180 o C, and the treatment time is 2-24 hours.

6. The method of claim 4, wherein the magnesium alloy surface is a medical magnesium alloy surface. In Step 3, the method for preparing a flexible piezoelectric polymer coating on the surface of the porous inorganic coating is coating, the coating speed is 300-3000 rpm, and the coating time is 30-600 s.

7. The method of claim 4, wherein the magnesium alloy surface is a medical magnesium alloy surface. In Step 3, the water mist spraying conditions are as follows: the water mist spraying holding time is 20-1200 s, and the distance between the magnesium alloy sample and the water mist is 3-30 cm.

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