CN112760023B - A kind of mixed charge polyurethane coating material and preparation method and application thereof - Google Patents

Abstract

The invention provides a mixed charge polyurethane coating material and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing N-methyldiethanolamine with ethyl 4-bromobutyrate, and reacting at 60 ℃ for 24 hours to obtain a dihydroxy quaternary ammonium monomer; (2) mixing the dihydroxy quaternary ammonium monomer obtained in the step (1) with 2, 3-dihydroxypropionic acid and isophorone diisocyanate according to NCO/OH of 1.2, and stirring and reacting for 4 hours at 80 ℃ in a nitrogen atmosphere to obtain a polyurethane prepolymer containing an end NCO group; (3) and (3) soaking the base material in the polyurethane prepolymer solution obtained in the step (2), taking out after the coating is completed, and curing to obtain the stable mixed charge polyurethane coating material. The coating material disclosed by the invention is coated on the surface of a base material, so that the coating material not only has good bactericidal performance, but also has excellent impedance protein adsorption effect, and shows excellent antifouling potential.

Description

A kind of mixed charge polyurethane coating material and preparation method and application thereof

technical field

The invention belongs to the technical field of preparation of solvent-borne polyurethane coating materials, and particularly relates to a mixed-charge polyurethane coating material and a preparation method and application thereof.

Background technique

Microbial colonization on various surfaces has always been an important issue, causing not only impairment of surface function and huge economic losses, but also microbial infections and environmental consequences. To address these issues, treatment and prevention are the two main application-based antimicrobial strategies. The purpose of prevention is to kill microorganisms before they settle on the surface. Once precipitation occurs, microorganisms can produce a protective exopolysaccharide (EPS) matrix, including polysaccharides, proteins, and DNA. Microbial colonies encapsulated in EPS, also known as biofilms, are 100 to 1000 times more resistant to fungicides in biofilms than in the planktonic state. Therefore, intervening in the early uptake and precipitation (i.e. prevention) of microorganisms on the surface is also crucial for the antibacterial effect.

Among various polymer coatings, multi-component polyurethane (PU) coatings are an important class of surface protection materials due to their excellent mechanical properties, wear resistance, corrosion resistance, chemical resistance and other properties. PU coatings can be tailored to provide the right toughness, gloss and specific functionality to meet the material requirements of most substrates. We can tune the molecular structure of polyurethane so that it can exhibit antibacterial properties. Antibacterial polyurethane coatings are one of the hottest areas of research at the moment, aiming to endow surfaces with the ability to withstand microbial colonization. Typical methods for the anti-biofilm and sterilization of polyurethane coatings are: 1) adding antibacterial ingredients to the coating substrate; 2) surface modification.

The method of adding antibacterial ingredients to the coating substrate is used to construct a polyurethane system, and coating it on the surface of the substrate generally has good antibacterial properties, but because the surface of the coating material obtained by this method is mostly positively charged, it is used in the application. In the process, a large amount of protein will be adsorbed, so it will not have antifouling properties and will resist the potential of biofilms. Therefore, the current polyurethane coating materials are in urgent need of improvement.

How to provide a polyurethane coating material that not only has good bactericidal properties, but also has excellent resistance to protein adsorption and exhibits excellent antifouling potential has become an urgent technical problem to be solved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned technical problems, and provide a mixed-charge polyurethane coating material and its preparation method and application. The method of the invention constructs a new polyurethane system, obtains a quaternary ammonium type mixed-charge polyurethane, and coats it on the surface of the substrate to obtain a substrate with mixed-charge polyurethane on the surface. It is found through experiments that it not only has good sterilization At the same time, it also has excellent resistance to protein adsorption, showing excellent antifouling potential.

One of the objects of the present invention is to provide a kind of preparation method of mixed charge polyurethane coating material, and the technical scheme that it adopts is as follows:

(1) Mixing N-methyldiethanolamine and ethyl 4-bromobutyrate, and reacting at 60°C for 24h to obtain dihydroxy quaternary ammonium monomer;

(2) Mix the bishydroxy quaternary ammonium monomer obtained in step (1) with 2,3-dihydroxypropionic acid and isophorone diisocyanate according to the NCO/OH ratio of 1.2, and stir and react at 80°C for 4h under nitrogen atmosphere , to obtain a polyurethane prepolymer containing terminal NCO groups;

(3) Immerse the base material in the polyurethane prepolymer solution obtained in step (2), take it out for curing after coating is complete, and obtain a stable mixed-charge polyurethane coating material.

Further, the mol ratio of N-methyldiethanolamine and ethyl 4-bromobutyrate described in step (1) is 1:1.

Further, the structural formula of the dihydroxy quaternary ammonium monomer described in step (1) is shown in the following formula (I):

Further, the molar ratio of the dihydroxy quaternary ammonium monomer and 2,3-dihydroxypropionic acid described in step (2) is 1:1.

Further, the diisocyanates described in step (2) include isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate. Any of the isocyanates.

Further, the structural formula of the terminal NCO group-containing polyurethane prepolymer described in step (2) is shown in the following formula (II):

where -R- is

Further, the curing in step (3) is curing at 80° C. for 12 h.

Further, in step (3), the base material includes biomedical materials, and the biomedical materials include cardiovascular system materials such as artificial heart valves, blood vessels, and intravascular catheters, or urinary system materials such as ureteral stents and urinary catheters. Material.

The second object of the present invention is to provide a mixed-charge polyurethane coating material obtained by the above-mentioned preparation method.

The third object of the present invention is to provide the application of the above mixed-charge polyurethane coating material. 50-100μm.

Specifically, the bacteria species targeted for the sterilization include Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa or other drug-resistant strains.

The beneficial effects of the present invention are as follows:

In the present invention, an antibacterial component quaternary ammonium salt is added to the coating substrate, and a negatively charged carboxyl group is introduced at the same time to prepare a mixed-charge polyurethane, which is coated on the surface of the substrate to obtain a quaternary ammonium type mixed-charge polyurethane coating. It is found that it not only has good bactericidal properties, but also has excellent resistance to protein adsorption, showing excellent antifouling potential. The invention brings new inspiration to the development and application of new antifouling coatings.

Description of drawings

Fig. 1 is the infrared spectrum of step (1) gained product CBD in embodiment 1;

Fig. 2 is the reaction scheme diagram that step (2) prepares MPU in embodiment 1;

Fig. 3 is the Zeta potential diagram of different coatings;

Figure 4 shows the SEM and AFM surface morphologies of different coatings;

Fig. 5 is that the surface element of coating is carried out XPS analysis result figure;

Fig. 6 is a graph of the test results of the bactericidal performance of the coating;

Figure 7 shows the microscopic morphology of bacteria on the coating surface;

Fig. 8 is the test result graph of the bactericidal performance of coatings obtained with different monomer ratios;

Figure 9 is a graph of the test results of quantitative protein adsorption on the coating;

Figure 10 is a graph showing the performance test results of different coatings on resistance to protein and cell adhesion.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the examples. It is necessary to point out that the following examples are only used to explain and illustrate the present invention, and are not intended to limit the present invention. . Some non-essential improvements and adjustments made by those skilled in the art based on the above-mentioned contents of the invention still belong to the protection scope of the present invention.

Example 1

A preparation method of a mixed-charge polyurethane coating material, comprising the following steps:

(1) Take 1 mol of N-methyldiethanolamine and 1 mol of ethyl 4-bromobutyrate, and react at 60° C. under magnetic stirring conditions for 24 h to obtain bishydroxy quaternary ammonium monomer (CBD), and the obtained product is not subjected to Any purification is used directly; the product CBD obtained in this step is characterized by infrared, and the obtained infrared spectrum is shown in Figure 1;

(2) the obtained bishydroxy quaternary ammonium monomer and 2,3-dihydroxypropionic acid and isophorone diisocyanate (IPDI) are fed in a ratio of NCO:OH=1.2:1, wherein the bishydroxy quaternary ammonium monomer The molar ratio with dihydroxypropionic acid is 1:1, and under the condition of nitrogen atmosphere and 80 ℃, mechanical stirring reaction is carried out for 4 hours to obtain the mixed charge polyurethane prepolymer (MPU) with terminal NCO group; the reaction formula of the mixed charge polyurethane MPU as shown in picture 2;

(3) The substrate was immersed in the prepolymer solution for 5s, taken out and cured at 80°C for 12h to obtain a substrate (MPU@PU) with a mixed charge polyurethane surface, which was characterized and tested.

Example 2

According to the method for embodiment 1, in step (2), adjust the mol ratio of dihydroxy quaternary ammonium monomer and 2,3-dihydroxypropionic acid monomer, respectively obtain the polyurethane prepolymer (MPU 2: 1. MPU 1:1, MPU 1:2) for characterization and testing.

Comparative Example 1

The step of adding 2,3-dihydroxypropionic acid in step (2) in Example 1 is removed, and CBD and IPDI are directly mixed to prepare polyurethane to obtain quaternary ammonium polyurethane (QPU), which is coated on the surface of the substrate to obtain a quaternary ammonium polyurethane (QPU). Ammonium polyurethane coated substrate (QPU@PU).

Test Example 1

The effect of different monomer ratios on the potential of the material in Example 2 was examined, and the results are shown in Figure 3. It can be seen from Figure 3 that the Zeta potential of the resulting coating is close to zero only when the monomer ratio is 1:1, confirming that the molar ratio of the monomers is 1:1.

Test case 2

SEM and AFM surface morphology observations were performed on the coatings of Example 1 and Comparative Example 1, and the obtained results are shown in FIG. 4 .

It can be seen from the three SEM pictures of a, b and c in Figure 4 that the coating is relatively flat, and the thickness of the coating is 60-70 microns. The appropriate thickness provides a guarantee for the good effect of the coating. It can be seen from the AFM image that the coated material becomes more flat, and this conclusion can be further confirmed in combination with the roughness in Figure 4e, which is due to the fact that the initial liquid coating liquid fills the defects of the substrate itself , the increased smoothness of the material is also beneficial for subsequent applications.

Test case 3

The surface element analysis (XPS) of the obtained coating was carried out to examine the roughness of the coating and the change of the contact angle. The results obtained are shown in Figure 5. From Figure 5a, it can be found that the materials coated with quaternary ammonium coating and mixed charge coating produced a new peak -Br peak, indicating that bromine has been introduced, which proves that the bishydroxyquaternium monomer has been fixed on the surface of the material . It is found that, compared with the original material, the surface of the material coated with quaternary ammonium coating and mixed charge coating has a new peak, which is CN ⁺ peak. The introduction of hydroxypropionic acid reduces the proportion of bishydroxyquaternium, therefore, the CN ⁺ peak intensity decreases, which indicates that the surfaces of both prepared coatings contain quaternary ammonium groups. From the change of the contact angle, it can be found that the contact angle of the mixed charge coating formed by the introduction of bishydroxypropionic acid is significantly reduced, this is because the mixed charge has a good hydration ability, similar to the zwitterion, so it produces a better affinity. water effect.

Test Example 4

To test the bactericidal performance of the coating, cut the sample into a 1*1cm ² square material, drop 20 μL of bacterial culture solution (10 ⁷ CFU/mL) on the surface of the sample, and cultivate it in a constant temperature incubator for 2 hours. Take out sterile water After washing, the quantitative washing solution was cultured in the medium for 24 hours, and the number of colonies formed was observed to investigate its antibacterial properties. The results are shown in Figure 6. It can be clearly seen from Figure 6 that the sterilization rates of the quaternary ammonium coating and the mixed charge coating on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and drug-resistant bacteria are all close to 100%, and have a good sterilization effect. It is well known that quaternary ammonium coatings have good bactericidal properties. The bactericidal mechanism of mixed charge coatings is that under the microstructure, the surface of the coating is still in a positive state, which will have bactericidal properties, but in the macroscopic state. The lower layer shows a near-electrically neutral state, which is why the mixed-charge coating still has good bactericidal properties.

The microscopic morphology of bacteria on the coating surface was observed, and the results are shown in Figure 7. The survival of bacteria on the surface of the material can be seen more clearly, taking Escherichia coli and Staphylococcus aureus as examples. It can be seen from Figure 7b and e that the materials coated with quaternary ammonium coating adhere more bacteria, which is due to the attraction of positively charged quaternary ammonium and negatively charged bacteria, resulting in more adhesion. However, we carefully observed the morphology of the bacteria and found that the bacteria adhering to the surface of the quaternary ammonium coating were all dry and not full, which indicated that these bacteria had been killed. The surface coated with the mixed charge coating has very little bacterial adhesion, which indicates that the mixed charge coating has a good resistance to bacterial adhesion, which is due to the hydration layer brought by the mixed charge. attached effect. Further observation of the bacterial morphology shows that micro-adherent bacteria, the cell membrane is ruptured, the bacterial morphology is shriveled, and has been killed. This shows that the mixed charge coating not only has good bactericidal properties but also has a good effect of resisting bacterial adhesion.

The bactericidal properties of the coatings obtained with different monomer ratios were tested, and the results are shown in Figure 8.

Test Example 5

The coating obtained in Example 1 was subjected to a quantitative protein adsorption test using a BCA protein concentration assay kit. In Figure 9, a, b, and c are the laser confocal images of the three materials adsorbing protein. It can be found that the material coated with quaternary ammonium coating has a higher protein adsorption capacity (the more protein adsorption, the brighter the picture), the mixed The charged coating has better resistance to protein adsorption. Picture d is the actual picture of the test. The darker the color, the more protein adsorbed. From picture e, we can clearly see the basic value of protein adsorption by the material. The adsorption amount of mixed charge to protein is 6.67 micrograms per square centimeter, which is at Better anti-protein adhesion state.

Test Example 6

The properties of the coating to resist protein and cell adhesion were examined. Using bovine serum albumin (BSA) as a model organic pollutant, the anti-adhesion properties of the samples were evaluated by static protein adsorption. Fluorescein-conjugated BSA (FITC-BSA) was dissolved in a pH 7.4 PBS solution to prepare a protein solution (0.05 mg·mL ^-1 ). The sample was placed in the cell culture plate, then FITC-BSA solution (3ml) was added to each cell culture well, and it was in contact with the sample surface for 3h with gentle shaking in the dark. Then, the solution was removed and rinsed twice with PBS buffer. sample surface to remove unbound proteins. The sample was then removed, placed on a glass slide with a drop of PBS buffer on it, and covered with a coverslip. The samples were imaged using a Nikon N-SIM camera equipped with a diode-pumped solid-state laser at 488 nm, a method that reflects the material's antifouling capabilities. The coating materials obtained with different monomer ratios were examined, and the test results are shown in Figure 10.

In Figure 10, a, b, c, d, and e are the fluorescent photos of anti-protein adhesion. It can be seen that the substrate itself has a certain adhesion to the protein, and the protein adhesion of the coating coated with pure quaternary ammonium is greatly intensified. Since most proteins are negatively charged, the attraction between positive and negative charges produces serious adhesion results. When negatively charged monomers are added, the adhesion effect is improved to a certain extent. When the ratio of positive and negative charges is adjusted to 1:1, the amount of protein adhesion Greatly reduced, this is due to the super hydration of the uniform mixed charge, which hinders the adhesion of proteins. When the negative charge is excessive, the reason for less adhesion is that the negative charges repel each other, and the anti-adhesion effect of the hydration effect of the 1:1 coating is not as good as that of the 1:1 coating. Well, this experiment also determined that the molar ratio of the monomers was 1:1 optimal. f, g, h, i, j are anti-cell adhesion. Since cells are also negatively charged, the results are the same as above. From Figure 10, it can be found that the material coated with quaternary ammonium coating has a higher protein adsorption capacity (the more protein adsorption, the brighter the picture), and the mixed charge coating has a better resistance to protein adsorption.

Claims (8)

1. a preparation method of mixed charge polyurethane coating material, is characterized in that, comprises the following steps: (1) Mixing N-methyldiethanolamine and ethyl 4-bromobutyrate, and reacting at 60° C. for 24 hours to obtain a bishydroxy quaternary ammonium monomer; the N-methyldiethanolamine and ethyl 4-bromobutyrate are The molar ratio of ester is 1:1; (2) Mix the bishydroxy quaternary ammonium monomer obtained in step (1) with 2,3-dihydroxypropionic acid and diisocyanate according to NCO/OH of 1.2, and stir and react at 80° C. for 4 h under nitrogen atmosphere to obtain end-containing Polyurethane prepolymer of NCO group; the molar ratio of the dihydroxyquaternary ammonium monomer to 2,3-dihydroxypropionic acid is 1:1; (3) Immerse the base material in the polyurethane prepolymer solution obtained in step (2), take it out for curing after coating is complete, and obtain a stable mixed-charge polyurethane coating material. 2. preparation method according to claim 1 is characterized in that, the structural formula of bishydroxy quaternary ammonium monomer described in step (1) is shown in following formula (I):

3. preparation method according to claim 1, is characterized in that, described in step (2), the diisocyanate comprises isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate , any one of hexamethylene diisocyanate and lysine diisocyanate. 4. preparation method according to claim 1 is characterized in that, the structural formula of the polyurethane prepolymer containing terminal NCO group described in step (2) is shown as following formula (II):

where -R- is

5 . The preparation method according to claim 1 , wherein the curing in step (3) is curing at 80° C. for 12 h. 6 . 6. The preparation method according to claim 1, characterized in that, in step (3), the base material comprises biomedical materials, and the biomedical materials comprise heart valves including artificial heart valves, blood vessels, and intravascular cannulae. Vascular system materials, or urinary system materials including ureteral stents and catheters. 7. The mixed-charge polyurethane coating material prepared by the method of any one of claims 1-6. 8. The application of the mixed-charge polyurethane coating material according to claim 7, characterized in that it is coated on the surface of a substrate for sterilization and antifouling, preferably, the coating thickness is 50 -100 μm; the sterilized bacterial species include Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa or other drug-resistant bacteria.

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