CN115124875B

CN115124875B - Self-cleaning multi-quaternary phosphonium cation antibacterial coating and preparation method thereof

Info

Publication number: CN115124875B
Application number: CN202210595393.XA
Authority: CN
Inventors: 汪中明; 赵金宇; 朱红
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2022-05-29
Filing date: 2022-05-29
Publication date: 2023-04-21
Anticipated expiration: 2042-05-29
Also published as: CN115124875A

Abstract

A self-cleaning multi-quaternary phosphonium cation antibacterial coating and a preparation method thereof belong to the technical field of organic compound antibacterial agents. The structure of the antibacterial agent is shown in the following two formulas, wherein a is selected from unsubstituted C2-C8 saturated alkyl chains, and b, C, d, e is selected from unsubstituted C1-C4 saturated alkyl chains; x is halogen, R ₁ Selected from hydrogen, methyl, ethyl, methoxy, benzyl; r is R ₂ A saturated perfluoroalkyl chain selected from C1-C12. The antibacterial unit of the antibacterial agent not only has high unit charge density, and can more rapidly attract bacteria with negative charges on cell membranes, thereby carrying out rapid contact sterilization, but also has good anti-adhesion property, and can effectively prevent the bacteria from colonizing on the surface of the material. The self-cleaning multi-quaternary phosphonium salt designed by the invention can be embedded into a main chain of a material through phenolic hydroxyl groups or double bonds to realize functional modification of the material, so that the sterilization capability of the material can be improved, and the self-cleaning capability of the material can be enhanced.

Description

Self-cleaning multi-quaternary phosphonium cation antibacterial coating and preparation method thereof

Technical Field

The invention belongs to the technical field of organic antibacterial coatings, and particularly relates to a self-cleaning multi-quaternary phosphonium cation antibacterial coating.

Background

The results of the study show that the larger atomic radius of P relative to N and the stronger polarization effect compared to the nitrogen atom on the quaternary ammonium salt (QAC) makes the Quaternary Phosphonium Compound (QPC) more readily adsorbed onto negatively charged bacterial membranes, thus the high charge density quaternary phosphonium salts exhibit lower resistance to bacteria and higher effective sterilization rates than other antibacterial agents (Chemical Engineering Journal,2022, 440:476-492). Meanwhile, fluorine-containing compounds are widely used as effective antibacterial agents for resisting bacterial adhesion, and fluorine-containing long-chain small molecules have superhydrophobicity. The addition of the agent can effectively reduce the surface energy of the material, thereby greatly reducing the probability of bacteria adhering to the surface of the material (ACS Applied Materials & Interfaces,2021,13 (8): 10553-10563). In addition, the superior chemical stability of the fluorochemical will also extend the useful life of the antimicrobial material.

The published reports and patents of antimicrobial agents related to self-cleaning and quaternary phosphonium salts are as follows:

literature (Biomacromolecules, 2022, 21:468-482) synthesized a novel copolymer poly (LAEMA-co-GMA-co-BA) by a simple free radical polymerization process by combining 2-lactated nano-amide ethyl methacrylamide with a structurally unique borneol compound. The amine containing silane layer is prepared on the substrate surface by a silylation reaction followed by grafting of the sugar polymer onto the silane layer by covalent bonding to give the glycosylated coating. The prepared coating shows good antibacterial adhesion performance to both E.coli and S.aureus. In addition, the coating was not observed to be cytotoxic to MRC-5 cells (lung fibroblasts) in vitro, indicating that the antimicrobial coating has good biocompatibility. Its disadvantage is that the antibacterial rate is not very high.

The technology disclosed in the patent of the subject group (application number 201910218873.2) shows that the antibacterial monomer is a hexaquaternary phosphonium antibacterial agent containing trihydroxy, and the structural general formula of the quaternary phosphonium cation is shown as formula (2), wherein a and b represent unsubstituted C1-C8 saturated alkyl chains; x is a halogen compound selected from Cl, br and I. The present invention is different from the structure of the present invention and has no self-cleaning capability.

These documents or patents do not relate to the study of antimicrobial coatings containing self-cleaning multi-quaternary phosphonium salts. The self-cleaning multi-quaternary phosphonium cation antibacterial paint prepared by the invention can realize synergistic antibacterial effect by combining tetrahydroxy octaquaternary phosphonium salt cations with high charge density and fluorine-containing long chains and utilizing two different antibacterial mechanisms of contact sterilization and antibacterial adhesion, and is remarkably different from that reported in literature disclosure.

Disclosure of Invention

The technical problem to be solved by the invention is that the cationic antibacterial agent can quickly kill pathogenic microorganisms through contact sterilization, but the probability of bacterial adhesion is increased because the quaternary phosphonium cations are hydrophilic. Over time, bacteria deposited by electrostatic adsorption form a layer of biofilm covering material, resulting in a decrease in antibacterial efficiency. Therefore, an antibacterial material which can sterilize through contact and has a certain degree of anti-adhesion capability is designed and synthesized. In order to solve the problems, a self-cleaning multi-quaternary phosphonium cation antibacterial coating film and a preparation method thereof are provided.

The invention provides a self-cleaning multi-quaternary phosphonium cation antibacterial coating film which is characterized by comprising an octaquaternary phosphonium cation containing tetrahydroxy and a fluorine-containing long-chain antibacterial agent, wherein the antibacterial agent comprises the following components in percentage by weight:

wherein a represents the number of carbon atoms of an unsubstituted C2-C8 saturated alkyl chain, and b, C, d, e represents the number of carbon atoms of an unsubstituted C1-C4 saturated alkyl chain; x is halogen, and Cl, br and I can be selected; r is R ₁ Selected from hydrogen, methyl, ethyl, methoxy, benzyl, etc.; r is R ₂ A saturated perfluoroalkyl chain selected from C1-C12.

The invention provides a preparation method of a self-cleaning multi-quaternary phosphonium cation antibacterial coating, which is characterized by comprising the following steps:

a) The monohydroxy-protected bisquaternary phosphonium salt of the structure shown in the compound formula (5) and the compound formula (6) are dissolved in an organic solvent, and an acid-binding agent is added, followed by stirring reaction at 60 ℃. Washing the reacted product with deionized water, collecting an organic layer, drying the organic layer with a drying agent, washing the reactant with a large amount of diethyl ether and a large amount of THF, and concentrating the solvent;

b) C, dissolving the product obtained in the step a in an organic solvent, performing deprotection on hydroxyl, adjusting pH to be neutral, and drying to obtain a target product formula (3);

c) The target product in the step b, namely (3) (0.1 g-0.5 g), isophorone diisocyanate (0.5 g-0.6 g), polyether polyol (3.9 g-4.27 g) and hydroxyethyl acrylate (0.1 g) are stirred and reacted at 60 ℃ to prepare 5g polyurethane acrylic ester/tetrahydroxy octaquaternary phosphonium salt oligomer by taking dibutyltin dilaurate (30 mg) as a catalyst, and then the compound (0.2 g-0.8 g) in the step b and a reactive diluent (TMPTMA 1.5g-1.7g, IBA 1.4g-1.6g and HDDA1.0g-1.2 g) are added into the oligomer, and finally the final product is prepared under the action of ultraviolet light after adding a photoinitiator 1173 (0.3 g).

Reactive diluents include TMPTMA, IBOA and HDDA.

The mass ratio of the product formula (3) to isophorone diisocyanate, polyether polyol, hydroxyethyl acrylate and catalyst is 0.1-0.5:0.5-0.6:3.9-4.27:0.1:0.030; polyurethane acrylate/tetrahydroxy octaquaternary phosphonium salt oligomer: a compound of formula (4): TMPTMA: IBOA: HDDA: the mass ratio of the photoinitiator 1173 is 5:0.2-0.8:1.5-1.7:1.4-1.6:1.0-1.2:0.3.

the acid binding agent is selected from potassium carbonate, sodium carbonate, triethylamine and other alkaline agents, preferably potassium carbonate. Step a the organic solvent may be selected from DMF, dichloromethane and other organic solvents, preferably DMF. The organic solvent in the step b can be selected from dichloromethane, chloroform and other organic solvents, preferably dichloromethane.

The self-cleaning multi-quaternary phosphonium salt ultraviolet light-cured antibacterial coating film prepared by the invention can be used in a plurality of fields such as medical materials, antibacterial catheters, vehicles, electronic products, home furnishings, ship industry and the like.

Compared with the prior antibacterial agent, the prepared antibacterial agent has the advantages that:

(1) The tetrahydroxy octaquaternary phosphonium salt in the designed self-cleaning multi-quaternary phosphonium salt antibacterial coating film has high unit charge density, and can more rapidly attract bacteria with negative charges on cell membranes, so that the antibacterial coating film can be more rapidly sterilized.

(2) The fluorine-containing long chain in the designed self-cleaning multi-quaternary phosphonium salt antibacterial coating improves the anti-adhesion property of the material, and can effectively prevent bacteria from colonizing the surface of the material.

(3) The designed self-cleaning multi-quaternary phosphonium salt antibacterial coating film shows good coordinated antibacterial capability and excellent antibacterial performance.

Drawings

FIG. 1 shows the hydrogen and phosphorus spectra of the multi-quaternary phosphonium salt of example 1

FIG. 2 is a graph of total reflection attenuated infrared spectra of self-cleaning multi-quaternary phosphonium salt antibacterial coating films prepared in examples 7-9 in different proportions. Wherein: a represents a photo-curable coating film added with 5wt% of tetrahydroxy octaquaternary phosphonium salt, B represents a photo-curable coating film of example 7, C represents a photo-curable coating film of example 8, and D represents a photo-curable coating film of example 9.

FIG. 3 is a schematic representation of the antibacterial results and inhibition zones of the coating films of the self-cleaning multi-quaternary phosphonium cationic antibacterial agents of examples 1-9 in different proportions against Staphylococcus aureus and Escherichia coli. Test bacteria 10 ⁷ CFU/mL s.aureus and e.coli. The test method is a plate counting method, and the antibacterial capacity of the coating film is demonstrated by the colony number on the culture dish. Wherein the pure PUA has no antibacterial component and the blank has no bacteria. Panel A shows, from left to right, the antibacterial results of pure PUA, example 1, example 2 and example 3 photocured films and a blank against both S.aureus and E.coli bacteria. Panel B shows, from left to right, the antibacterial results of the pure PUA, example 4, example 5 and example 6 photocured film and the blank against both S.aureus and E.coli bacteria. Panel C shows, from left to right, the antibacterial results of pure PUA, example 7, example 8 and example 9 photocured film and blank on both S.aureus and E.coli bacteria. Panel D represents the size of the inhibition zone of the photocurable coating film of examples 6, 7, 8 and 9, wherein a larger inhibition zone represents a better antibacterial property.

FIG. 4 is a graph of anti-adhesion test of coating films of the self-cleaning multi-quaternary phosphonium cationic antimicrobial agent of examples 7-9 to Staphylococcus aureus at varying ratios. Wherein: the A-D panels show the adhesion of Staphylococcus aureus to the photo-cured coatings of pure PUA, example 7, example 8 and example 9, respectively.

Detailed Description

The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Among them, compound a, compound B, and compound C are preferable as reactants of examples.

Example 1

Step 1, synthesizing a compound tetrahydroxy octaquaternary phosphonium salt. A100 mL three-necked flask was charged with 10mmol of Compound A and 2mmol of Compound B, followed by 20mmol of K ₂ CO ₃ And 50mL of DMF, and the reaction was stirred at 60℃for 24h. After the reaction is finished, CH is used ₂ Cl ₂ The reactants were dissolved. The organic layer was then treated with H ₂ O is cleaned for three times, and anhydrous SiO is taken ₂ Dry filtration followed by washing the reaction with copious amounts of diethyl ether and copious amounts of THF, concentrating the solvent, and then dissolving the product in CH ₂ Cl ₂ In which 2 mol.L is added ^-1 HCl solution, TLC was used to monitor the progress of the reaction, after which the organic layer was taken up with H ₂ O is washed three times. Concentrating the solvent to obtain a yellowish tetrahydroxy octaquaternary phosphonium salt solid product;

step 2A 100mL three-necked flask was taken, and 0.1g of the tetrahydroxy octaquaternary phosphonium salt obtained in step 1 and 0.53g of isophorone diisocyanate were added thereto, followed by mechanical stirring and heating to 60 ℃. After 30 minutes, 30mg of dibutyltin dilaurate was added to the flask, and 4.27g of polyether polyol HSH330N was slowly added dropwise to the flask via a constant pressure dropping funnel, and after 4 hours of reaction. Hydroxyethyl acrylate (HEA) 0.1g was slowly added dropwise to the bottle for capping, and after a few minutes removed and cooled to room temperature. 5.0g of tetrahydroxy octaquaternary phosphonium salt/PUA oligomer can be obtained;

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, was stirred uniformly with compound c0.2g, reactive diluents (tmptma 1.7g, iba 1.6g and hdda1.2 g) and photoinitiator 1173 (0.3 g) in a beaker according to mass percent=50/2/45/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was coated on the prepolymer to avoid oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 1wt% tetrahydroxy octaquaternary phosphonium salt/2 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 2

Step 1, preparing a pale yellow tetrahydroxy octaquaternary phosphonium salt solid product according to the corresponding method of the example 1;

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.5g, reactive diluents (tmptma 1.6g, iba 1.5g and hdda1.1 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50/5/42/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was covered on the prepolymer for avoiding oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 1wt% tetrahydroxy octaquaternary phosphonium salt/5 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 3

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.8g, reactive diluents (tmptma 1.5g, iba 1.4g and hdda1.0 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50//8/39/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was covered on the prepolymer for avoiding oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 1wt% tetrahydroxy octaquaternary phosphonium salt/8 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 4

step 2A 100mL three-necked flask was taken, 0.3g of the tetrahydroxy octaquaternary phosphonium salt obtained in step 1 and 0.6g of isophorone diisocyanate were added thereto, and mechanical stirring was performed and the temperature was raised to 60 ℃. After 30 minutes, 30mg of dibutyltin dilaurate was added to the flask, and 4.0g of polyether polyol HSH330N was slowly added dropwise to the flask via a constant pressure dropping funnel, followed by a reaction for 4 hours. Hydroxyethyl acrylate (HEA) 0.1g was slowly added dropwise to the bottle for capping, and after a few minutes removed and cooled to room temperature. 5.0g of tetrahydroxy octaquaternary phosphonium salt/PUA oligomer can be obtained;

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, was stirred uniformly with compound c0.2g, reactive diluents (tmptma 1.7g, iba 1.6g and hdda1.2 g) and photoinitiator 1173 (0.3 g) in a beaker according to mass percent=50/2/45/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was coated on the prepolymer to avoid oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 3wt% tetrahydroxy octaquaternary phosphonium salt/2 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 5

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.5g, reactive diluents (tmptma 1.6g, iba 1.5g and hdda1.1 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50/5/42/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was covered on the prepolymer for avoiding oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 3wt% tetrahydroxy octaquaternary phosphonium salt/5 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 6

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.8g, reactive diluents (tmptma 1.5g, iba 1.4g and hdda1.0 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50/8/39/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was covered on the prepolymer for avoiding oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 3wt% tetrahydroxy octaquaternary phosphonium salt/8 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 7

step 2A 100mL three-necked flask was taken, 0.5g of the tetrahydroxy octaquaternary phosphonium salt obtained in step 1 and 0.5g of isophorone diisocyanate were added thereto, and mechanical stirring was performed and the temperature was raised to 60 ℃. After 30 minutes, 30mg of dibutyltin dilaurate was added to the flask, and 3.9g of polyether polyol HSH330N was slowly added dropwise to the flask via a constant pressure dropping funnel, and after 4 hours of reaction. Hydroxyethyl acrylate (HEA) 0.1g was slowly added dropwise to the bottle for capping, and after a few minutes removed and cooled to room temperature. 5.0g of tetrahydroxy octaquaternary phosphonium salt/PUA oligomer can be obtained;

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, was stirred uniformly with compound c0.2g, reactive diluents (tmptma 1.7g, iba 1.6g and hdda1.2 g) and photoinitiator 1173 (0.3 g) in a beaker according to mass percent=50/2/45/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was coated on the prepolymer to avoid oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 5wt% tetrahydroxy octaquaternary phosphonium salt/2 wt% fluorine-containing chain/PUA target photocuring coating film.

Example 8

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.5g, reactive diluents (tmptma 1.6g, iba 1.5g and hdda1.1 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50/5/42/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was coated on the prepolymer, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 5wt% tetrahydroxy octaquaternary phosphonium salt/5 wt% fluorine-containing chain/PUA target photocurable coating film, in order to avoid oxygen aggregation during photocuring.

Example 9

step 3 the tetrahydroxy octaquaternary phosphonium salt/PUA oligomer prepared in step 2, 5.0g, compound c0.8g, reactive diluents (tmptma 1.5g, iba 1.4g and hdda1.0 g) and photoinitiator 1173 (0.3 g) were stirred uniformly in a beaker according to mass percent = 50/8/39/3 (wt%) for 1h. After the completion of the stirring, the prepolymer was uniformly smeared on a silica gel mold (50 mm. Times.50 mm), and a polyethylene film was covered on the prepolymer for avoiding oxygen agglomeration during photocuring, followed by exposure to an ultraviolet mercury lamp (optimum time of 90 seconds) to obtain a 5wt% tetrahydroxy octaquaternary phosphonium salt/8 wt% fluorine-containing chain/PUA target photocuring coating film.

The series of coatings of examples 1-9 were subjected to an antimicrobial test. Test bacteria 10 ⁷ CFU/mL s.aureus and e.coli. The average value measured by three parallel experiments was used as the experimental result using pure PUA without antimicrobial added as a control group. The results show that the colony number on the culture dish is obviously reduced along with the increase of the mass fractions of the tetrahydroxy octaquaternary phosphonium salt and the fluorine-containing long chain, which indicates that the antibacterial performance of the self-cleaning multi-quaternary phosphonium cation photocuring coating film is obviously improved along with the increase of the mass fractions of the tetrahydroxy octaquaternary phosphonium salt and the fluorine-containing long chain. The scanning electron microscope experiment result shows that with the increase of the mass fraction of fluorine-containing chains, the adhesion degree of bacteria on the surface of the coating film is obviously reduced, which proves that the coating film prepared by the invention has good self-cleaning capability.

Claims

1. A method for preparing a self-cleaning multi-quaternary phosphonium cation antibacterial coating, which is characterized by comprising the following steps:

a) Dissolving the monohydroxy-protected biquaternary phosphonium salt with the structure shown in the compound formula (5) and the compound formula (6) in an organic solvent, adding an acid binding agent, and then stirring at 60 ℃ for reaction; washing the reacted product with deionized water, collecting an organic layer, drying the organic layer with a drying agent, washing the reactant with a large amount of diethyl ether and a large amount of THF, and concentrating the solvent;

c) Stirring and reacting the target product in the step b with isophorone diisocyanate, polyether polyol and hydroxyethyl acrylate at 60 ℃, preparing polyurethane acrylic ester/tetrahydroxy octaquaternary phosphonium salt oligomer by taking dibutyltin dilaurate as a catalyst, then adding the compound in the formula (4) and a reactive diluent into the oligomer, adding a photoinitiator 1173, and preparing a final product under the action of ultraviolet light;

wherein a represents the number of carbon atoms of an unsubstituted C2-C8 saturated alkyl chain, and b, C, d, e represents the number of carbon atoms of an unsubstituted C1-C4 saturated alkyl chain; x is halogen selected from Cl, br and I; r is R ₁ Selected from hydrogen, methyl, ethyl, methoxy, benzyl; r is R ₂ A saturated perfluoroalkyl chain selected from C1-C12;

/>

2. the method of claim 1, wherein the reactive diluent comprises TMPTMA, IBOA, and HDDA.

3. The process according to claim 2, wherein the mass ratio of product formula (3) to isophorone diisocyanate, polyether polyol, hydroxyethyl acrylate, catalyst is 0.1-0.5:0.5-0.6:3.9-4.27:0.1:0.030; polyurethane acrylate/tetrahydroxy octaquaternary phosphonium salt oligomer: a compound of formula (4): TMPTMA: IBOA: HDDA: the mass ratio of the photoinitiator 1173 is 5:0.2-0.8:1.5-1.7:1.4-1.6:1.0-1.2:0.3.

4. the method according to claim 1, wherein the acid binding agent is selected from the group consisting of potassium carbonate, sodium carbonate, triethylamine; step a the organic solvent is selected from DMF and methylene dichloride; the organic solvent in the step b is selected from dichloromethane and trichloromethane.

5. A self-cleaning multi-quaternary phosphonium cationic antimicrobial coating prepared according to the method of any of claims 1-4.

6. Use of a self-cleaning multi-quaternary phosphonium cationic antibacterial coating prepared according to the process of any of claims 1-4 as a self-cleaning antibacterial film.