TWI840294B - Zwitterionic polymer, method of making the same and antibacterial coating composition including the same - Google Patents

Abstract

The present invention is related to a zwitterionic polymer, a method of making the same and an antibacterial coating composition including the same. The zwitterionic polymer includes acrylate functional groups and is therefore highly hydrophilic. Thus, the zwitterionic polymer can dissolved in water and subjected to a water plasma treatment to form free radical, which can contribute to the formation of an antibacterial coating with an excellent adhesive property.

Description

Diionic polymer, its production method and antibacterial coating composition containing the same

The present invention relates to a diionic polymer, in particular to a highly hydrophilic diionic polymer, a preparation method thereof and an antibacterial coating composition containing the diionic polymer.

With the improvement of public health systems and the improvement of medical standards, deaths caused by pathogens (such as viruses, bacteria or fungi, etc.) have dropped significantly. However, in recent years, emerging infectious diseases, reemerged infectious diseases and/or drug-resistant bacteria still threaten human health due to factors such as jungle and forest development, increased wildlife trade, more frequent human interaction and migration, and/or the abuse of antibiotics.

In order to reduce the threat of pathogens, the hygiene and safety of daily necessities are receiving more and more attention, so there are more and more products with antibacterial coatings on the surface of daily necessities. The known polymer material of the antibacterial coating may include diionic fragments, which can form a hydration layer on the surface of the object, thereby preventing pathogens from adhering to the surface of the object. In order to improve the adhesion of the antibacterial coating to the surface of daily necessities, this known polymer material usually also includes long-chain non-ionic fragments to form non-covalent bonds such as van der Waals forces on the surface of the object. However, the long-chain non-ionic fragments will reduce the hydrophilicity of the polymer, making the polymer insoluble in water, resulting in limited applications of the known polymer material.

Therefore, there is an urgent need for a diionic polymer to solve the above problems.

Therefore, one aspect of the present invention is to provide a diionic polymer containing an acrylate group, which is highly hydrophilic and soluble in water. The diionic polymer is treated with water plasma to have free radicals, thereby helping to form an antibacterial coating with good adhesion on the surface of the substrate.

Another aspect of the present invention is to provide a method for preparing a diionic polymer to prepare the diionic polymer.

Another aspect of the present invention is to provide an antibacterial coating composition comprising the above-mentioned diionic polymer.

According to the above aspects of the present invention, a diionic polymer is provided, comprising the copolymer described in Formula 1. Formula 1

^R1 is a thioether containing at least two acrylate groups. ^R2 and ^R3 are hydrogen atoms or methyl groups. ^R4 is COOR' and CONR", and R' and R" are betaine, sulfobetaine or carboxybetaine.

In one embodiment of the present invention, R ¹ is (CH ₂ ) _x S(CH ₂ ) _y CH(COOC ₂ H ₃ ) ₂ or (CH ₂ ) _x S(CH ₂ ) _y CH(COOC ₂ H ₃ )CH ₂ (COOC ₂ H ₃ ), x is an integer from 0 to 5, and y is an integer from 0 to 5.

In one embodiment of the present invention, the average molecular weight of the diionic polymer is 5,000 to 10,000.

In one embodiment of the present invention, the contact angle of the antibacterial coating formed by the diionic polymer to water is 10° to 40°.

According to the above aspects of the present invention, a method for producing a diionic polymer is provided. First, a starting material is provided, wherein the starting material comprises a first monomer and a second monomer. The first monomer comprises a thioether having at least two hydroxyl groups. The second monomer comprises a betaine group, a sulfobetaine group or a carboxybetaine group. Next, a first polymerization step is performed on the starting material, and then an acyl halide-containing olefin compound is added, and a second polymerization step is performed to obtain a diionic polymer.

In one embodiment of the present invention, the first monomer is _CH2CH ( _CH2 ) _mS ( _CH2 ) _nCH (OH) ₂ or _CH2CH ( _CH2 ) _mS ( _CH2 ) _nCHOHCH2OH , m is an integer from 0 to 5, _and n is an integer from 0 to 5.

In one embodiment of the present invention, the acyl halide group includes an acyl chloride group or an acyl bromide group.

In one embodiment of the present invention, a molar ratio of the first monomer to the second monomer is 2:3 to 3:2.

According to another aspect of the present invention, an antibacterial coating composition is provided, comprising the above-mentioned diionic polymer.

In one embodiment of the present invention, based on the usage of the antibacterial coating composition being 100 weight percent, the usage of the diionic polymer is 30 weight percent to 50 weight percent.

The diionic polymer, the preparation method thereof and the antibacterial coating composition containing the diionic polymer of the present invention are applied, wherein the diionic polymer contains an acrylate group and has high hydrophilicity, so it can be dissolved in water, and through water plasma treatment, the diionic polymer is given free radicals, which helps to form an antibacterial coating with good adhesion on the surface of the substrate.

As mentioned above, the present invention provides a diionic polymer, a method for preparing the same and an antibacterial coating composition containing the same. The diionic polymer contains an acrylate group and has high hydrophilicity, so it can be dissolved in water and treated with water plasma to make the diionic polymer have free radicals, thereby helping to form an antibacterial coating with good adhesion on the surface of the substrate.

The "high hydrophilicity" described herein means that the diionic polymer has a high affinity for water, so it can be dissolved in water, and the surface of the antibacterial coating formed can form a water film on water. In some embodiments, the high hydrophilicity can be evaluated by the solubility of the diionic polymer in water and/or the contact angle of the formed antibacterial coating to water. In some embodiments, the high hydrophilicity can be, for example, represented by the solubility of the diionic polymer in water being greater than 10 g/1000 mL water at 20°C. In some embodiments, the high hydrophilicity can be, for example, represented by the contact angle between the antibacterial coating formed by the diionic polymer and water being less than or equal to 40°, such as: 10° to 40°.

The "good adhesion" described herein refers to the tight adhesion, bonding or attachment between the antibacterial coating formed by the diionic polymer and the surface of the substrate. In some embodiments, the adhesion can be evaluated using a cross-sectional test, which is to use a sharp knife to carve multiple lines in two different directions on the surface of an object, then stick a pressure-sensitive tape on the surface of the object where the lines are located, and then quickly pull the tape from the surface of the object to observe whether the surface of the object is peeled off. In some embodiments, good adhesion means that after the tape is quickly pulled off, there is no antibacterial coating peeling off from the substrate, or the peeling only occurs around the lines or at the intersection of the lines, and the peeling area is less than 5%.

In other embodiments, adhesion can be evaluated using a steel wool test, which is to evaluate the weight loss rate of the surface of the object after rubbing the surface of the object with steel wool with a weight, wherein the weight loss rate is the percentage of the weight difference of the surface of the object before and after rubbing with steel wool and the weight of the surface of the object before rubbing with steel wool. The steel wool test is performed with different weights and different friction times to compare the durability of the surfaces of different objects to multiple frictions. In some specific examples, the weight loss rate of the surface with good adhesion is less than 1 weight percentage after rubbing back and forth 40 to 60 times with steel wool with a weight greater than 200 g to 400 g.

The antibacterial coating has antibacterial properties. The "antibacterial property" described herein refers to "biological inertness". In other words, after the diionic polymer forms an antibacterial coating on the surface of the substrate, it is difficult for pathogens and/or their vectors to be non-specifically adsorbed on the surface of the antibacterial coating. In some embodiments, pathogens may include but are not limited to fungi, bacteria and/or viruses. In some embodiments, the vectors of pathogens may include but are not limited to dust, droplets and/or aerosols carrying pathogens.

The antibacterial property can be evaluated by the relative bacterial percentage or relative antibacterial rate obtained by the antibacterial test. In some embodiments, the antibacterial test is to place the sheet (including the substrate without the antibacterial coating and the substrate with the antibacterial coating) in a bacterial solution and culture it at 35°C to 40°C for 20 hours to 30 hours, and then calculate the amount of bacteria on the surface of the sheet, wherein the bacteria can be, for example, Escherichia coli or Staphylococcus aureus.

The above relative bacterial percentage is the percentage of the amount of bacteria on the surface of the antibacterial coating (i.e., N ₁ ) relative to the amount of bacteria on the surface of the substrate (without the antibacterial coating formed) (i.e., N ₀ ) [i.e., (N ₁ /N ₀ )×100%]. The relative antibacterial rate is the difference between 100% and the relative bacterial percentage [i.e., 100%-(N ₁ /N ₀ )×100%], which is equivalent to the percentage of the difference between the amount of bacteria on the surface of the substrate (i.e., N ₀ ) and the amount of bacteria on the surface of the antibacterial coating (i.e., N ₁ ) relative to the amount of bacteria on the surface of the substrate (i.e., N ₀ ) [i.e., (N ₀ -N ₁ )/N ₀ ×100%]. In some embodiments, the antimicrobial property is a relative bacteria percentage of less than 20%, which is equivalent to a relative antimicrobial rate of greater than 80%.

The hydrophilic diionic polymer described herein includes the copolymer described in Formula 1. Formula 1

^R1 is _a thioether containing at least two acrylate groups. In some embodiments, ^R1 is ( _CH2 ) _xS ( _CH2 ) _yCH ( _COOC2H3 ) ₂ or ( _CH2 ) _xS ( _CH2 ) _yCH ( _{COOC2H3 ) CH2} ( _COOC2H3 ), wherein x is an integer from 0 to 5, and y is an integer from 0 to _5. In some embodiments, ^R1 is SCH( _COOC2H3 ) ₂ . In other embodiments, ^R1 is ( _CH2 )S( _CH2 ) _4CH ( _COOC2H3 ) _CH2 ( _COOC2H3 ). Since ^R1 has at least two _acrylate groups, the diionic polymer can not only have hydrophilicity, _but also form _an antibacterial coating with good adhesion.

^R2 and ^R3 are hydrogen atoms or methyl groups. ^R4 is COOR' and CONR", and R' and R" are betaine, sulfobetaine, carboxybetaine or derivatives thereof, so that the formed antibacterial coating has antibacterial properties. In some specific examples, the diionic polymer includes a copolymer as shown in Formula 2, Formula 3 or Formula 4. Formula 2 Formula 3 Formula 4

In some embodiments, the average molecular weight of the diionic polymer can be, for example, 5,000 to 10,000, so that after the diionic polymer is treated with water plasma, the antibacterial coating formed can be easily grafted onto the surface of the substrate to form a film, and the weight density of the diionic polymer contained in the antibacterial coating is sufficient to make the antibacterial coating biologically inert and antibacterial.

The preparation method of the diionic polymer is briefly described as follows. First, a starting material is provided, wherein the starting material comprises a first monomer and a second monomer. The first monomer comprises a thioether of at least two hydroxyl groups. In some embodiments, the first monomer is _CH2CH ( _CH2 ) _mS ( _CH2 ) _nCH (OH) ₂ or _CH2CH ( _{CH2 ) mS} ( _CH2 ) _nCHOHCH2OH , m is an integer from 0 to 5, and n is an integer from 0 to 5. In some embodiments, the first monomer can be obtained by reacting alkenyl mercaptan with alkenyl epoxy compound under alkaline catalysis. In some specific examples, the first monomer is obtained by reacting allyl mercaptan with glycidol under the catalysis of triethylamine (TEA).

The second monomer includes betaine, alkyl betaine, sulfo betaine or carboxy betaine. In some embodiments, the second monomer can be prepared by reacting aliphatic tertiary amine with sulfonic acid. In some specific examples, the second monomer is prepared by reacting 2-(2-dimethylamino) methacrylate with 1,3-propane sultone.

Then, the starting material is subjected to a first polymerization step. The first polymerization step may be, for example, an atom transfer radical polymerization method. In some embodiments, the first polymerization step is carried out in an anaerobic, inert gas environment (e.g., nitrogen, helium, or argon) with ethanol as a solvent, cuprous bromide/bipyridine (CuBr/2,2'-bipyridine; CuBr/bpy) as a catalyst, and methyl 2-bromopropionate (MBrP) as a polymerization initiator.

Next, an acyl halide-containing olefin compound is added and a second polymerization step is performed. In some embodiments, the acyl halide-containing olefin compound may include but is not limited to an acyl chloride or an acyl bromide. In some specific embodiments, the acyl halide-containing olefin compound is propyl olefin chloride. In some embodiments, the second polymerization step may be performed under the catalysis of triethylamine.

The above-mentioned manufacturing method can produce a highly hydrophilic diionic polymer as shown in the above formula 1. Experimental results show that the contact angle between the antibacterial coating formed by the diionic polymer and water is 10° to 40°.

Since the diionic polymer of the present invention has high hydrophilicity, it can be dissolved in water, and through water plasma treatment, the diionic polymer has free radicals, which helps to form an antibacterial coating with good adhesion on the substrate. The method of water plasma treatment is briefly described as follows. First, the diionic polymer is formulated into a diionic polymer aqueous solution. In some embodiments, the content of the diionic polymer in the diionic polymer aqueous solution is 30 weight percent to 50 weight percent, so that after the diionic polymer is treated with water plasma, the antibacterial coating formed is easier to graft with the surface of the substrate to form a film, and the weight density of the diionic polymer contained in this antibacterial coating is sufficient to make the antibacterial coating biologically inert and antibacterial.

The above-mentioned double ion polymer has high hydrophilicity. In some embodiments, the water contact angle of the substrate not treated with water plasma is 50° to 80°, but after the substrate is treated with water plasma of the above-mentioned double ion polymer, the water contact angle is 10° to 40°.

Next, the di-ion polymer aqueous solution is ionized by gas plasma to obtain a plasma-activated di-ion polymer aqueous solution. The gas plasma may be, for example, air or oxygen obtained by plasma treatment. The plasma treatment may be performed by known methods, such as low-temperature vacuum plasma or low-temperature atmospheric pressure plasma. In some specific examples, the low-temperature atmospheric pressure plasma may include but is not limited to jet plasma, dielectric layer discharge or coma discharge.

The ionization treatment may be, for example, passing gas plasma into a tank containing a diionic polymer aqueous solution, so that the diionic polymer in the diionic polymer aqueous solution has free radicals to enhance its reactivity, thereby facilitating the formation of an antibacterial coating with good adhesion on the surface of the substrate.

In some embodiments, the ionization treatment can be carried out at room temperature and normal pressure, wherein the room temperature can be, for example, 5°C to 50°C, or 10°C to 45°C, or 15°C to 35°C, or 20°C to 30°C. In some embodiments, the normal pressure can be, for example, 0.5 atmospheres (atm) to 1.5 atmospheres, or 0.8 atmospheres to 1.2 atmospheres. In some embodiments, the time of the ionization treatment can be, for example, 5 minutes to 120 minutes, such as: 10 minutes to 60 minutes, or 20 minutes to 60 minutes.

Then, the substrate is immersed in the plasma activated diionic polymer aqueous solution so that the diionic polymer in the plasma activated diionic polymer aqueous solution is grafted on the surface of the substrate to form an antibacterial coating. In some embodiments, the immersion time is not particularly limited, and can be, for example, 5 minutes to 120 minutes, so that the diionic polymer can be properly entangled, and the antibacterial coating formed can have better antibacterial properties. In some embodiments, the thickness of the antibacterial coating can be, for example, 0.5 μm to 50 μm.

In some embodiments, before immersing the substrate in the plasma activated di-ion polymer aqueous solution, the substrate is first subjected to plasma surface treatment to enhance the reactivity of the substrate surface. The plasma surface treatment includes using conventional plasma treatment. Conventional plasma treatment has been listed above and will not be described again.

The substrate may be a known material used to make eyeglass lenses, such as glass, polycarbonate (PC), triacetate cellulose film (TCF), nylon, poly(allyl carbonate) diglycol (CR-39), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), or polypropylene (PP).

In some embodiments, the substrate surface may further have a multi-layer anti-reflective coating (AR) layer, wherein the material of the multi-layer anti-reflective layer may be, for example, titanium dioxide, silicon dioxide, zirconium dioxide or magnesium fluoride. In other words, the antibacterial coating formed by the diionic polymer may be formed on the surface of the outermost anti-reflective layer.

According to the antibacterial test, compared with the substrate without antibacterial coating, the relative antibacterial rate of the antibacterial coating formed by the double ion polymer is greater than or equal to 80%, which is indeed antibacterial and can be used to prepare antibacterial coating compositions. Secondly, compared with the antibacterial coating formed by coating of conventional polymer materials (including double ion fragments and long-chain non-ionic fragments) with poor hydrophilicity, the antibacterial coating formed by the double ion polymer of the present invention through water plasma treatment has better antibacterial adhesion to the substrate.

It is to be noted that conventional plasma treatment (e.g., plasma-assisted chemical vapor deposition process) requires first heating the material to be deposited on the surface of the substrate to 40°C to 80°C to form a gaseous material, and then using a carrier gas to allow the gaseous material to flow into a cavity so that the gaseous material is deposited and grafted onto the surface of the substrate. However, di-ion polymers are difficult to vaporize, so it is not possible to form an antibacterial coating using conventional plasma treatment (e.g., plasma-assisted chemical vapor deposition process). The di-ion polymers of the present invention have high hydrophilicity and reactive functional groups, so they can be grafted onto the surface of the substrate by water plasma treatment, thereby improving the durability of the resulting antibacterial antifogging layer.

Several embodiments are used below to illustrate the application of the present invention, but they are not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Preparation Example 1

First, a monomer 1 as shown in Formula 5 is prepared, which is prepared by polymerization of allyl mercaptan and glycidol in ethyl acetate under the catalysis of triethylamine (TEA). Formula 5

Next, monomer 2 of formula 6 was obtained, which was prepared by betaineization reaction of 2-(2-dimethylamino) methacrylate and 1,3-propane sultone in acetone solvent for 24 hours. Formula 6

Then, in a nitrogen environment, using ethanol as a solvent, cuprous bromide/bipyridine (CuBr/bpy) as a catalyst, and methyl 2-bromopropionate (MBrP) as a polymerization initiator, monomer 1 and monomer 2 are subjected to atom transfer radical polymerization to form polymer 1 as shown in Formula 7. Formula 7

Next, triethylamine was used to catalyze the reaction of polymer 1 and propylvinyl chloride to obtain a diionic polymer (as shown in Formula 2). Then, the diionic polymer was prepared into a 40 weight percent diionic polymer aqueous solution. Air plasma was prepared using low-temperature atmospheric pressure plasma, and then the air plasma was passed into the diionic polymer aqueous solution at 25°C and 1 atmosphere to perform ionization treatment for 15 minutes, thereby obtaining a plasma-activated diionic polymer aqueous solution.

The lens is subjected to plasma surface treatment for 10 to 60 minutes by low temperature atmospheric pressure plasma. The lens is a commercially available correction lens, comprising a substrate and an anti-reflection layer, wherein the substrate is poly(allyl diglycol carbonate) (CR-39), and the anti-reflection layer is silicon dioxide. The lens subjected to plasma surface treatment is immersed in a plasma activated double ion polymer aqueous solution for 20 to 60 minutes to form a coating film on the surface of the lens, thereby preparing the sheet of Preparation Example 1. It is worth noting that although Preparation Example 1 only uses the diionic polymer containing the polymer shown in Formula 2 as an example, the sheet made using the diionic polymer containing the polymer shown in Formula 3 and Formula 4 or other similar polymers with similar structures should obtain the same results as Preparation Example 1 using the same evaluation method, and will not be repeated here. Preparation Comparison Example 1

The sheet material of Preparation Comparison Example 1 is the lens in Preparation Example 1, but is not immersed in the plasma-activated diionic polymer aqueous solution. Preparation Comparison Example 2

The preparation of the sheet of Comparative Example 2 is the same as that of Preparation Example 1, except that the diionic polymer of Preparation Example 2 comprises a polymer 2 as described in Formula 8, which is prepared using methanol allyl sulfide as a monomer 1, wherein the monomer 1 has only one acrylate group. Formula 8 Preparation Comparative Example 3

The sheet material of Preparation Example 3 is the same as that of Preparation Example 1, except that the coating of Preparation Example 3 is formed by dipping the sheet material in the coating composition and drying it at 120° C. for 30 minutes. The coating composition comprises a polymer 3 represented by Formula 9 and vinyltrimethoxysilane, which are polymerized at 60° C., and p in Formula 9 is 14. Equation 9 Evaluation method and results 1. Contact angle

5 μL of water was dropped on the sheets of Preparation Example 1, Preparation Comparative Example 1 to Preparation Comparative Example 3, and the contact angle was measured at 25°C using an automatic contact angle measuring instrument. 2. Antibacterial test

The antibacterial property of the sheet of Preparation Example 1 was evaluated. First, the front and back sides of the sheet of Preparation Example 1 were irradiated with ultraviolet light for 5 minutes each to sterilize the sheet of Preparation Example 1, wherein the front side of the sheet of Preparation Example 1 refers to the side where the number of bacteria on the surface is sampled in subsequent experiments. Then, the sheet of Preparation Example 1 was placed face up in a culture dish containing bacterial solution and cultured at 37°C for 24 hours to make the bacterial concentration in the bacterial solution range from 2.5×10 ⁵ colony-forming units (CFU)/mL to 10.0×10 ⁵ CFU/mL.

Then, the sheet of Preparation Example 1 was taken out from the culture dish, and after removing the liquid visible to the naked eye, the sheet of Preparation Example 1 was washed, and the liquid on the surface of the sheet of Preparation Example 1 was drained. The washing method was to soak the sheet in phosphate buffered saline (PBS) for 5 minutes, and then soak the sheet in fresh PBS. Next, the front of the test piece was washed with 10 mL of soybean casein digest lecithin polysorbate 80 medium (SCDLP) containing lecithin and Tween ^® 80 to obtain a washing solution. 1 mL of the washing solution was applied to the culture medium, and after incubation at 37°C for 24 hours, the number of colonies in the culture medium (i.e., N ₁ ) was calculated. The colony count of Preparation Comparative Example 1 (ie, N ₀ ) was obtained by the above method.

The percentage of the colony count of the culture medium of Preparation Example 1 (i.e., N ₁ ) and the colony count of the culture medium of Preparation Comparative Example 1 (i.e., N ₀ ) was calculated [i.e., (N ₁ /N ₀ )×100%] to obtain the relative bacterial count percentage of Preparation Example 1. Then, the difference between 100% and the relative bacterial count percentage of Preparation Example 1 was calculated [i.e., 100%-(N ₁ /N ₀ )×100%] to obtain the relative antibacterial rate.

Next, the relative bacterial count percentages of Preparation Comparison Example 2 and Preparation Comparison Example 3 relative to Preparation Comparison Example 1 were obtained by the same method. It should be noted that the above-mentioned bacteria are Escherichia coli, and the culture medium is LB culture medium agar. The results of the antibacterial test are recorded in Table 1, where "○" indicates that the relative antibacterial rate is ≥80%, which is antibacterial, and "╳" indicates that the relative antibacterial rate is <80%, which is not antibacterial. 3. Hundred Grid Test

First, a scoring area was set on the surface of the sheet of Preparation Example 1, and a blade was used to score several first scoring lines with a spacing of 1 mm on the surface of the sheet of Preparation Example 1 in the scoring area with a stable pressure. Then, a blade was used to score several second scoring lines with a spacing of 1 mm on the surface of the sheet of Preparation Example 1 in the scoring area with the same pressure, wherein the first scoring line was perpendicular to the second scoring line, and the first scoring line and the second scoring line formed a plurality of squares. It should be noted that the depth of the first scoring line and the second scoring line is the thickness of the coating.

Next, stick the tape on the surface of the sheet in the engraved area for 60 seconds, tear off the tape at nearly 180°, and then observe the surface of the sheet in the engraved area with a magnifying glass. The evaluation results are recorded in Table 1, where "○" indicates that the surface of the sheet in the square formed by the first and second engraved lines has no peeling, or the surface of the sheet is peeling only around the first or second engraved lines or at the intersection of the first and second engraved lines, and the peeling area is less than 5%, "╳" indicates that there is sawtooth peeling on both sides of the first or second engraved lines, or the surface of the sheet in the square formed by the first and second engraved lines has peeling, or the surface of the sheet outside the engraved area has peeling. 4. Wire wool test to evaluate adhesion

The first steel wool test was to first measure the weight of the sheet of Preparation Example 1, then rub the surface of the sheet of Preparation Example 1 20 times with steel wool weighing 200 g, and then measure the weight of the sheet of Preparation Example 1. The difference between the weight of the sheet of Preparation Example 1 before and after friction and the percentage of the weight before friction treatment were calculated to obtain the weight loss rate.

The second steel wool test was to first measure the weight of the sheet of Preparation Example 1, then rub the surface of the sheet of Preparation Example 1 60 times with steel wool weighing 400 g, and then measure the weight of the sheet of Preparation Example 1. The difference between the weight of the sheet of Preparation Example 1 before and after friction and the percentage of the weight before friction treatment were calculated to obtain the weight loss rate.

The weight loss rates of the sheets of Preparation Comparative Examples 1 to 3 were evaluated in the same manner. The smaller the weight loss rate, the better the durability of the coating. The results are recorded in Table 1, where "○" indicates that the weight loss rate is <1%, and the durability is good, and "╳" indicates that the weight loss rate is ≥1%, and the durability is poor.

Table 1 Evaluation Results Preparation example Preparation Comparison Example 1 1 2 3 Contact angle 20 70 50 60 Antibacterial test ○ N/A ○ ○ 100 grid test ○ ╳ ╳ ○ First steel velvet test ○ ╳ ╳ ○ Second velvet test ○ ╳ ╳ ╳ N/A means not assessed, not applicable

As shown in Table 1, the sheet of Preparation Example 1 has antibacterial properties, and the coating has adhesion. The surface of the sheet of Preparation Comparison Example 1 has no coating, and the surface of the sheet is easy to fall off after being subjected to external force. The coating of the sheet of Preparation Comparison Example 2 has less acrylate groups of diionic polymers, and although it has antibacterial properties, the adhesion of the coating is poor. The coating of the sheet of Preparation Comparison Example 3 is formed by coating the coating composition, and has antibacterial properties and adhesion, but its adhesion is poorer than that of the coating of Preparation Example 1.

As can be seen from the above embodiments, the diionic polymer, its preparation method and the antibacterial coating composition containing the same of the present invention have the advantage that the diionic polymer used contains an acrylate group, has high hydrophilicity, and can be dissolved in water. Therefore, the diionic polymer can be treated with water plasma to have free radicals, which helps to form an antibacterial coating with good adhesion on the surface of the substrate.

Although the present invention has been disclosed as above with several specific embodiments, various modifications, changes and substitutions may be made to the above disclosed contents, and it should be understood that, without departing from the spirit and scope of the present invention, certain features of the embodiments of the present invention will be adopted in certain situations but other features will not be used accordingly. Therefore, the spirit and scope of the claims of the present invention should not be limited to the above exemplary embodiments.

without

without

Claims (10)

A diionic polymer comprising a copolymer of formula 1, Formula 1 ^R1 is a thioether containing at least two acrylate groups; ^R2 and ^R3 are hydrogen atoms or methyl groups; ^R4 is COOR' and CONR", and R' and R" are betaine, sulfobetaine or carboxybetaine. The diionic polymer as claimed in claim 1, wherein R ¹ is (CH ₂ ) _x S(CH ₂ ) _y CH(COOC ₂ H ₃ ) ₂ or (CH ₂ ) _x S(CH ₂ ) _y CH(COOC ₂ H ₃ )CH ₂ (COOC ₂ H ₃ ), x is an integer from 0 to 5, and y is an integer from 0 to 5. The diionic polymer as described in claim 1, wherein an average molecular weight of the diionic polymer is 5000 to 10000. The diionic polymer as described in claim 1, wherein a contact angle of an antibacterial coating formed by the diionic polymer with water is 10° to 40°. A method for preparing a diionic polymer comprises: Providing a starting material, wherein the starting material comprises: A first monomer, comprising a thioether having at least two hydroxyl groups; and A second monomer, comprising a betaine group, a sulfobetaine group or a carboxybetaine group; Performing a first polymerization step on the starting material, then adding an acyl halide-containing olefin compound, and performing a second polymerization step to obtain the diionic polymer. The method for producing a diionic polymer as described in claim 5, wherein the first monomer is _CH2CH ( _CH2 ) _mS ( _CH2 ) _nCH (OH) ₂ or _CH2CH ( _CH2 ) _mS ( _CH2 ) _nCHOHCH2OH , m is an integer from 0 to 5, _and n is an integer from 0 to 5. A method for producing a diionic polymer as described in claim 5, wherein the acyl halide group comprises an acyl chloride group or an acyl bromide group. A method for producing a diionic polymer as described in claim 5, wherein a molar ratio of the first monomer to the second monomer is 2:3 to 3:2. An antibacterial coating composition comprises the diionic polymer as described in any one of claims 1 to 4. The antibacterial coating composition as described in claim 9, wherein the diionic polymer is used in an amount of 30 weight percent (wt%) to 50 weight percent based on a usage amount of the antibacterial coating composition of 100 weight percent.