Branched fluoroalkyl short chain quaternary ammonium salt antimicrobial agents

Abstract

This invention discloses a branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent, wherein the branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent is composed of one or more compounds of formula I, formula II, and formula III. This invention exhibits stronger hydrophobic and oleophobic properties, can maintain the quaternary ammonium salt immobilized in the bacterial cell to enhance and prolong the bactericidal effect, and significantly reduces biotoxicity.

Description

Technical Field

[0001] This invention relates to the field of antibacterial compound production technology, and in particular to a branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent. Background Technology

[0002] Since Damark pioneered the field of cationic antibacterial agents in 1935, quaternary ammonium salts have been widely used in daily life due to their strong bactericidal effect and low biohazard. Fluorocarbon chains have very low surface tension, exhibiting hydrophobic and oleophobic properties. When fluorocarbon chains are linked with quaternary ammonium salts, the fluorocarbon chains can immobilize the quaternary ammonium salts within the bacterial cells, enhancing the bactericidal effect. Currently, linear fluoroalkyl quaternary ammonium salts only exhibit high bactericidal and fluorine surface properties when the number of fluorocarbon groups reaches or exceeds eight. This is mainly because only when the number of linear fluorocarbon groups reaches or exceeds eight can fluorine crystals form on the material surface, resulting in a regular arrangement of fluorocarbon groups and stable fluorine surface properties. Figure 1 a). When there are fewer than 8 fluorocarbon groups, the fluorocarbon groups will be irregularly arranged on the material surface, making it difficult to form surface fluorine crystals. This results in reduced fluorine surface stability, incomplete fixation of quaternary ammonium salts within the bacterial cells, and decreased antibacterial effect. Figure 1 (b) Currently, quaternary ammonium salt antibacterial agents with fluoroalkyl chains are linear fluoroalkyl chain quaternary ammonium salts. CN103572594A describes a trimethoxysilylpropyl-N,N-dipropyltridecylfluorooctylammonium chloride antibacterial agent, which exhibits high antibacterial properties. However, perfluorooctyl compounds have high biotoxicity and are banned in many countries. For example, perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonic acid (PFOS) were partially banned by the EU in July 2020. Short-chain fluoroalkyl compounds have relatively lower toxicity, but they have fewer fluorocarbon groups, making it more difficult to form fluorine crystals or fluorine accumulation on the surface, resulting in less pronounced fluorine surface properties. Summary of the Invention

[0003] The purpose of this invention is to provide a branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent that, compared with linear alkyl quaternary ammonium salts, has stronger hydrophobic and oleophobic properties, can keep the quaternary ammonium salt fixed in the bacterial cell to improve and prolong the bactericidal performance, and at the same time significantly reduce biotoxicity.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent, characterized in that the branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent is composed of one or more compounds of formula I, formula II, and formula III:

[0006]

[0007] Where R is -CH3 or -CH2CH3, X is Cl or Br, n is 1 or 2; m is a natural number from 1 to 4, i is a natural number from 1 to 4, and h is 1 or 2.

[0008] This invention increases the number of short-chain fluoroalkyl chains to form branched fluoroalkyl short-chain quaternary ammonium salts. The multiple branches act as umbrellas or masks to shield hydrophilic groups, resulting in increased surface fluorine content and surface fluorine accumulation, which is beneficial for improving surface properties and stability control. Figure 1 c).

[0009] Short-chain linear fluorinated groups have relatively low surface energy, making the fluorine surface unstable and unable to exhibit strong fluorine properties. Figure 1 b). To enhance surface fluorine properties, existing technologies conventionally increase the length of linear fluoroalkyl chains so that fluorocarbon groups can form fluorine crystals on the material surface, better immobilizing quaternary ammonium salts within the bacterial cells, thereby improving fluorine surface properties and prolonging bactericidal performance. Figure 1 a). However, increasing the length of the linear fluoroalkyl chain significantly increases biotoxicity and processing difficulty.

[0010] The inventors discovered through research that increasing the number of short-chain fluorinated alkyl groups of a specific length can create an "umbrella-like" stacking on the material surface, increasing stability and resulting in stronger surface fluorine properties. Simultaneously, it can compress quaternary ammonium salts within the bacterial cell, preventing oil contamination and maintaining the bactericidal properties of the quaternary ammonium salts. This overcomes the problem of poor stability caused by the low surface energy of fluorine atoms, as seen with linear short-chain fluorinated alkyl groups. Furthermore, unlike long-chain linear fluorinated alkyl groups which can form fluorine crystals on the material surface, thus creating a stable fluorinated surface, the multi-branched fluorinated alkyl groups of this invention, by increasing the umbrella-like stacking of surface fluorine atoms, significantly reduce biotoxicity while achieving the same or even better surface fluorine and antibacterial properties.

[0011] This invention increases the amount of fluorine in the compound by increasing the number of fluorocarbon branches without increasing the length of the fluorocarbon chain. This facilitates the formation of fluorine deposits on the material surface, enhancing the surface fluorine properties of the compound. The increased fluorine deposits also compress the quaternary ammonium salt within the bacterial cells, preventing oil contamination and maintaining its bactericidal properties. By increasing the number of fluorocarbon branches, this invention improves the surface fluorine density and the regularity of the surface fluorocarbon chains, thereby enhancing the surface fluorine properties and stability. Simultaneously, the increased number of surface fluoroalkyl groups forces the quaternary ammonium salt to remain within the bacterial cells, resulting in a better antibacterial effect.

[0012] The compound described in Formula I is prepared by reacting a haloalkyltrialkoxysilane with a fluoroalkyl tertiary amine via a quaternization reaction to obtain a branched fluoroalkyl quaternary ammonium salt antibacterial agent. The process flow is as follows:

[0013]

[0014] The fluoroalkyl tertiary amine is selected from one of perfluorotriethylamine, perfluorotripropylamine, perfluorotributylamine, perfluorotripentylamine, and perfluorotrihexylamine.

[0015] The compound described in Formula II is prepared by reacting a fluoroalkyl primary amine with a fluoroalkyl acrylate to synthesize a branched fluoroalkyl tertiary amine, which is then reacted with a haloalkyltrialkoxysilane to obtain the final product. The process flow is as follows:

[0016]

[0017] The fluorinated alkyl acrylate is selected from one of perfluoromethyl ethyl acrylate, perfluoroethyl ethyl acrylate, perfluoropropyl ethyl acrylate, perfluorobutyl ethyl acrylate, perfluoropentyl ethyl acrylate, and perfluorohexyl ethyl acrylate.

[0018] The preparation method of the compound of Formula III is as follows: a fluoroalkyl primary amine is reacted with a fluoroalkyl epoxy compound to synthesize a branched fluoroalkyl tertiary amine, and the branched fluoroalkyl tertiary amine is then reacted with a haloalkyltrialkoxysilane to synthesize the branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent of Formula III; the process flow is as follows:

[0019]

[0020] The fluorinated alkyl epoxy compound is selected from one of the following: 2,2,3,3,3-pentafluoropropyl ethylene oxide, 2,2,3,3,4,4,4-heptafluorobutyl ethylene oxide, 2,2,3,3,4,4,5,5,5-nonafluoropentyl ethylene oxide, 2,2,3,3,4,4,5,5,6,6,6-undecylfluorohexyl ethylene oxide, and 2,2,3,3,4,4,5,5,6,6,7,7,7-tridecylfluoroheptyl ethylene oxide.

[0021] The fluoroalkyl primary amine is selected from one of 2,2,3,3,3-pentafluoropropylamine, 2,2,3,3,4,4,4-heptafluorobutylamine, and 2,2,3,3,4,4,5,5,5-nonafluorohexylamine.

[0022] The haloalkyltrialkoxysilane is selected from one of chloromethyltrimethoxysilane, chloroethyltrimethoxysilane, chloropropyltrimethoxysilane, chloromethyltriethoxysilane, chloroethyltriethoxysilane, chloropropyltriethoxysilane, bromomethyltrimethoxysilane, bromoethyltrimethoxysilane, bromopropyltrimethoxysilane, bromomethyltriethoxysilane, bromoethyltriethoxysilane, bromopropyltriethoxysilane, iodomethyltrimethoxysilane, iodoethyltrimethoxysilane, iodopropyltrimethoxysilane, and iodopropyltriethoxysilane.

[0023] The beneficial effects of the present invention are as follows: the antibacterial agent of the present invention has a siloxane end, which can react with the surface groups of the material to improve the adhesion and abrasion resistance of the branched fluoroalkyl quaternary ammonium salt on the material surface; the other end has a branched fluoroalkyl short chain, which can fix the quaternary ammonium salt in the bacteria to improve the bactericidal effect. At the same time, the branched fluoroalkyl side chain improves the hydrophobic and oleophobic properties of the material surface, preventing oil pollution and maintaining the bactericidal performance of the quaternary ammonium salt. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the arrangement of fluoroalkyl compounds with different structures at the interface;

[0025] Figure 2 This is the antibacterial test chart for the blank control, showing an inhibition rate of 9.48%.

[0026] Figure 3 This is the antibacterial test chart for Comparative Example 1, showing an inhibition rate of 95.3%.

[0027] Figure 4 This is the antibacterial test chart for Comparative Example 2, showing an inhibition rate of 44.8%.

[0028] Figure 5 This is the antibacterial test chart for Example 1, showing an inhibition rate of 99.5%.

[0029] Figure 6 This is the antibacterial test chart for Example 2, showing an inhibition rate of 98.6%.

[0030] Figure 7 This is the antibacterial test chart for Example 3, showing an inhibition rate of 97.7%.

[0031] Figure 8 This is a contact angle test diagram for Comparative Example 1. The left side shows the water contact angle, and the right side shows the oil contact angle.

[0032] Figure 9 This is a contact angle test diagram for Comparative Example 2. The left side shows the water contact angle, and the right side shows the oil contact angle.

[0033] Figure 10 This is a contact angle test diagram of Example 1, with the water contact angle on the left and the oil contact angle on the right;

[0034] Figure 11 This is a contact angle test diagram from Example 2, with the water contact angle on the left and the oil contact angle on the right.

[0035] Figure 12 This is a contact angle test diagram of Example 3. The left side shows the water contact angle, and the right side shows the oil contact angle. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0037] In this invention, unless otherwise specified, all raw materials and equipment used are commercially available or commonly used in the field. The methods described in the following embodiments are conventional methods in the field, unless otherwise specified.

[0038] Comparative Example 1: Linear long-chain fluorinated alkyl quaternary ammonium salt

[0039] Synthesis of N,-trimethoxysilylpropyl-N,N-dimethylheptadecylfluorodecyl quaternary ammonium bromide: The synthesis steps are as follows:

[0040]

[0041] (1) N,N-Dimethyl-Heptadecyl tertiary amine

[0042] In a three-necked flask equipped with a magnetic stirrer and a thermometer, 16.50 g of 33% dimethylamine aqueous solution and 4 g of sodium hydroxide were added. The mixture was heated to 70 °C, and then 20.85 g of heptadecyl bromide was added dropwise. After the addition was complete, the reaction was continued for 24 h. After the reaction was completed, ethyl acetate was added and extracted three times (100 mL each time). The extracts were combined and washed three times (100 mL each time) with water. The oil phase was dried for 24 h with 10 g of anhydrous sodium sulfate, and then the sodium sulfate was filtered off. The extractant was removed by rotary evaporation under reduced pressure, yielding 7.60 g of a pale yellow transparent product.

[0043] (2) Quaternization

[0044] 6.80 g of N,N-dimethyl-heptadecyl tertiary amine and 15 ml of acetonitrile were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. The mixture was heated to 85 °C, and then 8.20 g of bromopropyltrimethoxysilane was added dropwise. After the addition was complete, the reaction was continued for 24 h. After the reaction was completed, the solvent was removed by rotary evaporation under reduced pressure to obtain 6.50 g of a yellow product.

[0045] Comparative Example 2: Branched fluoroalkyl ultrashort-chain quaternary ammonium salt

[0046] The synthesis steps for preparing N-trimethoxyethyl-N,N-triperfluoroethyl quaternary ammonium bromide are as follows:

[0047]

[0048] Perfluorotriethylamine (17 g, 0.05 mol) was added to 100 mL of acetonitrile, followed by bromoethyltrimethoxysilane (20 g, 0.1 mL). The reaction was carried out at 85 °C for 6–8 hours. The mixture was then directly distilled under reduced pressure to remove the solvent acetonitrile, yielding the product N-trimethoxyethyl-N,N-triperfluoroethyl quaternary ammonium bromide.

[0049] Example 1

[0050] A branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agent has the following structure:

[0051]

[0052] R is -CH3 or -CH2CH3; X is Cl or Br; n is 1 or 2; m is 2, 3 or 4.

[0053] The synthesis steps for preparing N-trimethoxyethyl-N,N,N-triperfluorohexyl quaternary ammonium bromide are as follows:

[0054]

[0055] Perfluorotrihexylamine (25 g, 0.05 mol) was added to 100 mL of acetonitrile, followed by bromoethyltrimethoxysilane (20 g, 0.1 mL). The reaction was carried out at 85 °C for 6–8 hours. The mixture was then directly distilled under reduced pressure to remove the solvent acetonitrile, yielding the product N-trimethoxyethyl-N,N,N-triperfluorohexyl quaternary ammonium bromide.

[0056] The method described in this embodiment can be used to synthesize other branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agents as follows:

[0057] Serial Number Halogenated alkyl alkoxysilanes fluoroalkyl tertiary amines Product Name 1 bromoethyltrimethoxysilane perfluorotributylamine N-Trimethoxyethyl-N,N,N-Triperfluorohexyl quaternary ammonium bromide 2 bromoethyltrimethoxysilane perfluorotripropylamine N-Trimethoxyethyl-N,N,N-Triperfluorohexyl quaternary ammonium bromide 3 bromoethyltrimethoxysilane perfluorotriamylamine N-Trimethoxyethyl-N,N,N-Triperfluorohexyl quaternary ammonium bromide 4 Chloromethyltrimethoxysilane perfluorotributylamine N-Trimethoxymethyl-N,N,N-Triperfluorohexyl quaternary ammonium chloride 5 Chloromethyltrimethoxysilane perfluorotripropylamine N-Trimethoxymethyl-N,N,N-Triperfluorohexyl quaternary ammonium chloride 6 Chloromethyltrimethoxysilane perfluorotriamylamine N-Trimethoxymethyl-N,N,N-Triperfluorohexyl quaternary ammonium chloride .

[0058] Example 2

[0059] A branched short-chain fluorinated alkyl quaternary ammonium salt antibacterial agent has the following structure:

[0060]

[0061] R is -CH3 or -CH2CH3; X is Cl or Br; n and h are both 1 or 2; m and i are both 2, 3 or 4.

[0062] The preparation of N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester quaternary ammonium bromide was carried out via the following synthetic steps:

[0063]

[0064] (1) Synthesize N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester 2,2,3,3,4,4,4-heptafluorobutylamine (2.0 g, 10 mmol), add it to 10 ml of trifluorotoluene, add perfluoropentylethyl acrylate (8.4 g, 20 mmol), react at 25 °C for 6 hours, and then directly distill the mixture under reduced pressure to remove the solvent trifluorotoluene, to obtain N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentylethyl acetate.

[0065] (2) Synthesis of N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester bromide quaternary ammonium salt

[0066] 2.0 g (3.3 mmol) of N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester was added to 10 mL of acetonitrile, followed by 1.6 g (8.0 mmol) of bromoethyltrimethoxysilane. The reaction was carried out at 85 °C for 6–8 hours. The mixture was then directly distilled under reduced pressure to remove the solvent acetonitrile, yielding the product N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester quaternary ammonium bromide.

[0067] The intermediate (1) can be synthesized using the method of this embodiment as follows:

[0068]

[0069] The method described in this embodiment can be used to synthesize branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agents as follows:

[0070]

[0071]

[0072] Example 3

[0073] A branched short-chain fluorinated alkyl quaternary ammonium salt antibacterial agent has the following structure:

[0074]

[0075] R is -CH3 or -CH2CH3; X is Cl or Br; n and h are both 1 or 2; m and i are both 2, 3 or 4.

[0076] The synthesis steps for preparing N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentylisopropanolyl quaternary ammonium bromide are as follows:

[0077]

[0078] (1) Synthesis of N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentyl isopropanol

[0079] 2,2,3,3,4,4,4-Hepenobutylamine (2.0 g, 10 mmol) was added to 10 mL of trifluorotoluene, followed by 3-(perfluoropentyl)propane oxide (7.6 g, 20 mmol). The mixture was reacted at 25 °C for 6 hours. The mixture was then directly distilled under reduced pressure to remove the solvent trifluorotoluene, yielding N-2,2,3,3,4,4,4-Hepenobutyl-N,N-di-2-perfluoropentyl isopropanol.

[0080] (2) Synthesis of N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentylisopropanol quaternary ammonium bromide

[0081] N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentyl isopropanol (2.0 g, 5 mmol) was added to 10 mL of acetonitrile, followed by bromoethyltrimethoxysilane (2 g, 10 mmol). The reaction was carried out at 85 °C for 6–8 hours. The mixture was then directly distilled under reduced pressure to remove the solvent acetonitrile, yielding the product N-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-2-perfluoropentyl isopropanol quaternary ammonium bromide.

[0082] The intermediate (1) can be synthesized using the method of this embodiment as follows:

[0083]

[0084] The method described in this embodiment can be used to synthesize branched fluoroalkyl short-chain quaternary ammonium salt antibacterial agents as follows:

[0085]

[0086] Antibacterial test

[0087] Take 0.4 ml to 0.5 ml of the experimental bacterial solution and add it to the blank control sample, the antibacterial agent sample of Comparative Example 1, the antibacterial agent sample of Comparative Example 2, and the antibacterial agent samples of branched fluoroalkyl short-chain quaternary ammonium salts in Examples 1-3.

[0088] Using fire extinguishing tweezers, pick up the sterile covering film and place it on the sample surface, ensuring it is flat and free of air bubbles to allow the bacteria to evenly contact the sample. Place the sample in a sterile Petri dish and incubate for 24 hours at (37±1)℃ and relative humidity RH>9. Perform three parallel experiments for each sample.

[0089] Take out the samples after 24 hours of incubation, add 20 ml of washing solution, wash the sample plate and covering film repeatedly, shake well, and then inoculate the washing solution into nutrient agar medium. After incubation at (37±1)℃ for (24-48) hours, count the viable bacteria and determine the number of viable bacteria in the washing solution according to GB / T 4789.2.

[0090] Calculation of test results

[0091] Multiply the above-determined viable cell count by 1000 to obtain the actual recovered viable cell count after 24 hours of sample incubation. The three parallel viable cell counts of the same blank control should meet the condition that (highest log value - lowest log value) / average viable cell count log value is less than or equal to 0.3.

[0092] The formula for calculating the antibacterial rate is:

[0093] R = (AC) / A × 100

[0094] In the formula:

[0095] Antibacterial rate, expressed as (%), with the number being the most significant value, and is conducted in accordance with the provisions of GB / T 1250;

[0096] Average recovered bacterial count (cfu / plate) of blank control sample after 24 hours

[0097] Average number of bacteria recovered (cfu / plate) after 24 hours from C-antimicrobial samples.

[0098] Contact angle test

[0099] 1. Clean the glass slide (76mm*26mm*2mm) with alkaline water and deionized water and set aside.

[0100] 2. Prepare a DMF solution of N,-trimethoxysilylpropyl-N,N-dimethylheptadecyl quaternary ammonium bromide with a solid content of 10%; prepare a DMF solution of N,-trimethoxyethyl-N,N-triperfluoroethyl quaternary ammonium bromide with a solid content of 10%; prepare a DMF solution of N,-trimethoxyethyl-N,N,N-triperfluorohexyl quaternary ammonium bromide with a solid content of 10%; prepare a DMF solution of N,-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester quaternary ammonium bromide with a solid content of 10%; prepare a DMF solution of N,-trimethoxyethyl-N-2,2,3,3,4,4,4-heptafluorobutyl-N,N-di-acetic acid-(2-perfluoropentylethyl) ester quaternary ammonium bromide with a solid content of 10%.

[0101] 3○ Drop several solutions onto a glass slide, cover it completely, dry it at 50°C, and then measure the water contact angle using a contact angle measuring instrument.

[0102] The branched fluoroalkyl quaternary ammonium salt antibacterial agent prepared in the above examples and the comparative example were tested under the same conditions, and the results are as follows:

[0103] Product Name Contact angle (water) ° Contact angle (oil) ° Antibacterial rate (%) Comparative Example 1 145.9 87.2 95.3 Comparative Example 2 104.4 82.2 44.8 Example 1 145.5 95.4 99.5 Example 2 142.3 94.2 98.6 Example 3 141.9 82 97.7 .

[0104] In terms of antibacterial rate, the branched fluoroalkyl quaternary ammonium salt antibacterial agent of the present invention has a stronger bactericidal effect than the long-chain linear fluoroalkyl quaternary ammonium salt antibacterial agent of Comparative Example 1. As can be seen from Comparative Example 2, if the side chain is too short, even if there are multiple branches, it is impossible to form a specific fluorine accumulation to effectively improve the antibacterial and hydrophobic and oleophobic properties. Compared with Comparative Example 1, the hydrophobic and oleophobic properties of the branched fluoroalkyl quaternary ammonium salt of the present invention are close to or even exceed those of Comparative Example 1.

[0105] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

Claims

1. A branched fluoroalkyl short chain quaternary ammonium salt antimicrobial agent characterized in that, The branched fluoralkyl short-chain quaternary ammonium salt antibacterial agent is a compound as shown in formula I: In the formula, R is -CH3 or -CH2CH3, X is Cl or Br, n is 1 or 2, and m is a natural number of 1-4.

2. The method of preparing branched fluoroalkyl short-chain quaternary ammonium salt antimicrobial agent according to claim 1, wherein, The branched fluoralkyl quaternary ammonium salt antibacterial agent of formula I is obtained by quaternary ammonization of a halogenated alkyl trialkoxysilane and a fluoralkyl tertiary amine, and the process flow is as follows: 。 3. The production method according to claim 2, characterized by, The fluoralkyl tertiary amine is selected from one of perfluorotripropylamine, perfluorotributylamine, perfluorotripentylamine and perfluorotrihexylamine.

4. The production method according to claim 2, characterized by, The halogenated alkyl trialkoxysilane is selected from one of chloromethyltrimethoxysilane, chloroethyltrimethoxysilane, chloropropyltrimethoxysilane, chloromethyltriethoxysilane, chloroethyltriethoxysilane, chloropropyltriethoxysilane, bromomethyltrimethoxysilane, bromoethyltrimethoxysilane, bromopropyltrimethoxysilane, bromomethyltriethoxysilane, bromoethyltriethoxysilane and bromopropyltriethoxysilane.

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