Screening method of benzoxazine antibacterial agent based on electronic conjugation effect regulation and application thereof

Abstract

This invention discloses a screening method for benzoxazine antibacterial agents based on electronic conjugation effects and its application, belonging to the field of antibacterial materials technology. The method includes: obtaining the molecular electrostatic potential distribution and frontier molecular orbital energy levels of benzoxazine compounds through density functional theory calculations; analyzing their electronic effect characteristics based on the calculation results; and screening target antibacterial agents based on the correlation between electronic effect characteristics and antibacterial activity. The benzoxazine is prepared by a Mannich condensation reaction of polyphenolic compounds, furfurylamine, and paraformaldehyde. The polyphenolic compounds are selected from phenol, resorcinol, or phloroglucinol, corresponding to the synthesis of monofunctional, difunctional, or trifunctional benzoxazine monomers, respectively. The benzoxazine compounds obtained by the screening method of this invention can be used to prepare antibacterial polyolefin materials. The prepared modified polyolefin composite materials exhibit excellent antibacterial stability and enhanced mechanical properties. This method overcomes the shortcomings of traditional antibacterial agent screening that relies on empirical trial and error, revealing the intrinsic correlation between LUMO shift caused by benzene ring electronic conjugation and reduced antibacterial activity, providing a new approach for the molecular design of benzoxazine antibacterial agents.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial materials technology, specifically relating to a screening method for benzoxazine antibacterial agents based on electronic conjugation effect regulation, and the application of benzoxazine compounds screened by this method in the preparation of antibacterial polyolefin materials. Background Technology

[0002] With the increasingly severe global situation of bacterial contamination, bacterial infection has become a common challenge in many fields, seriously threatening human health. Therefore, the development of novel and highly efficient antibacterial materials is of great significance. Benzoxazines are a class of N- and O-containing heterocyclic compounds synthesized from phenolic compounds, primary amine compounds, and formaldehyde via the Mannich condensation reaction. Due to the wide availability of raw materials and the high designability of molecular structures, polybenzoxazines have been widely used in thermosetting resins, electronic packaging materials, and other fields. In recent years, the development of the antibacterial properties of benzoxazines has gradually attracted attention.

[0003] Current research on the antibacterial properties of benzoxazines largely focuses on utilizing their molecular designability to introduce functional groups with known antibacterial activities into their structures. For example, polyphenols with natural antibacterial activities (such as chitosan, curcumin, and eugenol) are often used as phenolic sources to synthesize antibacterial benzoxazine monomers. Primary amine compounds containing long alkyl chains have also received widespread attention in the molecular design of antibacterial benzoxazines because their lipophilic alkyl chains can penetrate and disrupt bacterial cell walls through hydrophobic interactions.

[0004] However, the above-mentioned studies generally suffer from the following technical shortcomings: First, the screening of antibacterial agents relies on empirical trial and error, lacking theoretical guidance. In current technologies, the development of benzoxazine antibacterial agents mainly depends on the introduction and combination of known antibacterial functional groups, screening for effective structures through repeated experimental trial and error. This traditional approach is inefficient, costly, and makes it difficult to reveal the intrinsic relationship between molecular structure and its antibacterial activity, resulting in significant blind spots in molecular design.

[0005] Second, the influence of the benzoxazine's own structure on its antibacterial activity remains unclear. Existing studies mainly focus on the antibacterial contribution of introduced functional groups (such as polyphenol structures and long alkyl chains), while neglecting the influence of the oxazine ring in the core structure of benzoxazine and the overall molecular configuration on antibacterial activity. The effects of factors such as the number, spatial arrangement, and molecular symmetry of the oxazine ring on antibacterial properties lack systematic research.

[0006] Third, there is a lack of molecular-level antibacterial agent screening methods. Currently, there is no method in the technology to reveal the intrinsic relationship between the molecular configuration and antibacterial activity of benzoxazine through theoretical calculations. This invention is the first to discover that when multiple oxazine rings in a benzoxazine molecule are in adjacent positions on the benzene ring, adjacent electron-withdrawing groups form a trans-benzene ring electron-withdrawing conjugated structure, leading to a partial transfer of LUMO to the furan ring, thereby reducing antibacterial activity.

[0007] Therefore, developing a theoretical calculation-based screening method for benzoxazine antibacterial agents, revealing the intrinsic relationship between benzoxazine molecular configuration and antibacterial activity, and establishing a clear screening index system are of great significance for the efficient screening and rational design of novel benzoxazine antibacterial agents. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies in screening benzoxazine antibacterial agents, which rely on empirical trial and error and lack theoretical guidance. It provides a screening method for benzoxazine antibacterial agents based on the regulation of electronic conjugation effects and its applications. This method uses density functional theory calculations to reveal, at the molecular level, the intrinsic correlation between LUMO shift caused by electronic conjugation of the benzene ring in the benzoxazine molecule and its antibacterial activity, providing a theoretical basis for the molecular design of antibacterial agents.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A method for screening benzoxazine antibacterial agents based on electron conjugation effect regulation and its application, characterized by comprising the following steps: S1: Construct molecular models of benzoxazine compounds to be screened, wherein the benzoxazine compounds are prepared by Mannich condensation reaction of phenolic compounds, amine compounds and paraformaldehyde; S2: Obtain the molecular electrostatic potential distribution and frontier molecular orbital energy levels of the benzoxazine compound through density functional theory calculations; S3: Determine whether there is a trans-benzene ring electron-withdrawing conjugation effect between electron-withdrawing groups on adjacent oxazine rings in the benzoxazine compound; S4: If the trans-benzene ring electron-withdrawing conjugation effect does not exist, and the lowest unoccupied molecular orbital (LUMO) is mainly distributed on the benzene ring and the oxazine ring, then the benzoxazine compound is selected as a candidate antibacterial agent; if the trans-benzene ring electron-withdrawing conjugation effect exists, and the lowest unoccupied molecular orbital is partially transferred to the electron-withdrawing group, then the benzoxazine compound is excluded.

[0010] Furthermore, the phenolic compound in step S1 is selected from phenol, resorcinol, or phloroglucinol, and reacts to obtain monofunctional, difunctional, or trifunctional benzoxazine monomers, respectively; the amine compound is furfurylamine.

[0011] Furthermore, the electron-withdrawing group on the adjacent oxazine rings in step S3 is a furan ring; the trans-benzene ring electron-withdrawing conjugation effect refers to the fact that when two or three oxazine rings are in adjacent positions on the benzene ring, the adjacent furan rings withdraw electrons from each other, forming an electron-withdrawing conjugation structure across the benzene ring.

[0012] Furthermore, the criterion for determining that the lowest unoccupied molecular orbitals (LUMOs) in step S4 are mainly distributed on the benzene ring and the oxazine ring is that the distribution ratio of the LUMO electron cloud density calculated by density functional theory on the benzene ring and the oxazine ring is greater than the distribution ratio on the furan ring.

[0013] This invention also protects the use of benzoxazine compounds obtained by the above screening method in the preparation of antibacterial polyolefin materials.

[0014] Furthermore, the antibacterial polyolefin material is prepared by melt blending benzoxazine compound with polyolefin, with a processing temperature of 150~200 ℃ and a processing time of 1~10 min.

[0015] Furthermore, the amount of the benzoxazine compound added is 0.1 to 10 wt% of the polyolefin mass.

[0016] The present invention also protects antimicrobial polyolefin materials prepared by the above applications.

[0017] Furthermore, the antibacterial polyolefin material possesses antibacterial stability and enhanced mechanical properties, making it suitable for applications in medical devices, food packaging, home building materials, and marine antifouling.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is the first to discover that when multiple oxazine rings in a benzoxazine molecule are in adjacent positions on a benzene ring, adjacent furan rings mutually withdraw electrons to form an electron-withdrawing conjugated structure across the benzene ring, leading to a partial transfer of LUMO to the furan ring, thereby reducing or eliminating antibacterial activity. This discovery provides entirely new theoretical guidance for the molecular design of benzoxazine antibacterial agents.

[0019] 2. Based on the above findings, this invention establishes a clear screening index: if there is no trans-benzene ring electron-withdrawing conjugation effect and LUMO is mainly distributed on the benzene ring and oxazine ring, the compound has antibacterial activity; if this effect exists and LUMO is transferred to the electron-withdrawing group, the antibacterial activity is reduced or lost. This index system overcomes the blindness of traditional empirical trial-and-error methods.

[0020] 3. The benzoxazine compounds obtained by the screening method of this invention have been experimentally verified to have significant antibacterial activity against Escherichia coli and Staphylococcus aureus, thus verifying the accuracy and reliability of the screening method.

[0021] 4. The benzoxazine compounds obtained by the screening method of this invention can be used to prepare antibacterial polyolefin materials. These materials have both excellent antibacterial properties and enhanced mechanical properties, and can be widely used in medical devices, food packaging, home building materials and marine antifouling fields. Attached Figure Description

[0022] Figure 1 The following is a synthetic route diagram of the benzoxazine monomers synthesized in Examples 1-3 of the present invention, wherein (a) is monofunctional, (b) is difunctional (structure 1 is a linear structure and structure 2 is an ortho isomer), and (c) is trifunctional. Figure 2 The diagram shows the molecular electrostatic potential distribution of the benzoxazine monomers synthesized in Examples 1-3 of this invention, where (a) is monofunctional, (b) is difunctional, and (c) is trifunctional. Figure 3 The diagram shows the frontier molecular orbital energy level distribution of the benzoxazine monomers synthesized in Examples 1-3 of this invention, where (a)-(c) are the highest occupied orbitals (HOMO) and (a')-(c') are the lowest unoccupied molecular orbitals (LUMO), corresponding to monofunctionality, difunctionality and trifunctionality, respectively. Figure 4 This is a comparison chart showing the antibacterial effects of antibacterial polyolefin materials prepared from benzoxazine compounds screened in this invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0024] I. Synthesis Examples Example 1: Synthesis of monofunctional benzoxazine (PH-f) Synthesis of phenol / furfurylamine type benzoxazine monomer: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, phenol (50 mmol, 4.71 g), furfurylamine (50 mmol, 4.86 g), and paraformaldehyde (100 mmol, 3.00 g) were added sequentially, followed by 40 mL of toluene / ethanol (3:1 v / v). The reaction system was heated to 100 °C and refluxed with stirring for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed several times with 1 wt% NaOH aqueous solution, and then washed with deionized water until neutral. After removing toluene using a rotary evaporator, the crude product was immediately poured into 20 mL of methanol and cooled overnight, precipitating white crystals, which were the target monofunctional benzoxazine monomer (structural formula see [link]). Figure 1 a), denoted as PH-f, yield 76.2%.

[0025] Example 2: Synthesis of a bifunctional benzoxazine (RE-f) Synthesis of resorcinol / furfurylamine type benzoxazine monomers: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, furfurylamine (40 mmol, 3.9 g), paraformaldehyde (80 mmol, 2.4 g), and 40 mL of toluene / ethanol (3:1 v / v) mixed solvent were added, and the mixture was heated to 80 °C and stirred for 2 h. Then, resorcinol (20 mmol, 2.2 g) was added, and the mixture was refluxed at 80 °C for another 6 h. After the reaction was complete, the mixture was added dropwise to 200 mL of n-hexane, precipitating a white solid. After filtration and vacuum drying, a white powder was obtained, which was a mixture of two bifunctional benzoxazine monomers (structural formulas are shown in [link to structural formula]). Figure 1 (b), denoted as RE-f, yield 82.4%. Further, utilizing the difference in solubility between the isomers, the two configurations were separated by recrystallization. Recrystallization was performed using ethyl acetate as the solvent. The linear molecule (structure 1), with its higher symmetry and ordered arrangement, was more likely to precipitate crystals; the ortho-isomer (structure 2), due to its slightly higher polarity and poorer symmetry, was more likely to remain in the solvent. Therefore, recrystallization yielded white crystals corresponding to the linear configuration.

[0026] Example 3: Synthesis of a trifunctional benzoxazine (PHL-f) Synthesis of pyrogallol / furfurylamine-type benzoxazine monomer: Furfurylamine (30 mmol, 2.91 g), paraformaldehyde (60 mmol, 1.8 g), and pyrogallol (10 mmol, 1.26 g) were dissolved in 10 mL, 10 mL, and 60 mL of dioxane, respectively. The paraformaldehyde solution was then added to a three-necked flask, and the mixture was stirred at room temperature while the furfurylamine solution was slowly added dropwise. After stirring for 30 min, the pyrogallol solution was added dropwise. After the addition was complete, the temperature was raised to 90 °C, and the mixture was stirred and refluxed for 8 h to obtain an orange-yellow suspension. After cooling to room temperature, 200 mL of petroleum ether was added, and the mixture was stirred for another 30 min. The clear supernatant was collected. The suspension was washed several times with 1 wt% NaOH solution, followed by washing with deionized water until neutral. Finally, ethanol was added dropwise to the aqueous solution, precipitating a white powder, which was the target trifunctional benzoxazine monomer (structural formula shown). Figure 1 c), denoted as PHL-f, yield 69.7%.

[0027] II. Theoretical Calculation and Analysis 1. Construction of molecular models Molecular models of monofunctional (PH-f), difunctional (RE-f), and trifunctional (PHL-f) benzoxazine monomers were established using Materials Studio software. These models included two different structures of the difunctional benzoxazine (the linear structure is structure 1, and the ortho-isomer is structure 2). Stable configurations were obtained after molecular structure optimization. The benzoxazine molecular structures are shown below. Figure 1 As shown.

[0028] 2. Calculation of molecular electrostatic potential Molecular electrostatic potentials of three benzoxazine monomers were calculated at the B3LYP / 6-31G(d) basis set level, and the results are as follows: Figure 2 As shown in the figure, the red area represents positive electrostatic potential, and the blue area represents negative electrostatic potential. The darker the red, the greater the positive electrostatic potential, and the darker the blue, the greater the negative electrostatic potential. The calculation results show that the benzoxazine molecule exhibits a positive electrostatic potential on its periphery, which is conducive to attracting the negatively charged bacterial cell membrane, allowing the benzoxazine molecule to attach to the bacterial surface.

[0029] 3. Frontier Molecular Orbital Energy Level Calculation At the same computational level, the frontier molecular orbital energy levels of the three benzoxazine monomers were calculated, and the results are as follows: Figure 3 As shown, the highest occupied molecular orbital (HOMO) represents the molecule's ability to donate electrons, while the lowest unoccupied molecular orbital (LUMO) reflects the molecule's ability to accept electrons.

[0030] 4. Correlation analysis between LUMO distribution and molecular configuration The frontier molecular orbital distribution reveals that for structure 1 (para structure) of monofunctional benzoxazine PH-f and difunctional benzoxazine RE-f, the LUMO is mainly located on the benzene and oxazine rings, representing the active sites that play a major role in bacterial inhibition. However, for structure 2 (ortho structure, with two oxazine rings adjacent to each other on the benzene ring) of RE-f and trifunctional benzoxazine PHL-f (all three oxazine rings adjacent to each other on the benzene ring), the LUMO shows significant migration, with the active site shifting towards the furan ring. The mechanism is analyzed as follows: Since the benzene ring is a typical aromatic system, its six carbon atoms form a closed conjugated system through alternating single and double bonds, allowing electrons to freely migrate and redistribute within the structure. When electron-withdrawing furan substituents are introduced at adjacent positions on the benzene ring, the adjacent furan rings mutually withdraw electrons, forming an electron-withdrawing conjugated structure across the benzene ring. Therefore, in the absence of an electric field, the LUMO in this conjugated system is more likely to form in the electron-withdrawing furan region, causing the LUMO to shift towards the furan ring.

[0031] 5. Establishment of screening indicators Based on the above calculations and analysis, the present invention establishes the following screening criteria: Screening criteria (antibacterial activity): When there is no trans-benzene ring electron-withdrawing conjugation effect between electron-withdrawing groups on adjacent oxazine rings in the benzoxazine molecule, and the lowest unoccupied molecular orbitals (LUMOs) are mainly distributed on the benzene ring and the oxazine ring, the compound has antibacterial activity.

[0032] Exclusion conditions (no antibacterial activity or extremely low activity): When there is a trans-benzene ring electron-withdrawing conjugation effect between electron-withdrawing groups on adjacent oxazine rings in the benzoxazine molecule, and LUMO is partially transferred to the electron-withdrawing group (furan ring), the antibacterial activity of the compound is reduced or lost.

[0033] III. Experimental Verification 1. Antibacterial Performance Test: The antibacterial properties of the monofunctional, difunctional, and trifunctional benzoxazine monomers synthesized in Examples 1-3, as well as the RE-f sample (a mixture of two configurations) before recrystallization in Example 2, were evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The test results are shown in Table 1. 2,3,5-Triphenyltetrazolium chloride was selected as a redox indicator to determine the presence of bacterial growth and reproduction, and the MIC test was performed using the two-fold dilution method.

[0034] Table 1. MIC and MBC results for Examples 1-3 (unit: μg / mL) To verify the effect of molecular configuration on antibacterial activity, the antibacterial properties of the RE-f configuration mixture (containing para structure 1 and ortho structure 2) before recrystallization and the pure RE-f structure 1 obtained after recrystallization in Example 2 were tested. The MIC of the monofunctional benzoxazine PH-f against Escherichia coli and Staphylococcus aureus was 625 μg / mL; the MIC of the bifunctional RE-f structure 1 (para structure) against E. coli and S. aureus were 156 μg / mL and 312 μg / mL, respectively; while the MIC of its configuration mixture (containing structure 2) against E. coli and S. aureus were 5000 μg / mL and 2500 μg / mL, respectively; the trifunctional PHL-f could not effectively inhibit the growth of E. coli in the detection range of 10000~1.25 μg / mL, and the MIC against S. aureus was 5000 μg / mL.

[0035] Based on the above experimental results, the order of antibacterial activity is: RE-f structure 1 (para position) > PH-f (monofunctional) > RE-f configuration mixture (including structure 2) > PHL-f (trifunctional). This indicates that the antibacterial activity of benzoxazine does not increase monotonically with the increase of the number of oxazine rings, but is closely related to the relative position of the oxazine rings on the benzene ring and the overall molecular configuration.

[0036] 2. Screening indicator verification: The monofunctional benzoxazine PH-f and bifunctional benzoxazine RE-f structures 1 (para structure): lacking trans-benzene ring electron-withdrawing conjugation effect, with LUMO mainly distributed on the benzene ring and oxazine ring, are predicted to have antibacterial activity.

[0037] Bifunctional RE-f configuration mixture (structure 1 and structure 2): Theoretical calculations show that structure 2 has an electron-withdrawing conjugation effect across the benzene ring, and the LUMO shifts to the furan ring, which predicts a significant decrease in activity.

[0038] Trifunctional benzoxazine PHL-f: If there is an electron-withdrawing conjugation effect across the benzene ring and the LUMO shifts towards the furan ring, then no antibacterial activity or very low activity is predicted.

[0039] As shown in Table 1, the MIC / MBC test results were in complete agreement with the above predictions: both PH-f and RE-f structures 1 showed significant antibacterial activity against E. coli and S. aureus. The activity of RE-f structure 1 was superior to that of PH-f, while the activity of the RE-f mixture containing structure 2 was significantly reduced. PHL-f had no inhibitory effect on E. coli in the detection range of 10000~1.25 μg / mL, and its MIC against S. aureus was as high as 5000 μg / mL, indicating extremely low activity.

[0040] This result fully verifies the accuracy and reliability of the screening method of the present invention.

[0041] IV. Application Examples Example 4: Preparation of antibacterial polyethylene material The monofunctional benzoxazine monomer (1 g), low-density polyethylene (100 g), and antioxidant (a 1:1 mass ratio of 1010 and 168, 0.2 g) prepared in Example 1 were mixed evenly in a high-speed mixer. The mixture was then melt-blended for 5 min at 160 °C and 100 rpm using a Haake torque rheometer. After discharging, cooling, and granulation, antibacterial polyethylene material was obtained.

[0042] Example 5: Preparation of antibacterial polypropylene material The monofunctional benzoxazine monomer (1 g), polypropylene (100 g), and antioxidant (a 1:1 mass mixture of 1010 and 168, 0.2 g) prepared in Example 1 were mixed evenly in a high-speed mixer. The mixture was then melt-blended for 5 min at 200 °C and 100 rpm using a Haake torque rheometer. After discharging, cooling, and granulation, an antibacterial polypropylene material was obtained.

[0043] V. Comparative Examples Comparative Example 1: Pure polyethylene Take 100 g of low-density polyethylene, add 0.2 g of antioxidant (a mixture of 1010 and 168 in a 1:1 mass ratio), and melt-blend at 160 ℃ and 100 rpm for 5 min as a blank control sample.

[0044] Comparative Example 2: Pure Polypropylene Take 100 g of polypropylene, add 0.2 g of antioxidant (a mixture of 1010 and 168 in a 1:1 mass ratio), and melt-blend at 200 ℃ and 100 rpm for 5 min as a blank control sample.

[0045] VI. Performance Testing 1. Antibacterial properties: such as Figure 4 The figure shows a comparison of the antibacterial effects of the antimicrobial polyolefin materials prepared in Examples 4 and 5 of this invention with those in Comparative Examples 1 and 2 against *E. coli* and *S. aureus*. It can be seen that the unmodified polyolefin samples exhibit dense colony growth on the agar plates, corresponding to their lack of antibacterial properties. The results show that the addition of 1.0 wt% PH-f endows the materials with excellent antibacterial capabilities, with the modified polyolefin samples showing antibacterial rates greater than 99.9% against both *E. coli* and *S. aureus*.

[0046] 2. Mechanical Properties: Table 2 shows the comparison of mechanical properties between the antibacterial polyethylene material prepared in Example 4 of this invention and the pure polyethylene in Comparative Example 1. According to GB / T 1040.2-2006, the samples from Example 4 and Comparative Example 1 were prepared into standard dumbbell-shaped specimens and subjected to tensile property testing on a universal testing machine. The average value of 5 specimens in each group was taken.

[0047] Table 2 Mechanical properties of samples from Comparative Example 1 and Example 4 The addition of monofunctional benzoxazine PH-f significantly improved the tensile strength and modulus of the composite material. This improvement is attributed to the rigidity and stability of the benzene ring, oxazine ring, and furan ring groups in the benzoxazine monomer, which enhance the tensile strength and modulus of the material. Furthermore, the micro-crosslinked structure of benzoxazine forms an interpenetrating network with the polyethylene molecular chains, enhancing the intermolecular interactions and thus improving the elongation at break of the material.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for screening benzoxazine antibacterial agents based on electron conjugation effect regulation, characterized in that, Includes the following steps: S1: Construct molecular models of benzoxazine compounds to be screened, wherein the benzoxazine compounds are prepared by Mannich condensation reaction of phenolic compounds, amine compounds and paraformaldehyde; S2: Obtain the molecular electrostatic potential distribution and frontier molecular orbital energy levels of the benzoxazine compound through density functional theory calculations; S3: Determine whether there is a trans-benzene ring electron-withdrawing conjugation effect between electron-withdrawing groups on adjacent oxazine rings in the benzoxazine compound; S4: If the trans-benzene ring electron-withdrawing conjugation effect does not exist, and the lowest unoccupied molecular orbital (LUMO) is mainly distributed on the benzene ring and the oxazine ring, then the benzoxazine compound is selected as a candidate antibacterial agent; if the trans-benzene ring electron-withdrawing conjugation effect exists, and the lowest unoccupied molecular orbital is partially transferred to the electron-withdrawing group, then the benzoxazine compound is excluded.

2. The screening method according to claim 1, characterized in that, The phenolic compound in step S1 is selected from phenol, resorcinol or phloroglucinol, and reacts to obtain monofunctional, difunctional or trifunctional benzoxazine monomers respectively; the amine compound is furfurylamine.

3. The screening method according to claim 1, characterized in that, In step S3, the electron-withdrawing group on the adjacent oxazine ring is a furan ring; the trans-benzene ring electron-withdrawing conjugation effect means that when two or three oxazine rings are in adjacent positions on the benzene ring, the adjacent furan rings withdraw electrons from each other, forming an electron-withdrawing conjugation structure across the benzene ring.

4. The screening method according to claim 1, characterized in that, The criterion for determining that the lowest unoccupied molecular orbitals (LUMOs) in step S4 are mainly distributed on the benzene ring and the oxazine ring is that the proportion of LUMO electron cloud density calculated by density functional theory on the benzene ring and the oxazine ring is greater than the proportion on the furan ring.

5. The use of benzoxazine compounds obtained by the screening method according to any one of claims 1-4 in the preparation of antibacterial polyolefin materials.

6. The application according to claim 4, characterized in that, The antibacterial polyolefin material is prepared by melt blending benzoxazine compound with polyolefin, with a processing temperature of 150~200 ℃ and a processing time of 1~10 min.

7. The application according to claim 5, characterized in that, The amount of the benzoxazine compound added is 0.1 to 10 wt% of the polyolefin mass.

8. The antibacterial polyolefin material prepared according to any one of claims 5-7.

9. The antibacterial polyolefin material according to claim 8, characterized in that, The antibacterial polyolefin material has antibacterial stability and enhanced mechanical properties, and is suitable for medical devices, food packaging, home building materials and marine antifouling applications.

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