Benzoxazine-siloxane polymer as well as preparation method and application thereof

Abstract

The invention discloses a benzoxazine-siloxane polymer and a preparation method and application thereof.The preparation method comprises the following steps that S1, a phenolic compound, an aldehyde compound and secondary amine containing a maleimide group are mixed and subjected to a Mannich reaction, and a maleimide functionalized benzoxazine monomer is prepared; and S2, carrying out a Diels-Alder addition reaction on the maleimide functionalized benzoxazine monomer and furan modified polysiloxane, so as to obtain the benzoxazine-siloxane polymer, wherein the maleimide functionalized benzoxazine monomer and the furan modified polysiloxane are subjected to the Diels-Alder addition reaction, so that the benzoxazine-siloxane polymer is obtained. The molecule of the phenolic compound in the step S1 contains two phenolic hydroxyl groups; in the step S2, the mass ratio of the maleimide functionalized benzoxazine monomer to the furan modified polysiloxane is 1 to (1 to 2). A coating finally prepared from the benzoxazine-siloxane polymer has good mechanical strength and toughness, and meanwhile, the coating can realize controllable thermal repair through dissociation and recombination of Diels-Alder dynamic bonds.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a benzoxazine-siloxane polymer and a preparation method and application thereof. Background Art

[0002] In various situations in modern industrial production, metals and semiconductor materials are inevitably often exposed to corrosive environments such as moisture, high salt, and chemical media, which greatly shortens the life of equipment and increases maintenance costs. For example, electronic devices are also easily corroded by salt spray, water vapor, etc. during actual use, and there may also be risks of short circuit leakage, which can seriously cause circuit failure. Coating protection technology has become a core means to extend the life of materials by physically isolating corrosive media and actively functionalizing the design. However, since the coating is usually thin, when its mechanical strength or toughness is poor, it is easy to break or even fall off when subjected to external forces such as collision and friction. Therefore, in order to ensure the durability of the coating, its mechanical strength and toughness must be taken into account.

[0003] Benzoxazine resins are considered ideal substrate materials for electronic packaging and anti-corrosion coatings due to their excellent high-temperature resistance, low dielectric constant, and molecular designability. However, conventional benzoxazine resins face three major bottlenecks: First, curing requires high temperatures (typically >180°C), making them unsuitable for use on heat-sensitive substrates such as flexible circuit boards and biomedical materials. Second, cured benzoxazine resins are brittle, lack toughness, and are prone to breakage. Third, the crosslinking network of conventional benzoxazine resins is based on static covalent bonds, lacking self-healing ability upon damage. Consequently, long-term performance degradation is easily caused by the accumulation of microcracks.

[0004] To circumvent the drawbacks of high-temperature curing and the coating's lack of toughness, existing technologies have proposed the use of photocurable silicone coatings (such as a photocurable organopolysiloxane composition). These coatings can rapidly cure under light at room temperature and exhibit good toughness. However, the crosslinking network of photocurable silicone coatings is still composed of static covalent bonds (such as siloxane condensation bonds), which cannot be repaired if damaged. Furthermore, photocurable silicone coatings have low mechanical strength, making them difficult to meet the requirements of high-load scenarios.

[0005] Dynamic covalent bonds are used in self-healing materials, but existing dynamic bond systems (such as disulfide bonds and thiol-ene systems) have poor compatibility with photocurable resins. Furthermore, disulfide bonds have poor oxidation resistance and are prone to breakage in humid or high-temperature environments. Thiol-ene systems have slow cure rates (>10 minutes) and residual thiol odors that hinder their application. Summary of the Invention

[0006] In order to solve the problem that existing coatings have difficulty in achieving both toughness and mechanical strength, lack self-repairing ability or have poor compatibility with existing dynamic bond systems, the present invention provides a method for preparing a benzoxazine-siloxane polymer. The coating made from the benzoxazine-siloxane polymer obtained by this preparation method has controllable self-repairing ability, can be photocured, and has both mechanical strength and toughness, thereby ensuring the durability of the coating.

[0007] Another object of the present invention is to provide a benzoxazine-siloxane polymer.

[0008] Another object of the present invention is to provide use of the benzoxazine-siloxane polymer in preparing coatings.

[0009] Another object of the present invention is to provide a coating comprising the benzoxazine-siloxane polymer.

[0010] Another object of the present invention is to provide a method for using the above-mentioned coating.

[0011] Another object of the present invention is to provide application of the above coating in the field of electronic packaging or material corrosion protection.

[0012] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A method for preparing a benzoxazine-siloxane polymer comprises the following steps: S1, mixing a phenolic compound, an aldehyde compound, and a secondary amine containing a maleimide group, and performing a Mannich reaction to prepare a maleimide-functionalized benzoxazine monomer; S2, performing a Diels-Alder addition reaction between the maleimide-functionalized benzoxazine monomer and the furan-modified polysiloxane to obtain the benzoxazine-siloxane polymer; The phenolic compound in step S1 contains two phenolic hydroxyl groups; In step S2, the mass ratio of the maleimide-functionalized benzoxazine monomer to the furan-modified polysiloxane is 1:(1-2).

[0013] Among them, it should be noted that: In step S1, a phenolic compound, an aldehyde compound, and a secondary amine containing a maleimide group are used as raw materials. Through the Mannich reaction, an intramolecular ring closure is generated to form a benzoxazine structure, and a maleimide group is introduced into the benzoxazine skeleton as an acceptor unit of the Diels-Alder dynamic bond.

[0014] In step S2, the pendant furan groups of the furan-modified polysiloxane serve as Diels-Alder dynamic bond donors, which undergo a Diels-Alder addition reaction with a maleimide-functionalized benzoxazine monomer. The resulting benzoxazine-siloxane polymer contains abundant Diels-Alder dynamic bonds, which are key to achieving controllable thermally triggered self-healing of the coating. These dynamic bonds are based on the following reversible reaction, enabling thermally triggered self-healing of damage.

[0015]

[0016] The benzoxazine-siloxane polymer of the present invention, when mixed with a conventional photocurable polysiloxane to form a coating, can be photocured and post-cured to form a coating that combines excellent mechanical strength and toughness. The principle is as follows: a maleimide-functionalized benzoxazine monomer undergoes a Diels-Alder addition reaction with a furan-modified polysiloxane to form a first polymer network, the benzoxazine-siloxane polymer. This is then mixed with a conventional photocurable polysiloxane and, after photocuring and post-curing, forms a semi-interpenetrating network, resulting in a coating with excellent tensile strength. The benzoxazine structure in the maleimide-functionalized benzoxazine monomer is crucial. It not only imparts a certain degree of rigidity to the coating, thereby enhancing its tensile strength, but also increases the Diels-Alder bond dissociation temperature to 120-140°C (compared to approximately 70-100°C in conventional systems). This extends the temperature range for post-curing (60-80°C) and self-healing, preventing Diels-Alder bond dissociation during the coating's post-curing process and ensuring the coating's tensile strength.

[0017] The mass ratio of maleimide-functionalized benzoxazine monomer to furan-modified polysiloxane is also critical. If the amount of maleimide-functionalized benzoxazine monomer is too low, the coating's tensile strength will be poor. However, if the amount of maleimide-functionalized benzoxazine monomer is too high, excessive entanglement within the benzoxazine-siloxane polymer chains will occur, leading to uneven crosslinking and hindering the formation of a semi-interpenetrating network. This hinders chain slippage, resulting in poor tensile strength and significantly reduced coating toughness.

[0018] It should be understood that the furan-modified polysiloxane in step S2 refers to a polymer having polysiloxane as the main chain and furan groups as side groups.

[0019] Preferably, the phenolic compound in step S1 is bisphenol A.

[0020] Preferably, the aldehyde compound in step S1 is at least one of paraformaldehyde or formaldehyde.

[0021] More preferably, the paraformaldehyde is at least one of trioxymethylene or polyoxymethylene.

[0022] More preferably, the number average molecular weight (Mn) of the polyoxymethylene is 3000-5000.

[0023] Preferably, the secondary amine containing a maleimide group in step S1 is at least one of N-(4-aminophenyl)maleimide and N-(3-aminopropyl)maleimide.

[0024] Preferably, in step S1, the molar ratio of the phenolic hydroxyl group of the phenolic compound, the secondary amine group of the secondary amine containing a maleimide group, and the aldehyde group of the aldehyde compound is 2:(2-2.4):(2-2.5).

[0025] Preferably, the mass ratio of the phenolic compound, the secondary amine containing a maleimide group, and the aldehyde compound in step S1 is (2-2.5):(4-4.5):(85-90).

[0026] Preferably, the Mannich reaction in step S1 is carried out in an organic solvent.

[0027] More preferably, the organic solvent in step S1 is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and toluene.

[0028] Preferably, the temperature of the Mannich reaction in step S1 is 100-120° C., and the time is 6-8 hours.

[0029] Preferably, after the Mannich reaction in step S1, the process further comprises washing the product, distilling under reduced pressure, recrystallizing, and filtering the product.

[0030] More preferably, the washing step is to first wash with an alkaline solution and then wash away the alkaline solution with deionized water.

[0031] More preferably, the solvent in the recrystallization step is an ethanol / water mixed solvent.

[0032] Preferably, the number average molecular weight of the furan-modified polysiloxane in step S2 is 4000-8000.

[0033] Preferably, the furan-modified polysiloxane in step S2 is prepared by the following method: dissolving a siloxane compound having a furan group in an organic solvent and performing a dehydration condensation reaction.

[0034] More preferably, the siloxane compound having a furan group is 2-(trimethylsilyloxy)furan.

[0035] More preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and toluene.

[0036] More preferably, the dehydration condensation reaction is carried out at a temperature of 80-120° C. and for a time of 4-6 h.

[0037] More preferably, the dehydration condensation reaction is catalyzed by a basic catalyst.

[0038] More preferably, the alkaline catalyst is one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate, and tetramethylammonium hydroxide.

[0039] Further preferably, the amount of the alkaline catalyst used is 0.1-0.8 wt % of the total mass of the maleimide-functionalized benzoxazine monomer and the furan-modified polysiloxane.

[0040] More preferably, after the dehydration condensation reaction, the process further comprises filtering the product and distilling it under reduced pressure.

[0041] Preferably, the mass ratio of the maleimide-functionalized benzoxazine monomer to the furan-modified polysiloxane in step S2 is 1:(1.1-1.6).

[0042] By controlling the mass ratio of the maleimide-functionalized benzoxazine monomer to the furan-modified polysiloxane within this range, the yield of the benzoxazine-siloxane polymer is higher, and the tensile strength and flexibility of the ultimately formed coating can be improved.

[0043] Preferably, the Diels-Alder addition reaction in step S2 is carried out in an organic solvent system under the protection of a nitrogen atmosphere.

[0044] More preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and toluene.

[0045] Preferably, the Diels-Alder addition reaction in step S2 is catalyzed by a basic catalyst.

[0046] More preferably, the alkaline catalyst is one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate, and tetramethylammonium hydroxide.

[0047] More preferably, the amount of the alkaline catalyst is 0.5-0.75% of the total mass of the maleimide-functionalized benzoxazine monomer and the furan-modified polysiloxane.

[0048] Preferably, the reaction temperature of the Diels-Alder addition reaction in step S2 is 100-120° C., and the reaction time is 12-20 h.

[0049] Preferably, after the Diels-Alder addition reaction in step S2, the process further includes the steps of precipitating and drying the product.

[0050] More preferably, the precipitant used in the precipitation is one or more of water, acetone, anhydrous methanol, ethyl ether, n-pentane, butyl ether, and anhydrous ethanol.

[0051] More preferably, the volume ratio of the precipitant used in the precipitation to the reaction solvent is (2-50):1.

[0052] The present invention also protects a benzoxazine-siloxane polymer prepared by the above preparation method.

[0053] The present invention also protects a use of the benzoxazine-siloxane polymer in preparing coatings.

[0054] The present invention also protects a coating comprising the following components in parts by weight: 50 parts of the above-mentioned benzoxazine-siloxane polymer, 5~30 parts of light-curing polysiloxane, 0.5~4 parts of photoinitiator.

[0055] Preferably, the coating further comprises 40 to 60 parts of an organic solvent.

[0056] More preferably, the organic solvent is tetrahydrofuran.

[0057] Preferably, the photocurable polysiloxane is a methacrylate-terminated polysiloxane, such as Momentive UV 9300 or HMS-082.

[0058] More preferably, the molecular weight of the methacrylate-terminated polysiloxane is 3000-7000.

[0059] Preferably, the photoinitiator in step S4 is (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoylphosphonate or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0060] The present invention also protects a method for using the above-mentioned coating, comprising the following steps: The coating is applied to the surface of an object and light-cured; and then post-cured to form a coating.

[0061] The benzoxazine-siloxane polymer is further combined with a photocurable component (e.g., methacrylate-terminated polysiloxane), which is first photocured and then post-cured to form a semi-interpenetrating network (IPN) structure, giving the coating the ability to photocure while ensuring the mechanical strength and toughness of the coating.

[0062] Preferably, the light used for the light curing is visible light, and the time is 3 to 5 minutes.

[0063] Preferably, the post-curing temperature is 60-80° C. and the time is 60-180 min.

[0064] A method for repairing a coating, comprising baking the coating at 120-140° C. for 20-40 minutes; the coating is formed from the above-mentioned coating.

[0065] Preferably, in the method for using the coating, the thermal repair method of the coating is to bake at 120-140° C. for 20-40 minutes.

[0066] The present invention also protects the application of the coating in the field of electronic packaging or material corrosion protection.

[0067] Compared with the prior art, the present invention has the following beneficial effects: The benzoxazine-siloxane polymer of the present invention is mixed with existing common photocurable silicone to form a coating, which can be formed through photocuring and post-curing. The coating has good mechanical strength and toughness. At the same time, the coating can achieve controllable thermal repair through the dissociation and recombination of Diels-Alder dynamic bonds, which makes the coating have great utilization value in the industrial field. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 Schematic diagram of the reaction expression of step (1) in Example 1.

[0069] Figure 2 Schematic diagram of the reaction expression of step (2) in Example 1.

[0070] Figure 3 Schematic diagram of the reaction expression of step (3) in Example 1.

[0071] Figure 4 This is the infrared spectrum (FTIR) of the maleimide-functionalized benzoxazine monomer prepared in Example 1.

[0072] Figure 5 This is the gel permeation chromatography (GPC) chart of the furan-modified polysiloxane prepared in Example 1.

[0073] Figure 6 This is a dynamic mechanical analysis (DMA) characterization diagram of the coating formed by the coating in Example 1.

[0074] Figure 7 Schematic diagram of the tensile strength of the coating formed by the coating in Example 1 in the intact and damaged repaired states. DETAILED DESCRIPTION

[0075] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0076] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0077] Example 1 This embodiment provides a benzoxazine-siloxane polymer and a coating prepared therefrom. The preparation method of the benzoxazine-siloxane polymer comprises the following steps: (1) Preparation of maleimide-functionalized benzoxazine monomer: 228g of bisphenol A (BPA) and 413.6g of N-(4-aminophenyl)maleimide (APMI) were dissolved in 2000ml of toluene solution, and 8800g of paraformaldehyde powder with an average molecular weight of 4000 was slowly added and stirred until completely dissolved. The mixture was heated to 110°C and refluxed for 6 hours. The generated water was removed through a water separator. The reaction solution was cooled to room temperature, and the filtrate was washed 3 times with 5% NaOH solution (to remove residual APMI), and then washed with deionized water until neutral. The toluene was removed by vacuum distillation to obtain a viscous liquid; the product was recrystallized from a mixed solvent of ethanol / water (volume ratio 1:1) to obtain a preliminary product. After the reaction was completed, the mixture was cooled to room temperature, and the unreacted paraformaldehyde was removed by filtration. The white crystals obtained were the maleimide-functionalized benzoxazine monomer. The reaction expression of this step is as follows: Figure 1 shown.

[0078] (2) Preparation of furan-modified polysiloxane: 200 g of 2-(trimethylsilyloxy)furan was dissolved in 200 mL of toluene. Under nitrogen protection, an alkaline catalyst (tetramethylammonium hydroxide or tetrabutylammonium hydroxide) at a concentration of 0.4% by mass of 2-(trimethylsilyloxy)furan was added. The reaction was controlled at 90°C for 5 h. After the reaction, the reaction solution was filtered through a neutral alumina column to remove the catalyst. The toluene was removed by vacuum distillation. The light yellow viscous liquid obtained was the furan-modified polysiloxane. The reaction expression of this step is as follows: Figure 2 shown.

[0079] (3) Preparation of benzoxazine-siloxane polymer: 100 g of maleimide-functionalized benzoxazine monomer and 150 g of furan-modified polysiloxane were dissolved in a mixed solution of DMF and toluene (volume ratio of 1:1), and tetramethylammonium hydroxide catalyst was added (the amount was 0.6% of the total mass of maleimide-functionalized benzoxazine monomer and furan-modified polysiloxane). The temperature was raised to 115 °C under nitrogen protection and the reaction was carried out for 16 h. The reaction solution was poured into 5 times the volume of anhydrous ethanol for precipitation. After filtration, the solution was vacuum-dried at 60 °C for 24 h. The obtained white solid was the benzoxazine-siloxane polymer.

[0080] The coating of this example comprises the following components: 50 g of benzoxazine-siloxane polymer, 25 g of methacrylate-terminated polysiloxane (Mn=5000) (brand: HMS-082), 3.6 g of TPO photoinitiator, and 50 g of tetrahydrofuran. The coating of this example is prepared by stirring and mixing the above ingredients at room temperature in the dark.

[0081] Example 2 This embodiment provides a benzoxazine-siloxane polymer and a coating prepared therefrom, which differs from Example 1 in that: in step (3), the amount of furan-modified polysiloxane used is 120 g.

[0082] Example 3 This embodiment provides a benzoxazine-siloxane polymer and a coating prepared therefrom, which differs from Example 1 in that: in step (3), the amount of furan-modified polysiloxane used is 200 g.

[0083] Comparative Example 1 This embodiment provides a benzoxazine-siloxane polymer and a coating prepared therefrom, which differs from Example 1 in that: in step (3), the amount of maleimide-functionalized benzoxazine monomer used is 150 g, and the amount of furan-modified polysiloxane used is 100 g.

[0084] Comparative Example 2 This comparative example provides a coating comprising the following components: 25 g of methacrylate-terminated polysiloxane (Mn=5000) (brand: HMS-082), a TPO photoinitiator (amount: 2.1 g), and 50 g of tetrahydrofuran.

[0085] Sample characterization and performance testing Figure 4 The infrared spectrum characterization results of the maleimide functionalized benzoxazine monomers in Examples 1 to 3 and Comparative Example 1 are shown. -1 and 1230 cm -1 The two characteristic peaks represent the C=O double bond of maleimide and the COC structure in the oxazine ring, respectively, which means that the benzoxazine monomer was successfully synthesized and the maleimide group was successfully integrated into benzoxazine.

[0086] Figure 5 Gel permeation chromatography molecular weight characterization results for the furan-modified polysiloxanes used in Examples 1-3 and Comparative Example 1. The furan-modified polysiloxane samples measured had a number average molecular weight (Mn) of 6584, a mass average molecular weight (Mw) of 10680, a Z-average molecular weight (Mz) of 17817, and a distribution index (PDI) of 1.62. This indicates that 2-(trimethylsilyloxy)furan successfully formed a furan-modified polysiloxane in polymer form.

[0087] The coatings of Examples 1 to 3 were applied to the surface of a steel plate (thickness 0.3-0.5 mm), cured at room temperature for 4 minutes under a 465 nm LED light source, and then baked at 70° C. for 1 hour for post-curing to form a coating.

[0088] Figure 6 This is a dynamic mechanical analysis (DMA) characterization of the coating formed from Example 1. The graph shows two Tg peaks. The glass transition temperature peak at 100.15°C indicates the benzoxazine-siloxane polymer component, which has a higher glass transition temperature due to its significant steric hindrance. The glass transition temperature peak at -9.7°C indicates the polysiloxane component, which has a lower glass transition temperature due to its softness.

[0089] The yields of the benzoxazine-siloxane polymers of Examples 1 to 3 and Comparative Example 1 were calculated according to the following formula. The yields of the benzoxazine-siloxane polymers of the Examples and Comparative Examples are shown in Table 1.

[0090]

[0091] Among them, m 马来酰亚胺功能化苯并噁嗪单体 、m 呋喃改性聚硅氧烷 、m 苯并噁嗪-硅氧烷聚合物 is the mass of maleimide-functionalized benzoxazine monomer, furan-modified polysiloxane, and benzoxazine-siloxane polymer.

[0092] The coatings obtained from the coatings of Examples 1 to 3 and Comparative Examples 1 to 2 were cooled to room temperature and then cut into dumbbell shapes. The mechanical properties thereof were measured. The specific data are shown in Table 1.

[0093] Table 1 Comparison of polymer yield, coating tensile strength and elongation displacement of Examples 1-3 and Comparative Examples 1-2

[0094] As shown in the table, Example 1 exhibits the highest yield for the benzoxazine-siloxane polymer, while Comparative Example 1 exhibits the lowest yield. This is because a slight excess of furan groups ensures that the maleimide participates in the reaction as fully as possible, minimizing side reactions and increasing yield. However, the excessive amount of maleimide in Comparative Example 1 prevents some maleimide from participating in the reaction (due to insufficient furan groups), resulting in unreacted free end groups and lowering yield. Furthermore, excessive rigid benzoxazine groups may cause excessive entanglement within the molecular chain, hindering the polycondensation reaction and reducing yield.

[0095] The coatings formed by the coatings made from the benzoxazine-siloxane polymers of Examples 1 to 3 all had tensile strengths exceeding 35 MPa, and elongation displacements exceeding 3.9 mm, indicating that the coatings formed by the coatings made from the benzoxazine-siloxane polymers of the present invention had good tensile strength and maintained good toughness.

[0096] In Comparative Example 1, the mass ratio of the maleimide-functionalized benzoxazine monomer to the furan-modified polysiloxane was not controlled within a certain range, resulting in significantly poor coating flexibility. In Comparative Example 2, which did not incorporate the benzoxazine-siloxane polymer, the coating exhibited excessive flexibility but significantly poor tensile strength, resulting in an unbalanced coating performance.

[0097] The coating obtained from the coating of Example 1 was tested for repair performance. The coating was cut into a dumbbell shape, and a 5 mm long and 30-50 μm deep scratch was made on the coating surface with a blade. The coating was placed in a 130°C oven for 30 minutes. After cooling, the mechanical properties of the repaired coating were tested. The tensile strength recovery rate after repair reached 92%. Figure 7 The tensile strength before damage was 40.48 MPa, and the tensile strength after repair was 37.47 MPa. This indicates that the coating has good thermally triggered self-healing properties. The repair performance test results of other examples are similar to those of Example 1.

[0098] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a benzoxazine-siloxane polymer, characterized in that: The following steps are involved: S1, mixing a phenolic compound, an aldehyde compound, and a secondary amine containing a maleimide group, and performing a Mannich reaction to prepare a maleimide-functionalized benzoxazine monomer; S2, performing a Diels-Alder addition reaction between the maleimide-functionalized benzoxazine monomer and the furan-modified polysiloxane to obtain the benzoxazine-siloxane polymer; The phenolic compound in step S1 contains two phenolic hydroxyl groups; In step S2, the mass ratio of the maleimide-functionalized benzoxazine monomer to the furan-modified polysiloxane is 1:(1-2).

2. The preparation method according to claim 1, characterized in that In step S1, the molar ratio of the phenolic hydroxyl group of the phenolic compound, the secondary amine group of the secondary amine containing a maleimide group, and the aldehyde group of the aldehyde compound is 2:(2-2.4):(2-2.5).

3. The preparation method according to claim 1, characterized in that: The reaction temperature of the Diels-Alder addition reaction in step S2 is 100-120° C., and the reaction time is 12-20 h.

4. A benzoxazine-siloxane polymer, characterized in that Prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the benzoxazine-siloxane polymer according to claim 4 in the preparation of coatings.

6. A coating, characterized in that: The composition comprises the following components in parts by weight: 50 parts of the benzoxazine-siloxane polymer according to claim 4, 5~30 parts of light-curing polysiloxane, 0.5~4 parts of photoinitiator.

7. The coating according to claim 6, characterized in that: The photocurable polysiloxane is a methacrylate-terminated polysiloxane.

8. The coating according to claim 6, characterized in that: The photoinitiator is (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl ethyl phosphonate or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

9. A method for using a coating, characterized in that: The coating according to any one of claims 6 to 8 is subjected to light curing; and then post-curing to form a coating.

10. Use of the coating according to claims 6 to 8 in the field of electronic packaging or material corrosion protection.

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