Super-hydrophobic, ultraviolet-resistant and high-durability modified bamboo and preparation method thereof

Abstract

The application discloses a kind of super-hydrophobic, ultraviolet-resistant, high-durability modified bamboo and preparation method thereof, belong to biomass material modification technical field.Pretreated bamboo is dried;The dried bamboo is placed in PDA solution and soaked, then taken out and washed, dried to obtain bamboo with PDA coating on the surface;The bamboo with PDA coating on the surface is placed in silane composite modification liquid and soaked, then taken out and washed, dried to obtain PDA / Ti-ODTMS synergistically modified super-hydrophobic bamboo.The modified bamboo prepared by the application has excellent super-hydrophobic performance, ultraviolet resistance, mechanical durability and environmental protection, and the process is simple and controllable, which can be widely used in outdoor bamboo sand barrier, preservative wood, outdoor building materials and other fields.

Description

Technical Field

[0001] This invention belongs to the field of biomass material modification technology, specifically relating to a superhydrophobic, UV-resistant, and highly durable modified bamboo material and its preparation method. Background Technology

[0002] Bamboo, as a renewable biomass material with a short growth cycle and excellent mechanical properties, has broad application prospects in outdoor engineering materials such as sand barriers, preservative-treated wood, and outdoor building materials. However, bamboo's inherent hydrophilicity makes it prone to water absorption and swelling, as well as mold growth. Furthermore, its sensitivity to ultraviolet light means that long-term outdoor exposure can lead to photo-aging degradation, severely limiting its service life and application range. Therefore, developing bamboo modification technologies that combine hydrophobic protection and UV resistance is of significant practical importance.

[0003] Existing modification technologies mostly rely on fluorinated reagents (such as perfluorooctyltriethoxysilane and fluorosilanes) or toxic organic solvents (such as toluene and tetrahydrofuran). These substances are bioaccumulative and persistently toxic, difficult to degrade naturally, and easily cause secondary pollution. While some fluorine-free modification schemes have improved environmental friendliness, they suffer from poor hydrophobicity and insufficient stability, making it difficult to balance environmental protection and performance. Bamboo surfaces are porous and have uneven structures. Existing modifications are mostly surface coatings or physical adsorption, resulting in weak interfacial bonding between the coating and the substrate and a lack of effective adhesive media. When subjected to wind and sand friction or external impacts, the coating is prone to peeling and flaking, leading to rapid failure of hydrophobic properties. At the same time, nanoparticles tend to agglomerate, further reducing the continuity and mechanical stability of the coating, making it difficult to adapt to harsh outdoor environments.

[0004] Traditional impregnation and spraying methods fail to allow hydrophobic components to penetrate the internal pores of bamboo, achieving only surface modification without fundamentally altering its internal hydrophilic properties. This results in uneven overall hydrophobicity and poor water resistance. Furthermore, the coating is prone to localized agglomeration or incomplete coverage, affecting its hydrophobic stability.

[0005] Bamboo is sensitive to ultraviolet light, and existing superhydrophobic coatings often lack UV protection or rely solely on organic UV stabilizers (which are easily degradable). Long-term exposure leads to photoaging, causing coating cracking and a decline in hydrophobic properties. Furthermore, coatings often focus solely on hydrophobic functionality, failing to address multiple issues such as photoaging and decay in bamboo, making them unsuitable for the harsh environments of deserts with strong UV radiation and large diurnal temperature variations. Some modification technologies rely on vacuum processing, high-temperature sintering, or complex equipment (such as chemical vapor deposition and plasma technology), resulting in cumbersome procedures and high costs. Moreover, the process parameters are sensitive, leading to poor coating performance stability and making them unsuitable for the large-scale modification needs of applications such as bamboo sand barriers.

[0006] To address the aforementioned issues, there is an urgent need to develop an environmentally friendly, low-toxicity bamboo modification technology that features strong coating adhesion, good uniformity, hydrophobicity, and UV resistance, while also being simple and controllable in its process, in order to meet the long-term use requirements of outdoor engineering materials. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a superhydrophobic, UV-resistant, and highly durable modified bamboo material and its preparation method, so as to solve the problems of poor environmental performance, weak coating adhesion, insufficient uniformity, lack of UV resistance and complex process in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing superhydrophobic, UV-resistant, and highly durable modified bamboo, comprising the following steps: S1. Dry the pretreated bamboo; S2. Soak the dried bamboo in a PDA solution, then take it out, wash and dry it to obtain bamboo with a PDA coating on the surface; S3. Bamboo with PDA coating on its surface is immersed in silane composite modification solution, then taken out, washed and dried to obtain superhydrophobic bamboo synergistically modified with PDA / Ti-ODTMS.

[0009] Preferably, the pretreatment method in S1 is as follows: select bamboo materials that are free from mold and damage, remove the green and yellow parts of the bamboo, and wash away surface impurities.

[0010] Preferably, the drying temperature in step S1 is 60-80℃, and the drying time is 8-12 hours. Drying removes internal moisture from the bamboo material, preventing moisture from interfering with the self-polymerization reaction of PDA and the hydrolysis and condensation process of titanium sol. This is a fundamental process step to ensure the uniformity and bonding strength of the subsequent coating.

[0011] Preferably, the method for preparing the PDA solution in S2 is as follows: Tris-HCl buffer solution was prepared by dissolving tris(hydroxymethyl)aminomethane in deionized water to a concentration of 50-100 mmol / L, adjusting the pH of the system to 8.0-8.5 with hydrochloric acid, and stirring until homogeneous. Add dopamine hydrochloride to Tris-HCl buffer, stir to dissolve, and prepare a PDA solution with a concentration of 1-3 g / L. Stir at room temperature for 10-20 min.

[0012] Preferably, the soaking time in S2 is 6-12 hours.

[0013] Preferably, the drying temperature in step S2 is 60°C and the drying time is 4-6 hours.

[0014] PDA coatings form a strong interface on bamboo surfaces through their strong adhesion properties. At the same time, the active groups (hydroxyl and amino groups) on the surface provide abundant reaction sites for the subsequent in-situ growth of TiO2 and chemical bonding of ODTMS, fundamentally solving the problem of weak adhesion between the coating and the substrate.

[0015] Preferably, the preparation method of the silane composite modified liquid in S3 is as follows: Tetrabutyl titanate and a mixed solvent are mixed, and the pH value is adjusted to 3.0-5.0. The mixture is stirred evenly to obtain a solution. Then, octadecyltrimethoxysilane is added and the mixture is stirred evenly to obtain titanium sol.

[0016] The concentration of the mixture is 4-8 ml / L; The mixed solvent is obtained by mixing deionized water and anhydrous ethanol at a volume ratio of 1:(3-10).

[0017] The mass ratio of the mixture to octadecyltrimethoxysilane is 100:(1-10).

[0018] Preferably, the soaking time in S3 is 8-16 hours.

[0019] Preferably, the drying temperature in step S3 is 60-100℃ and the drying time is 4-8h.

[0020] This step involves the in-situ growth of titanium sol and chemical modification with ODTMS to simultaneously construct a TiO2 micro / nano rough structure and a low surface energy layer on the PDA coating surface. TiO2 provides roughness and UV shielding, while ODTMS provides low surface energy properties. Together, they achieve a unified function of superhydrophobicity and UV resistance, while the bonding effect of PDA ensures the long-term stability of the coating.

[0021] The present invention also provides modified bamboo prepared by the above-described preparation method.

[0022] It contains at least the following beneficial technical effects: This invention utilizes a three-step synergistic process—"PDA adhesive layer construction - in-situ synthesis of titanium sol - long-chain silane modification"—to form a three-layer composite coating on the surface of bamboo, consisting of a "PDA adhesive layer + TiO2 micro / nano rough structure + ODTMS low surface energy layer," achieving the following beneficial technical effects: This invention first constructs a PDA adhesive layer on the surface of bamboo. Dopamine hydrochloride undergoes oxidative self-polymerization in Tris-HCl buffer (pH=8.0-8.5) to form a PDA coating rich in hydroxyl and amino groups. This coating, with its strong adhesive properties, forms a firm bond with the bamboo substrate. Simultaneously, the active groups on its surface serve as anchoring points for subsequent reactions, guiding the uniform nucleation and growth of titanium sol on the coating surface, and forming stable chemical bonds with TiO2 and ODTMS, respectively. This multi-layered chemical bonding structure significantly improves the bonding strength between functional layers and between the coating and the bamboo substrate, effectively preventing coating peeling during use, endowing the modified bamboo with excellent resistance to wind and sand abrasion and external impact, and ensuring long-term stability of its superhydrophobic properties.

[0023] Using tetrabutyl titanate as the titanium source, in-situ hydrolysis and condensation were performed on the surface of a PDA coating to generate a TiO2 micro / nano structure. This structure synergistically works with the PDA coating to construct and optimize the micro / nano rough morphology of the coating, providing the necessary roughness foundation for its superhydrophobic properties. Simultaneously, TiO2 itself possesses excellent UV shielding capabilities, which, combined with the UV absorption capacity of the PDA, significantly improves the overall UV resistance of the material, effectively inhibiting photoaging and decay degradation of bamboo under strong outdoor UV conditions, and extending its service life.

[0024] Octadecyltrimethoxysilane (ODTMS) is added to the composite modification solution at a ratio of 1wt%-10wt%. The silanol groups generated by its hydrolysis react chemically with the active groups on the surface of the TiO2 micro / nano structure and the PDA coating, forming a uniform low surface energy layer on the surface of the TiO2 micro / nano structure. This process parameter range can precisely match the requirements of the rough structure. Through the synergistic effect of "low surface energy + micro / nano roughness", the superhydrophobic properties of bamboo are stably achieved, and the water contact angle of the modified bamboo is significantly improved.

[0025] Through the permeation film formation of PDA and the in-situ growth of titanium sol, the hydrophobic components can penetrate deep into the internal pores of bamboo, achieving uniform modification of the bamboo surface and interior. This avoids the local defects of traditional modification technology, which can only achieve surface modification, and improves the uniformity and water resistance of hydrophobic properties, making it suitable for use in humid and water-rich outdoor environments.

[0026] This invention eliminates the use of fluorine-containing toxic reagents and highly polluting organic sols. Through the synergistic effect of PDA, titanium sol and long-chain silanes, the modification process achieves zero harmful emissions and the coating can be naturally degraded, which meets the "dual carbon" goal and the green and environmentally friendly requirements for desertification control.

[0027] This invention requires no complex equipment or harsh reaction conditions. It can modify bamboo through a gentle stepwise impregnation, self-polymerization and in-situ synthesis process. The process parameters are highly controllable, the operation is simple and the cost is low. It can meet the batch modification needs of large-scale application scenarios such as bamboo sand barriers. Attached Figure Description

[0028] Figure 1 Example 1 shows a comparison of the surface microstructure of bamboo before and after modification using SEM images. In the images, ac represents the original bamboo, df represents the modified bamboo, and the lower right corner of images a and c shows macroscopic images of the two types of bamboo, respectively.

[0029] Figure 2 This is an EDS elemental distribution diagram of the modified bamboo material in Example 1.

[0030] Figure 3 This is a comparison diagram of the water contact angle of bamboo before and after modification in Example 1, where a represents the original bamboo and b represents the modified bamboo.

[0031] Figure 4 The abrasion resistance test curve is shown for the modified bamboo material in Example 1.

[0032] Figure 5 The image shows the UV / Vis absorbance curves of bamboo before and after modification in Example 1.

[0033] Figure 6 The image shows the UV / Vis spectral transmittance curves of bamboo before and after modification in Example 1. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0039] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0040] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0041] Raw material preparation Select bamboo that is free from mold and damage, remove the green and yellow parts of the bamboo, wash the surface with deionized water to remove impurities, and set aside.

[0042] Reagents: Tris(hydroxymethyl)aminomethane (Tris), hydrochloric acid (HCl), dopamine hydrochloride (DA), tetrabutyl titanate (TBOT), octadecyltrimethoxysilane (ODTMS), anhydrous ethanol, and deionized water.

[0043] Example 1 S1. Bamboo Pretreatment The washed bamboo was placed in an oven and dried at 60°C for 8 hours until constant weight was achieved, thus obtaining pretreated bamboo.

[0044] S2. PDA adhesive layer preparation (1) Preparation of Tris-HCl buffer: Weigh Tris and dissolve it in deionized water to prepare a 50 mmol / L solution. Adjust the pH value to 8.0 with 1 mol / L hydrochloric acid and stir well.

[0045] (2) Preparation of PDA solution: Add dopamine hydrochloride to the above buffer solution to make its concentration 1g / L, stir magnetically for 10min at room temperature to start the oxidative self-polymerization reaction.

[0046] (3) Coating and drying: The pretreated bamboo is completely immersed in the PDA solution and soaked at room temperature for 6 hours; after taking it out, the unbonded PDA on the surface is rinsed with deionized water and dried in a 60°C oven for 4 hours to obtain bamboo with a PDA coating on the surface.

[0047] S3. Preparation and in-situ deposition of titanium sol-silane composite modified solution (1) Preparation of mixed solvent: Mix deionized water and anhydrous ethanol at a volume ratio of 1:3.

[0048] (2) Preparation of composite modified solution: Add tetrabutyl titanate to the mixed solvent to make its concentration 4 ml / L, adjust the pH of the system to 3.0 with hydrochloric acid, and stir magnetically for 30 min at room temperature; then add ODTMS, the mass of which is 1% of the total mass of the mixed solution, and continue stirring for 30 min to obtain a stable titanium sol-silane composite modified solution.

[0049] (3) In-situ composite deposition: The bamboo material containing PDA coating is immersed in the above composite modification liquid and soaked at room temperature for 8 hours.

[0050] (4) Drying and curing: Take out the bamboo material, rinse the unreacted reagents on the surface with anhydrous ethanol, put it in a 60℃ oven to dry and cure for 4 hours to obtain PDA / Ti-ODTMS synergistically modified superhydrophobic bamboo material.

[0051] Example 2 S1. Bamboo Pretreatment Place the washed bamboo in an oven and dry it at 70℃ for 10 hours until it reaches a constant weight.

[0052] S2. PDA adhesive layer preparation (1) Prepare Tris-HCl buffer: Prepare a 75 mmol / L Tris solution and adjust the pH to 8.25 with hydrochloric acid.

[0053] (2) Prepare PDA solution: Add dopamine hydrochloride to a concentration of 2 g / L and stir at room temperature for 15 min.

[0054] (3) Coating and drying: Immerse the bamboo in PDA solution at room temperature for 9 hours; take it out, wash it, and dry it at 60°C for 5 hours.

[0055] S3. Preparation and in-situ deposition of titanium sol-silane composite modified solution (1) Mixed solvent: deionized water to anhydrous ethanol in a volume ratio of 1:6.5.

[0056] (2) Composite modified solution: Add TBOT to a concentration of 6 ml / L, adjust pH to 4.0, and stir for 30 min; add ODTMS, the mass of which is 5.5% of the total mass of the mixture, and continue stirring for 45 min.

[0057] (3) Impregnation: Immerse the bamboo material with PDA coating in the modified solution and soak at room temperature for 12 hours.

[0058] (4) Drying: After washing, dry and cure at 80℃ for 6 hours.

[0059] Example 3 S1. Bamboo Pretreatment Place the washed bamboo in an oven and dry it at 80℃ for 12 hours until it reaches a constant weight.

[0060] S2. PDA adhesive layer preparation (1) Prepare Tris-HCl buffer: Prepare a 100 mmol / L Tris solution and adjust the pH to 8.5 with hydrochloric acid.

[0061] (2) Prepare PDA solution: Add dopamine hydrochloride to a concentration of 3 g / L and stir at room temperature for 20 min.

[0062] (3) Coating and drying: Immerse the bamboo in PDA solution at room temperature for 12 hours; take it out, wash it, and dry it at 60°C for 6 hours.

[0063] S3. Preparation and in-situ deposition of titanium sol-silane composite modified solution (1) Mixed solvent: deionized water to anhydrous ethanol in a volume ratio of 1:10.

[0064] (2) Composite modified solution: Add TBOT to a concentration of 8 ml / L, adjust pH to 5.0, stir for 30 min; add ODTMS, the mass of which is 10% of the total mass of the mixture, and continue stirring for 60 min.

[0065] (3) Impregnation: Immerse the bamboo material with PDA coating in the modified solution and soak at room temperature for 16 hours.

[0066] (4) Drying: After washing, dry and cure at 100℃ for 8 hours.

[0067] Experimental Example 1 Surface micromorphology observation The microstructure and coating structure of the modified bamboo surface were observed using field emission scanning electron microscopy (SEM). Before testing, bamboo samples were cut into small pieces of approximately 5 mm × 5 mm × 2 mm and fixed to the sample stage with conductive adhesive. Platinum spraying was applied to the samples to improve conductivity before testing. At an accelerating voltage of 3.0 kV, the coating uniformity, morphology, size, and distribution of TiO2 nanoparticles, as well as the construction of the micro / nano hierarchical rough structure, were observed at both low and high magnification.

[0068] like Figure 1 As shown, compared with the smooth fiber surface of unmodified bamboo, the surface roughness of modified bamboo is significantly increased. This micro-nano rough structure can capture air and form a solid-gas composite contact interface, effectively reducing the actual contact area between water droplets and solid surfaces, thereby endowing the material with superhydrophobic properties.

[0069] Experimental Example 2 Surface element distribution analysis Micro-area elemental surface scanning was performed on the above samples using energy-dispersive X-ray spectroscopy (EDS) to analyze the elemental composition and distribution of the coating area.

[0070] like Figure 2 As shown, the four elements are evenly distributed and overlap each other, indicating that the method of the present invention has successfully constructed a three-layer composite structure of PDA / TiO2 / ODTMS on the surface of bamboo. Moreover, each functional layer is evenly distributed, continuous and complete, which provides a guarantee for achieving stable and durable superhydrophobic properties.

[0071] Experimental Example 3 Surface wetting performance test Static water contact angle (WCA) test method: A static contact angle meter is used to test the contact angle. A 5 μL droplet of deionized water is gently dropped onto the surface of a horizontally placed bamboo sample. The instrument's camera captures a side view image of the droplet, and the static water contact angle when the droplet remains on the bamboo surface for 10 seconds is calculated using ellipse fitting. Each sample is measured at least 5 times at different locations, and the average value is taken. Sliding angle (SA) measurement method: A 10 μL droplet of water is placed on the bamboo surface, and the sample stage is slowly tilted. The angle between the platform and the horizontal plane when the droplet begins to roll is the rolling angle. Similarly, 5 measurements are taken, and the average value is taken.

[0072] like Figure 3 As shown, the results indicate that after modification by the method of this invention, the surface of bamboo changes from hydrophilic to superhydrophobic. Combined with Experiments 1 and 2, this confirms that the PDA / Ti-ODTMS composite coating successfully constructs a synergistic effect of "micro-nano rough structure + low surface energy". The TiO2 micro-nano structure provides the necessary roughness, and the ODTMS low surface energy layer reduces the surface free energy. The synergistic effect of the two gives the bamboo excellent superhydrophobic properties.

[0073] Experiment Example 4 Abrasion resistance test Place the bamboo sample face down on a flat surface of 1000-grit sandpaper, and apply a 100-g weight as a load. Drag the sample at a constant speed along the bamboo axis, moving it 10 cm in one direction, then moving it another 10 cm vertically, completing one cycle (total movement distance 20 cm). After every 10 cycles, test the WCA and SA of the sample surface according to the method described in Experimental Example 3.

[0074] like Figure 4 As shown, the contact angle decreases gradually throughout the friction process without any sharp drop, indicating a strong bond between the coating and the bamboo substrate, and excellent mechanical durability. Even after 50 friction cycles, the surface maintains high hydrophobicity.

[0075] This excellent wear resistance is attributed to the multi-layer chemical bonded structure constructed in this invention: the PDA coating is firmly bonded to the bamboo substrate through its strong adhesion properties, and at the same time, it forms chemical bonds with TiO2 and ODTMS through active groups, so that the functional layers form an integrated structure, effectively resisting coating peeling caused by external friction.

[0076] Experimental Example 5 UV resistance test The diffuse reflectance spectra of the samples were measured using a UV-Vis-NIR spectrometer equipped with an integrating sphere, with a wavelength range of 200-600 nm. By comparing the changes in reflectance or absorptivity of bamboo in the UV region before and after modification, the shielding ability of the coating against UV light was qualitatively and semi-quantitatively evaluated.

[0077] The absorbance test results are shown below. Figure 5 : Unmodified bamboo has low absorbance in the ultraviolet region (200-400nm), with an absorbance of about 1.31 at 300nm and about 0.61 at 400nm. This indicates that it has weak absorption capacity for ultraviolet light, and most ultraviolet light can pass through or be reflected, which cannot effectively block ultraviolet radiation from damaging the bamboo matrix.

[0078] The modified bamboo of this invention exhibits significantly improved absorbance in the ultraviolet region, reaching 1.63 at 300 nm, an increase of approximately 24% compared to unmodified bamboo; and 0.82 at 400 nm, an increase of approximately 34%. The most significant improvement in absorbance is observed in the 320-380 nm UVA band, which is precisely the main ultraviolet region leading to photoaging of materials.

[0079] Transmittance test results, see Figure 6 : Unmodified bamboo has a high transmittance in the ultraviolet region, with a transmittance of about 6.1% at 300nm and about 24.2% at 400nm, indicating that a large amount of ultraviolet light can penetrate the surface of bamboo and cause photo-oxidative degradation of the internal structure.

[0080] The modified bamboo of this invention exhibits a significant reduction in ultraviolet transmittance. At 300 nm, the transmittance drops to 2.4%, a reduction of approximately 61%; at 400 nm, the transmittance drops to 19.4%, a reduction of approximately 20%. This indicates that the TiO2 and PDA composite coating effectively blocks the transmission of ultraviolet light, providing excellent ultraviolet shielding protection for the bamboo matrix.

[0081] The improved UV resistance is attributed to the synergistic effect of two factors: the PDA coating itself has UV absorption capabilities, absorbing some of the UV light energy; and the TiO2 nanoparticles have excellent UV shielding properties, blocking UV light through a dual mechanism of scattering and absorption. This synergistic effect significantly enhances the overall UV resistance of bamboo, effectively delaying photoaging and degradation under strong outdoor UV conditions and extending its service life.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle 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 preparing superhydrophobic, UV-resistant, and highly durable modified bamboo, characterized in that, Includes the following steps: S1. Dry the pretreated bamboo; S2. Soak the dried bamboo in a PDA solution, then take it out, wash and dry it to obtain bamboo with a PDA coating on the surface; S3. Bamboo with PDA coating on its surface is immersed in silane composite modification solution, then taken out, washed and dried to obtain superhydrophobic bamboo synergistically modified with PDA / Ti-ODTMS.

2. The preparation method according to claim 1, characterized in that, The pretreatment method in S1 is as follows: select bamboo materials that are free from mold and damage, remove the green and yellow parts of the bamboo, and wash away surface impurities.

3. The preparation method according to claim 1, characterized in that, The drying temperature in S1 is 60-80℃, and the drying time is 8-12h.

4. The preparation method according to claim 1, characterized in that, The method for preparing the PDA solution in S2 is as follows: Tris-HCl buffer solution was prepared by dissolving tris(hydroxymethyl)aminomethane in deionized water to a concentration of 50-100 mmol / L, adjusting the pH of the system to 8.0-8.5 with hydrochloric acid, and stirring until homogeneous. Add dopamine hydrochloride to Tris-HCl buffer, stir to dissolve, and prepare a PDA solution with a concentration of 1-3 g / L. Stir at room temperature for 10-20 min.

5. The preparation method according to claim 1, characterized in that, The soaking time in S2 is 6-12 hours.

6. The preparation method according to claim 1, characterized in that, The drying temperature in S2 is 60℃, and the drying time is 4-6 hours.

7. The preparation method according to claim 1, characterized in that, The preparation method of the silane composite modified liquid in S3 is as follows: Tetrabutyl titanate and mixed solvent are mixed, and the pH value is adjusted to 3.0-5.0 and stirred evenly to obtain a mixed solution. Then, octadecyltrimethoxysilane is added and stirred evenly to obtain titanium sol. The concentration of tetrabutyl titanate in the mixture is 4-8 ml / L; The mixed solvent is obtained by mixing deionized water and anhydrous ethanol at a volume ratio of 1:(3-10); The mass ratio of the mixture to octadecyltrimethoxysilane is 100:(1-10).

8. The preparation method according to claim 1, characterized in that, The soaking time in S3 is 8-16 hours.

9. The preparation method according to claim 1, characterized in that, The drying temperature in S3 is 60-100℃, and the drying time is 4-8 hours.

10. Modified bamboo prepared by the preparation method according to any one of claims 1-9.

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