Self-cleaning composite coating material with photocatalytic and antibacterial functions and preparation method

Abstract

The application discloses a preparation method of a self-cleaning composite coating material with photocatalysis and antibacterial functions, and comprises the following steps: step (1), pretreatment of a PDMS base; step (2), preparation of SiO2 powder; step (3), preparation of BSO powder; step (4), preparation of TiO2 / BSO composite powder; step (5), dispersion of the SiO2 and TiO2 / BSO composite powder in anhydrous ethanol respectively, so as to obtain G liquid and H liquid; ultrasonic dispersion of the obtained G liquid and H liquid, and then spraying on the pretreated PDMS base by using a spraying method one by one, so as to obtain a PDMS-SiO2-TiO2 / BSO composite coating material. The obtained composite coating material is stable in structure, high in self-cleaning efficiency, and excellent in photocatalysis and antibacterial performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of anti-fouling coating, and particularly relates to a self-cleaning composite coating material with photocatalytic and antibacterial functions and a preparation method. BACKGROUND

[0002] The self-cleaning composite coating material has special microstructure, excellent hydrophobicity, antibacterial property, self-cleaning property and the like. At present, TiO2 coating material is one of the most typical coating materials, but single TiO2 coating material often cannot realize efficient utilization of visible light and self-cleaning function.

[0003] In the existing self-cleaning coating technology, a certain research is carried out on TiO2 photocatalytic function coating.

[0004] For example, Chinese patent CN108837818B discloses a TiO2 coating with photocatalytic function and a preparation method. The TiO2 coating is composed of nano TiO2 particles, a solvent and a binder. Although the coating can be applied to photocatalytic field application scenarios such as water treatment, air purification, sterilization and antibacterial property, the photocatalytic activity of the coating is low, which leads to certain limitations of the coating in actual application. In addition, the refractive index of single TiO2 coating material is generally high, and if it is not effectively controlled, the light energy utilization rate and actual service life of the coating material in actual application will be seriously affected. SUMMARY

[0005] In order to overcome the problems existing in the prior art, the purpose of the present application is to provide a self-cleaning composite coating material with photocatalytic and antibacterial functions and a preparation method. The obtained composite coating material has stable structure, high self-cleaning efficiency, excellent photocatalytic and antibacterial properties.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of a self-cleaning composite coating material with photocatalytic and antibacterial functions, comprising the following steps:

[0008] Step (1): pretreatment of a PDMS (polydimethylsiloxane) substrate;

[0009] Step (2): adding tetraethyl orthosilicate into anhydrous ethanol to form A liquid; adding deionized water and ammonia water into anhydrous ethanol to form B liquid, and then slowly dropping all the B liquid into the A liquid after uniform mixing and stirring, and then washing and centrifuging several times with deionized water and anhydrous ethanol, drying, and then grinding the dried blocky powder sample to obtain SiO2 powder;

[0010] Step (3): Dissolve bismuth nitrate in deionized water, stir, and add ethylene glycol during the stirring to form C liquid; dissolve sodium metasilicate nonahydrate in deionized water to form D liquid, slowly drop all the D liquid into the C liquid after stirring uniformly, and stir to obtain a white emulsion-like BSO precursor solution; pour the white emulsion-like BSO precursor solution into a polytetrafluoroethylene reaction kettle, place it in an electric heating drying oven, and reduce it to room temperature with the oven; wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry, grind, and obtain BSO powder;

[0011] Step (4): Dissolve titanium sulfate in deionized water, stir to form E liquid; weigh sodium hydroxide and dissolve it in deionized water, stir to form F liquid; slowly drop the F liquid into the E liquid and stir; add a certain amount of BSO powder obtained in step 3 and stir; wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry in an oven, calcine the dried blocky powder sample in a muffle furnace, and grind to obtain TiO2 / BSO composite powder;

[0012] Step (5): Disperse SiO2 and TiO2 / BSO composite powder in anhydrous ethanol respectively to obtain G liquid and H liquid;

[0013] After ultrasonic dispersion, the obtained G liquid and H liquid are sprayed onto the pretreated PDMS substrate one by one by the spraying method to obtain a PDMS-SiO2-TiO2 / BSO composite coating material.

[0014] The step (2) is specifically: weigh 20-30 ml of anhydrous ethanol, add 3-7 ml of tetraethyl orthosilicate to form A liquid; weigh 20-30 ml of anhydrous ethanol, add 5 ml of deionized water and 3.5 ml of ammonia water to form B liquid, slowly drop the B liquid into the A liquid after mixing and stirring uniformly, and stir for 12-14 h; wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry at 60-80°C, and grind to obtain SiO2 photonic crystal powder samples matching the photonic bandgap of TiO2 / BSO composite powder.

[0015] The step (3) is specifically: weigh 2-3 g of bismuth nitrate and dissolve it in 3-5 mL of deionized water, continuously stir for 25-40 min, and add 6-8 mL of ethylene glycol during the stirring to form C liquid; weigh 1-3 g of sodium metasilicate nonahydrate and dissolve it in 7-10 mL of deionized water to form D liquid, slowly drop the D liquid into the C liquid after stirring uniformly, and stir for 20-30 min to obtain a white emulsion-like BSO precursor solution; pour the BSO precursor solution into a 50 ml polytetrafluoroethylene reaction kettle, place it in an electric heating drying oven, and react at 100-150°C for 12-14 h; reduce it to room temperature with the oven, wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry in a 50-70°C oven, and grind. By controlling the raw material ratio and hydrothermal reaction temperature, BSO powder samples producing a large amount of hydrated bismuth nitrate can be obtained.

[0016] The step (4) is specifically: weighing 2-4 g of titanium sulfate and dissolving it in 40-60 mL of deionized water, continuously stirring for 20-40 min to form E liquid; weighing 0.4-0.6 g of sodium hydroxide and dissolving it in 35-40 mL of deionized water, continuously stirring for 20-40 min to form F liquid; slowly dropping F liquid into E liquid, stirring at 70-85 DEG C for 0.5-1.5 h; adding 0.05-0.2 g of BSO powder obtained in step 3, stirring for 1-3 h, washing and centrifuging several times with deionized water and anhydrous ethanol alternately, drying in a 70-90 DEG C oven for 7-9 h, and then drying at 110-130 DEG C for 3-5 h; placing the dried sample in a muffle furnace at 400-600 DEG C, calcining for 1-3 h, and then grinding. The TiO2 / BSO composite powder formed by the close combination of the sheet stack TiO2 and the rod-shaped BSO can be obtained by the sol-gel reaction time and temperature.

[0017] In the step (1), 0.45-0.55 g of PDMS (polydimethylsiloxane) is uniformly coated in a fixed area of a glass slide, and dried at 60-80 DEG C for 1-3 h to obtain a uniformly coated and low-surface-energy composite coating substrate.

[0018] In the step (5), the SiO2 and TiO2 / BSO composite powder are dispersed in anhydrous ethanol with a concentration of 0.06-0.09 M / L, and n(Si):n(Ti) is 2:1-1:3. Under the anhydrous ethanol concentration and the silicon-titanium ratio, the dispersibility of the SiO2 and TiO2-BSO composite powder and the overall optical performance of the composite coating are better. The PDMS-SiO2-TiO2 / BSO composite coating material is composed of the close combination of the sheet stack TiO2 with a length of 1-5 mu m, the rod-shaped BSO with a length of 1-4 mu m, and the spherical SiO2 with a particle size of 260-280 nm, and has a micro-nano scale rough surface structure.

[0019] In the composite coating, the micro-nano scale rough structure composed of the low-surface-energy PDMS and the SiO2-TiO2 / BSO composite produces a synergistic effect to form a hydrophobic coating, so that the coating has excellent self-cleaning performance; and since the titanium dioxide coating material has a narrow light response range and poor photocatalytic and antibacterial performance, the addition of SiO2 and BSO is used to adjust the optical performance (such as the refractive index) of the coating, enhance the photocatalytic response range, and improve the photocatalytic and antibacterial performance of the composite coating.

[0020] The beneficial effects of the present application are:

[0021] This invention provides a self-cleaning composite coating material with photocatalytic and antibacterial functions. By combining an organic coating material with an inorganic photofunctional material, an organic-inorganic composite coating is obtained. While retaining the original protective function, it achieves a highly efficient photocatalytic antibacterial effect, effectively improving the self-cleaning performance of the composite coating.

[0022] First, PDMS is used as an organic material substrate, and photonic crystals and photocatalytic materials are effectively combined on PDMS to construct a hydrophobic composite coating with photocatalytic and antibacterial functions. At the same time, the low surface energy and high reflectivity of PDMS, as well as the photonic bandgap and photonic localization effect of photonic crystals, effectively improve the stability and multiple protective functions of the composite material.

[0023] Secondly, the hydrothermal reaction process of bismuth nitrate and sodium silicate is controlled to produce hydrated bismuth nitrate. During the calcination of the composite catalytic material, the hydrated bismuth nitrate decomposes at high temperature to form nitrogen oxides and oxygen. The nitrogen oxides and oxygen then react with Bi... 3+ Oxidation to Bi 4+ Simultaneously, titanium dioxide loses some oxygen atoms at high temperatures, forming oxygen vacancies, thereby compensating for the charge imbalance caused by the valence change of Bi ions. High-valence Bi... 4+ The formation of high-valence states with O defects – defect energy levels – modulate the electronic band gap and promote carrier transfer.

[0024] Furthermore, by matching the electronic bandgap of TiO2 / BSO with the photonic bandgap of SiO2 based on the co-regulation of high-valence Bi ions and O defects, the photonic localization effect of the composite coating is enhanced. During photocatalysis, the absorbed photons are reflected by the PDMS substrate and photonic crystal to the TiO2 / BSO layer and generate photonic localization, thereby improving the light utilization efficiency of the composite coating and facilitating the generation of photogenerated carriers.

[0025] Ultimately, the self-cleaning function of the composite coating is significantly improved through the combined action of the above organic and inorganic materials. Attached Figure Description

[0026] Figure 1 This is a schematic SEM image of the cross-section of the PDMS-SiO2-TiO2 / BSO self-cleaning composite coating material.

[0027] Figure 2 This is a schematic diagram of the SEM image of the TiO2 / BSO composite powder.

[0028] Figure 3 This is a schematic diagram of the photocatalytic degradation of the PDMS-SiO2-TiO2 / BSO self-cleaning composite coating.

[0029] Figure 4 The contact angle test diagram is for the PDMS-SiO2-TiO2 / BSO self-cleaning composite coating.

[0030] Figure 5 The antibacterial test of PDMS-SiO2-TiO2 / BSO self-cleaning composite coating on E. coli is shown in the following figure. DETAILED DESCRIPTION

[0031] The application will be further described in detail below with reference to the accompanying drawings.

[0032] Example 1:

[0033] A preparation method of a self-cleaning composite coating material with photocatalytic and antibacterial functions, comprising the following steps:

[0034] (1) 0.55 g of PDMS is uniformly coated in a fixed area of a glass slide, and dried at 80°C for 2 h;

[0035] (2) 20 ml of anhydrous ethanol is weighed, 5 ml of tetraethyl orthosilicate is added and mixed and stirred for 0.5 h to form A liquid; 25 ml of anhydrous ethanol is weighed, 5 ml of deionized water and 3.5 ml of ammonia water are added and mixed and stirred for 0.5 h to form B liquid, and after uniform mixing and stirring, B liquid is slowly added into A liquid and mixed and stirred for 13 h, and then washed and centrifuged with deionized water and anhydrous ethanol for three times, dried at 70°C, and grinded to obtain SiO2 powder;

[0036] (3) 2.9 g of bismuth nitrate is dissolved in 4 mL of deionized water and continuously stirred for 30 min, and 7 mL of ethylene glycol is added during the stirring to form C liquid; 1.7 g of sodium metasilicate nonahydrate is dissolved in 7 mL of deionized water and continuously stirred for 30 min to form D liquid, and after uniform stirring, D liquid is slowly added into C liquid, and stirred for 20 min to obtain a white emulsion-like BSO precursor solution, which is loaded into a 50 ml polytetrafluoroethylene reaction kettle, placed in an electric heating air drying oven, and reacted at 100°C for 12 h, and then washed and centrifuged with deionized water and anhydrous ethanol for three times, dried in a 60°C oven for 12 h, and grinded to obtain BSO powder;

[0037] (4) 3 g of titanium sulfate is dissolved in 50 mL of deionized water and continuously stirred for 30 min to form E liquid; 0.5 g of sodium hydroxide is dissolved in 37.5 mL of deionized water and continuously stirred for 30 min to form F liquid; F liquid is slowly added into E liquid, and stirred at 80°C for 1 h; 0.05 g of BSO powder obtained in step three is added and stirred for 2 h, and then washed and centrifuged with deionized water and anhydrous ethanol for two times, dried in an 80°C oven for 8 h, and then dried at 125°C for 4 h; the dried sample is placed in a 500°C muffle furnace and calcined for 2 h, and then grinded to obtain TiO2-BSO composite powder;

[0038] (5) The SiO2 and TiO2-BSO composite powders were dispersed in anhydrous ethanol to obtain 0.06M dispersions, namely G liquid and H liquid, wherein the molar ratio of silicon and titanium raw materials was 2:1.

[0039] (6) The obtained liquids G and H were ultrasonically dispersed and then sprayed onto the PDMS substrate one by one using a spraying method to obtain a PDMS-SiO2-TiO2 / BSO composite coating material. The PDMS-SiO2-TiO2 / BSO composite coating material obtained in this embodiment has excellent hydrophobic properties. The water contact angle of the obtained composite coating was tested, and the test schematic diagram is shown below. Figure 4 As shown, the contact angle obtained by the test is 157.98°, indicating that it has excellent hydrophobic properties.

[0040] Example 2:

[0041] A method for preparing a self-cleaning composite coating material with photocatalytic and antibacterial functions includes the following steps:

[0042] (1) 0.45g of PDMS was uniformly coated on a fixed area of ​​a glass slide and dried at 70℃ for 1.5h;

[0043] (2) Weigh 25ml of anhydrous ethanol, add 6ml of tetraethyl orthosilicate and stir for 0.5h to form solution A; weigh 30ml of anhydrous ethanol, add 6ml of deionized water and 4ml of ammonia water and stir for 0.5h to form solution B. After mixing and stirring evenly, slowly add solution B to solution A and stir for 12h. Wash and centrifuge three times with deionized water and anhydrous ethanol alternately, dry at 80℃, and grind to obtain SiO2 powder.

[0044] (3) Weigh 3.2g of bismuth nitrate and dissolve it in 5mL of deionized water and stir continuously for 30min. During this period, add 6mL of ethylene glycol to form solution C. Weigh 1.85g of sodium metasilicate nonahydrate and dissolve it in 6mL of deionized water and stir continuously for 30min to form solution D. After stirring evenly, slowly add solution D to solution C and stir for 20min to obtain a white emulsion-like BSO precursor solution. Put it into a 50ml polytetrafluoroethylene reactor and place it in an electric heating drying oven. React at 160℃ for 12h. After cooling to room temperature, wash and centrifuge three times with deionized water and anhydrous ethanol alternately. Dry in an oven at 60℃ for 12h and grind to obtain BSO powder.

[0045] (4) Weigh 3.5g of titanium sulfate and dissolve it in 50mL of deionized water, and stir continuously for 30min to form solution E; weigh 0.5g of sodium hydroxide and dissolve it in 37.5mL of deionized water, and stir continuously for 30min to form solution F; slowly add solution F to solution E, and stir at 80℃ for 1h; add 0.1g of BSO powder obtained in step 3 and stir for 2h, wash and centrifuge twice with deionized water and anhydrous ethanol alternately, dry in an oven at 80℃ for 8h, and then dry at 140℃ for 4h; put the dried sample into a muffle furnace at 450℃ and calcine for 2h, and grind to obtain TiO2-BSO composite powder;

[0046] (5) The SiO2 and TiO2-BSO composite powders were dispersed in anhydrous ethanol to obtain 0.08M dispersions, namely G liquid and H liquid, wherein the molar ratio of silicon and titanium raw materials was 1:3.

[0047] (6) After ultrasonically dispersing the obtained G liquid and H liquid, they were sprayed onto the PDMS substrate one by one by spraying to obtain PDMS-SiO2-TiO2 / BSO composite coating material.

[0048] The PDMS-SiO2-TiO2 / BSO composite coating material obtained in this embodiment exhibits excellent photocatalytic performance. The photocatalytic degradation of Rhodamine B (5 mg / L) using the obtained coating was tested, and the results are as follows: Figure 3 As shown, the degradation rate can reach 96.39%, indicating that it has good photocatalytic degradation performance.

[0049] Example 3:

[0050] A method for preparing a self-cleaning composite coating material with photocatalytic and antibacterial functions includes the following steps:

[0051] (1) Coat 0.5g of PDMS evenly on a fixed area of ​​a glass slide and dry it at 70℃ for 2h;

[0052] (2) Weigh 30 ml of anhydrous ethanol, add 6 ml of tetraethyl orthosilicate and stir for 0.5 h to form solution A; weigh 30 ml of anhydrous ethanol, add 6 ml of deionized water and 4 ml of ammonia water and stir for 0.5 h to form solution B. After mixing and stirring evenly, slowly add solution B to solution A and stir for 12 h. Wash and centrifuge three times with deionized water and anhydrous ethanol alternately, dry at 80 °C, and grind to obtain SiO2 powder.

[0053] (3) Weigh 3.2g of bismuth nitrate and dissolve it in 5mL of deionized water and stir continuously for 30min. During this period, add 6mL of ethylene glycol to form solution C. Weigh 1.85g of sodium metasilicate nonahydrate and dissolve it in 6mL of deionized water and stir continuously for 30min to form solution D. After stirring evenly, slowly add solution D to solution C and stir for 20min to obtain a white emulsion-like BSO precursor solution. Put it into a 50ml polytetrafluoroethylene reactor and place it in an electric heating drying oven. React at 160℃ for 12h. After cooling to room temperature, wash and centrifuge three times with deionized water and anhydrous ethanol alternately. Dry in an oven at 60℃ for 12h and grind to obtain BSO powder.

[0054] (4) Weigh 3.5g of titanium sulfate and dissolve it in 50mL of deionized water. Stir continuously for 30min to form solution E. Weigh 0.5g of sodium hydroxide and dissolve it in 37.5mL of deionized water. Stir continuously for 30min to form solution F. Slowly add solution F to solution E and stir at 80℃ for 1h. Add 0.2g of BSO powder obtained in step 3 and stir for 2h. Wash and centrifuge twice with deionized water and anhydrous ethanol alternately. Dry in an oven at 80℃ for 8h, and then dry at 140℃ for 4h. Place the dried sample in a muffle furnace at 450℃ and calcine for 2h. Grind to obtain TiO2-BSO composite powder.

[0055] (5) The SiO2 and TiO2-BSO composite powders were dispersed in anhydrous ethanol to obtain 0.07M dispersions, namely G liquid and H liquid, wherein the molar ratio of silicon and titanium raw materials was 1:1.

[0056] (6) After ultrasonically dispersing the obtained G liquid and H liquid, they were sprayed onto the PDMS substrate one by one by spraying to obtain PDMS-SiO2-TiO2 / BSO composite coating material.

[0057] The PDMS-SiO2-TiO2 / BSO composite coating material obtained in this embodiment exhibits the best overall performance, maintaining hydrophobicity while also demonstrating good photocatalytic degradation and antibacterial functions. Figure 3 , 5 The results show that the obtained composite coating has good photocatalytic and antibacterial properties. The sterilization rate is almost 100%.

[0058] like Figure 1 The image shown is a cross-sectional SEM image of the PDMS-SiO2-TiO2 / BSO composite coating. It can be seen that its layered structure is clear and the layers are tightly bonded together, indicating that the composite coating is stable and reliable.

[0059] like Figure 2The image shown is a SEM image of the TiO2 and BSO composite powder. The microstructure of TiO2 has changed from a lamellar structure to a lamellar stack. More nanoparticles can be clearly observed on the surface of the lamellars. Their morphology can provide more active sites and bind tightly with BSO to form heterojunctions, thereby improving the reaction efficiency.

[0060] like Figure 3 The figure shows the photocatalytic degradation performance of the PDMS-SiO2-TiO2 / BSO composite coating on Rhodamine B (5 mg / L) under simulated visible light irradiation. By comparing it with the PDMS-SiO2-TiO2 composite coating and the PDMS-SiO2-BSO composite coating, it is further proved that the combination of TiO2 and BSO has a significant effect on improving the overall photocatalytic performance of the composite coating, with a degradation rate of up to 96.39%.

[0061] like Figure 4 The image shows the water contact angle test results of the obtained PDMS-SiO2-TiO2 / BSO composite coating. The tested contact angle is 157.98°, indicating that the coating has good hydrophobic properties.

[0062] like Figure 5 The image shows a comparison of the antibacterial test results of the composite coating against Escherichia coli. Taking Escherichia coli as an example, the bactericidal rate of the uniformly coated PDMS-SiO2-TiO2 / BSO composite coating is almost 100%.

Claims

1. A method for preparing a self-cleaning composite coating material with photocatalytic and antibacterial functions, characterized in that, Includes the following steps; Step (1): Prepare PDMS substrate by uniformly coating 0.45~0.55 g of PDMS onto a fixed area of ​​a glass slide and drying it at 60~80℃ for 1~3 h. Step (2): Add tetraethyl orthosilicate to anhydrous ethanol to form solution A; add deionized water and ammonia to anhydrous ethanol to form solution B. After mixing and stirring evenly, slowly add all of solution B to solution A and stir. Wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry, and then grind the dried block powder sample to obtain SiO2 powder. Step (3): Dissolve bismuth nitrate in deionized water and stir, adding ethylene glycol during the process to form solution C; dissolve sodium metasilicate nonahydrate in deionized water to form solution D. After stirring evenly, slowly add all of solution D to solution C and stir to obtain a white emulsion-like BSO precursor solution. Put the white emulsion-like BSO precursor solution into a polytetrafluoroethylene reactor and place it in an electric heating drying oven. Cool the oven to room temperature and wash and centrifuge several times with deionized water and anhydrous ethanol alternately. Dry and grind to obtain BSO powder. Step (4): Dissolve titanium sulfate in deionized water and stir to form solution E; weigh sodium hydroxide and dissolve it in deionized water and stir to form solution F; slowly add solution F to solution E and stir; add a certain amount of BSO powder obtained in step 3 and stir; wash and centrifuge several times with deionized water and anhydrous ethanol alternately; dry in an oven; calcine the dried block powder sample in a muffle furnace and grind to obtain TiO2 / BSO composite powder; Step (5): Disperse the SiO2 and TiO2 / BSO composite powders in anhydrous ethanol to obtain liquid G and liquid H respectively; After ultrasonic dispersion, the obtained liquid G and liquid H were sprayed onto the PDMS substrate one by one by spraying to obtain PDMS-SiO2-TiO2 / BSO composite coating material. The specific steps (3) are as follows: Weigh 2-3 g of bismuth nitrate and dissolve it in 3-5 mL of deionized water, stir continuously for 25-40 min, add 6-8 mL of ethylene glycol during the process to form solution C; Weigh 1-3 g of sodium metasilicate nonahydrate and dissolve it in 7-10 mL of deionized water to form solution D, stir evenly and slowly add solution D to solution C, stir for 20-30 min to obtain a white emulsion-like BSO precursor solution, put it into a 50 mL polytetrafluoroethylene reactor, place it in an electric heating drying oven, react at 100-150 ℃ for 12-14 h, cool it to room temperature with the furnace, wash it alternately with deionized water and anhydrous ethanol several times, centrifuge it several times, dry it in an oven at 50-70 ℃ and then grind it; Step (4) specifically involves: weighing 2-4 g of titanium sulfate and dissolving it in 40-60 mL of deionized water, stirring continuously for 20-40 min to form solution E; weighing 0.4-0.6 g of sodium hydroxide and dissolving it in 35-40 mL of deionized water, stirring continuously for 20-40 min to form solution F; slowly adding solution F dropwise into solution E, stirring at 70-85 ℃ for 0.5-1.5 h; adding 0.05-0.2 g of BSO powder obtained in step 3 and stirring for 1-3 h; washing and centrifuging several times alternately with deionized water and anhydrous ethanol; drying in an oven at 70-90 ℃ for 7-9 h, and then drying again at 110-130 ℃ for 3-5 h; placing the dried sample in a muffle furnace at 400-600 ℃, calcining for 1-3 h, and then grinding.

2. The method for preparing a self-cleaning composite coating material with photocatalytic and antibacterial functions according to claim 1, characterized in that, The specific steps (2) are as follows: Weigh 20-30 ml of anhydrous ethanol, add 3-7 ml of tetraethyl orthosilicate to form solution A; weigh 20-30 ml of anhydrous ethanol, add 5 ml of deionized water and 3.5 ml of ammonia to form solution B. After mixing and stirring evenly, slowly add solution B to solution A and stir for 12-14 h. Wash and centrifuge several times with deionized water and anhydrous ethanol alternately, dry at 60℃-80℃, and grind to obtain SiO2 photonic crystal powder sample that matches the photonic bandgap of TiO2 / BSO composite powder.

3. The method for preparing a self-cleaning composite coating material with photocatalytic and antibacterial functions according to claim 1, characterized in that, In step (5), SiO2 and TiO2 / BSO composite powders are dispersed in anhydrous ethanol with a concentration of 0.06~0.09M / L, where n(Si):n(Ti) is 2:1~1:

3.

4. The PDMS-SiO2-TiO2 / BSO composite coating material prepared by the method according to any one of claims 1-3, characterized in that, The PDMS-SiO2-TiO2 / BSO composite coating material is composed of a micro-nano-scale rough surface structure formed by the tight bonding of TiO2 sheets with a length of 1 μm to 5 μm, rod-shaped BSO with a length of 1 μm to 4 μm, and spherical SiO2 with a particle size of 260 to 280 nm. In the composite coating, the low surface energy PDMS and the micro-nano rough structure formed by the SiO2-TiO2 / BSO composite work synergistically to form a hydrophobic coating, giving the coating excellent self-cleaning properties. The addition of SiO2 and BSO is used to adjust the optical properties of the coating, enhance the photocatalytic response range, and improve the photocatalytic and antibacterial properties of the composite coating.

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