Ag@nh2-posss-bisdopo flame retardant, and preparation method and application thereof

Abstract

The application provides an Ag@NH2-POSS-bisDOPO flame retardant as well as a preparation method and application thereof, and relates to the technical field of flame retardants.The application is characterized in that: a new type of POSS-based flame retardant (Ag@bisDOPO-NH2-POSS) is synthesized by in-situ reaction of NH2-POSS-bisDOPO (referring to Chinese patent CN112961359A) and AgNPs, then the new type of POSS-based flame retardant is made into a polycation electrolyte solution, and wood is subjected to layer-by-layer self-assembly by combining the polycation electrolyte solution with a polyanion electrolyte solution, is alternately deposited on the surface of the wood, and a flame-retardant and antibacterial coating is constructed, so that the wood is subjected to flame-retardant and antibacterial treatment, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application provides an Ag@NH2-POSS-bisDOPO flame retardant as well as a preparation method and application thereof, and relates to the technical field of flame retardants. BACKGROUND

[0002] Wood, as a natural renewable biomass polymer material, has many advantages such as light weight, high strength, beautiful texture, easy processing, good environmental characteristics, and is widely used in furniture, indoor and building decoration materials and other fields. However, the flammability of wood not only limits its wide application, but also poses a threat to people's life and property due to the existence of fire hazards. At the same time, as a natural biological organic material, wood will be affected by environmental factors such as environment, temperature and humidity, and organisms, and thus be damaged to a certain extent. When the temperature and humidity of the environment rise to a certain extent, the moisture in the wood can provide a living environment for mold, making the wood vulnerable to mold erosion and damage, which will greatly limit the application effect and application scene of wood. For a long time, developing coatings with flame-retardant and antibacterial functions is one of the important directions of the functionalization development of wood coatings.

[0003] At present, the most commonly used method for wood flame-retardant treatment is impregnation treatment, which mainly impregnates flame-retardant into the wood to make the wood have flame-retardant performance as a whole, but this treatment process has defects such as large amount of flame-retardant, high cost, and adverse effects on the mechanical properties of wood. In addition, the current research on flame-retardant mainly focuses on halogen-based flame-retardant, metal compound-based flame-retardant and boron-based flame-retardant. Bromine and chlorine in halogen-containing flame-retardant can release harmful gases at high temperatures, which can cause potential harm to health and environment, and has been gradually eliminated. For example, brominated flame-retardant can release halogenated diphenyl ether (PBDE), which is considered to have potential harm to human health and environment. Metal compound-based flame-retardant has the advantages of flame-retardant, smoke suppression, environmental protection and the like, but has the disadvantages of low water solubility and dispersibility, high addition amount, and influence on the physical, mechanical properties and processing performance of wood. Although boron-based flame-retardant has the advantages of obvious improvement of wood durability, low toxicity, small influence on the physical and mechanical properties of wood and the like, it still has the disadvantages of poor resistance to loss, easy precipitation under humid conditions and the like. Therefore, it is very important to develop simple, environmentally friendly and efficient flame-retardant.

[0004] Layer-by-layer self-assembly (LBL) is a simple, easy-to-operate, multifunctional interface supramolecular self-assembly technology. For some materials with their own charges, they can be directly used as a substrate; and for materials without their own charges, they can be chemically modified to have charges on the surface, and then electrolytes with opposite charges are allowed to stay on the surface of the substrate by alternating adsorption, and through the weak interaction between molecules (such as electrostatic attraction, hydrogen bond, coordination bond, etc.), the sample is spontaneously associated to form a molecular aggregate or supramolecular structure with complete structure, stable performance and specific function. The application of this technology in the construction of flame-retardant coating on the surface of wood can overcome the shortcomings of traditional wood impregnation flame-retardant treatment, such as large amount of flame retardant and reduction of the mechanical properties of wood. Natural biomass materials such as chitosan, sodium alginate, phytic acid, carrageenan, etc. are not only green and environmentally friendly, but also good carbon (nitrogen) sources and carbonation agents, and their aqueous solutions all have charges, which are good polyelectrolyte solutions. Therefore, the use of the above polyelectrolyte to construct a flame-retardant coating on the surface of wood by layer-by-layer self-assembly technology is expected to achieve the flame retardation of wood. However, it has been reported that the flame-retardant coating constructed by using the above polyelectrolyte still has the disadvantage of low flame-retardant efficiency.

[0005] Polyhedral oligomeric silsesquioxane (POSS) is a hollow closed cage compound composed of silicon atoms and oxygen atoms, also known as cubic silane. Its structure is composed of Si-O-Si skeleton, which has designability, thermal stability and chemical stability, and its three-dimensional diameter is 1-3 nm, and its molecular formula is (RSiO 1.5) n, wherein R is the external organic group of POSS (which can be methyl, phenyl, epoxy, vinyl, amine propyl, etc.), and n can be 8, 10, 12, etc., and n = 8 is the most common. POSS is a true inorganic-organic hybrid system at the molecular level, which has nanoscale size effect and excellent heat resistance, flame retardance, radiation resistance, etc., and can form a physical barrier or barrier layer on the surface of the matrix, hinder the entry of heat, and inhibit the formation of volatile matter, thereby reducing the heat release and showing good flame retardant effect. Therefore, by using the POSS-based flame retardant in combination with the above biomass polyelectrolyte to construct a flame-retardant coating on the surface of wood, a simple, green, environmentally friendly and efficient flame-retardant technology can be achieved, which can realize the efficient flame retardation of wood. SUMMARY

[0006] Therefore, the present application aims to provide a method for layer-by-layer self-assembly of a flame-retardant and antibacterial coating on the surface of wood.

[0007] The preparation method of the Ag@NH2-POSS-bisDOPO flame retardant is prepared by in-situ reaction of the NH2-POSS-bisDOPO flame retardant and AgNPs.

[0008] Preferably, the preparation method of the Ag@NH2-POSS-bisDOPO flame retardant comprises the following steps:

[0009] S1, dissolving AgNO3 in deionized water to obtain an AgNO3 aqueous solution with a mass concentration of 0.3% to 0.5%;

[0010] S2, soaking the NH2-POSS-bisDOPO flame retardant in the AgNO3 aqueous solution for swelling and adsorption, the soaking time being 5 to 24 hours, and after the soaking is completed, filtering and washing, the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 is prepared;

[0011] S3, dissolving NaBH4 in deionized water to obtain a NaBH4 aqueous solution with a mass concentration of 0.05% to 0.8%;

[0012] S4, soaking the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 in the NaBH4 aqueous solution, the soaking time being 12 hours, and after the soaking is completed, filtering and drying to obtain the Ag@bisDOPO-NH2-POSS flame retardant.

[0013] The present application also provides an application method of the Ag@NH2-POSS-bisDOPO flame retardant, which specifically comprises the following steps:

[0014] (1) after the wood is surface cleaned, it is dried for standby use;

[0015] (2) preparing a polycationic composite electrolyte solution:

[0016] First, dissolving chitosan powder in an acetic acid aqueous solution with a mass concentration of 1% to obtain a chitosan acetic acid aqueous solution with a chitosan mass concentration of 2%;

[0017] Then, the Ag@NH2-POSS-bisDOPO flame retardant is added into the chitosan acetic acid aqueous solution, and a poly cationic complex electrolyte solution with a mass concentration of 5% of the Ag@NH2-POSS-bisDOPO flame retardant is obtained after uniform mixing;

[0018] (3) Preparation of a poly anionic electrolyte solution

[0019] Phytic acid (i.e., myo-inositol hexakisphosphate) is dissolved in water to obtain a phytic acid aqueous solution with a mass concentration of 2%, i.e., a poly anionic electrolyte solution;

[0020] (4) Layer-by-layer self-assembly

[0021] The wood treated in step (1) is first immersed in the poly cationic complex electrolyte solution for 5-30 min, washed to remove the excess liquid on the surface, and then dried, and then immersed in the poly anionic electrolyte solution for 5-10 min, washed to remove the excess liquid on the surface, and then dried, and then the above steps are repeated for 5-15 times, and finally dried to dryness.

[0022] 5. The use according to claim 4, wherein the drying temperature in step (1) is 60°C, and the drying time is 30 min.

[0023] Preferably, the drying temperature in step (4) is 60-100°C.

[0024] Preferably, the number of times of repeating the immersion in step (4) is 5-15 times.

[0025] More preferably, the number of times of repeating the immersion in step (4) is 7 times.

[0026] Compared with the prior art, the present application provides a new type of POSS flame retardant, specifically Ag@NH2-POSS-bisDOPO flame retardant. The present application is to synthesize a new type of POSS-based flame retardant (Ag@bisDOPO-NH2-POSS) by in-situ reaction of NH2-POSS-bisDOPO (referring to Chinese patent CN112961359A) and AgNPs, and then to prepare a poly cationic electrolyte solution, and to combine a poly anionic electrolyte solution to perform layer-by-layer self-assembly on wood, to alternately deposit on the surface of wood, to construct a flame-retardant and antibacterial coating, to realize the flame-retardant and antibacterial treatment of wood, and to have good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1Figure 1 is the SEM images of the residual char of pure wood and wood treated by Example 1, Comparative Example 1; wherein a is the photo of pure wood after burning; a1 is the SEM image of the residual char of pure wood; b is the photo of wood treated by Comparative Example 1 after burning; b1 is the SEM image of the residual char of wood treated by Comparative Example 1; c is the photo of wood treated by Example 1 after burning; c1 is the SEM image of the residual char of wood treated by Example 1.

[0028] Figure 2 Figure 4 is the antibacterial effect of different treatment groups on Aspergillus niger after one week, four weeks; wherein 1 is Comparative Example 3, 2 is Comparative Example 4.

[0029] Figure 3 Figure 5 is the antibacterial effect of different treatment groups on Cercospora arachidicola after one week, four weeks; wherein 1 is Comparative Example 3, 2 is Comparative Example 4.

[0030] Figure 4 Figure 6 is the TGA curve of Example 1, Comparative Example 1.

[0031] Figure 5 Figure 7 is the DTG curve of Example 1, Comparative Example 1.

[0032] Figure 6 Figure 8 is the HRR curve of Example 1, Comparative Example 1, Comparative Example 2.

[0033] Figure 7 Figure 9 is the THR curve of Example 1, Comparative Example 1, Comparative Example 2.

[0034] Figure 8 Figure 10 is the CO Product Rate curve of Example 1, Comparative Example 1, Comparative Example 2.

[0035] Figure 9 Figure 11 is the CO2 Product Rate curve of Example 1, Comparative Example 1, Comparative Example 2.

[0036] Figure 10 Figure 12 is the SPR curve of Example 1, Comparative Example 1, Comparative Example 2.

[0037] Figure 11 Figure 13 is the THR curve of Example 1, Comparative Example 1, Comparative Example 2.

[0038] Figure 12 Figure 14 is the Raman spectrum of the residual char of Example 1, Comparative Example 1, Comparative Example 2. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application more clear, the preferred embodiments of the present application are further described in detail below in combination with examples. All other examples obtained by those skilled in the art without creative labor based on the examples in the present application belong to the scope of protection of the present application.

[0040] The present application provides an Ag@NH2-POSS-bisDOPO flame retardant, and a preparation scheme thereof is as follows:

[0041] S1, dissolving 0.34g of AgNO3 in 100mL of deionized water to obtain an AgNO3 aqueous solution;

[0042] S2, soaking 0.1g of NH2-POSS-bisDOPO flame retardant in the AgNO3 aqueous solution for swelling adsorption, the soaking time is 10h, after soaking, filtering and washing, the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 is prepared;

[0043] S3, dissolving 0.14g of NaBH4 in 200mL of deionized water to obtain a NaBH4 aqueous solution;

[0044] S4, soaking the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 in the NaBH4 aqueous solution, the soaking time is 12h, after soaking, filtering and drying (drying at 60℃ for 24h), Ag@bisDOPO-NH2-POSS flame retardant is obtained.

[0045] The following examples are all Ag@NH2-POSS-bisDOPO flame retardants prepared by the above method.

[0046] Example 1

[0047] A method for layer-by-layer self-assembly of flame-retardant and antibacterial coating on the surface of wood, and the specific steps are as follows:

[0048] (1) After surface cleaning, the wood is dried for standby use;

[0049] (2) Preparation of polycation composite electrolyte solution:

[0050] First, dissolve chitosan powder in 1% acetic acid aqueous solution to obtain a chitosan acetic acid aqueous solution with a chitosan mass concentration of 2%;

[0051] Then, add the Ag@NH2-POSS-bisDOPO flame retardant to the chitosan acetic acid aqueous solution, and mix uniformly to obtain a polycation composite electrolyte solution with an Ag@NH2-POSS-bisDOPO flame retardant mass concentration of 5%;

[0052] (3) Preparation of polyanionic electrolyte solution

[0053] Dissolve phytic acid in water to obtain a 2% phytic acid aqueous solution, i.e. a polyanionic electrolyte solution;

[0054] (4) Layer-by-layer self-assembly

[0055] ① The wood treated in step (1) is first immersed in the polycationic composite electrolyte solution for 5 min, washed to remove excess liquid on the surface, and then dried (drying temperature: 60°C) to obtain wood 1.

[0056] ② The wood 1 is immersed in the polyanionic electrolyte solution for 5 min, washed to remove excess liquid on the surface, and then dried (drying temperature: 60°C) to obtain wood 2.

[0057] ③ The steps ① and ② are repeated for 7 cycles, and finally dried to dryness in an oven at 100°C to obtain a 7-layer composite flame-retardant coating modified wood.

[0058] The number of layers of immersion in step (4) of Example 1 is adjusted to obtain composite flame-retardant coating modified woods with different numbers of layers, and the limiting oxygen index is detected according to the GB / T2406-93 standard, as shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] The mass concentration of Ag@NH2-POSS-bisDOPO flame retardant in the polycationic composite electrolyte solution in Example 1 is adjusted, and the rest of the process remains unchanged to obtain a 7-layer composite flame-retardant coating modified wood, and the limiting oxygen index is detected according to the GB / T2406-93 standard, as shown in Table 2.

[0063] Table 2

[0064]

[0065] The mass concentration of phytic acid in the polyanionic electrolyte solution in Example 1 is adjusted, and the rest of the process remains unchanged to obtain a 7-layer composite flame-retardant coating modified wood, and the limiting oxygen index is detected according to the GB / T2406-93 standard, as shown in Table 3.

[0066] Table 3

[0067] Mass concentration of phytic acid (%) Limiting oxygen index (%) 1 28.6 2 30.3 3 30.1

[0068] As can be seen from Tables 1-3, the mass concentration of Ag@NH2-POSS-bisDOPO flame retardant is selected as 5%, the mass concentration of phytic acid is selected as 2%, the process is considered to be simple, and the self-assembly layer is less the better while achieving the purpose of flame retardation, and 7 layers are selected for subsequent experiments.

[0069] Comparative Example 1

[0070] A method for layer-by-layer self-assembly of a flame-retardant and antibacterial coating on the surface of wood, referring to Example 1, the only difference is that NH2-POSS-bisDOPO flame retardant is used instead of Ag@NH2-POSS-bisDOPO flame retardant, and the rest of the process remains unchanged, obtaining a modified wood with a 7-layer composite flame-retardant coating.

[0071] Comparative Example 2

[0072] A method for layer-by-layer self-assembly of a flame-retardant and antibacterial coating on the surface of wood, referring to Example 1, the only difference is that Ag@NH2-POSS-bisDOPO flame retardant is not used, i.e., the polycationic composite electrolyte solution is only a 2% mass concentration chitosan acetic acid aqueous solution, and the rest of the process remains unchanged, obtaining a modified wood with a 7-layer composite flame-retardant coating.

[0073] Comparative Example 3

[0074] A method for layer-by-layer self-assembly of a flame-retardant and antibacterial coating on the surface of wood, the specific steps are as follows:

[0075] (1) After the wood is surface cleaned, it is dried for standby use;

[0076] (2) Preparation of polycationic composite electrolyte solution:

[0077] First, chitosan powder is dissolved in a 1% mass concentration acetic acid aqueous solution to obtain a 2% mass concentration chitosan acetic acid aqueous solution;

[0078] Then, the NH2-POSS-bisDOPO flame retardant is added to the chitosan acetic acid aqueous solution, and a polycationic composite electrolyte solution with a NH2-POSS-bisDOPO flame retardant mass concentration of 5% is obtained after mixing uniformly;

[0079] (3) Layer-by-layer self-assembly

[0080] ① The wood treated in step (1) is first immersed in the polycationic composite electrolyte solution for 5 min, then washed to remove excess liquid and dried (drying temperature is 60°C) to obtain wood 1;

[0081] ② Wood 1 is repeated step ① for 7 cycles, and finally dried to absolute dryness in a 100°C oven to obtain a modified wood with a 7-layer single flame-retardant coating.

[0082] Comparative Example 4

[0083] A method for layer-by-layer self-assembly of a flame-retardant antibacterial coating on the surface of wood, the specific steps are as follows:

[0084] (1) After the wood is surface cleaned, it is dried for standby;

[0085] (2) Preparation of polycationic complex electrolyte solution:

[0086] First, the chitosan powder is dissolved in an aqueous acetic acid solution with a mass concentration of 1% to obtain a chitosan acetic acid aqueous solution with a chitosan mass concentration of 2%;

[0087] Then, the Ag@NH2-POSS-bisDOPO flame retardant is added to the chitosan acetic acid aqueous solution, and after uniform mixing, a polycationic complex electrolyte solution with a mass concentration of 5% of Ag@NH2-POSS-bisDOPO flame retardant is obtained;

[0088] (3) Layer-by-layer self-assembly

[0089] ① The wood treated in step (1) is first immersed in the polycationic complex electrolyte solution for 5 min, then washed to remove the excess liquid and dried (drying temperature is 60°C) to obtain wood 1;

[0090] ② The wood 1 is repeated step ① for 7 cycles, and finally dried to absolute dryness in an oven at 100°C to obtain modified wood with 7 layers of single flame-retardant coating.

[0091] From Figure 1 As can be seen from a, the surface of the wood without any treatment has a small amount of residual carbon of ash, indicating complete combustion, and the residual carbon presents the relatively clear structure of the original material surface of the wood, such as pore, cell wall, etc. However, the disadvantage of this structure of residual carbon is that the external thermal oxygen can easily pass through and enter the inner layer of the matrix, making the combustion degree more severe. From Figure 1 b, c, it can be seen that the wood treated by comparative example 1 and example 1 has residual carbon, and the surface carbon layer has a dense small hole and presents a honeycomb-like and broken bubble morphology. It shows that during the combustion process, the flame-retardant modified sample promotes the thermal decomposition of the system and releases non-combustible gas, and the thermal oxidative decomposition of DOPO into oxygen-containing phosphoric acid which can accelerate the dehydration and carbonization of the system. At the same time, the Si-O-Si in the structure of POSS decomposes into SiO2 small particles covering on the carbon layer, and it is reasonably inferred that the flame-retardant mechanism conforms to the gas phase and condensed phase mechanism. And the outer layer presents a continuous and dense structure, which plays the role of physical protective layer, blocks the transfer of thermal oxygen to the inner layer of the matrix, and slows down the ablation of the internal matrix.

[0092] From Figure 2As can be seen, after four weeks, the inhibition zone of Aspergillus niger of Comparative Example 3 reached 2 mm, and the inhibition zone of Aspergillus niger of Comparative Example 4 reached 3 mm.

[0093] From Figure 3 As can be seen, after four weeks, Comparative Example 4 showed better antibacterial effect, and the inhibition zone of Colletotrichum gloeosporioides reached 4 mm. When against Colletotrichum gloeosporioides, the material treated by Comparative Example 4 could maintain the integrity of the sample, while the sample treated by Comparative Example 3 was full of mold, showing that Ag@bisDOPO-NH2-POSS has good antibacterial performance.

[0094] From Figure 4 , Figure 5 As can be seen, compared with Comparative Example 1, the carbon residue rate of Example 1 decreased slightly, and the decomposition temperature of Ag@bisDOPO-NH2-POSS was about 250°C, which was also the main weight loss stage. The reason is that the chitosan component contained in Ag@bisDOPO-NH2-POSS is easy to decompose at high temperature, thereby causing a large weight loss rate. Although the thermal stability is slightly insufficient compared with before loading silver, the weight loss rate per unit time is significantly weakened, which is due to the complex formed by the chelation of phytic acid and silver covering the surface of the carbon residue to reduce the internal contact with the air, making the overall thermal decomposition process slow, and the carbon residue amount tends to be consistent after 600°C, which is attributed to the synergistic effect of multiple flame-retardant elements.

[0095] From Figure 6 As can be seen, compared with Comparative Example 2, the HRR peak value of Example 1 and Comparative Example 1 is reduced. After the introduction of the POSS-based flame retardant, the PHRR peak value appears to be delayed, indicating that the carbon layer generated in the first stage of the sample treated by POSS is better protected. But compared with the PHRR of chitosan-phytic acid modified without introducing POSS, it is slightly higher, which may be because the dispersion degree of P and Si elements in the modified material is low, but the heat release peak value of the modified material without introducing POSS appears in advance. This is not conducive to rescue in the event of a fire. But the peak value of the treated material with the introduction of POSS is significantly reduced and the appearance time is delayed, and the HRR is reduced by 42%. Compared with Comparative Example 1, the lower HRR of Example 1 may be due to the chelation of metal ions and phosphorus, which reduces the acidity of the reaction system, and the complex generated on the surface of the wood effectively inhibits the release of heat.

[0096] From Figure 7It can be seen from the figure that the slope of the THR curve shows that the embodiment 1 and the comparative example 1 are obviously slower than the comparative example 2, which may be due to the induction of chitosan to make the POSS deposited on the cell wall of the wood to form a hybrid structure, or may be caused by the combustion of more organic residues in the wood after modification. Meanwhile, the large amount of phosphorus element contained in the phytic acid can not only produce phosphoric acid and oxidized phosphorus to promote carbonization, but also can be used as a strong dehydrating agent to decompose many polymers in the wood to form carbonates and play a protective covering role when the sample is heated, and finally inhibit the spread of the flame.

[0097] From Figure 8 It can be seen from the figure that after about 200s, the curve shows a sharp peak, indicating that the CO release after the comparative example 2 is mainly released in the red-hot stage of the sample. At the same time, it shows that although the phytic acid can inhibit the thermal decomposition of poplar, it can increase the amount of CO release. The increase in the production of CO is due to the large amount of P element in the phytic acid and the P and N elements in the POSS, which are decomposed into NH3, PO·, polyphosphoric acid, and block air by covering and generating non-combustible gases, so that the phosphorus-containing flame retardant achieves the purpose of flame retardation. Especially after 360s, the sample is in the combustion stage because of the presence of phosphorus and nitrogen elements, which catalyze the sample and form more residual carbon, so that the internal combustion of the sample is incomplete, hindering the combustion of the sample, and therefore a large amount of toxic gas represented by CO is produced, resulting in an increase in COP.

[0098] From Figure 9 It can be seen from the figure that the generation of CO2 in the embodiment 1, the comparative example 1 and the comparative example 2 is mainly in the flaming combustion stage of the sample. The phytic acid can effectively inhibit the release of CO2 in the combustion process of the wood. And after the introduction of the POSS, the peaks of CO2P all appear after moving and are lower than the phytic acid, indicating that the carbon layer combustion lags behind.

[0099] From Figure 10 , Figure 11 It can be seen from the figure that the smoke release rate (SPR) of the wood is similar to the heat release rate curve. The first peak appears at about 50s, and at the moment of ignition, the sample will produce a large amount of smoke, and the water attached to the inside of the poplar will evaporate due to heating. After the wood is ignited, it enters the flaming combustion stage, and the smoke release rate first increases and then decreases. The total smoke yield of the comparative example 2 is higher than that of the other treatment groups. A curve valley appears at about 200s, mainly because the carbon protective layer is formed on the surface of the poplar, so the smoke release is reduced. But with the gradual increase of the combustion temperature, the carbon layer gradually produces cracks leading to cracking, at this time a second peak value appears, which appears after about 100s, and the SPR also reaches a peak value, releasing a large amount of smoke.

[0100] From Figure 12 It can be seen from the figure that in the spectrum of all samples, a sharp peak at 1350cm -1 and a sharp peak at 1600cm -1The two distinct peaks are called D band and G band. By comparing the ratio of the area of D peak to G peak (R = ID / IG), the smaller the ratio, the higher the degree of graphitization. The R of Comparative Example 2, Comparative Example 1, Example 1 is 2.65, 2.56, 2.69 respectively. The R of all the examples with the introduction of POSS-based flame retardant is lower than that of Comparative Example 2, indicating that the compactness of the residual carbon is enhanced, which can act as a physical barrier to oxygen and heat, and the R of Comparative Example 1 is the lowest, which is 2.56, indicating that the carbon layer has stronger stability.

[0101] The embodiments described above are part of, but not all, embodiments of the present application. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

Claims

1. Use of Ag@NH2-POSS-bisDOPO flame retardant characterized in that, It comprises the following steps: (1) After the wood surface is cleaned, it is dried for standby; (2) Preparation of polycationic complex electrolyte solution: First, the chitosan powder is dissolved in 1% acetic acid aqueous solution to obtain a chitosan acetic acid aqueous solution with a chitosan mass concentration of 2%; Then, the Ag@NH2-POSS-bisDOPO flame retardant is added to the chitosan acetic acid aqueous solution, and after uniform mixing, a polycationic complex electrolyte solution with a mass concentration of 5% of Ag@NH2-POSS-bisDOPO flame retardant is obtained; (3) Preparation of polyanion electrolyte solution Phytic acid is dissolved in water to obtain a phytic acid aqueous solution with a mass concentration of 2%, which is the polyanion electrolyte solution; (4) Layer-by-layer self-assembly The wood treated in step (1) is first immersed in the polycationic complex electrolyte solution for 5-30 min, then washed to remove excess liquid on the surface and dried, then immersed in the polyanion electrolyte solution for 5-10 min, then washed to remove excess liquid on the surface and dried, and then the cycle of immersion is repeated; finally, dry to absolute; The Ag@NH2-POSS-bisDOPO flame retardant is prepared by in-situ reaction of NH2-POSS-bisDOPO flame retardant with AgNPs.

2. Use of Ag@NH2-POSS-bisDOPO flame retardant according to claim 1, characterized in that, The preparation method of the flame retardant comprises the following steps: S1, dissolve AgNO3 in deionized water to obtain a AgNO3 aqueous solution with a mass concentration of 0.3%-0.5%; S2, soak the NH2-POSS-bisDOPO flame retardant in the AgNO3 aqueous solution for swelling and adsorption, the soaking time is 5-24h, after soaking, filter and wash, the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 is prepared; S3, dissolve NaBH4 in deionized water to obtain a NaBH4 aqueous solution with a mass concentration of 0.05%-0.8%; S4, soak the NH2-POSS-bisDOPO flame retardant adsorbed with AgNO3 in the NaBH4 aqueous solution, the soaking time is 12 hours, after soaking, filter and dry to obtain the Ag@bisDOPO-NH2-POSS flame retardant.

3. The use according to claim 1, wherein The drying temperature of step (1) is 60℃, and the drying time is 30min.

4. The use according to claim 1, wherein The drying temperature of step (4) is 60-100℃.

5. The use according to claim 3, wherein the compound is ###0002### The number of cycle immersions of step (4) is 5-15 times.

6. The use according to claim 5, wherein the compound is ###0002### The number of cycle immersions of step (4) is 7 times.

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