Broad temperature range amino-functionalized polyphosphazene, method for preparing same and use thereof

Abstract

This invention relates to a polymeric material, polyphosphazene, specifically to a wide-temperature-range amino-functionalized polyphosphazene, its preparation method, and its applications. This invention is the first to use a BOC group as a protecting group, introducing phenoxy and trifluorooxy groups onto the polyphosphazene. When the introduced group is phenoxy, the amino-functionalized polyphosphazene is a high-temperature-resistant poly(phenoxy / tyrosine)phosphazene. When the introduced group is trifluorooxy, the amino-functionalized polyphosphazene is a high-temperature-resistant poly(trifluorooxy / tyrosine)phosphazene. This invention successfully prepares a polyphosphazene material with excellent high-temperature and low-temperature resistance, expanding the application range of polyphosphazene materials in extreme temperature environments.

Description

Technical Field

[0001] This invention relates to a polymeric material, polyphosphazene, and more specifically, to a wide-temperature-range amino-functionalized polyphosphazene, its preparation method, and its applications. Background Technology

[0002] Polyphosphazenes are organic-inorganic hybrid polymers whose main chain consists of alternating single and double bonds of phosphorus and nitrogen atoms, while the side chains are replaced by organic groups. They are formed by nucleophilic substitution reactions between polydichlorophosphazene (PDCP) or hexachlorocyclotriphosphazene (HCCP) molecules and various reactive monomers, resulting in high-molecular-weight linear, branched, dendritic, and cross-linked structures. Linear polyphosphazenes, due to their molecular structure and flexible main chain, possess high-temperature resistance and high mechanical properties, making them a promising candidate for applications in high-temperature materials, biomaterials, and coating materials.

[0003] Sometimes, to further enhance the performance of linear polyphosphazenes or improve their overall properties, it is necessary to introduce reactive functional groups, such as carboxyl, hydroxyl, amino, and epoxy groups, into the polymer chain. Among these, amino groups, as a class of reactive functional groups, have wide applications, such as in biomedicine, amino resin synthesis, and epoxy curing. Introducing different amino functional groups into the polymer chain of linear polyphosphazenes can yield functionalized amino-functionalized polyphosphazenes. Zhu et al. developed amino-functionalized polyphosphazene vesicles for the encapsulation and delivery of carboplatin; they synthesized three polyphosphazenes with different amino contents by amidation of hydrophobic side groups, which can self-assemble into an amino-functionalized polymer nanovesicle to improve the therapeutic efficacy of carboplatin as an antitumor drug. Morozowich prepared amino-functionalized polyphosphazenes with tyramine and ferulic acid-based side groups and crosslinked them with aldehyde-functionalized dextran via Schiff base chemical crosslinking to form hydrogels. It is evident that the functions of the prepared amino-functionalized polyphosphazenes differ significantly depending on the amino functional groups introduced into the polymer chain of linear polyphosphazenes.

[0004] Furthermore, in the substitution process of amino-functionalized polyphosphazenes, the presence of active hydrogen in the amino group may lead to side reactions such as branching and cross-linking. Therefore, a two-stage reaction is generally used to introduce the amino group into the organic side group of the polyphosphazene. Common methods fall into two main categories: one is through the protection and deprotection of the amino group, i.e., after combining the active hydrogen of the amino group with a protecting group, the chlorine atom of the polyphosphazene side group is substituted, and after complete substitution, the protecting group is removed through a reaction to obtain the amino group; the other is through steps such as the hydrolysis of nitro-reduced amines to ultimately obtain the amino group. Summary of the Invention

[0005] The purpose of this invention is to provide a polyphosphazene with excellent high-temperature resistance or excellent low-temperature resistance, its preparation method, and its application.

[0006] This invention introduces amino functional groups into polyphosphazene and, for the first time, uses BOC groups as protecting groups to successfully introduce phenoxy and trifluorooxy groups, thus successfully preparing polyphosphazene materials with excellent high-temperature and low-temperature resistance, expanding the application range of polyphosphazene materials in extreme temperature environments.

[0007] One of the objectives of this invention is to provide a wide-temperature-range amino-functionalized polyphosphazene.

[0008] The aminopolyphosphazene has a linear structure and includes structural units shown in Formula 1, Formula 2 and Formula 3.

[0009]

[0010] The R is selected from

[0011] The total molar amount of R in the structural units shown in Equations 1, 2, and 3 The ratio of the total molar amounts is 1:(1±0.05).

[0012] When R is In this case, the amino polyphosphazene is a high-temperature resistant polyphosphazene—poly(phenoxy / tyramine)phosphazene. The number-average molecular weight of the poly(phenoxy / tyramine)phosphazene is 40,000–50,000, preferably 44,000–46,000, for example, 45269; the molecular weight distribution of the poly(phenoxy / tyramine)phosphazene is 2–2.5, preferably 2.3–2.4, for example, 2.38; and the glass transition temperature of the poly(phenoxy / tyramine)phosphazene is 40–100°C.

[0013] When R is The amino-polyphosphazene is a low-temperature resistant polyphosphazene—poly(trifluoroethoxy / tyramine)phosphazene. The number-average molecular weight of the poly(trifluoroethoxy / tyramine)phosphazene is 50,000–60,000, preferably 55,000–57,000, for example, 56071; the molecular weight distribution of the poly(trifluoroethoxy / tyramine)phosphazene is 2.5–3.0, preferably 2.8–3.0, for example, 2.9; the glass transition temperature of the poly(trifluoroethoxy / tyramine)phosphazene is -40 to -100°C.

[0014] A second objective of this invention is to provide a method for preparing the aminopolyphosphazene described in one of the objectives of this invention.

[0015] The preparation method includes:

[0016] (1) N-BOC-tyramine reacts with NaH to obtain N-BOC-tyramine sodium salt;

[0017] (2) Hexachlorocyclotriphosphazene ring-opening polymerization yields polydichlorophosphazene;

[0018] (3) N-BOC-tyramine sodium salt, a modifying agent, and polydichlorophosphazene are reacted to obtain poly(M / N-BOC-tyramine)phosphazene; the modifying agent is sodium phenolate or sodium trifluoroethanol, and M is...

[0019] (4) The BOC group (tert-butoxycarbonyl) on poly(M / N-BOC-tyramine) phosphazene is removed by hydrogen chloride to obtain amino polyphosphazene.

[0020] Step (1) includes: adding N-BOC-tyramine solution dropwise to NaH under ice bath conditions until NaH reacts completely.

[0021] In step (1), since polydichlorophosphazene can dissolve well in tetrahydrofuran solution, the sodium salt solution of its substituents must also be a tetrahydrofuran solvent; that is, the solvent of the N-BOC-tyramine solution is tetrahydrofuran.

[0022] Step (2) includes: under the protection of a protective gas, hexachlorocyclotriphosphazene is dissolved in an organic solvent and reacted at 200℃~215℃ with a catalyst and a co-catalyst until the product exhibits a cladding effect. After cooling, polydichlorophosphazene is precipitated.

[0023] In step (2), the protective gas is nitrogen to ensure that the system is free of oxygen and water.

[0024] In step (2), the organic solvent is 1,2,4-trichlorobenzene or α-chloronaphthalene. The ring-opening polymerization of cyclic phosphazenes to linear polyphosphazenes is a solution polymerization process, requiring a high reaction temperature. 1,2,4-trichlorobenzene, as a solvent, does not participate in the reaction and has a high boiling point; therefore, as a preferred option, 1,2,4-trichlorobenzene is used as the solvent.

[0025] In step (2), the catalyst is aminosulfonic acid or p-toluenesulfonic acid. Aminosulfonic acid is commonly used in experiments to create an acidic environment for the polymerization process; therefore, as a preferred option, the catalyst is aminosulfonic acid.

[0026] In step (2), the co-catalyst is calcium carbonate dihydrate or calcium sulfate dihydrate. The water of crystallization of calcium carbonate dihydrate or calcium sulfate dihydrate reacts with chloride ions on the cyclic polyphosphazene to generate hydrogen chloride, thereby promoting the above-mentioned acid catalysis.

[0027] In step (2), the mass ratio of hexachlorocyclotriphosphazene to organic solvent is (4-5):(5-6).

[0028] In step (2), the molar ratio of catalyst, co-catalyst and hexachlorocyclotriphosphazene is (0.015-0.020):(0.01-0.015):1.

[0029] In step (2): the reaction time is 4 to 8 hours; the "precipitation of polydichlorophosphazene after cooling" includes: precipitating polydichlorophosphazene with ultra-dry n-heptane or ultra-dry n-hexane after cooling to below 90°C.

[0030] Step (3) includes: under ice bath and stirring conditions, polydichlorophosphazene solution is added dropwise to a mixed solution of N-BOC-tyramine sodium salt, modified material and phase transfer catalyst, and reacted at room temperature until the system shows gelation phenomenon. The temperature is raised to 50-60℃ and heated to reflux. After the reflux reaction is completed, the precipitate is precipitated with extraction solvent. The precipitate is poly(M / N-BOC-tyramine)phosphazene.

[0031] In step (3), the phase transfer catalyst is tetrabutylammonium bromide.

[0032] In step (3), the solvent for the polydichlorophosphazene solution is tetrahydrofuran or xylene. However, the polydichlorophosphazene has low solubility in xylene, and a large amount of xylene is required for dissolution; therefore, as a preferred option, the solvent for the polydichlorophosphazene solution is tetrahydrofuran.

[0033] In step (3), the solvent of the mixed solution is tetrahydrofuran or xylene. The solvent of the mixed solution should be the same as the solvent of the polydichlorophosphazene solution.

[0034] In step (3), the extraction solvent is n-hexane or deionized water. Compared to deionized water, n-hexane has a lower boiling point and is easier to remove; therefore, as a preferred option, the extraction solvent is n-hexane.

[0035] In step (3), the molar ratio of polydichlorophosphazene, N-BOC-tyramine sodium salt, modified material and phase transfer catalyst is 1:(0.5~0.6):(0.5~0.6):(0.015~0.02), preferably 1:0.5:0.5:0.02.

[0036] In step (3), the polydichlorophosphazene solution is added dropwise in an ice bath with stirring to prevent the solution from boiling. After the addition is completed, the solution is slowly restored to room temperature.

[0037] In step (3), the endpoint of the reflux reaction is monitored by phosphorus NMR spectroscopy. The reflux reaction time is usually 48 hours.

[0038] In step (3), after the reflux reaction is completed, the reaction system can be heated to 90°C to evaporate and recover the tetrahydrofuran concentrated reaction solution in the system. When the system is distilled down to about one-quarter of its original volume, the precipitate is precipitated using an extraction solvent.

[0039] Step (4) includes: under stirring conditions, adding hydrochloric acid dropwise to the tetrahydrofuran solution of poly(M / N-BOC-tyramine)phosphazene until the pH drops to 1, continuing to stir the reaction until the BOC group is completely removed, adding excess sodium carbonate and stirring, filtering, and using an extraction solvent to precipitate the filtrate, the resulting precipitate being aminopolyphosphazene.

[0040] In step (4), the removal of the BOC group is monitored by 1H NMR spectroscopy.

[0041] One method for preparing the aminopolyphosphazene includes:

[0042] (1) Under ice bath conditions, N-BOC-tyramine tetrahydrofuran solution was added dropwise to NaH. The system produced a large number of bubbles and turned dark green until NaH was completely reacted.

[0043] (2) Under nitrogen protection, hexachlorocyclotriphosphazene was dissolved in 1,2,4-trichlorobenzene and reacted at 200℃~215℃ for 4~8h with aminosulfonic acid as catalyst and calcium carbonate dihydrate as co-catalyst until the product showed a cladding effect. After cooling to below 90℃, polydichlorophosphazene was precipitated in ultra-dry n-heptane solvent. The mass ratio of hexachlorocyclotriphosphazene to 1,2,4-trichlorobenzene was 5:6, and the molar ratio of catalyst, co-catalyst to hexachlorocyclotriphosphazene was 0.02:0.015:1. Polydichlorophosphazene was dissolved in ultra-dry tetrahydrofuran solvent for later use.

[0044] (3) Under ice bath and stirring conditions, the tetrahydrofuran solution of polydichlorophosphazene was added dropwise to a mixed solution of BOC-tyramine sodium salt, modified material and phase transfer catalyst. The addition process was carried out in an ice bath with stirring to prevent the solution from boiling. After the addition was completed, the temperature was slowly restored to room temperature and the reaction continued for 3 hours. The system showed obvious gelation phenomenon. The temperature was raised to 60°C and refluxed for 48 hours. The reaction endpoint was monitored by NMR phosphorus spectrum. After the reaction was completed, the temperature was raised to 90°C to evaporate and recover the tetrahydrofuran and concentrate the reaction solution in the system. When about one-quarter of the system remained, the precipitate was precipitated with n-hexane solvent. The precipitate was poly(M / BOC-tyramine)phosphazene. The phase transfer catalyst was tetrabutylammonium bromide. The solvent of the mixed solution was tetrahydrofuran. The molar ratio of polydichlorophosphazene, BOC-tyramine sodium salt, modified material and phase transfer catalyst was 1:0.5:0.5:0.02.

[0045] (4) Under stirring conditions, hydrochloric acid was added dropwise to the tetrahydrofuran solution of poly(M / BOC-tyramine)phosphazene until the pH dropped to 1. The reaction was continued for 48 hours with stirring. The removal of the protecting group was monitored by nuclear magnetic resonance spectroscopy until the BOC group was completely removed. Excess sodium carbonate was added and stirred. The mixture was filtered and the filtrate was precipitated with n-hexane. The precipitate obtained was aminopolyphosphazene.

[0046] The synthetic route for step (2) is as follows:

[0047]

[0048] The overall synthetic route for steps (3) and (4) is as follows:

[0049]

[0050] The third objective of this invention is to provide an application of the amino polyphosphazene described in the first objective of the invention or the amino polyphosphazene prepared by the preparation method described in the second objective of the invention in the field of flame retardant additives or heat protection coatings.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] The aminopolyphosphazene provided by this invention has the following effects:

[0053] This invention successfully introduces amino functional groups onto polyphosphazenes. The amino group is a highly useful active site, allowing for various subsequent modifications. Furthermore, the amino group can form hydrogen bonds, enhancing the material's cohesion and interactions with other substances. The degree of amino group introduction can be precisely controlled by adjusting the sodium salt dosage. The presence of the amino group provides potential for further functionalization and modification. It can undergo acylation reactions with acid anhydrides or acyl chlorides, react with aldehydes or ketones to form imines, undergo addition reactions with epoxides, isocyanates, etc., or undergo coupling reactions with other molecules via coupling agents. It can also be further expanded to include the introduction of other protected functional groups such as thiols and carboxylic acids. Click chemistry can be used for post-modification, or photoresponsive or thermoresponsive groups can be introduced to design smart materials.

[0054] The aminopolyphosphazene provided by the present invention, when R is In this case, the amino polyphosphazene is a high-temperature resistant polyphosphazene—poly(phenoxy / tyramine)phosphazene. Poly(phenoxy / tyramine)phosphazene is grafted with tyramine and phenoxy groups as side groups of the phosphazene. The tyramine group contains a benzene ring and an amino group, providing thermal stability and reactivity to the molecule, while the phenoxy group increases rigidity and thermal stability. Its high-temperature resistance is due to the following: the benzene ring structure provides thermal stability, absorbing and dispersing heat energy; simultaneously, the π-π stacking effect between benzene rings enhances the overall stability of the polymer; the exposed amino group may form intermolecular or intramolecular hydrogen bonds, further stabilizing the structure; the presence of the benzene ring increases the glass transition temperature of the polymer, allowing the material to maintain rigidity at high temperatures.

[0055] The aminopolyphosphazene provided by the present invention, when R is The aforementioned amino-polyphosphazene is a low-temperature resistant polyphosphazene—poly(trifluoroethoxy / tyramine)phosphazene. The tyramine group in poly(tyramine / trifluoroethoxy)phosphazene possesses a certain degree of flexibility, while the trifluoroethoxy group introduces fluorine atoms, lowering the glass transition temperature. This allows the material to maintain flexibility at low temperatures. Its presence may increase the free volume between polymer chains, improving low-temperature fluidity. Simultaneously, the introduction of fluorine atoms can reduce intermolecular interactions, increase chain segment flexibility, and also inhibit low-temperature crystallization.

[0056] This invention successfully developed a polyphosphazene material with excellent high-temperature and low-temperature resistance, expanding the application range of polyphosphazene materials in extreme temperature environments and providing a new solution for material requirements in extreme environments. The phosphazene material provided by this invention has multiple functions, such as pH responsiveness and modifiability, thereby expanding its application potential.

[0057] The preparation method of the present invention has the following effects:

[0058] 1. Increased selectivity

[0059] In traditional methods, amino compounds are directly reacted with polydichlorophosphazene. This reaction often suffers from difficulty in controlling the degree of substitution, and the amino group readily reacts directly with polydichlorophosphazene, leading to numerous side reactions. In contrast, this invention employs BOC protection followed by nucleophilic substitution. BOC protection offers advantages such as good stability, resistance to removal in subsequent reactions, selective removal under mild acidic conditions, increased molecular size, and reduced nucleophilicity of the amino group. During the subsequent nucleophilic substitution reaction, the chloride ion on the linear polyphosphazene is highly reactive. BOC protection reduces the reactivity of the amino group, allowing the nucleophilic substitution site to shift to the sodium oxy group formed by treating the hydroxyl group with sodium hydride. The subsequent preparation of N-BOC-tyramine sodium salt significantly enhances the nucleophilicity of the N-BOC-tyramine group, increases its solubility in nonpolar solvents, and improves its reactivity with polydichlorophosphazene. The key to this step lies in precisely controlling the degree of BOC protection to ensure the selectivity of subsequent reactions. It is also crucial to ensure the complete conversion of the N-BOC-tyramine group to the sodium salt to maximize the efficiency of subsequent substitution reactions. Strict anhydrous conditions must be maintained throughout the reaction to avoid side reactions. Through this step, we obtained a more active and selective intermediate, laying the foundation for subsequent reactions with polydichlorophosphazene. Furthermore, this pretreatment significantly improves the homogeneity and functionalization of the final product.

[0060] 2. Increased nucleophilicity

[0061] In this invention, N-BOC-tyramine is reacted with sodium hydride to form N-BOC-tyramine sodium salt, which is then further reacted with polydichlorophosphazene to undergo a nucleophilic substitution reaction to replace the chlorine atoms on the polyphosphazene backbone. Treating N-BOC-tyramine with sodium hydride to form a sodium salt significantly improves the nucleophilicity of the substituents. The subsequent nucleophilic substitution reaction is typically carried out in anhydrous polar aprotic solvent. Due to the increased nucleophilicity, the reaction can proceed in the temperature range from room temperature to reflux, while requiring inert gas protection to prevent hydrolysis. The reaction progress needs to be monitored using 31PNMR. By increasing the nucleophilicity of the substituents, the reactivity of the amino group after BOC protection is further reduced, minimizing over-substitution. Simultaneously, the degree of substitution can be more precisely controlled, achieving specific performance adjustments to obtain a more homogeneous product.

[0062] 3. Improved controllability

[0063] This invention aims to achieve precise control over the structure and properties of products through protecting group strategies and optimized reaction conditions. Simultaneously, this invention optimizes the synthesis process and post-processing methods, improving product purity and yield while reducing side reactions. By precisely controlling the synthesis strategy of aminopolyphosphazenes and introducing diverse functional groups, this invention significantly enhances the functionalization degree and potential of polyphosphazenes. Attached Figure Description

[0064] Figure 1 The phosphorus NMR spectrum of the polydichlorophosphazene prepared in Example 1;

[0065] Figure 2 The infrared spectra of di-tert-butyl dicarbonate, p-hydroxyphenylethylamine, and [2-(4-hydroxyphenyl)ethyl]carbamate tert-butyl ester prepared in Example 1 are shown.

[0066] Figure 3 The 1H NMR spectrum of [2-(4-hydroxyphenyl)ethyl]carbamate tert-butyl ester prepared in Example 1;

[0067] Figure 4 The carbon NMR spectrum of tert-butyl [2-(4-hydroxyphenyl)ethyl]carbamate prepared in Example 1;

[0068] Figure 5 The carbon NMR spectrum and Dept135 spectrum of the N-BOC-tyramine sodium salt prepared in Example 1;

[0069] Figure 6 The GPC spectrum of the poly(phenoxy / N-BOC-tyramine) phosphazene prepared in Example 1;

[0070] Figure 7 The phosphorus NMR spectrum of the poly(phenoxy / N-BOC-tyramine) phosphazene prepared in Example 1;

[0071] Figure 8 The 1H NMR spectrum of the poly(phenoxy / N-BOC-tyramine)phosphazene prepared in Example 1;

[0072] Figure 9 The infrared spectrum of the poly(phenoxy / N-BOC-tyramine) phosphazene prepared in Example 1;

[0073] Figure 10 The infrared spectrum of the poly(phenoxy / tyramine)phosphazene prepared in Example 1;

[0074] Figure 11 The GPC spectrum of poly(trifluorooxy / N-BOC-tyramine)phosphazene prepared in Example 2;

[0075] Figure 12 The phosphorus NMR spectrum of the poly(trifluorooxy / N-BOC-tyramine) phosphazene prepared in Example 2;

[0076] Figure 13 The infrared spectrum of the poly(trifluoroethoxy / tyramine)phosphazene prepared in Example 2;

[0077] Figure 14 Thermogravimetric curve of poly(phenoxy / tyramine)phosphazene prepared in Example 1;

[0078] Figure 15 Thermogravimetric curve of poly(trifluoroethoxy / tyramine)phosphazene prepared in Example 2. Detailed Implementation

[0079] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0080] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0081] Table 1 lists the raw materials involved in the embodiments. Table 2 lists the instruments involved in the embodiments.

[0082] Table 1. Raw materials used in the embodiments.

[0083]

[0084] The hexachlorocyclotriphosphazene mentioned in Table 1 needs to be dissolved in ultra-dry n-heptane, heated to remove water and recrystallize before use. All other raw materials mentioned are purchased and used after use.

[0085] Table 2. Instruments used in the embodiments

[0086]

[0087] 1 1H NMR Sample Preparation: Weigh approximately 8-10 mg of sample and dissolve it in a 2 ml centrifuge tube containing 0.6 ml of deuterated DMSO. Shake to dissolve and transfer to an NMR tube using a Pasteur pipette. The 1H NMR spectrometer used tetramethylsilane (TMS) as a reference and was tested at a frequency of 400 MHz.

[0088] Solid-state NMR 32 P NMR sample preparation: Weigh approximately 100 mg of sample, grind the sample into a fine powder, and ensure that the sample is dry, non-conductive, non-magnetic, uniform powder or non-elastic film; the sample should be stable and stable under high-speed rotation or strong radiation for solid-state NMR testing.

[0089] Infrared FTIR sample preparation: solid samples are directly cut to a size greater than 5 mm. 2 The sample is used directly for testing; the powder sample is ground and mixed evenly with KBr in an agate mortar and then pressed into a tablet for infrared testing.

[0090] Gel permeation chromatography (GPC) sample preparation: Weigh 6-10 mg of the post-processed and dried product and dissolve it in DMAC to prepare a solution with a concentration of 3-5 mg / mL. -1 The polymer solution was thoroughly dissolved by shaking and then injected into a 2 ml sample vial through an organic filter membrane with a pore size of 0.22 μm. The instrument was operated at a test temperature of 50℃ and a flow rate of 1 mL / min. -1 The results were obtained by processing the monodisperse polystyrene standard curve to obtain information on the molecular weight and molecular weight distribution of the samples.

[0091] Example 1

[0092] 1.1 Recrystallization of hexachlorocyclotriphosphazene

[0093] Add hexachlorocyclotriphosphazene to a three-necked flask, add a certain amount of ultra-dry n-heptane solvent to the flask until it slightly covers the hexachlorocyclotriphosphazene crystals, add a magnetic stir bar and stir, heat to 100℃, heat under reflux for 4 hours, pour out the reagent in the flask while it is hot, remove the n-heptane solvent after cooling, and place it in a vacuum oven for sublimation purification, and store it in a sealed container for later use.

[0094] 1.2 Preparation of polydichlorophosphazene

[0095] 60g of recrystallized hexachlorocyclotriphosphazene was weighed and added to a three-necked flask. Then, 50ml of 1,2,4-trichlorobenzene was weighed and added to the flask. Nitrogen gas was continuously bubbled into the flask, and the mixture was stirred and slowly heated to 100°C. Stirring continued until the hexachlorocyclotriphosphazene was completely dissolved. The temperature was then raised to 190°C, and the nitrogen gas was stopped. At this point, 127mg of aminosulfonic acid catalyst and 112mg of calcium carbonate dihydrate co-catalyst were added. The temperature was further raised to the reaction temperature of 218°C. After approximately 4 hours of reaction, the viscosity of the system increased. Heating was stopped when the product exhibited an encapsulation effect. After the product cooled to below 90°C, the precipitate was precipitated using ultra-dry n-heptane solvent.

[0096] The NMR phosphorus spectrum of the precipitate is as follows Figure 1 As shown. Figure 1 The result shows only a single peak at -18.24 ppm, which is the phosphorus-chlorine bond on the polydichlorophosphazene macromolecular chain. This indicates that the precipitate is polydichlorophosphazene.

[0097] Polydichlorophosphazene was dissolved in ultra-dry tetrahydrofuran to obtain a polydichlorophosphazene tetrahydrofuran solution for later use.

[0098] Preparation of 1.3N-BOC-tyramine sodium salt

[0099] (1) Amino protection of tyramine

[0100] 0.155 mol of tyramine (p-hydroxyphenylethylamine) was weighed into a flask, and THF was added and stirred to disperse it. 0.003 mol of NaHCO3 was added as a catalyst, and an ice bath was used to maintain the reaction system. Then, 0.155 mol of di-tert-butyl dicarbonate was weighed, dissolved in THF, and slowly added dropwise to the flask. The reaction was carried out at room temperature for 12 hours. As the reaction proceeded, the product was continuously generated and dissolved in the reaction solvent system, eventually forming a pale yellow, homogeneous, and transparent solution. Rotary evaporation and concentration yielded a yellow oily product.

[0101] Infrared spectroscopy was used to analyze di-tert-butyl dicarbonate, p-hydroxyphenylethylamine, and the prepared yellow oily product. Their infrared spectra are as follows: Figure 2 As shown. Figure 2 In the image, the blue curve represents the infrared spectrum of di-tert-butyl dicarbonate, the red curve represents the infrared spectrum of p-hydroxyphenylethylamine, and the black curve represents the infrared spectrum of the prepared yellow oily product. Figure 2 The infrared spectrum of the yellow oily product shows that at 1810 cm⁻¹... -1 The characteristic absorption peak of the carbonyl group in the acid anhydride weakens and disappears, and is located at 1684 cm⁻¹. -1 The characteristic absorption peak of the newly formed amide group indicates that the amino group combines with the acid anhydride during the reaction to generate the target product [2-(4-hydroxyphenyl)ethyl] tert-butyl carbamate (abbreviated as N-BOC-tyramine).

[0102] The 1H NMR spectrum of the target product [2-(4-hydroxyphenyl)ethyl]carbamate tert-butyl ester is as follows: Figure 3 As shown;

[0103] The carbon NMR spectrum of the target product [2-(4-hydroxyphenyl)ethyl] tert-butyl carbamate is as follows: Figure 4 As shown;

[0104] Depend on Figure 3 , Figure 4 It can be concluded that the protective reaction is clean and complete, with no obvious impurities or byproducts, yielding N-BOC-tyramine.

[0105] (2) Preparation of N-BOC-tyramine sodium salt

[0106] Weigh 0.155 mol of NaH and add it to a three-necked flask. Wash the flask three times with ultra-dry THF to remove the kerosene component. Weigh 0.155 mol of N-BOC-tyramine, dissolve it in THF, and add it to a constant pressure funnel. Slowly add the solution dropwise to the three-necked flask under ice bath conditions. The system produces a large number of bubbles and turns dark green. After the reaction is complete, add 0.003 mol of tetrabutylammonium bromide to obtain a sodium salt solution of N-BOC-tyramine containing tetrabutylammonium bromide.

[0107] The NMR 1C and Dept135 spectra of N-BOC-tyramine sodium salt aqueous solution (excluding tetrabutylammonium bromide) are as follows: Figure 5 As shown; Figure 5 In the image, the red curve represents the carbon NMR spectrum of the N-BOC-tyramine sodium salt aqueous solution, and the black curve represents the Dept135 spectrum of the N-BOC-tyramine sodium salt aqueous solution. Figure 5 The peak pattern in the Dept135 spectrum is as follows: CH is a negative peak, CH and CH2 are positive peaks, and quaternary carbons do not show peaks in the Dept spectrum. Therefore, comparing it with the normal carbon spectrum can determine the corresponding chemical shift of each carbon atom in the analyte molecule in different chemical environments. Figure 4 A comparison of the carbon spectroscopy (CPS) of N-BOC-tyramine reveals the following changes in the chemical shifts of carbon atoms on the benzene ring adjacent to the phenolic hydroxyl group after sodium substitution: the chemical shifts of the carbon atoms directly bonded to the hydroxyl group and the adjacent carbon atoms increase, the chemical shift of the meta carbon remains unchanged, and the chemical shift of the para carbon decreases; this is consistent with the changes in electron cloud density. A comparison of the two spectra confirms the successful preparation of N-BOC-tyramine sodium salt, indicating complete reaction of the corresponding phenolic hydroxyl group without any side reactions.

[0108] 1.4 Synthesis of poly(phenoxy / N-BOC-tyramine)phosphazene

[0109] The N-BOC-tyramine sodium salt solution containing tetrabutylammonium bromide (containing 0.155 mol of N-BOC-tyramine sodium salt) prepared in the above steps was mixed with 0.155 mol of sodium phenolate in THF solution to obtain a mixed system. An ice bath and a mechanical stirrer were added. The polydichlorophosphazene tetrahydrofuran solution obtained in step 1.2 (containing 0.155 mol of polydichlorophosphazene, each phosphazene structural unit has two active chloride ions that can undergo nucleophilic substitution) was added dropwise to the mixed system using a constant pressure funnel. After reacting for 2 hours, the ice bath was removed, and the reaction continued at room temperature for 3 hours. The system showed obvious gelation. The temperature was raised to 60°C and refluxed for 48 hours (the reaction endpoint was monitored by NMR phosphorus spectrum). Finally, the temperature was raised to 90°C to evaporate and recover the tetrahydrofuran in the system to concentrate the reaction solution. When about one-quarter of the system volume remained after distillation, it was slowly poured into n-hexane solvent to obtain the precipitate. The precipitate was completely dissolved in THF and then precipitated in petroleum ether. After washing 3 times, it was dried in a vacuum oven at 60°C to obtain the product.

[0110] Weigh 6 mg of the product, dissolve it in 2 ml of DMAC solvent, filter it through an organic phase membrane, and analyze it using a DMAC phase gel permeation chromatography system. The GPC spectrum of the product is shown below. Figure 6 As shown. Figure 6 The product showed a number-average molecular weight of 45,269 and a molecular weight distribution of 2.38.

[0111] The NMR spectrum of the product is as follows: Figure 7 As shown. Figure 7 The spectrum shows that peak a is a very strong and sharp peak at around -18 ppm, characteristic of phosphorus atoms substituted with N-BOC-tyramine and phenoxy groups. The surrounding smaller peaks may be due to differences in chemical shift caused by different substituents; for example, characteristic peaks of phosphorus atoms with both groups attached to BOC-tyramine or both groups attached to phenoxy groups. The main peak of this phosphorus spectrum is very sharp, indicating a very homogeneous phosphorus environment. All the prominent peaks are in the range of -12 to 22 ppm, which is typical of phosphorus-nitrogen compounds and consistent with the structure of polydichlorophosphazene. No peaks representing unreacted polydichlorophosphazene were observed, as unreacted polydichlorophosphazene peaks usually appear at lower fields, indicating that the reaction proceeded relatively completely.

[0112] The 1H NMR spectrum of the product is as follows Figure 8 As shown. Figure 8 The peaks at 0.85 ppm and 1.26 ppm are characteristic peaks of hydrogen from the extraction solvent n-heptane. The peak at 1.40 ppm is a characteristic peak of hydrogen on a group of methyl groups in the BOC protecting group, labeled as peaks a, b, and c. The peaks at e and f correspond to the methylene protons of the tyramine moiety. The broad peak in the 6.5-7.5 ppm region corresponds to the characteristic peaks of hydrogen on the aromatic ring, which are hydrogens from the phenoxy group and the benzene ring of the tyramine.

[0113] The infrared spectrum of the product is as follows Figure 9 As shown. Figure 9 The infrared spectrum shows that the absorption peaks of P=N and POC appear at 1250 cm⁻¹, respectively. -1 1196cm -1 and 1048cm -1 Location. 1699cm -1 The peak at 3000 cm⁻¹ represents the carbonyl group in the BOC group. -1 The peaks at the left and right are characteristic peaks of phosphorus atoms bonded to methoxy groups. (940 cm⁻¹) -1 The peak at this location is a characteristic absorption peak of the benzene ring.

[0114] The phosphorus NMR spectrum, hydrogen NMR spectrum, and infrared spectrum of the product fully demonstrated the presence of N-BOC-tyramine and phenoxy groups and the successful grafting reaction with polydichlorophosphazene, resulting in poly(phenoxy / N-BOC-tyramine)phosphazene. The number-average molecular weight of poly(phenoxy / N-BOC-tyramine)phosphazene was 45269, and the molecular weight distribution was 2.38.

[0115] 1.5 Preparation of poly(phenoxy / tyramine)phosphazene

[0116] The poly(phenoxy / N-BOC-tyramine)phosphazene prepared in step 1.4 was dissolved in ultra-dry tetrahydrofuran solution to obtain a homogeneous solution. Concentrated hydrochloric acid (36 wt%) was added dropwise under magnetic stirring until the pH dropped to 1. The reaction was continued with stirring, and the removal of the protecting group BOC was monitored by 1H NMR spectroscopy. After complete removal of BOC, the solution was evaporated to dryness to remove a large amount of hydrogen chloride before adding THF to dissolve it. Excess sodium carbonate was added and stirred overnight. After filtration, the filtrate precipitated in n-hexane, and the precipitate was dried at room temperature to obtain the target product.

[0117] The infrared spectrum of the target product is as follows Figure 10 As shown. With Figure 9 compared to, Figure 10 At 3422cm -1 The presence of a distinct amino peak indicates that the protecting group of poly(phenoxy / N-BOC-tyramine)phosphazene has been successfully removed, and the target product is poly(phenoxy / tyramine)phosphazene.

[0118] The final product, poly(phenoxy / tyramine)phosphazene, contains amino groups, which can damage the gel permeation chromatograph, making measurement impossible. Compared to the poly(phenoxy / N-BOC-tyramine)phosphazene prepared in step 1.4, the final product only removes one protecting group from the side chain and does not affect the length of the polymer molecular chain. For high molecular weight polymers, the removal of a small protecting group (such as BOC, approximately 101 Da) has a negligible impact on the overall molecular weight and molecular weight distribution of the polymer, especially when the molecular weight of the polymer is in the tens of thousands and the protecting group can be uniformly removed. This is because molecular weight calculations are mainly based on the number of repeating units on the main chain, rather than the presence or absence of a single group. Removing the BOC group, such a small-scale structural modification, has almost no effect on the molecular weight and molecular weight distribution of high molecular weight polymers. Therefore, the molecular weight and molecular weight distribution of poly(phenoxy / tyramine)phosphazene are the same as those of poly(phenoxy / N-BOC-tyramine)phosphazene; the number average molecular weight of the final product poly(phenoxy / tyramine)phosphazene is 45269, and the molecular weight distribution is 2.38.

[0119] Example 2

[0120] 2.1 Preparation of sodium trifluoroethoxy salt

[0121] Weigh 0.155 mol of NaH and add it to a three-necked flask. Wash the flask three times with ultra-dry THF to remove the kerosene component. Weigh 0.155 mol of trifluoroethanol, dissolve it in THF, and add it to a constant pressure funnel. Slowly add the solution dropwise to the three-necked flask under ice bath conditions until the system is stable and no bubbles are generated, indicating that the reaction is complete and the product sodium trifluoroethoxy is obtained.

[0122] 2.2 Synthesis of poly(trifluoroethoxy / N-BOC-tyramine)phosphazene

[0123] The N-BOC-tyramine sodium salt solution containing tetrabutylammonium bromide (containing 0.155 mol of N-BOC-tyramine sodium salt) prepared in step 1.3 of Example 1 was mixed with 0.155 mol of the THF solution of trifluoroethoxy sodium salt prepared in step 2.1 to obtain a sodium salt mixture system. An ice bath and a mechanical stirrer were added. The polydichlorophosphazene tetrahydrofuran solution (containing 0.155 mol of polydichlorophosphazene) obtained in step 1.2 of Example 1 was added dropwise to the sodium salt mixture system using a constant pressure funnel. After 2 hours, the ice bath should be removed, and the reaction should continue at room temperature for 3 hours. When obvious gelation occurs, the temperature should be raised to 60°C and refluxed for 48 hours (the reaction endpoint should be monitored by NMR phosphorus spectroscopy). Finally, the temperature should be raised to 90°C to evaporate and recover the tetrahydrofuran in the system to concentrate the reaction solution. When about one-quarter of the system volume remains after distillation, it should be slowly poured into n-hexane solvent to obtain the precipitate. The precipitate should be completely dissolved in THF and then precipitated in petroleum ether. After washing 3 times, the product should be dried in a vacuum oven at 60°C to obtain the product.

[0124] Weigh 6 mg of the product, dissolve it in 2 ml of DMAC solvent, filter it through an organic phase membrane, and analyze it using a DMAC phase gel permeation chromatography system. The GPC spectrum of the product is shown below. Figure 11 As shown. Figure 11 The product showed a number-average molecular weight of 56071 and a molecular weight distribution of 2.90.

[0125] The NMR spectrum of the product is as follows: Figure 12 As shown. Figure 12 The data shows a very strong peak at approximately -17 ppm, which is a characteristic peak of phosphorus atoms grafted with trifluoroethoxy and N-BOC-tyramine groups, representing the main phosphorus in the reactants. Several smaller peaks are present next to this main peak, which are characteristic peaks of phosphorus atoms grafted with different substituents, and characteristic peaks of phosphorus atoms grafted with two identical groups.

[0126] The NMR phosphorus spectrum of the product fully demonstrated the presence of N-BOC-tyramine and trifluoroethoxy groups and the successful grafting reaction with polydichlorophosphazene, resulting in poly(trifluoroethoxy / N-BOC-tyramine)phosphazene.

[0127] 2.3 Preparation of poly(trifluoroethoxy / tyramine)phosphazene

[0128] The poly(trifluoroethoxy / N-BOC-tyramine)phosphazene prepared in step 2.2 was dissolved in ultra-dry tetrahydrofuran solution to obtain a homogeneous solution. Concentrated hydrochloric acid (36 wt%) was added dropwise under magnetic stirring until the pH dropped to 1. The reaction was continued with stirring, and the removal of the protecting group BOC was monitored by 1H NMR spectroscopy. After complete removal of BOC, the solution was evaporated to dryness to remove a large amount of hydrogen chloride before adding THF to dissolve it. Excess sodium carbonate was added and stirred overnight. After filtration, the filtrate precipitated in n-hexane, and the precipitate was dried at room temperature to obtain the target product.

[0129] The infrared spectrum of the target product is as follows Figure 13 As shown. Figure 13 Displayed at 3422cm -1 The presence of a distinct amino peak indicates that the protecting group has been successfully removed, and the target product is poly(trifluoroethoxy / tyramine)phosphazene.

[0130] The final product, poly(trifluoroethoxy / tyramine)phosphazene, contains amino groups, which can damage the gel permeation chromatograph, making measurement impossible. Compared to the poly(trifluoroethoxy / N-BOC-tyramine)phosphazene prepared in step 2.2, the final product only removes one protecting group from the side chain and does not affect the length of the polymer molecular chain. For high molecular weight polymers, the removal of a small protecting group (such as BOC, approximately 101 Da) has a negligible impact on the overall molecular weight and molecular weight distribution of the polymer, especially when the molecular weight is in the tens of thousands and the protecting group can be uniformly removed. This is because molecular weight calculations are mainly based on the number of repeating units on the main chain, rather than the presence or absence of a single group. Removing the BOC group, a small-scale structural modification, has almost no effect on the molecular weight and molecular weight distribution of high molecular weight polymers. Therefore, the molecular weight and molecular weight distribution of poly(trifluoroethoxy / tyramine) phosphazene are the same as those of poly(trifluoroethoxy / N-BOC-tyramine) phosphazene; the number average molecular weight of the final product poly(trifluoroethoxy / tyramine) phosphazene is 56071, and the molecular weight distribution is 2.90.

[0131] Performance testing

[0132] The poly(phenoxy / tyramine)phosphazene sample was dried, and 20 mg was analyzed using a thermogravimetric analyzer. The heating rate was 10 °C / min, and the test temperature range was -100 °C to 100 °C. The obtained thermogravimetric curve is shown below. Figure 14 As shown. Figure 14 The results show that the glass transition temperature of poly(phenoxy / tyramine)phosphazene is 48.12℃, exhibiting high-temperature resistance. This indicates that the grafting of phenoxy groups contributes to the high glass transition temperature of poly(phenoxy / tyramine)phosphazene.

[0133] The poly(trifluoroethoxy / tyramine)phosphazene sample was dried, and 20 mg was analyzed using a thermogravimetric analyzer. The heating rate was 10 °C / min, and the test temperature range was -100 °C to 0 °C. The obtained thermogravimetric curve is shown below. Figure 15 As shown. Figure 5 The results show that the glass transition temperature of poly(trifluoroethoxy / tyramine)phosphazene is -40.35℃, exhibiting low-temperature resistance. This indicates that the grafting of trifluoroethoxy groups contributes to the lower glass transition temperature of poly(trifluoroethoxy / tyramine)phosphazene.

Claims

1. An aminopolyphosphazene characterized in that, The aminopolyphosphazene comprises the structural units shown in Formula 1, Formula 2 and Formula 3; Said R is selected from 2. The aminopolyphosphazene according to claim 1, characterized in that, The ratio of the total molar amount of R in the structural units of Formula 1, Formula 2, Formula 3 to the total molar amount of 1:(1±0.05).

3. The aminopolyphosphazene according to claim 1, characterized in that, when said R is the number average molecular weight of said aminopolyphosphazene is comprised between 40 000 and 50 000, preferably between 44 000 and 46 000; the molecular weight distribution of said aminopolyphosphazene is comprised between 2 and 2.5, preferably between 2.3 and 2.4; when said R is the number average molecular weight of said aminopolyphosphazene is comprised between 50 000 and 60 000, preferably between 55 000 and 57 000; the molecular weight distribution of said aminopolyphosphazene is comprised between 2.5 and 3.0, preferably between 2.9 and 3.

0.

4. The aminopolyphosphazene according to claim 1, characterized in that, when said R is the glass transition temperature of said aminopolyphosphazene is between 40 and 100°C; When said R is -40 to -100°C.

5. A process for the preparation of the amino polyphosphazene according to any one of claims 1 to 4, characterized in that, The preparation method includes: (1) N-BOC-tyramine reacts with NaH to obtain N-BOC-tyramine sodium salt; (2) Hexachlorocyclotriphosphazene ring-opening polymerization yields polydichlorophosphazene; (3) N-BOC-tyramine sodium salt, a modifying substance, and polydichlorophosphazene are reacted to obtain poly(M / N-BOC-tyramine group) phosphazene; the modifying substance is sodium phenoxide or sodium trifluoroethanolate, and M is (4) The BOC group on poly(M / N-BOC-tyramine)phosphazene is removed by hydrogen chloride to obtain aminopolyphosphazene.

6. The preparation method according to claim 5, characterized in that, Step (1) includes: adding N-BOC-tyramine solution dropwise to NaH under ice bath conditions until NaH has completely reacted; or / and, Step (2) includes: under a protective gas atmosphere, hexachlorocyclotriphosphazene is dissolved in an organic solvent, and then reacted at 200℃~215℃ with a catalyst and a co-catalyst until the product exhibits an encapsulation effect; after cooling, polydichlorophosphazene is precipitated; or / and, Step (3) includes: under ice bath and stirring conditions, adding a polydichlorophosphazene solution dropwise to a mixed solution of N-BOC-tyramine sodium salt, the modified material, and the phase transfer catalyst; reacting at room temperature until gelation occurs; heating to 50–60°C and refluxing; after the reflux reaction is complete, precipitating the precipitate with an extraction solvent; the resulting precipitate is poly(M / N-BOC-tyramine)phosphazene; or / and, Step (4) includes: under stirring conditions, adding hydrochloric acid dropwise to the tetrahydrofuran solution of poly(M / N-BOC-tyramine)phosphazene until the pH drops to 1, continuing to stir the reaction until the BOC group is completely removed, adding excess sodium carbonate and stirring, filtering, and using an extraction solvent to precipitate the filtrate, the resulting precipitate being aminopolyphosphazene.

7. The preparation method according to claim 6, characterized in that, In step (1), the solvent for the N-BOC-tyramine solution is tetrahydrofuran; or / and, In step (2), the protective gas is nitrogen; or / and, In step (2), the organic solvent is 1,2,4-trichlorobenzene or α-chloronaphthalene; or / and, In step (2), the catalyst is aminosulfonic acid or p-toluenesulfonic acid; or / and, In step (2), the co-catalyst is calcium carbonate dihydrate or calcium sulfate dihydrate; or / and, In step (3), the phase transfer catalyst is tetrabutylammonium bromide; or / and, In step (3), the solvent of the polydichlorophosphazene solution is tetrahydrofuran or xylene; or / and, In step (3), the solvent of the mixed solution is tetrahydrofuran or xylene; or / and, In step (3), the extraction solvent is n-hexane or deionized water.

8. The preparation method according to claim 6, characterized in that, In step (2), the mass ratio of hexachlorocyclotriphosphazene to the organic solvent is (4-5):(5-6); or / and, In step (2), the molar ratio of catalyst, co-catalyst, and hexachlorocyclotriphosphazene is (0.015–0.020):(0.01–0.015):1; or / and, In step (3), the molar ratio of polydichlorophosphazene, N-BOC-tyramine sodium salt, modified material and phase transfer catalyst is 1:(0.5~0.6):(0.5~0.6):(0.015~0.02).

9. The preparation method according to claim 6, characterized in that, In step (2), the reaction time is 4–8 hours; or / and, In step (2), the "precipitation of polydichlorophosphazene after cooling" includes: precipitating polydichlorophosphazene with ultra-dry n-heptane or ultra-dry n-hexane after cooling to below 90°C; or / and, In step (3), the endpoint of the reflux reaction is monitored by phosphorus NMR spectroscopy; or / and, In step (4), the removal of the BOC group is monitored by 1H NMR spectroscopy.

10. The application of the aminopolyphosphazene as described in any one of claims 1-4 in the field of flame retardant additives or thermal protective coatings.

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