阅读说明：本技术 一种聚磷腈及其制备方法及应用 (Polyphosphazene and preparation method and application thereof ) 是由 徐亮 刘平 肖学文 王鲁静 索伟 徐有敏 段金凤 刘婷 于 2021-08-31 设计创作，主要内容包括：本发明涉及阻燃剂技术领域,提供了一种聚磷腈及其制备方法。所述聚磷腈的制备方法是采用2,4,6-三溴苯酚、氢氧化钠与线性聚二氯磷腈为原料,先通过2,4,6-三溴苯酚与氢氧化钠反应生成2,4,6-三溴苯酚钠,再由2,4,6-三溴苯酚钠与线性聚二氯磷腈反应生成聚磷腈。制备方法工艺简单,易于控制,对生产设备要求不高,适用于工业化大规模生产。本发明制备的聚磷腈与高分子材料相容性好,并具有优良的阻燃性果,可用作多种高分子材料的阻燃剂。(The invention relates to the technical field of flame retardants, and provides polyphosphazene and a preparation method thereof. The preparation method of the polyphosphazene adopts 2,4, 6-tribromophenol, sodium hydroxide and linear polydichlorophosphazene as raw materials, firstly 2,4, 6-tribromophenol reacts with sodium hydroxide to generate 2,4, 6-tribromophenol sodium, and then 2,4, 6-tribromophenol sodium reacts with linear polydichlorophosphazene to generate polyphosphazene. The preparation method has simple process, easy control and low requirement on production equipment, and is suitable for industrial large-scale production. The polyphosphazene prepared by the invention has good compatibility with high polymer materials and excellent flame retardance, and can be used as a flame retardant for various high polymer materials.)

1. A preparation method of polyphosphazene is characterized by comprising the following steps:

s1, dissolving 2,4, 6-tribromophenol in a solvent, adding sodium hydroxide, heating to 30-80 ℃, reacting for 0.5-4 hours, and obtaining a reactant a after the reaction is finished;

s2, dissolving linear polydichlorophosphazene in a solvent to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a for reaction at the temperature of 60-90 ℃ for 3-20 hours;

and S4, recovering the solvent after the reaction is finished, and washing, filtering and drying to obtain the polyphosphazene.

2. The method according to claim 1, wherein the mass ratio of the linear polydichlorophosphazene to 2,4, 6-tribromophenol is 1: 6-8.5.

3. The method according to claim 1, wherein the reaction temperature in step S3 is 80-85 ℃ and the reaction time is 5-8 hours.

4. The preparation method according to claim 1, wherein in step S1, the mass ratio of 2,4, 6-tribromophenol to sodium hydroxide is 1: 0.24-0.3.

5. The method according to claim 1, wherein in step S1, the mass-to-volume ratio (g/mL) of 2,4, 6-tribromophenol to solvent is 1: 12-25.

6. The method of claim 1, wherein in step S2, the mass-to-volume ratio (g/mL) of the linear polydichlorophosphazene to the solvent is 1: 40-100.

7. The method according to claim 1, wherein the solvent is at least one of tetrahydrofuran, chlorobenzene, and acetonitrile.

8. The method of claim 1, wherein the steps S1-S3 are performed under nitrogen protection.

9. Polyphosphazene, characterized by being prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a polyphosphazene as claimed in claim 9 as a flame retardant in flame retarding polymers.

Technical Field

The invention relates to the technical field of flame retardants, in particular to polyphosphazene and a preparation method and application thereof.

Background

The high polymer material has the characteristics of light weight, good heat insulation and electrical insulation, excellent mechanical property and the like, is the most representative and most promising category of materials at present, and is increasingly widely applied to modern life. However, compared with inorganic materials and metal materials, high molecular materials are easy to burn, the oxygen index of the high molecular materials is generally lower than 21%, a large amount of harmful gases and smoke are generated in the burning process, and the flammability of the high molecular materials brings potential safety problems.

The addition of flame retardant is one of the effective methods for improving the flame retardant property of polymer materials. The polyphosphazene flame retardant is a novel flame retardant harmless to organisms and free of pollution to the environment, is a high molecular substance with a skeleton formed by alternatively arranging phosphorus and nitrogen single bonds and double bonds and a side chain consisting of inorganic or organic groups, and mainly comprises two categories of cyclic polyphosphazene and linear polyphosphazene. Among them, synthesis and application of hexachlorocyclotriphosphazene and its derivatives have been widely studied, for example, hexaphenoxycyclotriphosphazene and the like. The linear polyphosphazene and the derivative thereof have stable main chain structures and changeable side group types, provide theoretical basis for the application of the linear polyphosphazene and the derivative thereof in the aspect of multifunctional and high-performance materials, and are favorable for developing novel flame-retardant materials suitable for different application occasions. However, the research on the flame retardant of linear polyphosphazene and its derivatives is less, and the flame retardant effect of the existing linear polyphosphazene is not ideal. Therefore, the development of a novel linear polyphosphazene with high flame retardancy is of great significance.

Disclosure of Invention

The invention aims to find a novel linear polyphosphazene flame retardant, prepares a polyphosphazene with excellent flame retardant effect through extensive and intensive research, and researches the application of the polyphosphazene serving as a flame retardant in polymers.

It is an object of the present invention to provide polyphosphazenes.

Another object of the present invention is to provide a process for preparing the polyphosphazene.

Another object of the present invention is to provide the use of the polyphosphazenes described above as flame retardants for flame retarding polymers.

In order to achieve the purpose, the invention adopts the technical scheme that:

in a first aspect, the present invention provides a method for preparing polyphosphazene, comprising:

s1, dissolving 2,4, 6-tribromophenol in a solvent, adding sodium hydroxide, heating to 30-80 ℃, reacting for 0.5-4 hours, and obtaining a reactant a after the reaction is finished;

s2, dissolving linear polydichlorophosphazene in a solvent to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a for reaction at the temperature of 60-90 ℃ for 3-20 hours;

and S4, recovering the solvent after the reaction is finished, and washing, filtering and drying to obtain the polyphosphazene.

The chemical reaction formula of the preparation method of polyphosphazene provided by the invention is as follows:

the preparation method of the polyphosphazene adopts 2,4, 6-tribromophenol, sodium hydroxide and linear polydichlorophosphazene as raw materials, firstly, 2,4, 6-tribromophenol reacts with sodium hydroxide to generate 2,4, 6-tribromophenol sodium, and then 2,4, 6-tribromophenol sodium reacts with linear polydichlorophosphazene to generate polyphosphazene. The preparation method has simple process, easy control and low requirement on production equipment, and is suitable for industrial large-scale production. The polyphosphazene prepared by the preparation method of the polyphosphazene has good compatibility with high polymer materials and excellent flame retardance, and can be used as a flame retardant for various high polymer materials.

As a preferable embodiment of the preparation method provided by the present invention, the mass ratio of the linear polydichlorophosphazene to the 2,4, 6-tribromophenol is 1: 6-8.5.

Further preferably, the mass ratio of the linear polydichlorophosphazene to the 2,4, 6-tribromophenol is 1: 7.5-8.5.

As another preferable embodiment of the preparation method provided by the present invention, the reaction temperature in the step S3 is 80 to 85 ℃, and the reaction time is 5 to 8 hours.

As another preferable embodiment of the preparation method provided by the present invention, in step S1, the mass ratio of 2,4, 6-tribromophenol to sodium hydroxide is 1: 0.24-0.3.

As another preferred embodiment of the preparation method provided by the present invention, in step S1, the mass-to-volume ratio (g/mL) of 2,4, 6-tribromophenol to solvent is 1: 12-25.

As another preferable embodiment of the preparation method provided by the present invention, in step S2, the mass-to-volume ratio (g/mL) of the linear polydichlorophosphazene to the solvent is 1: 40-100.

As another preferable embodiment of the preparation method provided by the present invention, the solvent is at least one of tetrahydrofuran, chlorobenzene, and acetonitrile.

As another preferred embodiment of the preparation method provided by the invention, the steps S1-S3 are carried out under the protection of nitrogen.

In a second aspect, the invention provides a polyphosphazene prepared by the preparation method of the polyphosphazene.

In a third aspect, the invention provides a use of the polyphosphazene as a flame retardant in flame retarding of polymers.

The polyphosphazene provided by the invention can be used as a flame retardant to be blended with various polymers such as epoxy resin, polystyrene, polypropylene and the like, and plays a role in improving the flame retardant property of the polymers.

The invention has the beneficial effects that:

the preparation method of polyphosphazene provided by the invention has the advantages of simple process, easiness in control and low requirement on production equipment, and is suitable for industrial large-scale production. The polyphosphazene prepared by the preparation method of the polyphosphazene has good compatibility with high polymer materials and excellent flame retardance, and can be used as a flame retardant for various high polymer materials.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more apparent, the present invention is further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present patent and do not limit the scope of the invention in any way.

The preparation method of polyphosphazene provided by the invention comprises the following steps:

s1, dissolving 2,4, 6-tribromophenol in a solvent, adding sodium hydroxide, heating to 30-80 ℃, reacting for 0.5-4 hours, and obtaining a reactant a after the reaction is finished;

s2, dissolving linear polydichlorophosphazene in a solvent to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a for reaction at the temperature of 60-90 ℃ for 3-20 hours;

and S4, recovering the solvent after the reaction is finished, and washing, filtering and drying to obtain the polyphosphazene.

Further, the mass ratio of the linear polydichlorophosphazene to the 2,4, 6-tribromophenol is 1: 6-8.5, for example, 1: 6. 1: 6.8, 1: 7. 1: 7.5, 1: 8. 1: 8.3, 1: 8.5, and the like.

Further, the reaction temperature in step S3 is 80-85 ℃ and the reaction time is 5-8 hours, for example, the reaction temperature can be selected from 80 ℃, 81 ℃, 84 ℃, 85 ℃ and the like, and the reaction time can be selected from 5 hours, 6 hours, 7.5 hours, 8 hours and the like.

Further, in step S1, the mass ratio of 2,4, 6-tribromophenol to sodium hydroxide is 1: 0.24-0.3, for example, 1: 0.24, 1: 0.25, 1: 0.28, 1: 0.3, etc.

Further, in step S1, the mass-to-volume ratio (g/mL) of the 2,4, 6-tribromophenol to the solvent is 1: 12-25, for example, 1: 12. 1: 15. 1: 18. 1: 20. 1: 23. 1: 25, and the like.

Further, in step S2, the mass-to-volume ratio (g/mL) of the linear polydichlorophosphazene to the solvent is 1: 40-100, for example, 1: 40. 1: 50. 1: 55. 1: 68. 1: 75. 1: 83. 1: 90. 1: 95. 1: 100, etc.

Further, the solvent is at least one of tetrahydrofuran, chlorobenzene and acetonitrile. One of the solvents may be selected singly, or a mixed solvent of two or three of them may be selected.

Further, steps S1-S3 are all performed under nitrogen protection.

The invention is described in more detail by referring to a part of the tests, which are carried out in sequence, and the following detailed description is given by combining specific examples:

unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, equipment and the like used in the following examples are either commercially available or available by existing methods; the dosage of the reagent is the dosage of the reagent in the conventional experiment operation if no special description exists; the experimental methods are conventional methods unless otherwise specified.

The linear polydichlorophosphazenes used in the following examples and comparative examples were prepared by themselves.

The preparation method of the linear polydichlorophosphazene comprises the following steps: adding hexachlorocyclotriphosphazene into a reaction container, slowly heating to 250-260 ℃ under the conditions of drying, nitrogen protection and negative pressure, reacting for 4 hours, cooling, and cleaning with tetrahydrofuran under the protection of nitrogen to obtain linear polydichlorophosphazene.

Example 1

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 13.8g of polyphosphazene, wherein the yield is 75.7%.

The limiting oxygen index LOI of the polymer incorporating the polyphosphazene prepared in this example was tested and the results are shown in the following table:

the curing agent for the epoxy resin used in the examples of the present invention is diethylenetriamine.

Example 2

A method of preparing polyphosphazenes comprising:

s1, adding 300mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 6.00g (0.150 mol) of sodium hydroxide, heating to 30 ℃, reacting for 4h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.30g of linear polydichlorophosphazene is dissolved in 135mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 80 ℃, and reacting for 5 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 14.9g of polyphosphazene, wherein the yield is 74.3%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 30.1%.

Example 3

A method of preparing polyphosphazenes comprising:

s1, adding 625mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.50g (0.1875 mol) of sodium hydroxide, heating to 80 ℃, reacting for 1h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 2.95g of linear polydichlorophosphazene is dissolved in 295mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 8 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 13.8g of polyphosphazene, wherein the yield is 76.9%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 30.8%.

Example 4

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of acetonitrile and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the acetonitrile and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of acetonitrile to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 12.6g of polyphosphazene, wherein the yield is 69.1%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 28.6%.

Example 5

A method of preparing polyphosphazenes comprising:

s1, adding 375mL of tetrahydrofuran, 125mL of chlorobenzene and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the condition of nitrogen protection to dissolve the tetrahydrofuran, the chlorobenzene and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in a mixed solution of 150mL of tetrahydrofuran and 50mL of chlorobenzene to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 15.4g of polyphosphazene, wherein the yield is 84.4%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 30.1%.

Example 6

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.40g of linear polydichlorophosphazene is dissolved in 225mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 14.7g of polyphosphazene, wherein the yield is 71.1%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 28.2%.

Example 7

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 4.15g of linear polydichlorophosphazene is dissolved in 275mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 17.6g of polyphosphazene, wherein the yield is 69.8%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was found to be 26.5%.

Example 8

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 60 ℃, and reacting for 15 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 12.6g of polyphosphazene, wherein the yield is 69.1%.

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 27.1%.

Example 9

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 75 ℃, and reacting for 10 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 13.2g of polyphosphazene, wherein the yield is 72.4%. .

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 28.3%.

Example 10

A method of preparing polyphosphazenes comprising:

s1, adding 500mL of tetrahydrofuran and 25.00g (0.075 mol) of 2,4, 6-tribromophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2,4, 6-tribromophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 90 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 13.5g of polyphosphazene, wherein the yield is 74.0%. .

Polyphosphazene prepared in this example was cured according to the epoxy resin: polyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the LOI was 27.8%.

Comparative example 1

The preparation of the polyoxyphosphazene is carried out as follows:

(1) adding 10.00g (0.106 mol) of phenol, 25mL of dimethylbenzene, 30mL of methylbenzene and 50mL of benzene into a reaction device provided with a magnetic stirring, a thermometer and a reflux condenser, adding 2.30g (0.100 mol) of sodium metal under the protection of nitrogen, and reacting at 30 ℃ for 12 hours to obtain a reactant c;

(2) under the protection of nitrogen, 4.00g of linear polydichlorophosphazene is dissolved in 50mL of toluene to obtain a reactant d;

(3) slowly dripping the reactant d into the reactant c under the protection of nitrogen, controlling the reaction temperature to be 110 ℃, and reacting for 24 hours; after the reaction was completed, the solvent was recovered, washed with water, filtered and dried to obtain 4.3g of polyoxyphosphazene in 53.9% yield.

The chemical reaction formula is as follows:

the polyphenoxyphosphazene is prepared by reacting a mixture of an epoxy resin: polyphenoxyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the test limit oxygen index LOI was 22.7%.

Comparative example 2

The polydibromopropoxyphosphazene is prepared according to the following preparation method:

s1, adding 300mL of tetrahydrofuran and 15.25g (0.07 mol) of 2, 3-dibromopropanol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the protection of nitrogen to dissolve the tetrahydrofuran and the 2, 3-dibromopropanol; then adding 6.40g (0.16 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, dissolving 2.80g of linear polydichlorophosphazene in 190mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 7.0g of polydibromopropoxyphosphazene, wherein the yield is 60.5%.

The chemical reaction formula is as follows:

polydibromopropoxyphosphazene prepared in this example was cured according to the following epoxy resin: polydibromopropoxyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the test limit oxygen index LOI was 23.9%.

Comparative example 3

The preparation of poly 2,4, 6-trifluorophenoxyphosphazene was carried out as follows:

s1, adding 222mL of tetrahydrofuran and 11.10g (0.075 mol) of 2,4, 6-trifluorophenol into a reaction device provided with a magnetic stirring, thermometer and reflux condenser, and fully stirring under the condition of nitrogen protection to dissolve the tetrahydrofuran and the 2,4, 6-trifluorophenol; then adding 7.00g (0.175 mol) of sodium hydroxide, heating to 70 ℃, reacting for 3h, and obtaining a reactant a after the reaction is finished;

s2, under the protection of nitrogen, 3.00g of linear polydichlorophosphazene is dissolved in 200mL of tetrahydrofuran to obtain a reactant b;

s3, slowly dropwise adding the reactant b into the reactant a under the protection of nitrogen, controlling the reaction temperature to be 85 ℃, and reacting for 6 hours;

s4, after the reaction is finished, recovering the solvent, washing with water, filtering and drying to obtain 5.0g of poly (2, 4, 6-trifluorophenoxyphosphazene), wherein the yield is 56.9%.

The poly 2,4, 6-trifluorophenoxyphosphazene prepared in this example was cured according to the epoxy resin: poly 2,4, 6-trifluorophenoxyphosphazene: curing agent = 100: 15: 10 (mass ratio) was mixed and cured, and the test limit oxygen index LOI was 24.4%.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.