A method for preparing a water-soluble polyamino phosphorus-nitrogen compound modified titanium carbide composite

Abstract

The application discloses a preparation method of a water-soluble polyamino phosphorus-nitrogen compound modified titanium carbide composite, and the method comprises the following steps: sequentially performing nucleophilic substitution on chlorine elements in hexachlorotriphosphazene molecules by using melamine and ammonia water to synthesize HMN; then performing surface modification on hydroxylated titanium carbide by using the HMN to prepare HMN-MXene; and finally adding the HMN-MXene into a mixed solution of an epoxy resin (EP) precursor 1,4-butanediol glycidyl ether and triethylenetetramine by adopting a solution blending method, so that the obtained mixed solution can be rapidly formed at room temperature; after heat curing treatment, the prepared EP / HMN-MXene composite material is composed of surface wrinkle-shaped HMN-MXene nanosheets uniformly dispersed in an epoxy resin matrix, has a low glass transition temperature, excellent flexibility and flame retardant performance, and a fire safety early warning function, and has a wide application prospect in the fields of flame-retardant polymers, thermal safety monitoring and early warning, flexible sensing and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of phosphorus-nitrogen compounds and their application in surface modification of inorganic layered compounds, in particular to a preparation method of water-soluble multi-amino phosphorus-nitrogen compound modified titanium carbide composite. BACKGROUND

[0002] Epoxy resin (EP) has a wide range of applications in the fields of construction, coatings and aviation. However, the inherent flammability and high exothermic properties of EP can cause serious fire risk; and the complex preparation process of EP not only prolongs the material preparation time, but also increases the production cost. In addition, the EP resin after thermal curing has poor toughness, which limits its application in flexible sensing and other fields. It is of great importance to develop flexible EP composites with simple molding process and excellent flame retardant performance for expanding the application field of EP.

[0003] In recent years, the research on EP / MXene nanocomposites has become one of the hotspots at home and abroad. Due to the unique physical barrier effect and catalytic performance of MXene, it has a wide application in improving the flame retardant performance of EP, but MXene cannot effectively improve the flexibility of EP, nor can it promote the rapid molding of EP precursor at room temperature to simplify the process flow. Therefore, it is of great significance to develop a multifunctional new filler based on surface modified MXene to simplify the preparation process of EP and improve its flexibility and flame retardant performance.

[0004] Therefore, the present application first attempts to synthesize a water-soluble multi-amino phosphorus-nitrogen compound (HMN), and use it to modify the surface of hydroxylated MXene (MXene-OH) to obtain HMN modified MXene composite (HMN-MXene); then use HMN-MXene as a nano filler to add to the EP resin precursor, which can simplify the EP molding process while giving the EP / HMN-MXene composite material excellent comprehensive performance, and can be applied to flame-retardant polymers, thermal safety monitoring and early warning, and flexible sensing and other fields. SUMMARY

[0005] In order to overcome the above-mentioned defects existing in the prior art, the application provides a water-soluble multi-amino phosphorus nitrogen compound (HMN), a preparation method of an HMN modified titanium carbide (HMN-MXene) composite and an EP / HMN-MXene composite material. The prepared HMN has high reactivity, the HMN-MXene can promote the rapid molding of a mixed solution of an EP precursor 1,4-butanediol glycidyl ether (BDGE) and triethylene tetramine (TETA) at room temperature, the EP / HMN-MXene composite material after thermal curing is composed of surface wrinkle-shaped HMN-MXene nanosheets uniformly dispersed in an epoxy resin matrix, has low glass transition temperature, excellent flexibility and flame retardant performance, and a fire safety early warning function, and has wide application prospects in the fields of flame-retardant polymers, thermal safety monitoring and early warning, flexible sensing and the like.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is:

[0007] A preparation method of a water-soluble multi-amino phosphorus nitrogen compound modified titanium carbide composite, steps are as follows:

[0008] (1) Preparation of melamine modified hexachlorotriphosphazene intermediate (HM):

[0009] Melamine (MA) is dissolved in hot deionized water, triethylamine (TEA) is added under nitrogen protection and stirred, acetonitrile solution of hexachlorotriphosphazene (HCCP) is added dropwise, and the reaction is maintained at 60-80 DEG C for 15-20 h; after the reaction is completed, the generated triethylamine hydrochloride is removed by centrifugation, the supernatant after centrifugation is placed in an ice water bath to promote the precipitation of unreacted MA, and the separation is carried out by vacuum filtration; the filtrate is rotary evaporated, and finally the obtained product is dried in a vacuum oven to obtain the product melamine modified hexachlorotriphosphazene intermediate (HM);

[0010] (2) Preparation of water-soluble multi-amino phosphorus nitrogen compound (HMN):

[0011] A certain amount of HM is dissolved in deionized water, the temperature is maintained at 0-3 DEG C, TEA is added under nitrogen protection and stirred, ammonia water is added dropwise and stirred for 15-20 h; after the reaction is completed, the generated triethylamine hydrochloride is removed by centrifugation, the supernatant is rotary evaporated, and finally the obtained product is dried in a vacuum oven to obtain the product water-soluble multi-amino phosphorus nitrogen compound (HMN);

[0012] (3) Preparation of HMN-MXene composite:

[0013] The MXene water dispersion liquid is added into a sodium hydroxide aqueous solution, and after stirring and reacting at 20-30 DEG C for 2-4 h, the supernatant is repeatedly centrifuged and washed until the pH value of the supernatant is neutral; the precipitate after centrifugation is ultrasonically dispersed in deionized water to obtain a hydroxylated MXene (MXene-OH) water dispersion liquid; then, under the protection of nitrogen, the HMN water dispersion liquid is added into the MXene-OH water dispersion liquid, and after stirring and reacting at 60-80 DEG C for 2-4 h, a water dispersion liquid of the HMN-MXene composite is obtained.

[0014] As a preferred technical scheme of the present application, in the preparation method:

[0015] In step (1), the mass ratio of MA, TEA and HCCP is 1:(2.2-2.6):(1.2-1.5), in step (2), the mass ratio of HM, TEA and ammonia is 1:(0.8-1):(0.2-0.3), and in step (3), the mass ratio of MXene-OH and HMN is 1:(0.05-0.2). In steps (1) and (2), the rotary evaporation temperature is 60-80 DEG C, and the rotary evaporation time is 1.5-2.5 h; the drying temperature of the obtained product in the vacuum oven is 50-70 DEG C, and the drying time is 20-28 h.

[0016] The present application uses melamine and ammonia to sequentially perform nucleophilic substitution on the chlorine elements in the hexachlorotriphosphazene molecules to synthesize HMN, then uses HMN to perform surface modification on hydroxylated titanium carbide (MXene-OH) to prepare HMN-MXene composite, and finally uses a solution blending method to add the HMN-MXene into a mixed solution of EP precursor 1,4-butanediol glycidyl ether (BDGE) and triethylenetetramine (TETA), and the obtained mixed solution can be quickly formed at room temperature; after heat curing treatment, the prepared EP / HMN-MXene composite material is composed of surface wrinkled HMN-MXene nanosheets uniformly dispersed in an epoxy resin matrix, has a low glass transition temperature, excellent flexibility and flame retardant performance, and a fire safety early warning function, and has a wide application prospect in the fields of flame-retardant polymers, thermal safety monitoring and early warning, flexible sensing and the like.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] (1) The present application successfully prepares a water-soluble phosphorus-nitrogen compound HMN with multiple amino characteristics by means of organic synthesis.

[0019] (2) The modification of MXene by HMN can promote the subsequent preparation of epoxy resin to quickly complete the forming process at room temperature, thereby simplifying the forming process of the epoxy resin.

[0020] (3), The epoxy resin / HMN-MXene composite material prepared by the method has multifunctionality, and expands the application field of the epoxy resin. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the nuclear magnetic phosphorus spectrum of HCCP.

[0022] Figure 2 is the nuclear magnetic phosphorus spectrum of the HMN prepared in Example 1.

[0023] Figure 3 is the infrared spectrum of HCCP and the HMN prepared in Example 1.

[0024] Figure 4 is the mass spectrum spectrum of the HMN prepared in Example 1.

[0025] Figure 5 is the thermogravimetric spectrum of the HMN-MXene composite prepared in Examples 2, 3 and 4.

[0026] Figure 6 is the scanning electron microscope photo of MXene.

[0027] Figure 7 is the scanning electron microscope photo of the HMN-MXene composite prepared in Example 3.

[0028] Figure 8 is the XRD spectrum of MXene and the HMN-MXene composite prepared in Example 3.

[0029] Figure 9 is the digital photo of the pure EP prepared in Example 5, and the EP / HMN-MXene composite material prepared in Examples 6, 7 and 8.

[0030] Figure 10 is the dynamic thermal mechanical curve of the EP / HMN-MXene composite material prepared in Example 7.

[0031] Figure 11 is the relative resistance change curve of the EP / HMN-MXene composite material prepared in Examples 6, 7 and 8 under flame attack. DETAILED DESCRIPTION

[0032] The present application is further described in detail below in conjunction with the embodiments and the accompanying drawings.

[0033] Example 1

[0034] The synthesis method of the water-soluble polyamino phosphorus nitrogen compound (HMN) comprises the following steps:

[0035] (1) Synthesis of melamine modified hexachlorotriphosphazene intermediate (HM): 1 g of MA was dissolved in 100 mL of deionized water at 70°C, 2.41 g of triethylamine (TEA) was added under nitrogen protection and stirred for 15 min; 1.38 g of HCCP was dissolved in 30 mL of acetonitrile solution, which was added dropwise into the above three-necked flask, and reacted at 70°C for 18 h, wherein the mass ratio of MA, TEA and HCCP was 1:2.41:1.38. After the reaction was completed, the hydrochloric acid triethylamine produced in the reaction was removed by centrifugation, the centrifuge speed was 9500 rpm, and the centrifugation time was 5 min; the supernatant after centrifugation was placed in an ice water bath to promote the precipitation of unreacted MA, which was separated by vacuum filtration; the filtrate was rotary evaporated at 70°C for 2 h; the obtained product was dried in a vacuum oven at 60°C for 24 h, to obtain the product melamine modified hexachlorotriphosphazene intermediate (HM).

[0036] (2) Synthesis of water-soluble polyamino phosphorus nitrogen compound (HMN): 2 g of HM was dissolved in 100 mL of deionized water, the temperature was maintained at 1°C, 1.97 g of TEA was added under nitrogen protection and stirred for 15 min; 0.5 mL of ammonia water was added dropwise and stirred for 18 h, wherein the mass ratio of HM, TEA and ammonia water was 1:0.985:0.23; after the reaction was completed, the hydrochloric acid triethylamine produced in the reaction was removed by centrifugation, the centrifuge speed was 9500 rpm, and the centrifugation time was 5 min; the supernatant was rotary evaporated at 70°C for 2 h; the obtained product was dried in a vacuum oven at 60°C for 24 h, to obtain the product water-soluble polyamino phosphorus nitrogen compound (HMN).

[0037] Figure 1 and Figure 2 are the nuclear magnetic resonance spectra (P NMR) of HCCP and HMN prepared in Example 1, respectively, 31 Figure 3 are the infrared spectra of HCCP and HMN prepared in Example 1, respectively, Figure 4 is the mass spectrum of HMN prepared in Example 1. From Figure 1 and Figure 2 only one single peak can be seen, indicating that the chemical environments of the three phosphorus atoms in HCCP and HMN are the same; compared with HCCP, the chemical shift of phosphorus element in HMN moves to the high field direction, indicating that the group connected with the phosphorus element has changed from the electron-withdrawing chlorine atom to the electron-donating nitrogen atom. From Figure 3 it can be seen that HCCP has a stretching vibration absorption peak belonging to phosphorus-chlorine bond at 605 cm -1 , while HMN has no corresponding absorption peak, indicating that the chlorine atoms on HCCP have been completely replaced; at the same time, in the range of 1545 cm -1 ​The bending vibration absorption peak of N-H appeared at 3100-3500 cm -1 The stretching vibration absorption peak of N-H appeared in the region, indicating the presence of amino groups in the molecule. The peak at 1689 cm -1 -1 The peak at 1398 cm -1 The peak at 1398 cm Figure 4 The mass-to-charge ratio value of the theoretical molecular ion peak of HMN is consistent with the relative molecular mass of the compound.

[0038] Example 2

[0039] The synthesis method of HMN modified MXene includes the following steps:

[0040] (1) 100 mL of MXene water dispersion solution with a concentration of 4 mg / mL was added to 200 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, and stirred at 25°C for 3 h. The supernatant was repeatedly washed by centrifugation until the pH value was neutral, the centrifugal speed was 9500 rpm, and the centrifugal time was 5 min. The precipitate after centrifugation was ultrasonically dispersed in 100 mL of deionized water to obtain a hydroxylated MXene (MXene-OH) water dispersion solution with a concentration of 4 mg / mL.

[0041] (2) Under the protection of nitrogen, 10 mL of HMN water dispersion solution (prepared by dispersing in water after preparation according to the preparation method of step 1, the same below) with a concentration of 2 mg / mL was added to 100 mL of MXene-OH water dispersion solution with a concentration of 4 mg / mL, and reacted at 70°C for 3 h to obtain a HMN-MXene composite water dispersion solution with a concentration of 3.82 mg / mL, wherein the mass ratio of MXene to HMN was 1:0.05.

[0042] Example 3

[0043] The synthesis method of HMN modified MXene includes the following steps:

[0044] (1) 100 mL of MXene water dispersion solution with a concentration of 4 mg / mL was added to 200 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, and stirred at 25°C for 3 h. The supernatant was repeatedly washed by centrifugation until the pH value was neutral, the centrifugal speed was 9500 rpm, and the centrifugal time was 5 min. The precipitate after centrifugation was ultrasonically dispersed in 100 mL of deionized water to obtain a hydroxylated MXene (MXene-OH) water dispersion solution with a concentration of 4 mg / mL.

[0045] (2), under the protection of nitrogen, 100 mL of MXene-OH water dispersion solution with a concentration of 4 mg / mL was added with 20 mL of HMN water dispersion solution with a concentration of 2 mg / mL, and after 3 h of reaction at 70°C, a HMN-MXene composite water dispersion solution with a concentration of 3.67 mg / mL was obtained, wherein the mass ratio of MXene to HMN was 1:0.1;

[0046] Example 4

[0047] The synthesis method of the HMN modified MXene includes the following steps:

[0048] (1), 100 mL of MXene water dispersion solution with a concentration of 4 mg / mL was added to 200 mL of sodium hydroxide aqueous solution with a concentration of 1 mol / L, and stirred at 25°C for 3 h, and repeatedly centrifuged and washed until the pH value of the supernatant was neutral, the centrifugal speed was 9500 rpm, and the centrifugal time was 5 min; the precipitate after centrifugation was ultrasonically dispersed in 100 mL of deionized water to obtain a hydroxyl modified MXene (MXene-OH) water dispersion solution with a concentration of 4 mg / mL.

[0049] (2), under the protection of nitrogen, 100 mL of MXene-OH water dispersion solution with a concentration of 4 mg / mL was added with 40 mL of HMN water dispersion solution with a concentration of 2 mg / mL, and after 3 h of reaction at 70°C, a HMN-MXene composite water dispersion solution with a concentration of 3.43 mg / mL was obtained, wherein the mass ratio of MXene to HMN was 1:0.2.

[0050] Figure 5 is the thermogravimetric spectrum of the HMN-MXene composite prepared in Examples 2, 3, and 4. The HMN-MXene shows excellent carbon formation performance, and the residual carbon content of Examples 2, 3, and 4 at 750°C is 95.4%, 96.9%, and 90.7% respectively, which is higher than the theoretical residual carbon content of 94.0%, 90.2%, and 84.2% respectively.

[0051] Figure 6 , 7 are scanning electron microscope photos of MXene and HMN-MXene composite prepared in Example 3 respectively. As can be seen from the figure, the surface of MXene is smooth and the interlayer spacing is small; while the surface of HMN-MXene is wrinkled and the interlayer spacing is obviously enlarged. Figure 8 is the XRD spectrum of MXene and HMN-MXene composite prepared in Example 3. The disappearance of the (002) characteristic peak (2θ = 6.7°) of MXene in the HMN-MXene composite indicates that the interlayer spacing of MXene is increased and presents a delaminated state, which is consistent with the scanning electron microscope result.

[0052] Example 5

[0053] The preparation of pure epoxy resin (EP) includes the following steps:

[0054] BDGE and 0.6 mL of TETA were measured by a pipette, stirred in an ice water bath for 30 min at a speed of 400 rpm, and then the mixture was transferred to a polytetrafluoroethylene mold and placed in an oven at 25°C. The sample was shaped after 45 min. The shaped sample was taken out and cured at 110°C for 12 h. The obtained product was an epoxy resin (EP).

[0055] Example 6

[0056] As a comparison, the preparation of EP / HMN-MXene composite includes the following steps:

[0057] BDGE and 0.21 mL of TETA were measured by a pipette and added to 1.95 mL of HMN-MXene aqueous dispersion (the HMN-MXene aqueous dispersion prepared in Example 3 was filtered under vacuum, and then dispersed in deionized water to prepare, the same below) with a concentration of 5.12 mg / mL. The mixture was stirred in an ice water bath for 30 min at a speed of 400 rpm, and then the mixture was transferred to a polytetrafluoroethylene mold and placed in an oven at 25°C. The sample was shaped after 20 min. The shaped sample was taken out and cured at 110°C for 12 h. The obtained product was an EP / HMN-MXene composite, and the mass ratio of EP to HMN-MXene was 1:0.01.

[0058] Example 7

[0059] As a comparison, the preparation of EP / HMN-MXene composite includes the following steps:

[0060] BDGE and 0.21 mL of TETA were measured by a pipette and added to 5.25 mL of HMN-MXene aqueous dispersion with a concentration of 5.12 mg / mL. The mixture was stirred in an ice water bath for 30 min at a speed of 400 rpm, and then the mixture was transferred to a polytetrafluoroethylene mold and placed in an oven at 25°C. The sample was shaped after 20 min. The shaped sample was taken out and cured at 110°C for 12 h. The obtained product was an EP / HMN-MXene composite, and the mass ratio of EP to HMN-MXene was 1:0.027.

[0061] Example 8

[0062] As a comparison, the preparation of EP / HMN-MXene composite includes the following steps:

[0063] 0.84 mL of BDGE and 0.21 mL of TETA were measured by a pipette and added into 10.80 mL of HMN-MXene aqueous dispersion with a concentration of 5.12 mg / mL, stirred in an ice water bath for 30 min at a speed of 400 rpm, and then the mixture was transferred into a polytetrafluoroethylene mold and placed in an oven at 25°C. The sample was shaped after 20 min. The shaped sample was taken out and cured at 110°C for 12 h. The obtained product was an EP / HMN-MXene composite material, in which the mass ratio of EP to HMN-MXene was 1:0.055.

[0064] Figure 9 are digital photos of pure EP prepared in Example 5 and EP / HMN-MXene composite materials prepared in Examples 6, 7 and 8. The pure EP prepared in Example 5 cracked and broke after thermal curing, while the EP / HMN-MXene composite materials prepared in Examples 6, 7 and 8 had complete morphology. Figure 10 is a dynamic thermal mechanical curve of the EP / HMN-MXene composite material prepared in Example 7. As shown in the figure, the glass transition temperature of the EP / HMN-MXene composite material was 44.9°C, which was significantly lower than that of pure EP. This indicates that the addition of HMN-MXene reduces the crosslinking degree of EP and significantly increases the flexibility of the EP / HMN-MXene composite material. Figure 11 are relative resistance change curves of the EP / HMN-MXene composite materials prepared in Examples 6, 7 and 8 under flame attack. As shown in the figure, the EP / HMN-MXene composite materials all exhibited a negative temperature effect, and the resistance sharply decreased at the moment when it contacted the flame, which indicates that the material has high sensitivity to the flame and can be applied to fire warning. In addition, its excellent flame retardant performance provides the possibility for continuous fire warning signal.

[0065] The above is only an example and description of the concept of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as they do not deviate from the concept of the present application or exceed the scope defined by the present claims, which shall fall within the protection scope of the present application.

Claims

1. A method for preparing a water-soluble polyaminophosphorus nitrogen compound-modified titanium carbide composite, characterized in that, A water-soluble polyamino phosphorus nitrogen compound (HMN) was synthesized by nucleophilic substitution of the chlorine element in the hexachlorotriphosphazene molecule with melamine and ammonia water. Then, the surface of hydroxylated titanium carbide (MXene-OH) was modified with HMN to prepare a water-soluble polyamino phosphorus nitrogen compound modified titanium carbide composite (HMN-MXene).

2. The preparation method according to claim 1, characterized in that, The steps are as follows: (1) Preparation of melamine-modified hexachlorotriphosphazene intermediate (HM): Melamine (MA) was dissolved in hot deionized water. Under nitrogen protection, triethylamine (TEA) was added and stirred. An acetonitrile solution of hexachlorotriphosphazene (HCCP) was added dropwise, and the reaction was maintained at 60–80 °C for 15–20 h. After the reaction was completed, the triethylamine hydrochloride produced by centrifugation was removed. The supernatant after centrifugation was placed in an ice-water bath to promote the precipitation of unreacted MA, which was then separated by vacuum filtration. The filtrate was rotary evaporated, and the resulting product was dried in a vacuum oven to obtain the melamine-modified hexachlorotriphosphazene intermediate (HM). (2) Preparation of water-soluble polyamino phosphorus nitrogen compound (HMN): Weigh a certain amount of HM and dissolve it in deionized water. Maintain the temperature at 0-3℃ and add TEA under nitrogen protection while stirring. Add ammonia water dropwise and stir for 15-20 hours. After the reaction is complete, centrifuge to remove the triethylamine hydrochloride produced in the reaction and rotary evaporate the supernatant. Finally, dry the obtained product in a vacuum oven to obtain the product water-soluble polyamino phosphorus nitrogen compound (HMN). (3) Preparation of HMN-MXene complex: The MXene aqueous dispersion was added to an aqueous sodium hydroxide solution and stirred at 20–30°C for 2–4 hours. After repeated centrifugation and washing, the pH of the supernatant was neutral. The precipitate after centrifugation was ultrasonically dispersed in deionized water to obtain a hydroxylated MXene (MXene-OH) aqueous dispersion. Then, under nitrogen protection, an HMN aqueous dispersion was added to the MXene-OH aqueous dispersion and stirred at 60–80°C for 2–4 hours to obtain an HMN-MXene complex aqueous dispersion.

3. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of MA, TEA and HCCP is 1:(2.2~2.6):(1.2~1.5).

4. The preparation method according to claim 2, characterized in that, In step (2), the mass ratio of HM, TEA and ammonia is 1:(0.8~1):(0.2~0.3).

5. The preparation method according to claim 2, characterized in that, In step (3), the mass ratio of MXene-OH to HMN is 1:(0.05~0.2).

6. The preparation method according to claim 2, characterized in that, In steps (1) and (2), the rotary evaporation temperature is 60-80℃ and the rotary evaporation time is 1.5-2.5h; the product is dried in a vacuum oven at a temperature of 50-70℃ for 20-28h.

7. The water-soluble polyaminophosphorus nitrogen compound modified titanium carbide composite prepared by the method according to any one of claims 1 to 6.

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