Assistant polyoxadiazole polymer as well as synthesis method and application thereof

Abstract

The invention discloses an auxiliary agent polyoxadiazole polymer and a synthesis method and application thereof, hydrazine compounds and ester compounds are polymerized and synthesized through a three-step esterification reaction, and a final product is obtained. Compared with polyhydrazide, the prepared polyoxadiazole polymer has higher thermal stability, tensile strength and wear resistance, and is suitable for being applied to preparation of high-strength, high-toughness and friction-resistant PET high-strength foamed plastics, fibers, emulsions, coatings and adhesives.

Description

Technical Field

[0001] The invention belongs to the field of polymer compound synthesis, and in particular relates to an auxiliary polyoxadiazole polymer and a synthesis method and application thereof. Background Art

[0002] Aromatic polyoxadiazole refers to a polymer material with a benzene ring and an oxadiazole ring in the main chain. It is a high-temperature resistant polymer with an initial decomposition temperature above 500°C. It only decomposes but does not melt at high temperatures. It has no obvious glass transition temperature and can only be dissolved in strong acids such as concentrated sulfuric acid for processing, which makes its molding process difficult. For polyoxadiazole materials, the main focus is on basic research such as optoelectronic materials and proton conductive separation membranes. Polyoxadiazole materials have excellent heat resistance, insulation, and chemical corrosion resistance, so they have broad application prospects in high-temperature resistant and corrosion-resistant insulating materials. Compared with the mainstream high-temperature resistant insulating materials (PI, PET, PC, PPS) on the market, polyoxadiazole materials have the advantages of low cost and easy synthesis while meeting the use requirements of high-temperature resistance, electrical insulation, and low moisture absorption, and have strong competitiveness. At present, the traditional method for preparing polyoxadiazole has limitations. The traditional polymerization method generally includes low-temperature polymerization method and high-temperature polymerization method. However, the obtained polymer solution has not only low solid content but also high viscosity. In addition, the molecular weight of the polymer obtained by the traditional method is small or the molecular weight cannot be controlled, making it difficult to make breakthrough progress in the subsequent processing technology and application of oxadiazole polymer materials. The relevant research progress of polyoxadiazole is slow. Therefore, the existing technology needs to be solved urgently. Summary of the invention

[0003] In view of the above-mentioned deficiencies of the prior art, the present invention solves the problem of providing a polyoxadiazole polymer having high thermal stability and being able to effectively enhance the mechanical properties and thermal stability of PET, as well as a synthesis method and application thereof.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A method for synthesizing an auxiliary polyoxadiazole polymer, comprising the following steps:

[0006] S1. Synthesis of hydrazide ester compounds: a hydrazine compound, an ester compound, a solvent and a catalyst are sequentially added to a glass reaction container, nitrogen is filled in, stirring is continued and heating is performed, after a period of reaction, the reaction phase is a slightly yellow solution, and after the temperature is lowered, a white solid is precipitated; the solid-liquid mixture is solid-liquid separated to obtain a white powder; the white powder is washed several times to remove the residual solvent and then dried to obtain a product hydrazide ester compound;

[0007] S2, synthesis reaction of oxadiazole ester compounds: add the white solid in step S1 into a glass reaction container, add phosphorus oxychloride solvent, start continuous stirring and heat to increase the temperature, after a period of reaction, the reaction phase is a light yellow solution, and solid precipitates from the reaction; separate the solid and liquid to obtain a light yellow powder, wash the powder several times to remove the residual solvent, and then dry to obtain the product oxadiazole ester compound;

[0008] S3, polycondensation synthesis reaction: add the oxadiazole ester compound and hydrazine compound of step S2 into a glass reaction container, add reaction solution and catalyst, fill with nitrogen, start continuous stirring and heat to raise the temperature. After a period of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After a period of time, the reaction liquid becomes a viscous solid block product. Add a solvent for ultrasonic washing, filter, and dry to obtain a yellow powder product.

[0009] Further, in step S1, the hydrazine compound is any one or two of terephthalic acid dihydrazide and isophthalic acid dihydrazide; the ester compound is any one or more of dimethyl terephthalate, diethyl terephthalate, 1,4-naphthalene dicarboxylic acid dimethyl ester, 2,6-naphthalene dicarboxylic acid dimethyl ester, 2,7-naphthalene dicarboxylic acid dimethyl ester, 1,8-naphthalene dicarboxylic acid dimethyl ester, and 5-(hydroxymethyl)isophthalic acid diethyl ester; the solvent is any one or any combination of trifluoromethanesulfonic acid, NMP, acetic acid, phosphoric acid, dimethyl sulfoxide, and ethylene glycol; the catalyst is any one or any combination of anhydrous magnesium sulfate, Al(i-Bu)3, Nd(naph)3, and CoCl.

[0010] Furthermore, in step S1, the reaction temperature is 80-150° C., and the reaction time is 12-18 hours.

[0011] Furthermore, in step S1, the molar ratio of the reactant ester compound to the hydrazine compound is (2:1) to (10:1), and the amount of the catalyst is 1% to 5% by mass.

[0012] Furthermore, in step S2, the reaction time is 8-14 hours and the reaction temperature is 120-135°C.

[0013] Furthermore, in step S2, the detergent used to wash the reactants multiple times is saturated sodium bicarbonate or sodium hydroxide, purified water, or ethanol.

[0014] Furthermore, in step S3, the molar ratio of the product oxadiazole ester compound to the hydrazine compound is (2:1) to (10:1); the reaction time of the product oxadiazole ester compound and the hydrazine compound is 16-20 hours and the reaction temperature is 90-140 degrees.

[0015] Further, in the step S3, the reaction solution of the product oxadiazole ester compound and the hydrazine compound is any one of N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide and dichloromethane; the catalyst of the product oxadiazole ester compound and the hydrazine compound is one of lithium chloride, aluminum chloride and Oxone; the solvent used for ultrasonication of the product is saturated sodium bicarbonate, purified water and anhydrous ethanol, and the washing order is one of saturated sodium bicarbonate, purified water and anhydrous ethanol.

[0016] The invention discloses a method for synthesizing an auxiliary polyoxadiazole polymer. The auxiliary polyoxadiazole polymer is synthesized.

[0017] The invention discloses an auxiliary polyoxadiazole polymer which is used as a chain extender or a polyurethane block in polyurethane rubber and elastomer, PET high-strength foam plastic, fiber, rubber, emulsion, coating and adhesive materials.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention provides a simple and inexpensive synthesis preparation method, using the three-step esterification polycondensation reaction of ester compounds and hydrazide compounds, the oxadiazole group in the polyoxadiazole polymer provided by the present invention has a repeating structure and a high molecular weight, which makes the PET prepared by it have high thermal stability and mechanical strength. The position and number of oxygen atoms and nitrogen atoms in the molecular structure of the polyoxadiazole polymer provided by the present invention can be adjusted, and the product structure can be enriched and varied by regulating the molecular structure, which makes the polyoxadiazole polymer have more diverse application performance, which is of great significance to enriching the types and uses of PET. A synthesis method of a polyoxadiazole polymer provided by the present invention, the polymer is synthesized using safe, economical, and environmentally friendly raw materials and reaction conditions, which makes it have broad application prospects and market potential. High-performance PET materials, coatings, adhesives, etc. can be prepared, and it also has broad application prospects in catalysts, chelating agents, drug carriers, etc. The high molecular polymer of the present invention has a high potential application value in the neighborhood of PET and polyurethane materials, and promotes the development of science and engineering fields.

[0020] 2. The present invention synthesizes polyoxadiazole polymers through polycondensation by ester compounds and terephthalic acid dihydrazide and isophthalic acid dihydrazide, and is used as the soft segment structure or chain extender of synthetic PET and polyurethane materials. A kind of polyoxadiazole polymer provided by the present invention has the advantages that the PET and polyurethane obtained therefrom have higher mechanical strength, heat resistance, tensile strength, elastic modulus and wear resistance, and is particularly suitable for application in the preparation of high-strength PET foam plastics, PET polyester fiber, casting polyurethane rubber, emulsion and coating, adhesive, etc. The oxygen atoms, nitrogen atoms and carbon atom positions and quantities in the molecular structure of the polyoxadiazole polymer provided by the present invention are combined and regulated to make its structure rich and varied, and the molecular weight of polyoxadiazole can be timely regulated according to the reaction conditions, which makes the polyoxadiazole polymer have the characteristics of high selectivity, and more diversified application performance, which is of great significance to enriching the types of oxadiazole products and expanding the application fields of PET and polyurethane. The technology of the present invention will promote the further development of PET and polyurethane applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 4 is a Fourier transform infrared spectrum of each embodiment of the present invention.

[0022] Figure 2 It is the stress-strain spectrum of each embodiment of the present invention and PET blend material.

[0023] Figure 3 The DSC spectra of the blended materials of various embodiments of the present invention and PET are shown in FIG.

[0024] Figure 4 It is the thermal stability spectrum of each embodiment of the present invention and PET blend material. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0026] Example 1

[0027] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0028] S1. Synthesis of hydrazide ester compounds: 3.89 g of terephthalic acid dihydrazide, 11.65 g of dimethyl terephthalate, 100 ml of ethylene glycol and

[0029] 0.1554gAl(i-Bu)3, nitrogen (flow rate 10mL / min), stirring (stirring speed 400r / min), and heating to 100 degrees. After 12h of reaction, the reaction phase is a slightly yellow solution. After the temperature is lowered to room temperature, a white solid precipitates. The solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven and dried at 100°C for 10 h to obtain 8.50g of the product hydrazide ester compound.

[0030] S2: Synthesis reaction of oxadiazole ester compounds: Add 8.50g of the white solid in step S1 into a 4-mouth glass reaction container, add 25ml of phosphorus oxychloride solvent, start stirring (stirring speed is 400r / min), and heat to 120 degrees. The reaction time is 8h. The reaction phase is a light yellow solution, and solid precipitates from the reaction. The reaction solution is cooled to room temperature, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, saturated sodium bicarbonate or sodium hydroxide, purified water, ethanol, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C and dried for 24h to obtain 25.9g of product oxadiazole ester compound.

[0031] S3: Condensation synthesis reaction: Add 25.9g (0.05mol) of oxadiazole ester compound and 19.42g (0.1mol) of terephthalic acid dihydrazide in step S2 into a 500ml four-necked glass reaction container, add 100ml N-methylpyrrolidone solvent and 0.45g lithium chloride catalyst, fill with nitrogen (flow rate is 10mL / min), start stirring (stirring speed is 400r / min), and heat to 110 degrees. After 16h of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After standing for one night, the reaction liquid becomes a viscous solid block product. Saturated sodium bicarbonate is added for ultrasonic washing. The solid-liquid mixture is vacuum filtered under -0.08MPa conditions for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 10 h to obtain 30.05g of yellow powder product.

[0032] The conversion rate of the polyoxadiazole polymer of Example 1 was 85% and the intrinsic viscosity [η] was 1.34 (dl / g).

[0033] The polymer of Example 1 and PET were blended in a ratio of 1:30 and then melt-molded at high temperature to form dumbbell-shaped sheets to obtain material-modified PET1. The mechanical properties of the modified PET1 were measured using a single-arm tensile tester CZ-8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2 As shown, the stress and strain values ​​are 47MPa and 4.78% respectively.

[0034] Example 2

[0035] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0036] S1. Synthesis of hydrazide ester compounds: 3.89g of isophthalic acid dihydrazide, 11.65g of 1,4-naphthalene dicarboxylic acid dimethyl ester, 100ml of acetic acid and 0.1554g of CoCl were added to a 500ml four-necked glass reaction container, nitrogen was introduced (flow rate was 10mL / min), stirring was started (stirring speed was 400r / min), and the temperature was raised to 110 degrees. After 14h of reaction, the reaction phase was a slightly yellow solution. After the temperature was lowered to room temperature, a white solid precipitated. The solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 18h to obtain 11.05g of the product hydrazide ester compound.

[0037] S2: Synthesis reaction of oxadiazole ester compounds: Add 11.05g of the white solid in step S1 into a 250ml four-necked glass reaction vessel, add 100ml of phosphorus oxychloride solvent, start stirring (stirring speed is 400r / min), and heat to 125 degrees. The reaction time is 8h. The reaction phase is a light yellow solution, and solid precipitates from the reaction. The reaction solution is cooled to room temperature, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 24h to obtain 32.9g of product oxadiazole ester compound.

[0038] S3: Condensation synthesis reaction: 32.9g (0.06mol) of oxadiazole ester compound and 19.42g (0.1mol) of isophthalic acid dihydrazide in step S2 are added to a 500ml four-necked glass reaction container, 120ml of N-methylpyrrolidone solvent and 0.52g of lithium chloride catalyst are added, nitrogen is filled (flow rate is 10mL / min), stirring is turned on (stirring speed is 400r / min), and the temperature is heated to 125 degrees. After 15h of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After standing for one night, the reaction liquid becomes a viscous solid block product. Saturated sodium bicarbonate is added for ultrasonic washing. The solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 10 h to obtain 40.58g of yellow powder product.

[0039] The conversion rate of the high molecular weight polymer of Example 2 was 85.5% and the intrinsic viscosity [η] was 1.57 (dl / g).

[0040] The polymer of Example 2 was blended with PET in a ratio of 1:30 and then melt-molded at high temperature to form a dumbbell-shaped sheet to obtain a material-modified PET2. The mechanical properties of the material were measured using a single-arm tensile testing machine CZ-8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2 As shown, the stress and strain values ​​are 50 MPa and 4.75% respectively.

[0041] Example 3

[0042] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0043] S1. Synthesis of hydrazide ester compounds: 3.89g of isophthalic acid dihydrazide, 11.65g of 2,7-naphthalene dicarboxylic acid dimethyl ester, 100ml of acetic acid and 0.18g of anhydrous magnesium sulfate were added to a 500ml four-necked glass reaction container, nitrogen was charged (flow rate was 10mL / min), stirring was turned on (stirring speed was 400r / min), and the temperature was raised to 110 degrees. After 16h of reaction, the reaction phase was a slightly yellow solution. After the temperature was lowered to room temperature, a white solid precipitated and the filtrate was slightly yellow. The solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 18h to obtain 13.5g of the product hydrazide ester compound.

[0044] S2: Synthesis reaction of oxadiazole ester compounds: 13.5g of the white solid in step S1 was added to a 500ml four-necked glass reaction vessel, 100ml of phosphorus oxychloride solvent was added, stirring was started (stirring speed was 400r / min), and the temperature was raised to 125 degrees. The reaction time was 8h. The reaction phase was a light yellow solution, and solid precipitated from the reaction. The reaction solution was cooled to room temperature, and the solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C and dried for 24h to obtain 30.5g of product oxadiazole ester compound.

[0045] S3: Condensation synthesis reaction: 30.5g (0.06mol) of oxadiazole ester compound and 19.42g (0.1mol) of isophthalic acid dihydrazide in step S2 are added to a 500ml four-necked glass reaction container, 120ml of dimethyl sulfoxide solvent and 0.6g of lithium chloride catalyst are added, nitrogen is filled (flow rate is 10mL / min), stirring is turned on (stirring speed is 400r / min), and the temperature is heated to 125 degrees. After 14h of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After standing for one night, the reaction liquid becomes a viscous solid block product, saturated sodium bicarbonate is added for ultrasonic washing, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 10 h to obtain 39.58g of yellow powder product.

[0046] The conversion rate of the high molecular weight polymer of Example 3 was 86.5% and the intrinsic viscosity [η] was 2.45 (dl / g).

[0047] The polymer of Example 3 was blended with PET in a ratio of 1:30 and then melt-molded at high temperature into dumbbell-shaped sheets to obtain material-modified PET 3. The mechanical properties of the modified PET 3 were measured using a single-arm tensile testing machine CZ-8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2As shown, the stress and strain values ​​are 53MPa and 3.67% respectively.

[0048] Example 4

[0049] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0050] S1. Synthesis of hydrazide ester compounds: 3.89g of terephthalic acid dihydrazide, 11.65g of 1,8-naphthalene dicarboxylic acid dimethyl ester, 100ml of acetic acid and 0.167g of anhydrous magnesium sulfate were added to a 500ml four-necked glass reaction container, nitrogen was charged (flow rate was 10mL / min), stirring was turned on (stirring speed was 400r / min), and the temperature was raised to 110 degrees. After 14h of reaction, the reaction phase was a slightly yellow solution. After the temperature was lowered to room temperature, a white solid precipitated and the filtrate was slightly yellow. The solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven and dried at 100°C for 20h to obtain 15.02g of the product hydrazide ester compound.

[0051] S2: Synthesis reaction of oxadiazole ester compounds: Add 15.02g of the white solid in step S1 into a 500ml four-necked glass reaction vessel, add 100ml of phosphorus oxychloride solvent, start stirring (stirring speed is 400r / min), and heat to 125 degrees. The reaction time is 10h. The reaction phase is a light yellow solution, and solid precipitates from the reaction. The reaction solution is cooled to room temperature, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 24h to obtain 33.03g of product oxadiazole ester compound.

[0052] S3: Condensation synthesis reaction: 33.03g (0.06mol) of oxadiazole ester compound and 38.84g (0.2mol) of isophthalic acid dihydrazide in step S2 are added to a 500ml four-necked glass reaction container, 120ml of dimethyl sulfoxide solvent and 0.55g of aluminum chloride catalyst are added, nitrogen is filled (flow rate is 10mL / min), stirring is turned on (stirring speed is 400r / min), and the temperature is heated to 125 degrees. After 14h of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After standing for one night, the reaction liquid becomes a viscous solid block product, saturated sodium bicarbonate is added for ultrasonic washing, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 10 h to obtain 45.06g of yellow powder product.

[0053] The conversion rate of the high molecular weight polymer of Example 4 was 84.5% and the intrinsic viscosity [η] was 2.61 (dl / g).

[0054] The polymer of Example 4 was blended with PET in a ratio of 1:30 and then melt-molded at high temperature into dumbbell-shaped sheets to obtain material-modified PET4. The mechanical properties of the modified PET4 were measured using a single-arm tensile testing machine CZ8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2 As shown, the stress and strain values ​​are 60 MPa and 5.47% respectively.

[0055] Example 5

[0056] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0057] S1. Synthesis of hydrazide ester compounds: 3.89g of terephthalic acid dihydrazide, 11.65g of 5-(hydroxymethyl)isophthalic acid diethyl ester, 100ml of acetic acid and 0.10g of anhydrous magnesium sulfate were added to a 500ml four-necked glass reaction container in sequence, nitrogen was charged (flow rate was 10mL / min), stirring was started (stirring speed was 400r / min), and the temperature was raised to 120 degrees. After 13h of reaction, the reaction phase was a slightly yellow solution. After the temperature was lowered to room temperature, a white solid precipitated and the filtrate was slightly yellow. The solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven and dried at 100°C for 20h to obtain 16.85g of the product hydrazide ester compound.

[0058] S2: Synthesis reaction of oxadiazole ester compounds: Add 16.85g of the white solid in step S1 into a 500ml four-necked glass reaction vessel, add 100ml of phosphorus oxychloride solvent, start stirring (stirring speed is 400r / min), and heat to 130 degrees. The reaction time is 11h. The reaction phase is a light yellow solution, and solid precipitates from the reaction. The reaction solution is cooled to room temperature, and the solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 24h to obtain 34.09g of product oxadiazole ester compound.

[0059] S3: Condensation synthesis reaction: 34.09 (0.063 mol) of oxadiazole ester compounds in step S2 and 38.84 g (0.2 mol) of terephthalic acid dihydrazide were added to a 500 ml four-necked glass reaction container, 120 ml of dimethyl sulfoxide solvent and 0.63 g of aluminum chloride catalyst were added, nitrogen was filled in (flow rate was 10 mL / min), stirring was turned on (stirring speed was 400 r / min), and the temperature was raised to 130 degrees. After 13 hours of reaction, the reaction phase was a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitated. After standing for one night, the reaction liquid became a viscous solid block product. Saturated sodium bicarbonate was added for ultrasonic washing. The solid-liquid mixture was filtered under reduced pressure at -0.08 MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 24h to obtain 40.06g of yellow powder product.

[0060] The conversion rate of the high molecular weight polymer of Example 5 was 86.5% and the intrinsic viscosity [η] was 3.56 (dl / g).

[0061] The polymer of Example 5 was blended with PET in a ratio of 1:30 and then melt-molded at high temperature into dumbbell-shaped sheets to obtain material-modified PET5. The mechanical properties of the modified PET5 were measured using a single-arm tensile testing machine CZ8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2 As shown, the stress and strain values ​​are 65MPa and 6.54% respectively.

[0062] Example 6

[0063] A method for preparing a polyoxadiazole polymer, comprising the following steps:

[0064] S1. Synthesis of hydrazide ester compounds: 4.20g terephthalic acid dihydrazide, 12.65g 1,4-dimethyl phthalate, 110ml acetic acid and 0.10g anhydrous magnesium sulfate were added to a 500ml four-necked glass reaction container in sequence, nitrogen was charged (flow rate was 10mL / min), stirring was started (stirring speed was 400r / min), and the temperature was raised to 120 degrees. After 15h of reaction, the reaction phase was a slightly yellow solution. After the temperature was lowered to room temperature, a white solid precipitated and the filtrate was slightly yellow. The solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a white powder; the white powder was washed 3 times with ethanol, and then washed 3 times with pure water to remove the residual solvent, and finally the powder was placed in a vacuum oven and dried at 100°C for 20h to obtain 17.83g of the product hydrazide ester compound.

[0065] S2: Synthesis reaction of oxadiazole ester compounds: 17.83g of the white solid in step S1 was added to a 500ml four-necked glass reaction vessel, 100ml of phosphorus oxychloride solvent was added, stirring was started (stirring speed was 400r / min), and the temperature was raised to 125 degrees. The reaction time was 16h. The reaction phase was a light yellow solution, and solid precipitated from the reaction. The reaction solution was cooled to room temperature, and the solid-liquid mixture was filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper) to obtain a light yellow powder, the powder was washed 3 times with saturated sodium bicarbonate, then washed 3 times with purified water, and finally washed 3 times with ethanol to remove residual solvent, and finally the powder was placed in a vacuum oven at 100°C for 19h to obtain 32.09g of product oxadiazole ester compound.

[0066] S3: Polycondensation reaction: 32.09 g (0.063 mol) of the oxadiazole ester compound from step S2 and 38.84 g (0.2 mol) of terephthalic acid dihydrazide were added to a 500 ml four-necked glass reaction vessel, 120 ml of dimethylacetamide solvent and 0.58 g of aluminum chloride catalyst were added, and nitrogen (flow rate:

[0067] 10mL / min), stirring (stirring speed is 400r / min), and heating to 125 degrees. After 15 hours of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After standing overnight, the reaction liquid becomes a viscous solid block product. Saturated sodium bicarbonate is added for ultrasonic washing. The solid-liquid mixture is filtered under reduced pressure at -0.08MPa for solid-liquid separation (using Buchner funnel, 500mL suction filtration bottle, medium-speed qualitative filter paper), and finally the powder was placed in a vacuum oven and dried at 100°C for 24h to obtain 41.21g of yellow powder product.

[0068] The conversion rate of the high molecular weight polymer of Example 6 was 85.5% and the intrinsic viscosity [η] was 4.56 (dl / g).

[0069] The polymer of Example 6 was blended with PET in a ratio of 1:30 and then melt-molded at high temperature to form a dumbbell-shaped sheet to obtain material-modified PET6. The mechanical properties of the modified PET6 were measured using a single-arm tensile testing machine CZ8000A106 (Guangdong Zhongzhi Testing Instrument Co., Ltd., China) using the tensile test method of GB2651-1989. Figure 2 As shown, the stress and strain values ​​are 63MPa and 3.35% respectively.

[0070] Depend on Figure 1 It can be seen that the wavelengths in the figure correspond to the relevant groups of the structure: 721.41cm-1 is a single substitution of the benzene ring, 1237cm-1, 1246cm-1, 1306cm-1 are CN bonds, 1375cm-1, 1306cm-1 are C=NN=C bonds, 1610.75184cm-1 are C=C bonds, 2959.45cm-1 are saturated CH bonds, 3282.66cm-1 are CH stretching vibration areas on unsaturated bonds, 998cm-1, 994.80cm-1, 980.77cm-1 are -COC- bonds. This shows that the polymer of the polyoxadiazole modified PET modified by the additive was successfully synthesized.

[0071] Depend on Figure 2 It can be seen from the above figure that the stress of pure PET is about 30MPa. After 6 kinds of polyoxadiazole polymers with different molecular weights are blended and modified with PET, the stress values ​​of the modified polymers are 47MPa, 50MPa, 53MPa, 60MPa, 65MPa, and 63MPa respectively. This shows that the additive polyoxadiazole polymer is beneficial to improving the mechanical strength of PET materials.

[0072] Depend on Figure 3It can be seen from the above figure that the melting point of pure PET is about 230 degrees, and the melting point of PET modified by additives increases. Among them, PET6 has no melting point and is a thermosetting polymer. The melting points of PET2, PET4 and PET5 are about 250 degrees, and the melting points of PET1 and PET3 are about 300 degrees. This shows that the additive polyoxadiazole polymer is beneficial to improving the rigidity of thermoplastic PET materials.

[0073] Depend on Figure 4 It can be seen from the above figure that the thermal decomposition temperature of pure PET is about 226 degrees. The thermal decomposition temperature of PET modified with the additive polyoxadiazole is increased, and the temperature value is between 300-450 degrees. This shows that the additive polyoxadiazole polymer is beneficial to improving the thermal stability of PET materials.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing an auxiliary polyoxadiazole polymer, characterized in that: Here are the steps: S1. Synthesis of hydrazide ester compounds: a hydrazine compound, an ester compound, a solvent and a catalyst are sequentially added to a glass reaction container, nitrogen is filled in, stirring is continued and heating is performed, after a period of reaction, the reaction phase is a slightly yellow solution, and after the temperature is lowered, a white solid is precipitated; the solid-liquid mixture is solid-liquid separated to obtain a white powder; the white powder is washed several times to remove the residual solvent and then dried to obtain a product hydrazide ester compound; S2, synthesis reaction of oxadiazole ester compounds: add the white solid in step S1 into a glass reaction container, add phosphorus oxychloride solvent, start continuous stirring and heat to increase the temperature, after a period of reaction, the reaction phase is a light yellow solution, and solid precipitates from the reaction; separate the solid and liquid to obtain a light yellow powder, wash the powder several times to remove the residual solvent, and then dry to obtain the product oxadiazole ester compound; S3, polycondensation synthesis reaction: add the oxadiazole ester compound and hydrazine compound of step S2 into a glass reaction container, add reaction solution and catalyst, fill with nitrogen, start continuous stirring and heat to raise the temperature. After a period of reaction, the reaction phase is a light yellow viscous liquid. After cooling the reaction liquid, a yellow solid precipitates. After a period of time, the reaction liquid becomes a viscous solid block product. Add a solvent for ultrasonic washing, filter, and dry to obtain a yellow powder product.

2. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S1, the hydrazine compound is any one or two of terephthalic acid dihydrazide and isophthalic acid dihydrazide; the ester compound is any one or more of dimethyl terephthalate, diethyl terephthalate, 1,4-naphthalene dicarboxylic acid dimethyl ester, 2,6-naphthalene dicarboxylic acid dimethyl ester, 2,7-naphthalene dicarboxylic acid dimethyl ester, 1,8-naphthalene dicarboxylic acid dimethyl ester, and 5-(hydroxymethyl) isophthalic acid diethyl ester; the solvent is any one or any combination of trifluoromethanesulfonic acid, NMP, acetic acid, phosphoric acid, dimethyl sulfoxide, and ethylene glycol; the catalyst is any one or any combination of anhydrous magnesium sulfate, Al(i-Bu)3, Nd(naph)3, and CoCl.

3. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S1, the reaction temperature is 80-150° C. and the reaction time is 12-18 hours.

4. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S1, the molar ratio of the reactant ester compound to the hydrazine compound is (2:1) to (10:1), and the amount of the catalyst used is 1% to 5% by mass.

5. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S2, the reaction time is 8-14 hours, and the reaction temperature is 120-135° C.; the detergent used for multiple washings of the reactants is saturated sodium bicarbonate or sodium hydroxide, purified water, or ethanol.

6. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S3, the molar ratio of the product oxadiazole ester compound to the hydrazine compound is (2:1) to (10:1); the reaction time of the product oxadiazole ester compound and the hydrazine compound is 16-20 hours and the reaction temperature is 90-140 degrees.

7. The method for synthesizing the auxiliary polyoxadiazole polymer according to claim 1, characterized in that: In the step S3, the reaction solution of the product oxadiazole ester compound and the hydrazine compound is any one of N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide and dichloromethane; the catalyst of the product oxadiazole ester compound and the hydrazine compound is one of lithium chloride, aluminum chloride and Oxone; the solvent used in the ultrasonication of the product is saturated sodium bicarbonate, purified water and anhydrous ethanol, and the washing order is one of saturated sodium bicarbonate, purified water and anhydrous ethanol.

8. An auxiliary polyoxadiazole polymer synthesized according to the method for synthesizing an auxiliary polyoxadiazole polymer according to claim 1.

9. Use of the auxiliary polyoxadiazole polymer according to claim 8 as a chain extender or polyurethane block in polyurethane rubber and elastomer, PET high-strength foam plastic, fiber, rubber, emulsion, coating and adhesive materials.

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