Thermoplastic heat-conducting polyester containing disulfide bonds as well as preparation method and application of thermoplastic heat-conducting polyester

Abstract

The invention belongs to the field of heat-conducting polymer materials, and discloses disulfide bond-containing thermoplastic heat-conducting polyester as well as a preparation method and application thereof. According to the method, biphenyl diol and disulfide bond-containing dicarboxylic acid are subjected to an esterification reaction and a condensation polymerization reaction under the action of a catalyst, and the thermoplastic heat-conducting polyester is prepared. The disulfide bond is introduced into a polyester system, the S-S bond can serve as a Lewis base to act with a proton donor to form hydrogen bonds with sulfur as the center, such as hydrogen bonds such as CH.S, NH. S, SH. S and OH.S, and the intermolecular force of the polyester can be improved. And a large number of biphenyl structures are introduced into a molecular chain, so that the heat-conducting property and the mechanical property can be greatly improved.

Description

Technical Field

[0001] The present invention belongs to the field of thermal conductive polymers, and particularly relates to a disulfide bond-containing thermoplastic thermal conductive polyester and a preparation method and application thereof. Background Art

[0002] With the rapid development of fifth-generation (5G) mobile communications and internet technologies, flexible electronics have attracted significant interest in wearable devices and soft robotics. However, the increasing integration and power density pose significant challenges in heat dissipation. Flexible polymers with high thermal conductivity are ideal materials for effectively dissipating heat and maintaining the proper functioning of electronic devices.

[0003] While the preparation of thermally conductive polymer composites by doping them with thermally conductive fillers can significantly improve the thermal conductivity of polymer composite systems, this typically comes at the expense of mechanical properties, processability, density, and cost. The strategy of obtaining intrinsically thermally conductive polymers (ITCPs) by enhancing the structural order of disordered polymers not only simultaneously improves dielectric strength and thermal conductivity, but also retains the polymer's inherent advantages, such as chemical resistance and high insulation resistance, excellent mechanical flexibility, optical transparency, and ease of processing. ITCPs are categorized as thermoplastic polymers and thermosetting polymers based on whether the molecular chains are cross-linked. However, compared to thermoplastic polymers, the polymerization process for thermosetting polymers is cumbersome and demanding, and once formed, they cannot be repeatedly processed. Therefore, modulating the multiscale molecular chain structure, increasing structural order, suppressing various types of phonon scattering, and constructing low-resistance thermal pathways that facilitate phonon transmission can improve and regulate the thermal conductivity of thermoplastic polymers. By introducing disulfide bonds into the polyester system, the SS bonds can act as Lewis bases and interact with proton donors to form sulfur-centered hydrogen bonds, such as CH···S, NH···S, SH···S, and OH···S. This improves the intermolecular forces of the polyester. Simultaneously, the introduction of a large number of biphenyl mesogens into the molecular chain enhances both thermal conductivity and mechanical properties. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the primary purpose of the present invention is to provide a thermoplastic thermally conductive polyester containing disulfide bonds.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned thermoplastic polyester containing disulfide bonds; the method is to prepare the thermoplastic thermal conductive polyester containing disulfide bonds by esterification reaction and polycondensation reaction of biphenyl diol and dicarboxylic acid containing disulfide bonds, and utilize the special structure of the disulfide bond to form stable chemical bonds between polymer molecules, so that the polymer has good mechanical properties.

[0006] Another object of the present invention is to provide an application of the above-mentioned disulfide bond-containing thermoplastic thermally conductive polyester.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A disulfide bond-containing thermoplastic thermally conductive polyester, wherein the disulfide bond-containing thermoplastic thermally conductive polyester has a structure shown in the following formula (I) or formula (II):

[0009]

[0010] Wherein m is a natural number between 1 and 10. Preferably, m is a natural number between 3 and 9.

[0011] The above-mentioned method for preparing a disulfide bond-containing thermoplastic thermally conductive polyester comprises the following steps:

[0012] Biphenyl diol, dicarboxylic acid and a catalyst are mixed, and then a prepolymerization reaction is carried out under nitrogen protection. After the prepolymerization reaction, by-product water in the reaction system is removed, and then a polymerization reaction is continued. After the polymerization reaction, the target product, a disulfide bond-containing thermoplastic thermally conductive polyester, is obtained.

[0013] The biphenyl diol is prepared by the following method: biphenyl diphenol, a halogen-containing long-chain alcohol, anhydrous potassium carbonate and a solvent are mixed, and then heated under reflux for 12 to 36 hours under nitrogen protection. After the reflux reaction is completed, the obtained reaction solution is purified to obtain the biphenyl diol.

[0014] The biphenyl diol is any one of biphenyl dipropanol, biphenyl dihexanol and biphenyl dinonanol;

[0015] The dicarboxylic acid is at least one of 3,3-dithiodipropionic acid and 2,2-dithiodibenzoic acid;

[0016] The molar ratio of the biphenyl diol to the dicarboxylic acid is 1-3:1-3, preferably 1:1;

[0017] The catalyst is antimony trioxide and anhydrous zinc acetate, wherein the mass of the anhydrous zinc acetate is 0.1-0.3% of the total mass of the reaction system, preferably 0.2%, and the mass of the antimony trioxide is 0.2-0.5% of the total mass of the reaction system, preferably 0.3%.

[0018] The prepolymerization reaction is carried out at 160-190°C for 2-5 hours, preferably at 180°C for 3 hours;

[0019] The polymerization reaction refers to the polymerization reaction at a temperature increased by 10 to 20°C (preferably 10°C) based on the prepolymerization reaction temperature, and the polymerization reaction time is 3 to 5 hours, preferably 3 hours;

[0020] The by-product water in the reaction system is removed by vacuuming, and the vacuum degree is lower than 30Pa.

[0021] The halogen-containing long-chain alcohol is at least one of 3-chloro-1-propanol, 6-chloro-1-hexanol and 9-bromo-1-nonanol; the molar ratio of the halogen-containing long-chain alcohol to biphenol is 2 to 4:1, preferably 3:1; the solvent is one of N,N-dimethylformamide, ethyl acetate and toluene, preferably N,N-dimethylformamide.

[0022] The above-mentioned disulfide bond-containing thermoplastic thermally conductive polyester is used in the fields of electronic packaging and thermal management.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The present invention introduces dicarboxylic acid containing a disulfide bond, and through esterification reaction and polycondensation reaction, the thermoplastic polyester material prepared has better thermal conductivity than general thermoplastic polymers.

[0025] (2) The linear polyester obtained by the present invention contains two disulfide bonds. The S-S bond can act as a Lewis base to interact with a proton donor to form sulfur-centered hydrogen bonds, such as CH···S, NH···S, SH···S, and OH···S hydrogen bonds, which can enhance the intermolecular forces of the polyester. In addition, the introduction of a large number of biphenyl structures into the molecular chain can significantly improve thermal conductivity and mechanical properties.

[0026] (3) The disulfide bonds in the polyesters prepared by the present invention are dynamic covalent bonds with reducing properties. Under the action of reducing agents such as glutathione, which are present in high concentrations in cells, the disulfide bonds can be rapidly broken, thereby achieving polymer degradation. This degradation property makes the disulfide-bonded polymers more safe and controllable in vivo. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an infrared image of the disulfide bond-containing thermoplastic thermally conductive polyester prepared in Examples 3 and 4 of the present invention.

[0028] Figure 2 This is the infrared image of the thermoplastic thermal conductive polyester material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below with reference to examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market, and the process parameters not specifically noted can be carried out with reference to conventional techniques.

[0030] Example 1:

[0031] Weigh biphenyldiphenol (0.1 mol, 18.62 g), 3-chloro-1-propanol (0.3 mol, 28 mL), potassium carbonate (0.7 mol, 100 g), and 150 mL of DMF (N,N-dimethylformamide) into a three-necked flask equipped with a magnetic stirrer and a reflux condenser. Heat under reflux for 24 hours under a nitrogen atmosphere. Cool to room temperature, filter, and collect the residue. Pour the residue into a beaker, add 500 mL of deionized water, stir, filter, and collect the residue. Add hydrochloric acid solution dropwise until neutral, remove excess potassium carbonate, and wash three times with deionized water. Dry the resulting product in a vacuum oven at 80°C for 24 hours to obtain biphenyldipropanol.

[0032] Biphenyl diol (0.1 mol, 3.02 g), 3,3-dithiodipropionic acid (0.1 mol, 2.10 g), anhydrous zinc acetate (0.2 wt%, 0.0102 g), and antimony trioxide (0.3 wt%, 0.0154 g) were uniformly mixed and prepolymerized at 170°C under a nitrogen atmosphere for 3 hours. The nitrogen flow was then stopped. The temperature was then slowly raised to 190°C and maintained for 3 hours for polymerization. Water and small molecules were removed from the system by vacuum filtration. The system was then vacuumed (less than 30 Pa) and cooled to room temperature to obtain a thermoplastic thermally conductive polyester material. The H-NMR spectrum data of the resulting thermoplastic thermally conductive polyester material were as follows: 1 H NMR (400 MHz, CDCl3); δ7.47 (d, 2H, Ar–Ar); δ6.96 (m, 2H, Ar–O–); δ4.14 (s, 2H, Ar–O–CH2); δ3.91 (s, 2H, CH2–O–CO–); δ2.93 (d, 2H, CH2–COO); δ2.69 (d, 2H, CH2-COO); δ1.82 (s, 2H, CH2–CH2OCO); δ1.63 (s, 3H, Ar–O–CH2–CH2); δ1.43 (d, 4H, OCH2CH2CH2O). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0033]

[0034] Example 2:

[0035] Biphenyl dipropanol was prepared by referring to the method of Example 1.

[0036] A mixture of diphenyl propanol (0.1 mol, 3.02 g), 2,2-dithiodibenzoic acid (0.1 mol, 3.06 g), anhydrous zinc acetate (0.2 wt%, 0.0122 g), and antimony trioxide (0.3 wt%, 0.0182 g) was uniformly mixed and prepolymerized at 190°C under a nitrogen atmosphere for 3 hours. The nitrogen flow was then stopped. The temperature was then slowly raised to 200°C and maintained for 3 hours for polymerization. Water and small molecules were removed from the system by vacuum filtration. The system was then cooled to room temperature after the vacuum was reduced to below 30 Pa to obtain a thermoplastic thermally conductive polyester material. The H-NMR spectrum data of the resulting thermoplastic thermally conductive polyester material were as follows: 1 H NMR (400 MHz, CDCl3): δ8.02 (s, 2H, Ar–CH(CO)O); δ7.69 (s, 2H, Ar–S); δ7.48 (s, 7H, Ar–CH(CO)O); 6.92 (s, 5H, Ar–O–); 4.32 (s, 4H, Ar–O–CH2); δ4.02 (s, 5H, Ar–CH(CO)O–); δ1.80 (m, 10H, CH2–CH2OCO); δ1.54 (s, 8H, OCH2–(CH2)2–CH2O); δ1.23 (s, 2H, Ar–O–CH2–CH2). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0037]

[0038] Example 3:

[0039] Biphenyl diol was prepared by the method of Example 1.

[0040] Diphenyl dihydroxyethanol (0.1 mol, 3.86 g), 3,3-dithiodipropionic acid (0.1 mol, 2.10 g), anhydrous zinc acetate (0.2 wt%, 0.0119 g) and antimony trioxide (0.3 wt%, 0.0179 g) were uniformly mixed and heated to 190°C for 3 hours under nitrogen atmosphere for prepolymerization. The temperature was then slowly raised to 200°C and kept at this temperature for 3 hours for polymerization. Water and small molecules in the system were removed by vacuum filtration. The vacuum degree of the system was reduced (below 30 Pa) and cooled to room temperature to obtain a thermoplastic thermally conductive polyester material. The infrared image of the thermoplastic thermally conductive polyester material prepared in this example is shown below. Figure 1 As shown, the H NMR spectrum data is: 1 H NMR(400MHz, CDCl3); δ7.45(d,2H,Ar–Ar); δ6.94(m,2H,Ar–O–); δ4.11(s,2H,Ar–O–CH2); δ3.93(s,2H,CH2–O–CO–); δ2.91(d,2H,CH2–COO);

[0041] δ2.74 (d, 2H, CH2-COO); δ1.80 (s, 2H, CH2–CH2OCO); δ1.68 (s, 3H, Ar–O–CH2–CH2); δ1.47 (d, 4H, OCH2 CH2)4CH2O). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0042]

[0043] Example 4:

[0044] Biphenyl diol was prepared by the method of Example 1.

[0045] Evenly mix diphenyl diol (0.1mol, 3.86g), 2,2-dithiodibenzoic acid (0.1mol, 3.06g), (0.02wt%, 0.0138g), and anhydrous zinc acetate (0.02wt%, 0.0208g) as catalysts. In a nitrogen atmosphere, heat to 190℃ for prepolymerization for 3h, stop introducing nitrogen; then slowly heat to 200℃ and keep warm for 3h to carry out polymerization reaction. Remove water and small molecules in the system by vacuum filtration. Reduce the vacuum degree of the system (below 30Pa) and cool to room temperature to obtain a thermoplastic thermal conductive polyester material. The infrared image of the thermoplastic thermal conductive polyester material prepared in this example is as follows: Figure 1 As shown, the H NMR spectrum data is: 1 H NMR (400MHz, CDCl3): δ8.05(s,2H,Ar–CH(CO)O); δ7.74(s,2H,Ar–S); δ7.45(S,7H,Ar–CH(CO)O); δ6.94(s,5H,Ar–O–); δ4.42(s,4H,Ar–O–CH2);

[0046] δ4.00 (s, 5H, Ar–CH(CO)O–); δ1.86 (s, 10H, CH2–CH2OCO); δ1.57 (s, 16H, OCH2–(CH2)2–CH2O); δ1.26 (s, 2H, Ar–O–CH2–CH2). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0047]

[0048] Example 5:

[0049] Biphenyl dinonanol was prepared by referring to the method of Example 1.

[0050] Biphenyl dinonanol (0.1 mol, 4.71 g), 3,3-dithiodipropionic acid (0.1 mol, 2.10 g), anhydrous zinc acetate (0.02 wt%, 0.0136 g), and antimony trioxide (0.3 wt%, 0.0204 g) were uniformly mixed and prepolymerized at 190°C under a nitrogen atmosphere for 3 hours. The nitrogen flow was then stopped. The temperature was then slowly raised to 200°C and maintained for 3 hours for polymerization. Water and small molecules were removed from the system by vacuum filtration. The system was then reduced to below 30 Pa and cooled to room temperature to obtain a thermoplastic thermally conductive polyester material. The H-NMR spectrum data of the thermoplastic thermally conductive polyester material prepared in this example are as follows: 1 H NMR(400MHz, CDCl3); δ7.52(d,2H,Ar–Ar); δ6.98(m,2H,Ar–O–); δ4.14(s,2H,Ar– O–CH); δ3.95(s,2H,CH2–O–CO–); δ2.93(d,2H,CH2–COO); δ2.67(d,2H,CH2-COO);

[0051] δ1.85 (s, 2H, CH2–CH2 OCO); δ1.66 (s, 3H, Ar–O–CH2–CH2); δ1.37 (d, 8H, OCH2(CH2)7CH2O). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0052]

[0053] Example 6:

[0054] Biphenyl dinonanol was prepared by referring to the method of Example 1.

[0055] Biphenyl dinonanol (0.1 mol, 4.71 g), 2,2-dithiodibenzoic acid (0.1 mol, 3.06 g), anhydrous zinc acetate (0.02 wt%, 0.0155 g), and antimony trioxide (0.03 wt%, 0.0233 g) were uniformly mixed and prepolymerized at 180°C under a nitrogen atmosphere for 3 hours. The nitrogen flow was then stopped. The temperature was then slowly raised to 200°C and maintained for 3 hours for polymerization. Water and small molecules were removed from the system by vacuum filtration. The system was then reduced to a vacuum level (less than 30 Pa) and cooled to room temperature to obtain a thermoplastic thermally conductive polyester material. The H-NMR spectrum data of the thermoplastic thermally conductive polyester material prepared in this example are as follows: 1H NMR (400 MHz, CDCl3): δ8.07 (s, 2H, Ar–CH(CO)O); δ7.67 (s, 2H, Ar–S); δ7.42 (s, 7H, Ar–CH(CO)O); δ6.91 (s, 5H, Ar–O–); δ4.35 (s, 4H, Ar–O–CH2); δ4.12 (s, 5H, Ar–CH(CO)O–); δ1.86 (s, 10H, CH2–CH2OCO); δ1.57 (s, 24H, OCH2–(CH2)2–CH2O); δ1.21 (s, 2H, Ar–O–CH2–CH2). Based on the characterization data, it can be concluded that the thermoplastic thermally conductive polyester material obtained in this example has the following structure:

[0056]

[0057] Comparative Example 1:

[0058] Diphenyl diol (0.1 mol, 3.86 g), diphenyl dicarboxylic acid (0.1 mol, 2.42 g), anhydrous zinc acetate (0.02 wt%, 0.0126 g) and antimony trioxide (0.003 wt%, 0.0188 g) catalyst were uniformly mixed and prepolymerized at 180°C for 3 h under nitrogen atmosphere, and the nitrogen was stopped. The temperature was then slowly raised to 200°C and kept at this temperature for 3 h to carry out polymerization reaction. Water and small molecules in the system were removed by vacuum filtration. The vacuum degree of the system was reduced (below 30 Pa) and cooled to room temperature to obtain the infrared image of the thermoplastic thermal conductive polyester material as shown below. Figure 2 shown.

[0059] The thermal conductivity and mechanical properties of the products prepared in Comparative Example 1 and Examples 1 to 6 were characterized. The characterization methods and results are shown below:

[0060] 1. Thermal conductivity

[0061] Thermoplastic thermal conductive polyester material, the thermal diffusivity and thermal conductivity of which are determined in accordance with GB / T 22588-2008, with a sample size of 3×3×1mm 3 The results are shown in Table 1:

[0062] Table 1 Thermal conductivity test

[0063]

[0064] 2. Mechanical properties

[0065] The tensile properties of the materials were tested using a CMT4303SANS universal testing machine (MTS Systems, Shenzhen, China) according to the GB / T1447-2005 test method. The tensile strength and elongation at break were measured according to the GB / T2568-1995 standard, and the results are shown in Table 2.

[0066] Table 2 Mechanical properties test

[0067]

[0068] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A thermoplastic thermally conductive polyester containing disulfide bonds, characterized in that: The disulfide bond-containing thermoplastic thermally conductive polyester has a structure as shown in the following formula (I) or formula (II): Where m is a natural number between 1 and 10.

2. The disulfide bond-containing thermoplastic thermally conductive polyester according to claim 1, characterized in that: The m is a natural number between 3 and 9.

3. The method for preparing a disulfide bond-containing thermoplastic thermally conductive polyester according to claim 1, characterized in that The following steps are included: Biphenyl diol, dicarboxylic acid and a catalyst are mixed, and then a prepolymerization reaction is carried out under nitrogen protection. After the prepolymerization reaction, by-product water in the reaction system is removed, and then a polymerization reaction is continued. After the polymerization reaction, the target product, a disulfide bond-containing thermoplastic thermally conductive polyester, is obtained. The biphenyl diol is prepared by the following method: biphenyl diphenol, a halogen-containing long-chain alcohol, anhydrous potassium carbonate and a solvent are mixed, and then heated under reflux for 12 to 36 hours under nitrogen protection. After the reflux reaction is completed, the obtained reaction solution is purified to obtain the biphenyl diol.

4. The preparation method according to claim 3, wherein: The biphenyl diol is any one of biphenyl dipropanol, biphenyl dihexanol and biphenyl dinonanol; the dicarboxylic acid is at least one of 3,3-dithiodipropionic acid and 2,2-dithiodibenzoic acid; the molar ratio of the biphenyl diol to the dicarboxylic acid is 1-3:1-3; the catalyst is antimony trioxide and anhydrous zinc acetate, wherein the mass of the anhydrous zinc acetate is 0.1-0.3% of the total mass of the reaction system, and the mass of the antimony trioxide is 0.2-0.5% of the total mass of the reaction system.

5. The preparation method according to claim 4, characterized in that: The molar ratio of biphenyl diol to dicarboxylic acid is 1:1; the catalyst is antimony trioxide and anhydrous zinc acetate, wherein the mass of anhydrous zinc acetate is 0.2% of the total mass of the reaction system, and the mass of antimony trioxide is 0.3% of the total mass of the reaction system.

6. The preparation method according to claim 3, wherein: The prepolymerization reaction refers to a reaction at 160-190° C. for 2-5 hours; the polymerization reaction refers to a polymerization reaction at a temperature increased by 10-20° C. on the basis of the prepolymerization temperature, and the polymerization reaction time is 3-5 hours; the removal of by-product water in the reaction system is carried out by vacuuming, and the vacuum degree is lower than 30 Pa.

7. The preparation method according to claim 6, characterized in that: The prepolymerization reaction refers to a reaction at 180° C. for 3 hours; the polymerization reaction refers to a polymerization reaction at a temperature increased by 10° C. based on the prepolymerization temperature, and the polymerization reaction time is 3 hours.

8. The preparation method according to claim 3, wherein: The halogen-containing long-chain alcohol is at least one of 3-chloro-1-propanol, 6-chloro-1-hexanol and 9-bromo-1-nonanol; the molar ratio of the halogen-containing long-chain alcohol to biphenol is 2 to 4:1; and the solvent is one of N,N-dimethylformamide, ethyl acetate and toluene.

9. The preparation method according to claim 8, characterized in that: The molar ratio of the halogen-containing long-chain alcohol to biphenol is 3:1; and the solvent is N,N-dimethylformamide.

10. Use of the disulfide bond-containing thermoplastic thermally conductive polyester according to claim 1 in the fields of electronic packaging and thermal management.

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