High-stretch, fast self-healing, high-thermal-conductivity, memoryable conductive polyurethane composite material and preparation method and application thereof

Abstract

The application belongs to the field of organic materials, and particularly relates to a high-stretch, fast self-healing, high-thermal-conductivity and memoryable conductive polyurethane composite material as well as a preparation method and application thereof. The conductive polyurethane composite material is crosslinked by borate ester bonds, B-N coordination bonds and hydrogen bonds, and further introduces hydroxyl boron nitride, carbon nanotubes and graphene nanosheets to obtain the high-stretch, fast self-healing, high-thermal-conductivity and memoryable conductive polyurethane composite material. The raw materials are inexpensive and the operation is simple, and the obtained conductive polyurethane composite material has high-stretch, fast self-healing, high-thermal-conductivity and memoryability, and has potential application prospects in the fields of conductive films, sensors and wearable devices.

Description

Technical Field

[0001] This invention belongs to the field of organic materials, and particularly relates to a high-strength, fast-self-healing, high-thermal-conductivity, memory-memory conductive polyurethane composite material, its preparation method, and its application. Background Technology

[0002] Wearable and flexible stretchable strain sensors, capable of converting mechanical deformation into electrical signals, have found widespread application in soft robotics, health monitoring systems, and human motion monitoring. Traditional rigid strain sensors can only withstand very small strains (less than 5%), while flexible / stretchable strain sensors can withstand much larger external strains. There are many types of stretchable strain sensors, including resistive, capacitive, piezoelectric, and triboelectric sensors. Therefore, stretchable strain sensors with high sensitivity are highly sought after.

[0003] However, for wearable strain sensors that need to be attached to human skin, the temperature rise caused by heat can lead to extreme discomfort and even harm to human health. Because human skin has low thermal conductivity, heat accumulation can occur at the interface between the sensor and the skin; therefore, good heat dissipation is essential for flexible sensors. Simultaneously, to meet the requirements of wearable technology, there is an urgent need for flexible composite materials that are highly tensile, conductive, highly sensitive, and have good heat dissipation. Summary of the Invention

[0004] The purpose of this invention is to provide a conductive polyurethane composite material that is readily available from raw materials, easy to prepare, and has high tensile strength, fast self-healing properties, high thermal conductivity, and memory properties.

[0005] The technical solution adopted in this invention is a conductive polyurethane composite material with high tensile strength, fast self-healing, high thermal conductivity, and memory function. It uses boron ester bonds, BN coordination bonds, and hydrogen bonds as crosslinking networks, and then introduces boron nitride, carbon nanotubes, and graphene nanosheets to obtain a conductive polyurethane composite material with high tensile strength, fast self-healing, high thermal conductivity, and memory function.

[0006] A method for preparing a conductive polyurethane composite material with high tensile strength, fast self-healing properties, high thermal conductivity, and memory properties includes the following steps: under N2 protection, polyethylene glycol (PEG), diphenylmethane diisocyanate (MDI), and dibutyltin dilaurate are stirred for 2 hours; a diboron ester is added and stirred for another 2 hours; 1,1,-((3-(dimethylamino)propyl)azonyl)di(prop-2-ol) is added and stirred for 2 hours; hydroxylated carbon nanotubes, graphene nanosheets, and boron hydroxynitride are added and stirred for 2 hours; finally, the mixture is poured into a mold and dried to obtain the target product.

[0007] The above-mentioned method for preparing a high-tensile, fast-self-healing, high-thermal-conductivity, and memory-memory conductive polyurethane composite material involves stirring at 80°C.

[0008] The preparation method of the above-mentioned high tensile strength, fast self-healing, high thermal conductivity, and memory-retaining conductive polyurethane composite material, wherein the preparation method of the diboronic ester is as follows: 1,4-phenyldiboronic acid, 1-thioglycerol and anhydrous magnesium sulfate are dissolved in ultra-dry tetrahydrofuran, and after gentle stirring, the mixture is filtered, the filtrate is precipitated with n-hexane, and the precipitated mixture is rotary evaporated to obtain a white powder, namely the diboronic ester.

[0009] The preparation method of the above-mentioned high tensile strength, fast self-healing, high thermal conductivity, and memory-retaining conductive polyurethane composite material is as follows: the preparation method of hydroxy boron nitride is as follows: the h-BN powder is heated to 800℃ at a heating rate of 5℃ / min, held at 800℃ for 8h, the temperature is reduced to 250℃ at a rate of 10℃ per minute, and then naturally cooled to 25℃ to obtain hydroxyl-functionalized h-BN, i.e., OH-BN.

[0010] The above-mentioned high-strength, fast-self-healing, high-thermal-conductivity, and memory-memory conductive polyurethane composite material is used in the preparation of flexible devices.

[0011] The beneficial effects of this invention are:

[0012] 1. This invention uses inexpensive raw materials, is easy to prepare, and produces products with excellent performance, which greatly overcomes the shortcomings of flexible film systems such as low stretching, lack of self-healing, and low thermal conductivity.

[0013] 2. This invention utilizes borate ester bonds, BN coordination bonds, and hydrogen bonds as a crosslinking network, which significantly improves the tensile strength and self-healing properties of the composite material.

[0014] 3. Based on the above, boron nitride hydroxyl, carbon nanotubes and graphene nanosheets are introduced to make it a conductive composite material with high thermal conductivity.

[0015] 4. Composite materials possess comprehensive properties such as high tensile strength, rapid self-healing, high thermal conductivity, shape memory, and electrical conductivity, making them valuable for applications in flexible equipment. Attached Figure Description

[0016] Figure 1 These are images of the self-healing polyurethane prepared in Example 3, where a is the self-healing image without water; b is the self-healing image with water present; and c is a real image showing the material that can be easily lifted to 200g after 1 hour of self-healing.

[0017] Figure 2 This is the polyurethane shape memory function prepared in Example 3.

[0018] Figure 3This is the conductive pattern prepared in Example 4.

[0019] Figure 4 These are infrared thermal images of Examples 4, 5, and 7.

[0020] Figure 5 These are the stress-strain curves for Examples 6, 7, and 8. Detailed Implementation

[0021] Example 1: Preparation of diboronic ester

[0022] The preparation method is as follows:

[0023] 3 g of 1,4-phenyldiboronic acid, 4 g of 1-thioglycerol, and 10 g of anhydrous magnesium sulfate were dissolved in 50 mL of ultra-dry tetrahydrofuran. The mixture was gently stirred at 25 °C for 24 h, then filtered. The filtrate was precipitated with 50 mL of n-hexane. The precipitate mixture was rotary evaporated at 55 °C to obtain a white powder, namely a diboronic ester.

[0024] Example 2: Preparation of boron hydroxynitride

[0025] The preparation method is as follows:

[0026] 2g of h-BN powder was added to an alumina crucible and then heated in a muffle furnace. The temperature was first uniformly increased from room temperature to 800℃ at a rate of 5℃ / min. The temperature was then maintained at 800℃ for 8 hours. After the holding period, the temperature was reduced to 250℃ at a rate of 10℃ / min. Finally, it was allowed to cool naturally to 25℃ to obtain hydroxyl-functionalized h-BN, i.e., OH-BN.

[0027] Example 3: Preparation of PU

[0028] The preparation method is as follows:

[0029] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added, and the mixture was stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and the mixture was gently stirred for 2 h. Finally, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and the mixture was gently stirred for 2 h. The resulting product was then placed in a forced-air drying oven for 96 h to obtain PU.

[0030] Example 4: Preparation of PU / C / G

[0031] The preparation method is as follows:

[0032] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added and stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and stirred gently for 2 h. Next, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and stirred gently for 2 h. Finally, 3% of carbon nanotubes (CNTs) and graphene nanosheets (GNSs) (total weight 3%) were added and stirred for 2 h, with a CNTs to GNSs weight ratio of 1:1. The resulting product was then placed in a forced-air drying oven for 96 h to obtain PU / C / G.

[0033] Example 5: Preparation of BN10 / PU / C / G

[0034] The preparation method is as follows:

[0035] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added and stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and stirred gently for 2 h. Next, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and stirred gently for 2 h. Then, 3% carbon nanotubes (CNTs) and graphene nanosheets (GNSs) (total weight 3%) were added and stirred for 2 h, with a CNTs to GNSs weight ratio of 1:1. Finally, BN with a specific gravity of 10% PU was added and stirred vigorously for 2 h. The resulting product was then placed in a forced-air drying oven for 96 h to obtain BN10 / PU / C / G.

[0036] Example 6: Preparation of OH-BN5 / PU / C / G

[0037] The preparation method is as follows:

[0038] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added and stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and stirred gently for 2 h. Next, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and stirred gently for 2 h. Then, 3% carbon nanotubes (CNTs) and graphene nanosheets (GNSs) (total weight 3%) were added and stirred for 2 h, with a CNTs to GNSs weight ratio of 1:1. Finally, OH-BN with a specific gravity of 5% PU was added and stirred vigorously for 2 h. The resulting product was dried in a forced-air drying oven for 96 h to obtain OH-BN5 / PU / C / G.

[0039] Example 7: Preparation of OH-BN10 / PU / C / G

[0040] The preparation method is as follows:

[0041] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added and stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and stirred gently for 2 h. Next, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and stirred gently for 2 h. Then, 3% carbon nanotubes (CNTs) and graphene nanosheets (GNSs) (total weight 3%) were added and stirred for 2 h, with a CNTs to GNSs weight ratio of 1:1. Finally, OH-BN with a specific gravity of 10% PU was added and stirred vigorously for 2 h. The resulting product was dried in a forced-air drying oven for 96 h to obtain OH-BN10 / PU / C / G.

[0042] Example 8: Preparation of OH-BN15 / PU / C / G

[0043] The preparation method is as follows:

[0044] In a three-necked flask, 3 mmol of polyethylene glycol (10000), 9 mmol of diphenylmethane diisocyanate, and (0.45) g of dibutyltin dilaurate were added and stirred at 80 °C under a N2 atmosphere for 2 h. Then, 2 mmol of diboronate was added and stirred gently for 2 h. Next, 4 mmol of 1,1,-((3-(dimethylamino)propyl)azonidinediyl)di(propane-2-ol) was added and stirred gently for 2 h. Then, 3% carbon nanotubes (CNTs) and graphene nanosheets (GNSs) (total weight 3%) were added and stirred for 2 h, with a CNTs to GNSs weight ratio of 1:1. Finally, OH-BN with a specific gravity of 15% PU was added and stirred vigorously for 2 h. The resulting product was dried in a forced-air drying oven for 96 h to obtain OH-BN15 / PU / C / G.

[0045] Figure 1 a shows the self-healing properties of the polyurethane (PU) prepared in Example 3 in the absence of water. It is readily apparent that the polyurethane rapidly self-heals within 75 minutes in the absence of water. Figure 1 b shows the self-healing properties of polyurethane in the presence of water. When water is involved, the reversible decomposition of borate esters upon contact with water enhances intramolecular chain migration, reducing the self-healing time to 30 minutes and significantly accelerating the self-healing properties of polyurethane. Figure 1 c shows that the shortened polyurethane can easily lift a 200g weight after 1 hour of repair.

[0046] Figure 2The shape memory function of the polyurethane (PU) prepared in Example 3 is demonstrated. Its excellent plasticity is mainly due to the rapid breaking and recombination of borate ester bonds and hydrogen bonds under thermal stimulation. The polyurethane readily reforms into "L" and "S" shapes at 80°C. When the polyurethane is subjected to thermal stimulation, the exchange rate of borate ester bonds accelerates, causing the polyurethane to change from a hard state to an elastic state, allowing it to be molded after the application of external force. When the temperature drops to room temperature, the exchange of borate ester bonds almost ceases, and the polyurethane reverts to a hard state, ultimately achieving the shape memory recovery effect.

[0047] Figure 3 The conductivity of the PU / C / G prepared in Example 4 is demonstrated. When the PU / C / G film is connected to the circuit, the light bulb lights up. When the film is cut, the light bulb goes out. When the cut film is repaired, the light bulb lights up again, indicating that PU / C / G has good self-healing and conductivity properties.

[0048] Figure 4 Infrared thermal imaging comparisons of Examples 4, 5, and 7 are shown. The figures clearly show that when 10 wt% BN and 10 wt% OH-BN are introduced into PU / C / G, OH-BN10 / PU / C / G cools from 80°C to room temperature in the shortest time, followed by BN10 / PU / C / G, and lastly pure PU / C / G. These results indicate that the introduction of BN and OH-BN significantly improves the thermal conductivity of the PU / C / G film, with OH-BN showing a more pronounced effect.

[0049] Figure 5 The results show that when the OH-BN content is 5%, the elongation at break of OH-BN5 / PU / C / G is 2292%. When the OH-BN content is 10%, the elongation at break of OH-BN10 / PU / C / G further increases to 2558%. This is likely because the increase in OH-BN introduces more hydrogen bonds, which enhance the interactions within the material, thereby improving the overall mechanical properties. When the OH-BN content is 15%, the elongation at break of OH-BN15 / PU / C / G decreases to 2472%. This is likely because the excessive introduction of OH-BN leads to the formation of unparticipated OH-BN agglomerates within the material, which may disrupt the material's homogeneity and thus reduce mechanical properties. Therefore, the appropriate OH-BN content has a significant impact on the mechanical properties of the composite material. Nevertheless, the mechanical properties of Examples 6, 7, and 8 fully meet the requirements for practical applications.

[0050] In summary, the high-tensile, fast-self-healing, high-thermal-conductivity, and shape-memory conductive polyurethane composite material of this invention possesses excellent comprehensive properties. It has potential application value in fields such as conductive films, sensors, and wearable devices.

Claims

1. The application of a highly tensile, fast-healing, highly thermally conductive, and memory-memory conductive polyurethane composite material in the fabrication of flexible devices, characterized in that, The preparation method of the high-tensile, fast-self-healing, high-thermal-conductivity, and memory-retaining conductive polyurethane composite material includes the following steps: under N2 gas protection, polyethylene glycol (PEG), diphenylmethane diisocyanate (MDI), and dibutyltin dilaurate are stirred for 2 h; a diboronate ester is added and stirred for another 2 h; 1,1 ， -((3-(dimethylamino)propyl)azanediyl)di(prop-2-ol) was stirred for 2 h, then hydroxylated carbon nanotubes, graphene nanosheets and boron hydroxynitride were added and stirred for 2 h. Finally, the mixture was poured into a mold and dried to obtain the target product.

2. The application according to claim 1, characterized in that, The stirring is carried out at 80°C.

3. The application according to claim 1, characterized in that, The preparation method of the aforementioned diboronic ester is as follows: 1,4-phenyldiboronic acid, 1-thioglycerol and anhydrous magnesium sulfate are dissolved in ultra-dry tetrahydrofuran. After gentle stirring, the mixture is filtered, the filtrate is precipitated with n-hexane, and the precipitate mixture is rotary evaporated to obtain a white powder, namely the diboronic ester.

4. The application according to claim 1, characterized in that, The preparation method of boron hydroxynitride is as follows: h-BN powder is heated to 800℃ at a heating rate of 5℃ / min, held at 800℃ for 8 h, and then the temperature is reduced to 250℃ at a rate of 10℃ / min. It is then naturally cooled to 25℃ to obtain hydroxyl-functionalized h-BN, i.e., OH-BN.

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