Enhanced self-healing nano cellulose polyurethane material and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of self-healing high polymer materials, and particularly discloses an enhanced self-healing nano-cellulose polyurethane material and a preparation method thereof.The self-healing nano-cellulose polyurethane material is prepared by reacting polyurethane, nano-cellulose and a cross-linking agent under certain conditions; the self-healing purpose is achieved by using hydrogen bonds and reversible covalent bonds between polyurethane, hydrogen bonds between nano cellulose and hydrogen bonds between polyurethane and nano cellulose, and the self-healing nano cellulose polyurethane material is obtained. The mechanical strength is remarkably improved, the self-healing efficiency is higher, and the tensile strength after healing is high.

Description

Technical Field

[0001] The invention belongs to the technical field of self-healing polymer material preparation, and specifically relates to an enhanced self-healing nano-cellulose polyurethane material and a preparation method thereof. Background Art

[0002] Polyurethane (PU) is prepared by polymerization of polyol and isocyanate, and has mechanical properties such as high tensile strength, low temperature resistance and good aging resistance. However, during processing, transportation and use, polyurethane materials may be damaged to a certain extent, reducing the stability of the material, and it is difficult to repair it with existing technology.

[0003] Nowadays, as a promising smart material, the research trend of self-healing polymers has shifted from external self-healing to intrinsic self-healing. Intrinsic self-healing polyurethanes can automatically repair physically damaged materials through intramolecular or intermolecular interactions, which can not only extend their service life but also reduce maintenance costs. However, the common self-healing polyurethane materials currently have problems such as long healing time and poor healing effect, which limit the application of self-healing polyurethane materials.

[0004] Cellulose is the largest and most widely distributed natural polymer material in nature and is widely used in paper, building materials, furniture and fabrics. With the progress of society, traditional cellulose materials are difficult to meet human needs. It is necessary to develop cellulose materials with better performance to meet human needs for high-performance materials. Nanocellulose, as a nano-scale natural polymer, has attracted much attention in recent years due to its wide source, biodegradability, good mechanical properties, large specific surface area and green and non-toxic properties.

[0005] Since traditional self-healing materials usually require a highly dynamic polymer network structure to achieve self-healing properties, an irreconcilable contradiction has formed between the mechanical strength and self-healing properties of the material. The tensile strength of common self-healing materials is low (<10MPa), and the self-healing ability of a small number of high mechanical strength self-healing materials is also unsatisfactory, with problems such as high healing temperature (>80℃) and long healing time (>12h). This material uses polyurethane as the matrix and enhances the self-healing and mechanical properties of the material by adding nanocellulose. The rich functional groups in nanocellulose can enhance the material's mechanical strength while improving the material's self-healing ability. Summary of the invention

[0006] The purpose of the present invention is to provide an enhanced self-healing nano-cellulose polyurethane material and a preparation method thereof, which has solved the problems of the difficulty in reconciling the self-healing effect and mechanical properties of existing self-healing materials, slow healing efficiency, and a large difference in the mechanical strength of the material before and after healing, so as to enhance the self-healing performance and mechanical properties of the material.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: A reinforced self-healing nanocellulose polyurethane material is prepared by reacting polyurethane, nanocellulose and a cross-linking agent under certain conditions.

[0008] Preferably, the preparation method of the enhanced self-healing nanocellulose polyurethane material comprises the following steps: first, preparing polyurethane, using soft segment and hard segment B to react under specific conditions to obtain a colloid, then adding an appropriate amount of chain extender to the colloid and continuing the reaction, and the obtained viscous liquid is polyurethane; secondly, preparing nanocellulose, taking cellulose and putting it into a ball mill, adding concentrated acid and strong oxidant for ball milling to obtain slurry a, then adding ethylene glycol solution to the slurry a and placing it in a beaker, wrapping the beaker with tin foil to block light and stir, standing the liquid to separate, pouring out the upper liquid to obtain slurry c, adjusting the pH of slurry c to neutral, performing ultrasonic cleaning, centrifugal operation and drying to obtain nanocellulose; then preparing a self-healing nanocellulose gel material, dissolving gelatin in water and heating, stirring until completely dissolved, and then adding the prepared nanocellulose to obtain a self-healing nanocellulose gel material; finally, preparing a self-healing polyurethane nanocellulose composite material, reacting polyurethane, self-healing nanocellulose gel and cross-linking agent under certain conditions to obtain a self-healing nanocellulose polyurethane material.

[0009] Preferably, the method for preparing the enhanced self-healing nanocellulose polyurethane material comprises the following steps: (1) 14-28 g of polytetrahydrofuran diol was placed in a 250 ml four-necked flask, 9.32-18.64 g of isophorone diisocyanate and 0.1-0.3% of dibutyltin dilaurate were added, and the mixture was heated in an oil bath at 60-80° C. for 60-120 min to obtain a solution A; (2) Add 0.67-1.34 g of methyldiethanolamine, 0.75-1.50 g of 2,2-dihydroxymethylpropionic acid, 0.5-1 g of 1,4-butanediol and 5-15 ml of N,N-dimethylacetamide to solution A, heat in an oil bath at 60-80°C and react for 120-180 min to obtain solution B; (3) Cool solution B to room temperature, keep the temperature at 10-20°C in a cold water bath, add 100-120 ml of acetone to obtain solution C; (4) In solution C, add 30-90 ml of a dichloromethane solution containing 1.02-3.06 g of isophorone diamine dropwise at a rate of 5-15 ml / min using a peristaltic pump. After the addition is complete, remove the solution from the ice water bath and allow it to react at room temperature for 120-180 min. Add 0.5-2.0 g of 1-(3-aminopropyl)imidazole to obtain a light yellow liquid, which is recorded as solution D. (5) Add 0.18-0.27 g of zinc trifluoromethanesulfonate in acetonitrile solution to solution D and stir thoroughly to disperse the zinc ions evenly in the solution to obtain a final light yellow solution E. The light yellow solution E is polyurethane.

[0010] Preferably, the method for preparing the enhanced self-healing nanocellulose polyurethane material comprises the following steps: (1) Weigh 12-16.0 g of cellulose and put it into a ball mill, add 15-20 mL of 60% sulfuric acid and 15-20 g of sodium periodate, and perform ball milling pretreatment. After 2-3 hours, stop grinding, take out the ball mill, and obtain slurry a; (2) Add 2.0-4.0 g of sodium periodate to slurry a and continue oxidative grinding for 2-3 hours to obtain slurry b; (3) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 15-25 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (4) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (5) After the slurry d is ultrasonically treated for 2-3 hours using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge with the speed set to 6000-8000 r / min and the time set to 30-45 min. After the centrifugation, the upper milky white suspension is collected and placed in a beaker for concentration to obtain slurry e, which is nanocellulose.

[0011] Preferably, the method for preparing the enhanced self-healing nanocellulose polyurethane material, the method for preparing the self-healing nanocellulose gel material comprises the following steps: (1) Dissolve 10-20 g of gelatin in 80-90 g of water, heat to 60-80°C, and stir until completely dissolved to obtain solution a; (2) Cool solution a to room temperature, add 5.0-6.5 g of slurry e, and quickly stir and mix to obtain a self-healing nanocellulose gel material.

[0012] Preferably, the method for preparing the enhanced self-healing nanocellulose polyurethane material comprises the following steps: (1) Take 50g of light yellow solution E and add it to a 250ml three-necked flask, place it in an oil pan at 60-80℃ and heat it. After passing nitrogen at a flow rate of 20-30mL / min for 10min, add self-healing nanocellulose gel at a mass percentage of 0.1%-5%, stir at a speed of 4000-8000r / min for 10-15min, take it out of the oil bath, continue to stir slowly until it cools to room temperature, and obtain colloid A; (2) 0.5-2 g of bis(4-aminophenyl)sulfide was dissolved in 2-5 mL of tetrahydrofuran solution to prepare a cross-linking agent, and the cross-linking agent was slowly dripped into colloid A to react for 15 min to obtain colloid B; (3) Pour colloid B into a mold and place it in a horizontal position, let it stand for 2-3 hours, and then put the colloid B into a 60°C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) Self-healing is achieved by utilizing hydrogen bonds and reversible covalent bonds between polyurethanes, hydrogen bonds between nanocelluloses, and hydrogen bonds between polyurethane and nanocellulose.

[0014] (2) Compared with traditional self-healing materials, the self-healing nanocellulose polyurethane material obtained by the present invention has the properties of significantly improved mechanical strength, faster self-healing efficiency, and high tensile strength after healing.

[0015] (3) The preparation method of the present invention has the advantages of simple preparation process, strong controllability, low cost, etc. The raw materials for production are easily available, and it is a self-healing material suitable for mass production.

[0016] (4) The self-healing material obtained by the present invention can obtain self-healing nanocellulose polyurethane composite materials with different strengths by adjusting the content of the self-healing nanocellulose gel within a certain range. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 A comparison diagram of the relationship between time and healing rate of traditional polyurethane and self-healing nanocellulose polyurethane prepared in Examples 1, 2, 3 and 4; Figure 2 A comparison diagram of the relationship between time and healing rate of traditional polyurethane and self-healing nanocellulose polyurethane prepared in Examples 3, 5 and 6; Figure 3 A comparison diagram of the relationship between tensile strain and tensile stress of conventional polyurethane and the self-healing nanocellulose polyurethane prepared in Examples 1, 2, 3 and 4; Figure 4 A comparison diagram of the relationship between tensile strain and tensile stress of conventional polyurethane and the self-healing nanocellulose polyurethane prepared in Examples 3, 5 and 6; Figure 5 This is a comparison chart of the mechanical loss after healing of traditional polyurethane and the self-healing nanocellulose polyurethane prepared in Examples 3, 5 and 6. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with specific embodiments: Example 1 (1) 28 g of PTMG (polytetramethylene glycol) was placed in a 250 ml four-necked flask, 18.64 g of IPDI (isophorone diisocyanate) and 0.1% of DBTDL (dibutyltin dilaurate) were added, and the mixture was heated in an oil bath at 80 °C for 60 min to obtain solution A; (2) Add 1.34 g MDEA (methyldiethanolamine), 1.50 g MDPA (2,2-dihydroxymethylpropionic acid), 0.5 g BDO (1,4-butanediol) and 10 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 80° C. and react for 120 min to obtain solution B; (3) Cool solution B to room temperature, maintain a cold water bath at 15°C, add 120 ml of acetone, and obtain solution C; (4) A dichloromethane solution (60 ml) containing 2.04 g IPDA (isophorone diamine) was added dropwise to solution C using a peristaltic pump at a rate of 5 ml / min. After the addition was completed, the solution was removed from the ice water bath and allowed to react at room temperature for 120 min. 1.0 g API (1-(3-aminopropyl)imidazole) was added to obtain a light yellow liquid, which was recorded as solution D. (5) Add 0.18 g of (zinc trifluoromethanesulfonate) in acetonitrile solution, stirring thoroughly to make the zinc ions disperse evenly in the solution, and obtaining a final light yellow solution E, which is polyurethane; (6) Weigh 16.0 g of cellulose and put it into a ball mill. Add 20 mL of 60% sulfuric acid and 20 g of (sodium periodate), perform ball milling pretreatment, stop grinding after 3 hours, take out the ball mill jar, and obtain slurry a; (7) Add 4.0g of (Sodium periodate) continued oxidative grinding for 3 h to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 25 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated for 2 h using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge, the speed is set to 6000 r / min, and the time is set to 30 min. After the centrifugation is completed, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 15 g of gelatin in 85 g of water, heat to 60° C., and stir until completely dissolved to obtain solution a; (12) cooling solution a to room temperature, adding 6.5 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in a 70°C oil pan and pass it into (flow rate is 25 mL / min) After standing for 10 min, add self-healing nanocellulose gel at a mass percentage of 0.1%, stir at a speed of 6000 r / min for 10 min, take it out from the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 1 g of bis(4-aminophenyl)sulfide was dissolved in 2 mL of tetrahydrofuran solution to prepare a crosslinking agent, and the crosslinking agent was slowly dropped into colloid A to react for 15 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 3 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0019] Example 2 (1) Take 25 g of PTMG (polytetramethylene glycol) and place it in a 250 ml four-necked flask. Add 14.34 g of IPDI (isophorone diisocyanate) and 0.2% of DBTDL (dibutyltin dilaurate). Heat in an oil bath at 70 °C and react for 80 min to obtain solution A. (2) Add 1.14 g MDEA (methyldiethanolamine), 1.34 g MDPA (2,2-dihydroxymethylpropionic acid), 0.7 g BDO (1,4-butanediol) and 12 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 70°C for 140 min to obtain solution B; (3) Cool solution B to room temperature, maintain a cold water bath at 17°C, add 110 ml of acetone, and obtain solution C; (4) In solution C, add 2.86 g IPDA (isophorone diamine) in dichloromethane (80 ml) dropwise at a rate of 9 ml / min using a peristaltic pump. After the addition is complete, remove the solution from the ice water bath and allow it to react at room temperature for 130 min. Add 1.2 g API (1-(3-aminopropyl)imidazole) to obtain a light yellow liquid, which is recorded as solution D. (5) Add 0.21 g of (zinc trifluoromethanesulfonate) in acetonitrile solution, stirring thoroughly to make the zinc ions disperse evenly in the solution, and obtaining a final light yellow solution E, which is polyurethane; (6) Weigh 22.0 g of cellulose and place it in a ball mill. Add 17 mL of 60% sulfuric acid and 17 g of (sodium periodate), ball milling pretreatment, grinding was stopped after 2.5 hours, the ball mill was taken out to obtain slurry a; (7) Add 3.0g of (Sodium periodate) continued oxidative grinding for 2.5 hours to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 23 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 h, let the liquid stand to separate, and pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated for 2.5 h using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge with the speed set to 7000 r / min and the time set to 35 min. After the centrifugation, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 17 g of gelatin in 86 g of water, heat to 65°C, and stir until completely dissolved to obtain solution a; (12) Cooling solution a to room temperature, adding 6.3 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in a 75°C oil pan and pass it into (flow rate is 27 mL / min) After standing for 10 min, add self-healing nanocellulose gel at a mass percentage of 0.3%, stir at a speed of 7000 r / min for 13 min, take it out from the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 1.5 g of bis(4-aminophenyl)sulfide was dissolved in 3 mL of tetrahydrofuran solution to prepare a crosslinking agent, which was slowly dropped into colloid A to react for 15 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 2.5 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0020] Example 3 (1) 14 g of PTMG (polytetramethylene glycol) was placed in a 250 ml four-necked flask, 9.32 g of IPDI (isophorone diisocyanate) and 0.1% of DBTDL (dibutyltin dilaurate) were added, and the mixture was heated in an oil bath at 60 °C for 120 min to obtain solution A; (2) Add 0.67 g MDEA (methyldiethanolamine), 0.75 g MDPA (2,2-dihydroxymethylpropionic acid), 0.5 g BDO (1,4-butanediol) and 5 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 60° C. and react for 180 min to obtain solution B; (3) Cool solution B to room temperature, maintain a cold water bath at 10°C, add 100 ml of acetone, and obtain solution C; (4) A dichloromethane solution (content: 30 ml) containing 1.02 g IPDA (isophorone diamine) was added dropwise to solution C using a peristaltic pump at a rate of 5 ml / min. After the addition was completed, the solution was removed from the ice water bath and allowed to react at room temperature for 120 min. 0.5 g API (1-(3-aminopropyl)imidazole) was added to obtain a light yellow liquid, which was recorded as solution D. (5) In solution D, 0.18 g (zinc trifluoromethanesulfonate) in acetonitrile solution, stir thoroughly to make the zinc ions disperse evenly in the solution, and obtain the final light yellow solution E; (6) Weigh 12.0 g of cellulose and put it into a ball mill. Add 15 mL of 60% sulfuric acid and 15 g of (sodium periodate), perform ball milling pretreatment, stop grinding after 2 hours, take out the ball mill jar, and obtain slurry a; (7) Add 2.0g of (Sodium periodate) continued oxidative grinding for 2 h to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 15 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated for 2 h using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge, the speed is set to 6000 r / min, and the time is set to 30 min. After the centrifugation is completed, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 10 g of gelatin in 80 g of water, heat to 60° C., and stir until completely dissolved to obtain solution a; (12) cooling solution a to room temperature, adding 5.0 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in a 60°C oil pan and pass it into (Flow rate: 25 mL / min) After standing for 10 min, add self-healing nanocellulose gel at a mass percentage of 0.1%, stir at a speed of 4000 r / min for 10 min, take it out of the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 0.5 g of bis(4-aminophenyl)sulfide was dissolved in 2 mL of tetrahydrofuran solution to prepare a crosslinking agent, and the crosslinking agent was slowly dropped into colloid A to react for 15 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 2 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0021] Example 4 (1) 28 g of PTMG (polytetramethylene glycol) was placed in a 250 ml four-necked flask, 18.64 g of IPDI (isophorone diisocyanate) and 0.3% of DBTDL (dibutyltin dilaurate) were added, and the mixture was heated in an oil bath at 80 °C for 60 min to obtain solution A; (2) Add 1.34 g MDEA (methyldiethanolamine), 1.50 g MDPA (2,2-dihydroxymethylpropionic acid), 1.0 g BDO (1,4-butanediol) and 15 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 80° C. and react for 120 min to obtain solution B; (3) Cool solution B to room temperature, maintain a cold water bath at 20°C, add 120 ml of acetone, and obtain solution C; (4) A dichloromethane solution (90 ml) containing 3.06 g IPDA (isophorone diamine) was added dropwise to solution C using a peristaltic pump at a rate of 15 ml / min. After the addition was completed, the solution was removed from the ice water bath and allowed to react at room temperature for 180 min. 2.0 g API (1-(3-aminopropyl)imidazole) was added to obtain a light yellow liquid, which was recorded as solution D. (5) In solution D, 0.27 g (zinc trifluoromethanesulfonate) in acetonitrile solution, stirring thoroughly to make the zinc ions disperse evenly in the solution, and obtaining a final light yellow solution E, which is polyurethane; (6) Weigh 16.0 g of cellulose and put it into a ball mill. Add 20 mL of 60% sulfuric acid and 20 g of (sodium periodate), perform ball milling pretreatment, stop grinding after 3 hours, take out the ball mill jar, and obtain slurry a; (7) Add 4.0g of (Sodium periodate) continued oxidative grinding for 3 h to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 25 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated for 3 h using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge, the speed is set to 8000 r / min, and the time is set to 45 min. After the centrifugation is completed, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 20 g of gelatin in 90 g of water, heat to 80° C., and stir until completely dissolved to obtain solution a; (12) cooling solution a to room temperature, adding 6.5 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in an oil pan at 80 °C. (flow rate is 30 mL / min) After standing for 10 min, add 5% by mass of self-healing nanocellulose gel, stir at a speed of 8000 r / min for 15 min, take it out from the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 2 g of bis(4-aminophenyl)sulfide was dissolved in 5 mL of tetrahydrofuran solution to prepare a crosslinking agent, and the crosslinking agent was slowly dropped into colloid A to react for 15 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 3 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0022] Example 5 (1) 23 g of PTMG (polytetramethylene glycol) was placed in a 250 ml four-necked flask, 10.64 g of IPDI (isophorone diisocyanate) and 0.25% of DBTDL (dibutyltin dilaurate) were added, and the mixture was heated in an oil bath at 65 °C for 115 min to obtain solution A; (2) Add 0.78 g MDEA (methyldiethanolamine), 0.89 g MDPA (2,2-dihydroxymethylpropionic acid), 0.86 g BDO (1,4-butanediol) and 9.5 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 75° C. and react for 145 min to obtain solution B; (3) Solution B was cooled to room temperature, maintained at 13°C in a cold water bath, and 109 ml of acetone was added to obtain Solution C; (4) A dichloromethane solution (65 ml) containing 1.76 g IPDA (isophorone diamine) was added dropwise to solution C using a peristaltic pump at a rate of 8.5 ml / min. After the addition was completed, the solution was removed from the ice water bath and allowed to react at room temperature for 165 min. 0.96 g API (1-(3-aminopropyl)imidazole) was added to obtain a light yellow liquid, which was recorded as solution D. (5) In solution D, 0.19 g (zinc trifluoromethanesulfonate) in acetonitrile solution, stirring thoroughly to make the zinc ions disperse evenly in the solution, and obtaining a final light yellow solution E, which is polyurethane; (6) Weigh 14.0 g of cellulose and place it in a ball mill. Add 17 mL of 60% sulfuric acid and 17 g of (sodium periodate), ball milling pretreatment, grinding was stopped after 2.3 hours, the ball mill was taken out, and slurry a was obtained; (7) Add 2.9g of (Sodium periodate) continued oxidative grinding for 2.3 h to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 19 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated with a high-power CNC ultrasonic cleaner for 2.3 h, the slurry d is centrifuged using a centrifuge, the speed is set to 7500 r / min, and the time is set to 39 min. After the centrifugation, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 19 g of gelatin in 89 g of water, heat to 65° C., and stir until completely dissolved to obtain solution a; (12) cooling solution a to room temperature, adding 5.9 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in a 65°C oil pan and pass it into (flow rate is 29 mL / min) After standing for 10 min, add 3% by mass of self-healing nanocellulose gel, stir at a speed of 7500 r / min for 12 min, take it out from the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 0.9 g of bis(4-aminophenyl)sulfide was dissolved in 4 mL of tetrahydrofuran solution to prepare a crosslinking agent, and the crosslinking agent was slowly dropped into colloid A to react for 15 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 2.3 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0023] Example 6 (1) 19 g of PTMG (polytetramethylene glycol) was placed in a 250 ml four-necked flask, 11.35 g of IPDI (isophorone diisocyanate) and 0.18% of DBTDL (dibutyltin dilaurate) were added, and the mixture was heated in an oil bath at 67 °C for 90 min to obtain solution A; (2) Add 0.86 g MDEA (methyldiethanolamine), 0.95 g MDPA (2,2-dihydroxymethylpropionic acid), 0.8 g BDO (1,4-butanediol) and 8 ml DMAc (N,N-dimethylacetamide) to solution A, heat in an oil bath at 70° C. for 120 min to obtain solution B; (3) Cool solution B to room temperature, maintain a cold water bath at 18°C, add 118 ml of acetone, and obtain solution C; (4) A dichloromethane solution (80 ml) containing 2.85 g IPDA (isophorone diamine) was added dropwise to solution C using a peristaltic pump at a rate of 8 ml / min. After the addition was completed, the solution was removed from the ice water bath and allowed to react at room temperature for 150 min. 1.8 g API (1-(3-aminopropyl)imidazole) was added to obtain a light yellow liquid, which was recorded as solution D. (5) In solution D, 0.23 g (zinc trifluoromethanesulfonate) in acetonitrile solution, stirring thoroughly to make the zinc ions disperse evenly in the solution, and obtaining a final light yellow solution E, which is polyurethane; (6) Weigh 13.0 g of cellulose and place it in a ball mill. Add 18 mL of 60% sulfuric acid and 20 g of (sodium periodate), perform ball milling pretreatment, stop grinding after 3 hours, take out the ball mill jar, and obtain slurry a; (7) Add 3.8g of (Sodium periodate) continued oxidative grinding for 3 h to obtain slurry b; (8) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 25 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (9) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (10) After the slurry d is ultrasonically treated for 3 h using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge, the speed is set to 7300 r / min, and the time is set to 45 min. After the centrifugation is completed, the upper milky white suspension is collected and placed in a beaker, and concentrated to obtain slurry e, which is nanocellulose; (11) Dissolve 20 g of gelatin in 86 g of water, heat to 77° C., and stir until completely dissolved to obtain solution a; (12) cooling solution a to room temperature, adding 5.5 g of nanocellulose (slurry e), and rapidly stirring and mixing to obtain a self-healing nanocellulose gel material; (13) Take 50 g of the light yellow solution E and add it to a 250 ml three-necked flask. Heat it in a 70°C oil pan and pass it into (flow rate is 25 mL / min) After standing for 10 min, add self-healing nanocellulose gel at a mass percentage of 3.2%, stir at a speed of 5500 r / min for 11 min, take it out of the oil bath, and continue to stir slowly until it cools to room temperature to obtain colloid A; (14) 2 g of bis(4-aminophenyl)sulfide was dissolved in 4 mL of tetrahydrofuran solution to prepare a crosslinking agent, and the crosslinking agent was slowly dropped into colloid A to react for 13 min to obtain colloid B; (15) Pour colloid B into a mold and place it in a horizontal position for 2.5 h. Place the colloid B in a 60 °C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

[0024] The healing rates of the polyurethanes prepared in Examples 1-6 and traditional polyurethanes were experimentally observed. By comparison, it was found that the healing rates of the polyurethanes prepared in Examples 1-6 were higher than those of traditional amino acids at the same time point. The experimental results are as follows: Figure 1 and Figure 2 shown.

[0025] The tensile strain and tensile stress of the polyurethanes prepared in Examples 1-6 were compared with those of conventional polyurethanes. It was found that the polyurethanes prepared in Examples 1-6 had greater deformation and could withstand greater stress. Compared with conventional polyurethanes, the polyurethanes prepared in Examples 1-6 had greater tensile stress under the same tensile strain value. The experimental results are as follows: Figure 3 and Figure 4 shown.

[0026] The mechanical loss properties of the polyurethanes prepared in Examples 3, 5 and 6 were tested after healing with the traditional polyurethane. The results showed that the mechanical loss of the polyurethanes prepared in Examples 3, 5 and 6 after healing was smaller than that of the traditional polyurethane, and the mechanical loss properties after healing were better. The experimental results are as follows: Figure 5 shown.

Claims

1. An enhanced self-healing nanocellulose polyurethane material, characterized in that: Polyurethane, nanocellulose and a cross-linking agent are reacted under certain conditions to prepare a self-healing nanocellulose polyurethane material.

2. The method for preparing an enhanced self-healing nanocellulose polyurethane material according to claim 1, characterized in that The method comprises the following steps: firstly preparing polyurethane, using a soft segment and a hard segment B to react under specific conditions to obtain a colloid, then adding a proper amount of a chain extender to the colloid and continuing the reaction, and obtaining a viscous liquid as polyurethane; secondly preparing nanocellulose, taking cellulose and putting it into a ball mill, adding concentrated acid and a strong oxidant for ball milling to obtain a slurry a, then adding an ethylene glycol solution into the slurry a and putting it into a beaker, wrapping the beaker with tin foil to shield light and stirring, standing the liquid to separate, pouring out the upper liquid to obtain a slurry c, adjusting the pH of the slurry c to neutral, performing ultrasonic cleaning, centrifugal operation and drying to obtain the nanocellulose; then preparing a self-healing nanocellulose gel material, dissolving gelatin in water and heating, stirring until completely dissolved, and then adding the prepared nanocellulose to obtain the self-healing nanocellulose gel material; finally preparing a self-healing polyurethane nanocellulose composite material, reacting polyurethane, self-healing nanocellulose gel and a cross-linking agent under certain conditions to obtain a self-healing nanocellulose polyurethane material.

3. The method for preparing an enhanced self-healing nanocellulose polyurethane material according to claim 2, characterized in that The method for preparing polyurethane comprises the following steps: (1) 14-28 g of polytetrahydrofuran diol was placed in a 250 ml four-necked flask, 9.32-18.64 g of isophorone diisocyanate and 0.1-0.3% of dibutyltin dilaurate were added, and the mixture was heated in an oil bath at 60-80° C. for 60-120 min to obtain a solution A; (2) Add 0.67-1.34 g of methyldiethanolamine, 0.75-1.50 g of 2,2-dihydroxymethylpropionic acid, 0.5-1 g of 1,4-butanediol and 5-15 ml of N,N-dimethylacetamide to solution A, heat in an oil bath at 60-80°C and react for 120-180 min to obtain solution B; (3) Cool solution B to room temperature, keep the temperature at 10-20°C in a cold water bath, add 100-120 ml of acetone to obtain solution C; (4) In solution C, add 30-90 ml of a dichloromethane solution containing 1.02-3.06 g of isophorone diamine dropwise at a rate of 5-15 ml / min using a peristaltic pump. After the addition is complete, remove the solution from the ice water bath and allow it to react at room temperature for 120-180 min. Add 0.5-2.0 g of 1-(3-aminopropyl)imidazole to obtain a light yellow liquid, which is recorded as solution D. (5) Add 0.18-0.27 g of zinc trifluoromethanesulfonate in acetonitrile solution to solution D and stir thoroughly to disperse the zinc ions evenly in the solution to obtain a final light yellow solution E. The light yellow solution E is polyurethane.

4. The method for preparing an enhanced self-healing nanocellulose polyurethane material according to claim 2, characterized in that The method for preparing nanocellulose comprises the following steps: (1) Weigh 12-16.0 g of cellulose and put it into a ball mill, add 15-20 mL of 60% sulfuric acid and 15-20 g of sodium periodate, and perform ball milling pretreatment. After 2-3 hours, stop grinding, take out the ball mill, and obtain slurry a; (2) Add 2.0-4.0 g of sodium periodate to slurry a and continue oxidative grinding for 2-3 hours to obtain slurry b; (3) Take enough deionized water to rinse the slurry b in the grinding tank into a beaker, measure 15-25 mL of ethylene glycol solution and add it to the beaker, wrap the beaker with tin foil to block light and stir for 6 hours, let the liquid stand and separate, pour off the upper layer of liquid to obtain slurry c; (4) Deionized water is added to slurry c, and this separation operation is repeated until the pH value of the lower slurry reaches neutral, thereby obtaining slurry d; (5) After the slurry d is ultrasonically treated for 2-3 hours using a high-power CNC ultrasonic cleaner, the slurry d is centrifuged using a centrifuge with the speed set to 6000-8000 r / min and the time set to 30-45 min. After the centrifugation, the upper milky white suspension is collected and placed in a beaker for concentration to obtain slurry e, which is nanocellulose.

5. The method for preparing an enhanced self-healing nanocellulose polyurethane material according to claim 2, characterized in that The method for preparing the self-healing nanocellulose gel material comprises the following steps: (1) Dissolve 10-20 g of gelatin in 80-90 g of water, heat to 60-80°C, and stir until completely dissolved to obtain solution a; (2) Cool solution a to room temperature, add 5.0-6.5 g of slurry e, and quickly stir and mix to obtain a self-healing nanocellulose gel material.

6. The method for preparing an enhanced self-healing nanocellulose polyurethane material according to claim 2, characterized in that The method for preparing a self-healing polyurethane nanocellulose composite material comprises the following steps: (1) Take 50g of light yellow solution E and add it to a 250ml three-necked flask, place it in an oil pan at 60-80℃ and heat it. After passing nitrogen at a flow rate of 20-30mL / min for 10min, add self-healing nanocellulose gel at a mass percentage of 0.1%-5%, stir at a speed of 4000-8000r / min for 10-15min, take it out of the oil bath, continue to stir slowly until it cools to room temperature, and obtain colloid A; (2) 0.5-2 g of bis(4-aminophenyl)sulfide was dissolved in 2-5 mL of tetrahydrofuran solution to prepare a cross-linking agent, and the cross-linking agent was slowly dripped into colloid A to react for 15 min to obtain colloid B; (3) Pour colloid B into a mold and place it in a horizontal position, let it stand for 2-3 hours, and then put the colloid B into a 60°C vacuum drying oven to dry, thereby obtaining a self-healing nanocellulose polyurethane material.

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