CN116789563A - Bio-based polyurethane chain extender containing single imine bond and preparation method thereof - Google Patents
Bio-based polyurethane chain extender containing single imine bond and preparation method thereof Download PDFInfo
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Abstract
本发明公开了一种含单个亚胺键的生物基聚氨酯扩链剂及其制备方法：该制备方法先以香草醛、环氧氯丙烷和强碱为原料，将香草醛酚羟基转化为缩水甘油醚键，得到香草醛基缩水甘油醚；分别使用仅含仲胺以及同时含有伯胺与伯羟基的物质对香草醛缩水甘油醚进行改性；最终得到含有动态亚胺键的生物基扩链剂。本发明生生物基聚氨酯扩链剂中含有亚胺键，能够使材料在一定条件下实现对微裂纹等缺陷的自修复，延长材料的使用寿命；与此同时，亚胺键的存在赋予了材料良好的可降解性；而且该生物基扩链剂结构中仅含有单个亚胺键，不会发生因亚胺键动态性较强而使结构中小分子流失，造成亚胺键数量减少，影响最终材料的机械性能与重复自修复性能的现象。
The invention discloses a bio-based polyurethane chain extender containing a single imine bond and a preparation method thereof: the preparation method first uses vanillin, epichlorohydrin and strong alkali as raw materials, and converts the vanillin phenolic hydroxyl group into glycidol ether bonds to obtain vanillin-based glycidyl ether; vanillin glycidyl ether was modified with substances containing only secondary amines and substances containing both primary amines and primary hydroxyl groups; finally, a bio-based chain extender containing dynamic imine bonds was obtained. . The bio-based polyurethane chain extender of the present invention contains imine bonds, which can enable the material to self-repair defects such as microcracks under certain conditions and extend the service life of the material; at the same time, the presence of imine bonds gives the material Good degradability; and the structure of the bio-based chain extender only contains a single imine bond, which will not cause the loss of small molecules in the structure due to the strong dynamic nature of the imine bond, resulting in a reduction in the number of imine bonds and affecting the final material. The phenomenon of mechanical properties and repeated self-healing properties.
Description
Technical Field
The invention relates to a polyurethane chain extender, in particular to a biological polyurethane chain extender containing a single imine bond and a preparation method thereof.
Background
Polyurethanes are generally polymerized from an oligomeric diol, a diisocyanate, and a chain extender, with the oligomeric diol as the soft segment and the diisocyanate and the chain extender as the hard segment. The soft segment and the hard segment have different cohesive energy and poor compatibility, so that a microphase separation structure can be formed. It is the existence of microphase separation structure that makes polyurethane possess the elasticity of rubber while possessing the intensity of plastics. Polyurethane is widely applied to various fields of medical treatment, construction, aerospace and the like by virtue of excellent strength, toughness and wear resistance.
Currently, most of the raw materials for polyurethane are derived from non-renewable fossil energy sources. Fossil energy is limited and is not renewable, and along with continuous consumption of fossil energy, raw material cost is continuously increased, so that development of polyurethane materials is limited. In addition, polyurethane is used as a polymer, has large molecular weight and stable chemical property, is difficult to degrade in a natural state, and can continuously generate a large amount of micro plastic particles. These microplastic particles on the one hand can continuously pollute the ecological environment and cause immeasurable effects; on the other hand, the plant and animal feed can be continuously enriched in a food chain along with ecological cycle, so that the life health of various animals, plants and even human beings is affected.
The preparation of the bio-based degradable polyurethane can effectively reduce the dependence of polyurethane on fossil energy and relieve the problem of environmental pollution. The common method is to introduce ester bonds into the polyurethane main chain, and realize the degradation of the polymer by utilizing the principle of ester bond hydrolysis. For example, chinese patent application CN202211234604.3 prepared polyurethanes using degradable polylactic acid glycols and bio-based polyols. The degradability of the material is imparted by the introduction of ester linkages in the backbone. Chinese patent application CN202211104812.1 discloses a biodegradable slow rebound polyurethane foam and a preparation method thereof, wherein L-lysine is introduced into a polyurethane main chain, and an ester bond existing therein is utilized to impart degradability to polyurethane. Chinese patent application CN202210960377.6 discloses a method for preparing polysorbate-modified polylactic acid polyurethane, which uses all natural raw materials and has the characteristic of green and degradable. Although the ester bonds in the prior art can endow polyurethane with degradability, the characteristic of easy breakage can also make the performance of the polyurethane greatly reduced in the use process, and the long-term practical use requirement of the material can not be met.
Thus, in addition to the incorporation of ester linkages in the backbone, the incorporation of dynamic covalent bonds in the polyurethane can also impart degradability properties to the material. In addition, the polyurethane material with dynamic covalent bonds can repair the defects of the material under specific conditions through the breaking and recombination of the dynamic bonds, so that the service life of the material is prolonged and the waste of resources is reduced. For example, chinese patent application CN202010951771.4 uses degradable bio-raw castor oil as a cross-linking agent, and prepares a bio-based degradable polyurethane with self-repairing function by introducing disulfide bonds.
The Chinese patent application CN202111369673.0 takes vanillin as a raw material, and introduces dynamic imine bonds into a main chain to endow the material with degradability. Enabling the material to be degraded in the diethylamine solution. However, both ends of the vanillin dimer in the bio-based chain extender structure prepared by the technology are imine bonds, and as the vanillin dimer has higher cohesive energy, the vanillin dimer gradually aggregates and crystallizes out along with the breaking and the multiple bonds of the imine bonds in the use process, so that the number of the imine bonds in the material is reduced, the mechanical property of the material is reduced, and the repeated repair performance is weakened.
Disclosure of Invention
In order to reduce the dependence of polyurethane preparation on fossil resources and relieve the problem that conventional polyurethane cannot be degraded to pollute the environment, the invention provides the bio-based polyurethane chain extender containing single imine bond, which is prepared by taking vanillin as a raw material and can give the self-repairing property and the degradability of the chain extender, and ensure that small molecules are not lost in the use process, so that the mechanical property of the material is reduced and the self-repairing property is weakened, the material can realize repeated damage-repairing circulation, the safety and the reliability of the material applied in a high-loss environment are greatly improved, and the service life of the material is prolonged.
The aim of the invention can be achieved by the following technical scheme:
a biobased polyurethane chain extender containing a single imine bond having the structural formula:
wherein R is 1 Is one of the following groups:
R 2 is one of the following groups:
the preparation method of the bio-based polyurethane chain extender containing the single imine bond comprises the following steps:
(1) Mixing vanillin, epichlorohydrin and a phase transfer catalyst, heating to 70-90 ℃ for reaction for 2-4 hours, cooling to 20-40 ℃, then adding strong base, and converting phenolic hydroxyl of vanillin into glycidyl ether bond to obtain vanillin glycidyl ether;
(2) Adding vanillin glycidyl ether and a secondary amine-containing substance into a solvent system, and reacting for 1-8 hours at normal temperature to obtain an epoxy ring-opened vanillin derivative;
(3) And (3) reacting the vanillin derivative subjected to epoxy ring opening with a substance containing primary amine and secondary hydroxyl at the same time in a solvent at normal temperature for 0.5-4 hours, and removing the solvent and excessive raw materials to obtain the bio-based polyurethane chain extender containing single imine bond.
For further achieving the object of the invention, it is preferred that the molar ratio of vanillin to epichlorohydrin is from 1:5 to 1:10.
Preferably, the strong base is one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide; the phase transfer catalyst is one or more of tetrabutylammonium bromide, tetraethylammonium bromide, triethylbenzyl ammonium chloride and trimethylbenzyl ammonium chloride.
Preferably, the secondary amine-containing substance is one or more of dimethylamine, N-ethylmethylamine, N-ethylpropylamine, N-ethylisopropylamine, diethylamine, dipropylamine and di-sec-butylamine.
Preferably, the molar ratio of vanillin glycidyl ether to secondary amine-containing substance is 1:1-1:10.
Preferably, the substance containing primary amine and primary hydroxyl is one or more of ethanolamine, propanolamine, 2-amino-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol and 4-amino-1-butanol.
Preferably, the molar ratio of the vanillin derivative after epoxy ring opening to the substances simultaneously containing primary amine and primary hydroxyl is 1:1-1:2.
Preferably, the solvent is one or more of water, ethanol, N-propanol, isopropanol, N-dimethylformamide, tetrahydrofuran, acetone and dimethyl sulfoxide.
Preferably, the solvent is removed after standing for 8-24 hours at 40-70 ℃ under negative pressure.
Compared with the prior art, the invention has the following advantages and effects:
1. the preparation of the bio-based polyurethane chain extender containing single imine bonds takes biomass vanillin as a raw material, and develops the bio-based polyurethane chain extender containing only single imine bonds in the structure through molecular design.
2. The polyurethane material prepared by the bio-based polyurethane chain extender containing the single imine bond can be quickly repaired at 60 ℃, and can be degraded under the acidic condition of 0.1mol/L, and the self-repairing and degradation conditions are mild, the energy consumption is low and the pollution is small.
3. According to the invention, through changing amine substances used in the preparation of the bio-based chain extender, the molecular structure of a polymer molecular chain can be properly adjusted, different amine substances have different steric hindrance, and the motion capability and crystallization capability of a microscopic polymer molecular chain can be influenced, so that the macroscopic mechanical property of the material can be regulated and controlled, and the use requirements under different environmental conditions can be met.
4. The bio-based polyurethane chain extender containing single imine bond has the advantages of simple synthesis process, mild condition, easily obtained raw materials and low cost, can select a green and environment-friendly solvent system, and is easy to realize large-scale production and use.
5. Compared with the related self-repairing polyurethane, the polyurethane prepared by the chain extender has excellent repeatable repairing performance, and can realize repeated damage-repairing cycle of the material. The chain extender is used for preparing materials in a high-loss working environment, so that the safety and reliability of the materials can be greatly improved, and the service life of the materials can be greatly prolonged.
Drawings
FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of vanillin glycidyl ether of example 1.
FIG. 2 shows the nuclear magnetic resonance spectrum of the vanillin derivative of example 1 after ring opening of vanillin epoxy.
FIG. 3 is a nuclear magnetic resonance hydrogen spectrum of the bio-based polyurethane chain extender of example 1.
Detailed Description
For a better understanding of the present invention, reference is made to the following examples which are not intended to limit the scope of the claims hereof, but to other examples which may be obtained by persons skilled in the art without the benefit of the teachings herein.
The invention prepares the biobased polyurethane chain extender containing dynamic imine bonds by epoxidizing biomass vanillin to obtain vanillin glycidyl ether, then ring-opening epoxy groups in a mixed solvent by using a substance containing secondary amine, reacting the substance containing primary amine and primary hydroxyl with aldehyde groups, standing the solvent for 8-24 hours at 40-70 ℃ under vacuum condition, and removing the solvent. Because the chain extender contains dynamic imine bonds, the polyurethane material can be endowed with excellent self-repairing performance and degradation performance. The bio-based polyurethane chain extender only contains a single imine bond in the structure, and the phenomenon that the number of the imine bonds is reduced and the mechanical property is reduced due to the loss of small molecules after the bio-based polyurethane chain extender is connected into a polyurethane main chain is avoided. The application of the chain extender can effectively improve the repeated self-repairing cycle times of the damaged and repaired material, so that the material can still have enough safety and reliability under severe and complex working environments such as high loss and the like, and has longer service life.
The related test method in the embodiment of the invention is as follows:
and (3) mechanical property testing, namely, carrying out tensile property characterization on the original sample and the repaired sample by adopting a universal material testing machine, cutting a sample film with the thickness of 0.5-0.8 mm into 3 dumbbell-shaped sample strips with the size of 4 multiplied by 75mm according to GB/T528-2009, the gauge length of 16mm, the tensile rate of 500mm/min, the testing temperature of 25+/-2 ℃ and the humidity of 60+/-10%, repeating each sample at least 3 times, and taking an average value.
And (3) performing self-repairing performance test, namely cutting the self-repairing performance test into 3 dumbbell-shaped splines according to the national standard GB/T528-2009, cutting the splines from the middle, and then placing the cut-off splines in a 60 ℃ oven under the condition of keeping the sections in contact with each other, and heating for 4 hours to obtain corresponding repairing samples. The tensile strength of the sample strip before repair is recorded as sigma 1 The tensile strength of the repaired spline is recorded as sigma 2 The self-healing efficiency is noted as η, where η=σ 2 /σ 1 X 100%; reference is made to chinese patent application CN112979919a.
The degradation performance is tested, and the degradation performance is tested,taking 2.0-2.5g of polyurethane sample film with the thickness less than 2mm, and recording the mass of the polyurethane sample film as m 1 . The sample was placed in a 0.1mol/L hydrochloric acid solution, and the solution was allowed to stand at 25℃for 24 hours to take out. Standing in an oven at 60 ℃ for 24 hours and weighing and recording as m 2 . Degradation rate is delta= (m 1 -m 2 )/m 1 ×100％。
Example 1
A preparation method of a bio-based polyurethane chain extender containing a single imine bond comprises the following steps:
(1) Synthesis of vanillin glycidyl ether: 60.86g of vanillin (0.40 mol), 185.04g of epichlorohydrin (2.00 mol) and 2.27g of triethylbenzyl ammonium chloride (0.01 mol) were mixed and heated to 70℃for reaction for 4h. Subsequently cooled to 20℃and 100.00g of 40% strength by weight aqueous sodium hydroxide (1.00 mol) are added dropwise over 0.5 h. After completion of the dropwise addition, 100.00g of ethanol was added for dilution, and the reaction was continued for 1 hour after completion of the dilution. After the reaction was completed, the product was washed 3 times with deionized water. 60.35g of vanillin glycidyl ether are finally obtained, with a yield of approximately 73.51%. The nuclear magnetic resonance hydrogen spectrum of the vanillin glycidyl ether is shown in figure 1, and the absorption peak representing the phenolic hydroxyl hydrogen in the figure is disappeared, and simultaneously, the characteristic absorption peak representing the epoxy group appears, so that the epoxy group grafting is proved to be successful.
(2) Synthesis of Vanilla derivatives after epoxy ring opening: 8.32g of vanillin glycidyl ether (0.04 mol) was dissolved in 100g of 1.83wt% dimethylamine aqueous solution (0.04 mol), and after reaction at 30℃for 1 hour, water and the remaining raw materials were removed in vacuo to give an epoxy ring-opened vanillin derivative. The nuclear magnetic resonance spectrum of the vanillin derivative after epoxy ring opening is shown in figure 2. In the figure, it can be seen that the characteristic peak of the epoxy group disappeared, while an absorption peak representing dimethylamine methyl appears, proving that dimethylamine was successfully ring-opened.
(3) The preparation method of the bio-based polyurethane chain extender comprises the following steps: dissolving 10.13g of vanillin derivative (0.04 mol) subjected to epoxy ring opening in ethanol, adding 2.44g of ethanolamine (0.04 mol) after the solution is clarified uniformly, stirring for 0.5h at 30 ℃, and removing the solvent and the residual raw materials in vacuum for 8h at 70 ℃ after the reaction is finished, thereby finally obtaining the bio-based chain extender capable of realizing self-repairing and degradation of polyurethane. The nuclear magnetic hydrogen spectrum is shown in figure 3. It can be seen that the absorption peak representing the aldehyde hydrogen has been substantially disappeared, while the characteristic absorption peak of ethanolamine appears, proving that the ethanolamine grafting was successful and the bio-based polyurethane chain extender containing a single imine bond was successfully synthesized.
The nuclear magnetic resonance spectra of vanillin glycidyl ether, vanillin epoxy ring-opened intermediate and bio-based polyurethane chain extender in the following examples are substantially similar to those of fig. 1-3, but are not provided.
Example 2
A preparation method of a bio-based polyurethane chain extender containing a single imine bond comprises the following steps:
(1) Synthesis of vanillin glycidyl ether: 60.86g of vanillin (0.40 mol), 370.80g of epichlorohydrin (4.00 mol) and 1.85g of trimethylbenzyl ammonium chloride (0.01 mol) were mixed and reacted for 2 hours at a temperature of 90 ℃. Subsequently, the temperature was lowered to 40℃and 100.00g of 40% by weight aqueous potassium hydroxide (0.71 mol) were added dropwise over 0.5 h. After completion of the dropwise addition, 100.00g of ethanol was added for dilution, and the reaction was continued for 1 hour after completion of the dilution. After the reaction was completed, the product was washed 3 times with deionized water. 63.51g of vanillin glycidyl ether were finally obtained in a yield of approximately 77.36%.
(2) Synthesis of Vanilla derivatives after epoxy ring opening: 8.32g of vanillin glycidyl ether (0.04 mol) is dissolved in n-propanol, 29.52g of diethylamine (0.4 mol) is added, and the mixture is reacted for 8 hours at 50 ℃ and then is dehydrated in vacuum, so that the vanillin derivative after epoxy ring opening is obtained.
(3) The preparation method of the bio-based polyurethane chain extender comprises the following steps: 10.13g of vanillin derivative (0.04 mol) after epoxy ring opening is dissolved in n-propanol, 6.00g of propanolamine (0.08 mol) is added after the solution is clarified evenly, the mixture is stirred for 4 hours at 50 ℃, the solvent and the excessive propanolamine are removed in vacuum for 24 hours at 40 ℃ after the reaction is finished, and finally the bio-based polyurethane chain extender containing single imine bond, which can realize self-repairing and degradation of polyurethane, is obtained.
Example 3
A preparation method of a bio-based polyurethane chain extender containing a single imine bond comprises the following steps:
(1) Synthesis of vanillin glycidyl ether: 60.86g vanillin (0.40 mol), 227.56g epichlorohydrin (3.00 mol) and 3.22g tetrabutylammonium bromide (0.01 mol) were mixed and heated to 85℃for 2.5h. Subsequently, the temperature was reduced to 25℃and 100.00g of 40% by weight aqueous calcium hydroxide (0.54 mol) were added dropwise over 0.5 h. After completion of the dropwise addition, 100.00g of ethanol was added for dilution, and the reaction was continued for 1 hour after completion of the dilution. After the reaction was completed, the product was washed 3 times with deionized water. 62.39g of vanillin glycidyl ether are finally obtained in a yield of approximately 75.99%.
(2) Synthesis of Vanilla derivatives after epoxy ring opening: 8.32g of vanillin glycidyl ether (0.04 mol) is dissolved in tetrahydrofuran, 29.52g of diethylamine (0.4 mol) is added, the reaction is carried out for 8 hours at 50 ℃, and tetrahydrofuran is removed in vacuum, so that the vanillin derivative after epoxy ring opening is obtained.
(3) The preparation method of the bio-based polyurethane chain extender comprises the following steps: 10.13g of vanillin derivative (0.04 mol) after epoxy ring opening is dissolved in tetrahydrofuran, 7.13g of 2-aminobutanol (0.08 mol) is added after the solution is clarified evenly, the mixture is stirred for 4 hours at 50 ℃, and after the reaction is finished, the mixture is vacuumized for 12 hours at 50 ℃ and excessive tetrahydrofuran is used, so that the bio-based polyurethane chain extender containing single imine bond, which can realize self-repairing and degradation of polyurethane, is finally obtained.
Example 4
A preparation method of a bio-based polyurethane chain extender containing a single imine bond comprises the following steps:
(1) Synthesis of vanillin glycidyl ether: 60.86g vanillin (0.40 mol), 227.56g epichlorohydrin (3.00 mol) and 2.11g tetraethylammonium bromide (0.01 mol) were mixed and heated to 85℃for 2.5h. Subsequently cooled to 25℃and 100.00g of 40% strength by weight aqueous sodium hydroxide (1.00 mol) are added dropwise over 0.5 h. After completion of the dropwise addition, 100.00g of ethanol was added for dilution, and the reaction was continued for 1 hour after completion of the dilution. After the reaction was completed, the product was washed 3 times with deionized water. 66.76g of vanillin glycidyl ether were finally obtained, with a yield of about 81.32%.
(2) Synthesis of Vanilla derivatives after epoxy ring opening: 8.32g of vanillin glycidyl ether (0.04 mol) is dissolved in tetrahydrofuran, 25.85g of diethylamine (0.2 mol) is added, the reaction is carried out for 8 hours at 40 ℃, and tetrahydrofuran is removed in vacuum, so that the vanillin derivative after epoxy ring opening is obtained.
(3) The preparation method of the bio-based polyurethane chain extender comprises the following steps: 10.13g of vanillin derivative (0.04 mol) after epoxy ring opening is dissolved in tetrahydrofuran, 7.13g of 2-aminobutanol (0.08 mol) is added after the solution is clarified evenly and stirred for 2 hours at 40 ℃, and after the reaction is finished, the solvent, the excessive tetrahydrofuran and the raw materials are removed in vacuum, and finally the bio-based polyurethane chain extender containing single imine bond, which can realize self-repairing and degradation of polyurethane, is obtained.
Example 5
A preparation method of a bio-based polyurethane chain extender containing a single imine bond comprises the following steps:
(1) Synthesis of vanillin glycidyl ether: 60.86g vanillin (0.40 mol), 227.56g epichlorohydrin (3.00 mol) and 3.00g triethylbenzyl ammonium chloride (0.01 mol) were mixed and heated to 85℃for 2.5h. Subsequently cooled to 25℃and 100.00g of 40% strength by weight aqueous sodium hydroxide (1.00 mol) are added dropwise over 0.5 h. After completion of the dropwise addition, 100.00g of ethanol was added for dilution, and the reaction was continued for 1 hour after completion of the dilution. After the reaction was completed, the product was washed 3 times with deionized water. 59.21g of vanillin glycidyl ether were finally obtained, with a yield of about 72.12%.
(2) Synthesis of Vanilla derivatives after epoxy ring opening: 8.32g of vanillin glycidyl ether (0.04 mol) is dissolved in acetone, 25.85g of diethylamine (0.2 mol) is added, the reaction is carried out for 8 hours at 30 ℃, and then the acetone is removed in vacuum, so that the vanillin derivative after epoxy ring opening can be obtained.
(3) The preparation method of the bio-based polyurethane chain extender comprises the following steps: 10.13g of vanillin derivative (0.04 mol) after epoxy ring opening is dissolved in acetone, 5.35g of 2-aminobutanol (0.06 mol) is added after the solution is clarified evenly and stirred for 2 hours at 40 ℃, and after the reaction is finished, the solvent, excessive acetone and raw materials are removed in vacuum, and finally the bio-based polyurethane chain extender containing single imine bond, which can realize self-repairing and degradation of polyurethane, is obtained.
Application examples
Preparation method of bio-based polyurethane
20g of the mixture having an average molecular weight of 1000Polytetrahydrofuran (0.02 mol) is dehydrated in vacuo at 120℃for 2h and then cooled to 60 ℃. After completion of the cooling, 15.74g of 4,4' -dicyclohexylmethane diisocyanate (0.06 mol) and 25. Mu.L of N, N-dimethylformamide as solvent were added to a 0.1g/mL dibutyltin dilaurate solution in N 2 The NCO content was monitored by titration during the stirring reaction under protective conditions. After the completion of the prepolymerization, 11.85g of the bio-based polyurethane chain extender (0.04 mol) prepared in example 1 and 500. Mu.L of the prepared dibutyltin dilaurate catalyst solution were added and the reaction was continued with stirring at 75℃for 4 hours, and finally 50mL of N, N-dimethylformamide was added to reduce the viscosity. Pouring the prepared polyurethane solution into a polypropylene mold, drying for 24 hours in a blast oven at 70 ℃, and then continuing to dry for 24 hours in a vacuum oven at 70 ℃ to finally obtain a transparent polyurethane film sample.
Comparative example
30.43g of vanillin (0.20 mol) and 10.00g of sodium hydroxide (0.25 mol) were dissolved in 200mL of absolute ethanol, and 15mL of 1, 2-dibromoethane and 2.49g of potassium iodide (0.15 mol) were added as phase transfer catalysts. Reacting for 24 hours at 60 ℃ to obtain vanillin dimer. 12.21g of ethanolamine (0.30 mol) and 34.43g of vanillin dimer (0.10 mol) were dissolved in 200mL of ethanol, reacted at 60℃for 4 hours, and then washed with deionized water 5 times to obtain a bio-based chain extender.
20g of polytetrahydrofuran (0.02 mol) having an average molecular weight of 1000 were dehydrated in vacuo at 120℃for 2h and then cooled to 60 ℃. After completion of the cooling, 15.74g of 4,4' -dicyclohexylmethane diisocyanate (0.06 mol) and 25. Mu.L of N, N-dimethylformamide as solvent were added to a 0.1g/mL dibutyltin dilaurate solution in N 2 The NCO content was monitored by titration during the stirring reaction under protective conditions. After the completion of the prepolymerization, 12.24g of the bio-based polyurethane chain extender (0.04 mol) prepared in the previous step and 500. Mu.L of the prepared dibutyltin dilaurate catalyst solution were added, and the temperature was raised to 75℃with continuous stirring for 4 hours, and finally 50mL of N, N-dimethylformamide was added to reduce the viscosity. Pouring the prepared polyurethane solution into a polypropylene mold, drying for 24 hours in a blast oven at 70 ℃, and then continuing to dry for 24 hours in a vacuum oven at 70 ℃ to finally obtain a transparent polyurethane film sample.
Table 1 shows the results of the performance tests of comparative examples 1 and 2.
TABLE 1
The polyurethane in the application example was prepared using the bio-based polyurethane chain extender prepared in example 1 of the present invention, which contains only a single imine bond; the polyurethane in the comparative example uses biomass vanillin as a raw material, firstly prepares vanillin dimer, and then completes the preparation of a chain extender by reacting with ethanolamine, wherein both ends of the vanillin dimer are imine bonds. The ratio of the polyether polyol to the isocyanate and the amount of the biobased chain extender used in the preparation of the two polyurethanes in the application examples and the comparative examples was the same. As can be seen from Table 1, the mechanical strength of the two polyurethanes is not very different and is substantially the same. And cutting off sample strips of the two polyurethane materials by a blade, and then completing self-repairing of the sample within 4 hours at 60 ℃. Tests show that the self-repairing efficiency of the two materials can reach higher levels of 94.68% and 95.74% respectively. The material can realize self-repairing under mild conditions, and can meet most of use requirements.
In addition, the material is placed in a hydrochloric acid solution with the concentration of 0.1mol/L for 24 hours, most of samples can be degraded, and the degradation rate of the samples can reach 83.56%. The degradation condition of the surface material is mild, and the degradation rate can reach a higher level. Thereby greatly reducing the pollution degree of the waste materials to the environment.
Taken together, the polyurethane of the application examples has an imine bond content of only half that of the comparative examples, but the degradation rate of the first damaged self-repairing efficiency is equivalent to that of the comparative examples, which proves that the polyurethane prepared by using the chain extender prepared by the invention can maintain excellent self-repairing performance and degradation performance. However, as the repair times increase, after ten damaged repairs are performed, the strength of the polyurethane prepared by the comparative example is only 48.67% compared with the original strength, the self-repair efficiency of the polyurethane is greatly reduced, and the repair efficiency of the polyurethane prepared by the application example is still at a higher level and reaches 88.46%. In the process of repairing multiple damages, because the two ends of the vanillin dimer in the comparative example are imine bonds, the vanillin dimer also has stronger cohesive energy, and the vanillin dimer gradually crystallizes and precipitates in the processes of breaking and recombining the imine bonds, so that the loss of the imine bonds is caused, and the self-repairing efficiency is greatly reduced. In the application embodiment of the invention, the chain extender structure only contains a single imine bond, so that the problem that the self-repairing efficiency is affected due to the reduction of the imine bond caused by the loss of small molecular substances in the repairing process is avoided, the repeated repairing times of the material can be greatly increased, and the service life of the material is further prolonged. The chain extender can be prepared by using biomass vanillin as a raw material at a lower temperature, and the raw material and various solvents used in the chain extender can be recycled, so that the cost can be greatly reduced, the pollution degree to the environment can be reduced, and the chain extender has the potential of large-scale production.
The biomass vanillin is used as a raw material, the preparation of the bio-based chain extender containing imine bonds can realize repeated self-repair of the material for many times, the self-repair performance is not reduced along with the damage-repair cycle times, the safety reliability and the service life of the material under the high-loss environment are improved, and the application of the bio-based raw material and the degradability can also reduce the dependence on fossil raw materials and relieve the environmental pollution problem.
Therefore, the bio-based polyurethane chain extender prepared by the invention not only can degrade the material, but also can endow the material with multiple self-repairing performance, and prolongs the service life of the material.
Claims (10)
1. A biobased polyurethane chain extender containing a single imine bond, characterized by the following structural formula:
wherein R is 1 Is one of the following groups:
R 2 is one of the following groups:
2. the method for preparing the bio-based polyurethane chain extender containing single imine bonds according to claim 1, characterized by comprising the following steps:
(1) Mixing vanillin, epichlorohydrin and a phase transfer catalyst, heating to 70-90 ℃ for reaction for 2-4 hours, cooling to 20-40 ℃, then adding strong base, and converting phenolic hydroxyl of vanillin into glycidyl ether bond to obtain vanillin glycidyl ether;
(2) Adding vanillin glycidyl ether and a secondary amine-containing substance into a solvent system, and reacting for 1-8 hours at normal temperature to obtain an epoxy ring-opened vanillin derivative;
(3) And (3) reacting the vanillin derivative subjected to epoxy ring opening with a substance containing primary amine and secondary hydroxyl at the same time in a solvent at normal temperature for 0.5-4 hours, and removing the solvent and excessive raw materials to obtain the bio-based polyurethane chain extender containing single imine bond.
3. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the mol ratio of vanillin to epichlorohydrin is 1:5-1:10.
4. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the strong alkali is one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide; the phase transfer catalyst is one or more of tetrabutylammonium bromide, tetraethylammonium bromide, triethylbenzyl ammonium chloride and trimethylbenzyl ammonium chloride.
5. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the substance containing secondary amine is one or more of dimethylamine, N-ethylmethyl amine, N-ethylpropyl amine, N-ethylisopropyl amine, diethylamine, dipropylamine and di-sec-butylamine.
6. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the mol ratio of vanillin glycidyl ether to secondary amine-containing substances is 1:1-1:10.
7. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the substance containing primary amine and primary hydroxyl is one or more of ethanolamine, propanol ammonia, 2-amino-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol and 4-amino-1-butanol.
8. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the molar ratio of the vanillin derivative after epoxy ring opening to substances simultaneously containing primary amine and primary hydroxyl is 1:1-1:2.
9. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the solvent is one or more of water, ethanol, N-propanol, isopropanol, N-dimethylformamide, tetrahydrofuran, acetone and dimethyl sulfoxide.
10. The method for preparing the bio-based polyurethane chain extender containing single imine bond according to claim 2, wherein the method comprises the following steps: the solvent is kept stand for 8 to 24 hours under the negative pressure condition of 40 to 70 ℃ and then is removed.
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| CN119661809A (en) * | 2024-11-01 | 2025-03-21 | 化学与精细化工广东省实验室揭阳分中心 | Water-resistant self-repairing polyurethane elastomer, preparation method thereof and application thereof in humidity sensor |
| CN119822994A (en) * | 2024-12-16 | 2025-04-15 | 华南理工大学 | Amide bond-containing chain extender for single-component moisture-curing polyurethane coating and preparation method thereof |
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| US20180162987A1 (en) * | 2015-05-03 | 2018-06-14 | Adesso Advanced Materials Wuhu Co., Ltd. | Degradable polyurethanes and composites thereof |
| CN114015003A (en) * | 2021-11-17 | 2022-02-08 | 长春工业大学 | Degradable polyurethane elastomer based on vanillin imine-containing structure and preparation method thereof |
| CN116355173A (en) * | 2023-03-28 | 2023-06-30 | 华南理工大学 | Self-healing degradable bio-based polyurethane containing single imine bond and preparation method thereof |
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| US20180162987A1 (en) * | 2015-05-03 | 2018-06-14 | Adesso Advanced Materials Wuhu Co., Ltd. | Degradable polyurethanes and composites thereof |
| CN114015003A (en) * | 2021-11-17 | 2022-02-08 | 长春工业大学 | Degradable polyurethane elastomer based on vanillin imine-containing structure and preparation method thereof |
| CN116355173A (en) * | 2023-03-28 | 2023-06-30 | 华南理工大学 | Self-healing degradable bio-based polyurethane containing single imine bond and preparation method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN119661809A (en) * | 2024-11-01 | 2025-03-21 | 化学与精细化工广东省实验室揭阳分中心 | Water-resistant self-repairing polyurethane elastomer, preparation method thereof and application thereof in humidity sensor |
| CN119822994A (en) * | 2024-12-16 | 2025-04-15 | 华南理工大学 | Amide bond-containing chain extender for single-component moisture-curing polyurethane coating and preparation method thereof |
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