A water-based photocurable multi-reversible room temperature self-healing elastomer and its preparation method and application

Abstract

The present invention discloses a water-based photocurable multiple reversible room temperature self-healing elastomer and its preparation method and application, which belongs to the technical field of wearable devices. The present invention adds 2,2-dimethylol propionic acid, disulfide, diisocyanate monomer, polyetheramine and end-capping agent in the process of preparing the water-based photocurable multiple reversible room temperature self-healing elastomer, introduces the hydrophilic chain extender into the elastomer resin structure to make it water-based; disulfide bonds and urea groups and carbamate groups are introduced into the main chain of waterborne polyurethane, and the multiple dynamic reversibility of disulfide bonds and multiple hydrogen bonds gives it high stretchability and autonomous self-healing properties at room temperature; the photocuring end-capping agent gives the elastomer photocuring properties. The water-based photocurable multiple reversible room temperature self-healing elastomer disclosed by the present invention and its preparation method and application have the characteristics of high efficiency, energy saving, environmental protection and economy; good self-healing efficiency (up to 100%) can be achieved at room temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of wearable devices, and in particular relates to a water-based photocurable multi-reversible room temperature self-healing elastomer and a preparation method and application thereof. Background Art

[0002] In recent years, wearable strain sensors (WSS) have been widely used in human health monitoring, soft robotics, biomedical engineering, human-computer interaction and other fields, especially high-sensitivity and high-elasticity wearable devices. As a typical representative of emerging synthetic materials, waterborne polyurethane has received extensive attention in the field of flexible electronic materials in recent years due to its excellent performance, flexible chemical structure and environmental friendliness. Considering the importance of sustainable development of society and the growing demand for high-performance materials, the design and manufacture of a new generation of intelligent self-healing materials with excellent comprehensive performance has special significance for the practical value of wearable field.

[0003] CN 109836550 A discloses a water-based self-repairing polyurethane resin. First, a prepolymer is obtained by using polyol, polyisocyanate, anionic hydrophilic chain extender, small molecule disulfide bond chain extender, etc. as raw materials, and then emulsified, and then a small molecule water-soluble diamine chain extender is added to react to obtain a water-based self-repairing polyurethane resin, and then mixed with hexamethylene diisocyanate trimer and cured. The prepared material has many excellent properties of solvent-based self-repairing high-performance polyurethane elastomer and additional water dilutability. At 70°C, the self-repair efficiency of repairing 24h micro-scratch strength can exceed 70%, and can reach up to 88.3%.

[0004] CN 116589659 A discloses a self-repairing polyurethane elastomer. First, polyester polyol, diphenylmethane diisocyanate, and light-curing diol chain extender are used as raw materials to synthesize a thermoplastic polyurethane matrix, and then the thermoplastic polyurethane matrix, 2-hydroxymethyl furan, 1,4-(bismaleimide) butane, etc. are used as raw materials to synthesize a solvent-based self-repairing polyurethane elastomer containing DA bonds. The obtained material has excellent performance. After one cycle stretching, the tensile strength can reach 12.18MPa after self-repair, the elongation at break can reach 950.41%, the shape recovery after 10 cycles of stretching can reach 95%, and the tensile strength can reach 11.85MPa after self-repair at 120°C after cutting.

[0005] CN 110452353 A discloses a hyperbranched self-repairing waterborne polyurethane emulsion, which is prepared from dried and dehydrated polyols, dithiodiols, diisocyanates, hyperbranched polyol hydrophilic chain extenders, etc. The waterborne polyurethane emulsion prepared by the patent can effectively reduce the viscosity of the emulsion, has good chemical stability and interface adhesion, can achieve self-repair at room temperature, and its self-repair efficiency can reach up to 90.6%.

[0006] CN 115785383 A discloses a self-repairing polyurethane material containing double crosslinking of DA bonds and acylhydrazone bonds. The material is obtained by adding a small molecule diol containing acylhydrazone bonds and DA bonds as a chain extender into a polyurethane prepolymer. The self-repairing polyurethane material has mild repair conditions and significantly improved self-repairing efficiency compared with a single DA bond or a single acylhydrazone bond. Under the conditions of a pH value of 3 to 5 and a temperature of 60 to 90° C., the self-repairing efficiency can reach 95.16%.

[0007] In summary, existing wearable device elastomers have the following problems: ①. Some elastomer materials need to be diluted with a large amount of organic solvents before molding, which makes it difficult to meet environmental protection requirements; ②. Some elastomer materials are molded by thermal curing or room temperature curing, which has a slow curing speed, high energy consumption and complex process; ③. Microcracks or microdamages generated during the use of elastomer materials cannot be repaired, affecting the service life of the material and causing serious economic losses; ④. Elastomer materials containing DA bonds need to be heated to achieve self-repair, and the conditions are limited; ⑤. 100% self-repair cannot be achieved. Summary of the invention

[0008] In order to solve the above technical problems, the present invention proposes a water-based photocurable multiple reversible room temperature self-healing elastomer and its preparation method and application. The present invention uses a water-based polyurethane resin that meets environmental protection requirements, and introduces disulfide bonds, urea groups and carbamate groups into the main chain of the water-based polyurethane to prepare multiple dynamic reversible water-based photocurable polyurethanes containing disulfide bonds and multiple hydrogen bonds, giving it high stretchability and autonomous self-healing properties at room temperature; in addition, compared with thermal curing, UV curing technology is widely used due to its high efficiency, energy saving, environmental protection and economic characteristics; and it does not require too high a temperature, and can achieve good self-healing efficiency at room temperature.

[0009] To achieve the above objectives, the present invention provides a water-based photocurable multi-reversible room temperature self-healing elastomer, the raw materials of which contain 2,2-dihydroxymethylpropionic acid and disulfide, and the molar ratio of the 2,2-dihydroxymethylpropionic acid to the disulfide is 7-14:4-8.

[0010] Furthermore, the water-based photocurable multi-reversible room temperature self-healing elastomer includes the following raw materials: 2,2-dihydroxymethylpropionic acid, a neutralizer, a diisocyanate, a catalyst, a polyetheramine, a disulfide, an inhibitor and a capping agent.

[0011] In the present invention, 2,2-dimethylol propionic acid is used as a hydrophilic extender, which has a neopentyl glycol structure and can give the product certain heat resistance and hydrolysis resistance. It has a low relative molecular mass and a small amount of use. At the same time, anionic groups can be introduced into the polyurethane chain to make it sufficiently hydrophilic and dispersed in water to form a stable emulsion, in which the hydrophilic group carboxyl is blocked by two hydroxymethyl groups, and is not easy to react with isocyanate, so as to maintain its hydrophilic function. The two active hydroxyl groups wrapped outside can react with isocyanate, thereby being introduced into the main chain of carbamate, and play the role of an internal emulsifier. The role of disulfide is to introduce disulfide bonds. The covalent bonds between sulfur-sulfur atoms are easy to break, and the translocation exchange effect can be realized without external conditions. Therefore, the polymer prepared by using disulfide bonds can realize the self-repairing behavior of the material without the action of external factors such as heating and pressure, and can be repaired multiple times.

[0012] Further, the neutralizing agent is dimethylethanolamine or triethylamine. The above two neutralizing agents are used to neutralize the carboxyl group in the hydrophilic extender to form a salt, so that the elastomer resin has water-based properties. At the same time, the above two neutralizing agents have a low boiling point and will evaporate along with the water during the elastomer film forming process. Further, the diisocyanate is lysine diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, trimethyl hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate or isophorone diisocyanate. Further, the disulfide is bis(2-hydroxyethyl) disulfide or dihydroxydiphenyl disulfide.

[0013] Furthermore, the catalyst is dibutyltin dilaurate (DBTDL); the polyetheramine is at least one of polyetheramine PEA400 and polyetheramine PEA2000; and the inhibitor is p-hydroxyanisole. Dibutyltin dilaurate acts as a catalyst to accelerate the reaction, and the inhibitor prevents the acryloxy group in the acrylate monomer from being cross-linked by heat. The molecular structure of the polyetheramine is a diamine with a flexible segment and -NH2. The flexible segment can provide better flexibility for the elastomer, and -NH2 can react with -NCO to generate a urea group. The urea group can provide more hydrogen bonds, and the carbamic acid group generated by the reaction of the isocyanate group and the hydroxyl group can also provide hydrogen bonds for the elastomer. The multiple hydrogen bonds formed between the carbamate group and the carbamate group, the carbamate group and the urea group, and the urea group and the urea group can give the elastomer better room temperature repair performance.

[0014] Furthermore, the end-capping agent is hydroxyethyl acrylate, hydroxypropyl acrylate or hydroxyethyl methacrylate. These end-capping agents used in the present invention provide the elastomer with a photocurable group acryloxy.

[0015] The present invention prepares an anionic waterborne polyurethane, which uses 2,2-dimethylol propionic acid as a fixed hydrophilic extender. Its hydrophilic group carboxyl group as a polar group can only form an emulsion when mixed with water, and needs to be neutralized into salts with triethylamine or dimethylethanolamine to obtain water solubility. The isocyanate group in diisocyanate is a very active group that can react with many compounds containing active hydrogen, such as hydroxyl and amine groups, and plays the role of a hard segment. The reaction of diisocyanate with polyetheramine can generate urea groups, and the urea group has a large polarity and can form more hydrogen bonds, which can give the elastomer better self-healing properties. The main chain of the polyetheramine is a flexible segment, which can give the elastomer better flexibility.

[0016] A method for preparing the water-based photocurable multi-reversible room temperature self-healing elastomer comprises the following steps:

[0017] 7-14 mmol of 2,2-dimethylol propionic acid is added to 17-90 mmol of solvent, and 5-7 mmol of neutralizer is added at a temperature of 25-50° C. After the reactant becomes clear and transparent, the temperature is raised to 50-70° C., and then 0.028-0.049 mmol of catalyst and 28-56 mmol of diisocyanate are added in sequence to react for 2-4 hours;

[0018] The product is cooled to 0-10°C, 10-16 mmol of polyetheramine is added to react for 1-2 hours, the temperature is raised to room temperature to react for 1-3 hours, the temperature is raised to 35-55°C, 4-8 mmol of disulfide and 0.019-0.034 mmol of catalyst are added, the temperature is kept constant for 2-4 hours, the temperature is raised to 55-75°C, 0.0975-0.83 mmol of polymerization inhibitor, 0.028-0.049 mmol of catalyst and 14-28 mmol of end-capping agent are added, the temperature is kept constant for 3-6 hours, the system is finally cooled to 40°C, 4-9 mmol of neutralizing agent is added to react while stirring for 0.5-1 hour, and the solvent is removed to obtain a water-based light-curable multi-reversible room temperature self-healing elastomer resin;

[0019] The water-based light-curable multiple reversible room temperature self-healing elastomer resin is dispersed at a speed of 1000 r / min for 5 to 8 minutes, then the speed is increased to 3000 r / min, and deionized water is dripped into the mixture to adjust the solid content of the system to 50%, and the mixture is dispersed for 20 to 40 minutes to obtain a water-based light-curable multiple reversible room temperature self-healing elastomer emulsion;

[0020] 4 to 5 mmol of photoinitiator is added to the water-based photocurable multiple reversible room temperature self-healing elastomer emulsion, stirred evenly and then applied on a substrate or placed in a mold to dry the moisture, and irradiated with ultraviolet light to obtain the water-based photocurable multiple reversible room temperature self-healing elastomer.

[0021] The present invention adopts polyetheramine as a soft segment, diisocyanate as a hard segment, dimethylol propionic acid as a chain extender, adds disulfide and a capping agent, and adopts ultraviolet light curing technology to prepare a water-based light-cured multiple reversible room temperature self-healing polyurethane elastomer. The present invention uses water as a solvent when preparing the elastomer to reduce the use of volatile organic matter; adopts ultraviolet light curing technology, which has the characteristics of high efficiency, energy saving, environmental protection, and economy; through the synergistic effect of disulfide bonds and multiple hydrogen bonds, the elastomer has the characteristics of high tensile strength and autonomous self-healing at room temperature, giving the water-based light-cured polyurethane better elastomer characteristics and room temperature self-healing ability. The polyurethane elastomer obtained by the present invention has excellent mechanical properties (elongation at break can reach 682%), and the repair rate can reach 100% after repairing at room temperature for 36 hours.

[0022] Furthermore, the irradiation intensity is 1600 mW / cm 2 , the irradiation time is 50s.

[0023] Furthermore, the photoinitiator is 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone).

[0024] The application of the water-based photocurable multi-reversible room temperature self-healing elastomer in the preparation of wearable strain sensors.

[0025] Supramolecular polyurethane is composed of polyurethane and supramolecular interactions, and is currently a hot topic in the field of self-healing polymers. By introducing reversible supramolecular interactions such as hydrogen bonds, it is made dynamically reversible and physically cross-linked, and can be destroyed and reconstructed, effectively dissipating strain energy, thereby obtaining a polymer material with outstanding performance. Therefore, using non-covalent aggregates as dynamic cross-linking junctions is an effective strategy to simultaneously enhance and toughen self-healing materials. It is worth noting that a large number of theories have proved that the type and number of non-covalent bonds have a great influence on the mechanical behavior of the material, that is, materials prepared by only a single type of supramolecular bonds often have poor mechanical strength. Based on this, the present invention designs an autonomous self-healing material based on reversible dynamic covalent bonds and non-covalent bonds, which has high strength, high toughness and room temperature self-healing function.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] The advantages of the water-based photocurable multi-reversible room temperature self-healing elastomer synthesized by the present invention are: ①, the method for synthesizing the water-based photocurable polyurethane elastomer is energy-saving, more convenient to operate, does not pollute the environment, and is more in line with the concept of green environmental protection; ②, the ultraviolet light curing technology adopted has the characteristics of high efficiency, energy saving, environmental protection, and economy; ③, by synergistically incorporating disulfide bonds and multiple hydrogen bonds into the elastomer, it has the characteristics of high stretchability and autonomous self-healing at room temperature; ④, after repairing at room temperature for 36 hours, its self-healing efficiency can reach up to 100%. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] Unless otherwise specified, the room temperature in the embodiments and comparative examples of the present invention refers to 25±2°C.

[0034] The raw materials used in the examples and comparative examples of the present invention were all purchased.

[0035] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0036] Example 1

[0037] A method for preparing a water-based photocurable multi-reversible room temperature self-healing elastomer:

[0038] Step 1: Add 2,2-dihydroxymethylpropionic acid (1.16 g, 8.64 mmol) to N,N-dimethylformamide (2.32 g, 31.74 mmol), add triethylamine (0.61 g, 6.00 mmol) at 50°C, and after the reactant becomes clear and transparent, heat to 60°C, then add catalyst DBTDL (0.023 g, 0.036 mmol) and trimethylhexamethylene diisocyanate (8.41 g, 40.00 mmol) in sequence and react for 3 hours;

[0039] Step 2: The product obtained in the first step was cooled to 0°C, polyetheramine PEA400 (4.63 g, 11.57 mmol) and polyetheramine PEA2000 (5.34 g, 2.67 mmol) were added, and the mixture was reacted for 1 hour, and then the mixture was heated to room temperature for 2 hours, and then the mixture was heated to 45°C, bis(2-hydroxyethyl) disulfide (1.10 g, 7.12 mmol) and catalyst DBTDL (0.015 g, 0.024 mmol) were added, and the mixture was reacted at a constant temperature for 3 hours, and then the mixture was heated to 45°C. The temperature was raised to 65°C, p-hydroxyanisole (0.029 g, 0.23 mmol), catalyst DBTDL (0.027 g, 0.042 mmol) and hydroxypropyl acrylate (2.86 g, 22.00 mmol) were added, and the reaction was carried out at a constant temperature for 4 hours. Finally, the system was cooled to 40°C, triethylamine (0.81 g, 8.00 mmol) was added, and the reaction was carried out while stirring for 0.8 hours. The solvent was removed to obtain a water-based light-curable multi-reversible room temperature self-healing elastomer resin;

[0040] Step 3: Add the prepared resin into the dispersion barrel, disperse at 1000r / min for 7 minutes, then increase the speed to 3000r / min, and drip deionized water to adjust the solid content of the system to 50%. After dripping the deionized water, disperse for 40 minutes to obtain a water-based light-curable multi-reversible room temperature self-healing elastomer emulsion;

[0041] Step 4: Add photoinitiator 1173 (0.78 g, 4.73 mmol) to the emulsion prepared above, stir evenly and apply to the substrate to dry the water. 2 The irradiation time under the ultraviolet lamp is 50s, and the water-based light-cured multi-reversible room temperature self-healing elastomer is obtained.

[0042] Example 2

[0043] A method for preparing a water-based photocurable multi-reversible room temperature self-healing elastomer:

[0044] Step 1: Add 2,2-dihydroxymethylpropionic acid (1.59 g, 11.82 mmol) to N,N-dimethylformamide (3.17 g, 43.37 mmol), add triethylamine (0.61 g, 6.00 mmol) at 50°C, raise the temperature to 60°C after the reactant becomes clear, then add catalyst DBTDL (0.023 g, 0.036 mmol) and trimethylhexamethylene diisocyanate (8.41 g, 40.00 mmol) in turn and react for 3 hours.

[0045] Step 2: The obtained product was cooled to 5°C, polyetheramine PEA400 (1.52 g, 3.79 mmol) and polyetheramine PEA2000 (16.66 g, 8.33 mmol) were added, and the mixture was reacted for 1 hour, and then the mixture was heated to room temperature for 2 hours, and then the mixture was heated to 45°C, bis(2-hydroxyethyl) disulfide (0.933 g, 6.06 mmol) and catalyst DBTDL (0.015 g, 0.024 mmol) were added, and the mixture was reacted at a constant temperature for 3 hours, and then the mixture was heated to 45°C. The mixture was heated to 65°C, p-hydroxyanisole (0.029 g, 0.23 mmol), catalyst DBTDL (0.027 g, 0.042 mmol) and hydroxyethyl acrylate (2.55 g, 22.00 mmol) were added, and the mixture was reacted at a constant temperature for 4 hours. Finally, the system was cooled to 40°C, triethylamine (0.81 g, 8.00 mmol) was added, and the mixture was reacted for 0.6 hours while stirring. The solvent was removed to obtain a water-based light-curable multi-reversible room temperature self-healing elastomer resin.

[0046] Step 3: Add the prepared resin into the dispersion barrel, disperse at 1000r / min for 8 minutes, then increase the speed to 3000r / min, and drip deionized water to adjust the solid content of the system to 50%. After dripping the deionized water, disperse for 30 minutes to obtain a water-based light-curable multi-reversible room temperature self-healing elastomer emulsion;

[0047] Step 4: Add photoinitiator 1173 (0.76 g, 4.60 mmol) to the emulsion prepared above, stir evenly and place in a mold to dry the water. 2 A water-based photocurable multi-reversible room temperature self-healing elastomer is obtained by irradiating under ultraviolet light for 50 seconds.

[0048] Example 3

[0049] A method for preparing a water-based photocurable multi-reversible room temperature self-healing elastomer:

[0050] Step 1: Add 2,2-dihydroxymethylpropionic acid (1.84 g, 13.70 mmol) to N,N-dimethylformamide (3.76 g, 51.44 mmol), add dimethylethanolamine (0.53 g, 6.00 mmol) at 50°C, raise the temperature to 60°C after the reactant becomes clear, then add catalyst DBTDL (0.023 g, 0.036 mmol) and isophorone diisocyanate (8.89 g, 40.00 mmol) in turn and react for 3 hours.

[0051] Step 2: The obtained product was cooled to 8°C, and polyetheramine PEA2000 (22.20 g, 11.10 mmol) was added and reacted for 1 hour, and then heated to room temperature for 2 hours, and then heated to 45°C, and bis(2-hydroxyethyl) disulfide (1.84 g, 5.60 mmol) and catalyst DBTDL (0.015 g, 0.024 mmol) were added, and the reaction was carried out at a constant temperature for 3 hours, and then heated to 65°C, and p-hydroxyanisole (0.029 g, 0.23 mmol), catalyst DBTDL (0.027 g, 0.042 mmol), hydroxyethyl methacrylate (2.86 g, 22.00 mmol) were added, and the reaction was carried out at a constant temperature for 4 hours, and finally the system was cooled to 40°C, and dimethylethanolamine (0.71 g, 8.00 mmol) was added and reacted with stirring for 0.5 hours, and the solvent was removed to obtain a water-based light-cured multi-reversible room temperature self-healing elastomer resin;

[0052] Step 3: Add the prepared resin into the dispersion barrel, disperse at 1000r / min for 6 minutes, then increase the speed to 3000r / min, and drip deionized water to adjust the solid content of the system to 50%, and disperse for 25 minutes after the dripping, to obtain the water-based light-curable multi-reversible room temperature self-healing elastomer emulsion;

[0053] Step 4: Add photoinitiator 1173 (0.76 g, 4.62 mmol) to the emulsion prepared above, stir evenly and apply to the substrate to dry the water. 2 The irradiation time under the ultraviolet lamp is 50s, and the water-based light-cured multi-reversible room temperature self-healing elastomer is obtained.

[0054] Example 4

[0055] Same as Example 2, except that the diisocyanate is toluene diisocyanate, and the added amount is 6.97 g (40.00 mmol).

[0056] Example 5

[0057] Same as Example 2, except that the diisocyanate is lysine diisocyanate, and the added amount is 9.05 g (40.00 mmol).

[0058] Example 6

[0059] Same as Example 2, except that the diisocyanate is diphenylmethane diisocyanate, and the added amount is 10.01 g (40.00 mmol).

[0060] Example 7

[0061] Same as Example 2, except that the diisocyanate is 1,6-hexamethylene diisocyanate, and the added amount is 6.73 g (40.00 mmol).

[0062] Example 8

[0063] Same as Example 2, except that the disulfide is dihydroxydiphenyl disulfide, and the added amount is 1.52 g (6.06 mmol).

[0064] Comparative Example 1

[0065] The same as Example 1, except that the added chain extender is 1,4-butanediol, and the added amount is 0.78 g (8.64 mmol).

[0066] Comparative Example 2

[0067] The same as Example 1, except that bis(2-hydroxyethyl) disulfide is replaced by an equal millimole of 1,4-butanediol, and the added amount is 0.64 g (7.12 mmol).

[0068] Comparative Example 3

[0069] The same as Example 1, except that the polyetheramine is replaced by an equal amount of 1,4-butanediol, and the added amount is 1.28 g (14.24 mmol).

[0070] Effect verification example 1

[0071] The emulsion prepared above was tested for centrifugal stability (3000 r / min, 30 min), freeze-thaw stability (GB / T11175-2002), and emulsion particle size (laser particle size analyzer). The results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, the water-based photocurable multi-reversible room temperature self-healing elastomer resin emulsion prepared by each embodiment of the present invention has a small particle size, good freeze-thaw stability and centrifugal stability. Comparative Example 1 Since the added chain extender does not contain a -COOH group, there is no hydrophilic segment in the resin structure, resulting in failure to emulsify.

[0076] Effect verification example 2

[0077] The samples were tested according to GB / T1040-2006 "Determination of tensile properties of plastics", with a maximum tensile force of 2kN and a tensile rate of 15mm / min. Five specimens from different groups were measured repeatedly and the average value was taken. Self-repair test operation of mechanical properties.

[0078] Each group selected several splines with uniform texture, cut them in the middle with a knife, and made their cross sections contact without applying external force. They were kept at room temperature for 12h, 24h, and 36h, respectively. The repair efficiency was defined as the ratio of the elongation at break before and after repair by measuring the stress-strain curves at different repair times.

[0079] μ=σ1 / σ0 Formula 1

[0080] In formula 1:

[0081] μ: Repair efficiency (%)

[0082] σ1: Elongation at break of repaired sample (%)

[0083] σ0: Elongation at break of initial sample (%)

[0084] The test results are shown in Table 2.

[0085] Table 2

[0086]

[0087]

[0088] As can be seen from Table 2, the elastomers in the embodiments of the present invention can achieve self-repair at room temperature without heating. Among them, Example 2 has the highest elongation at break of 682%, suitable tensile strength and elastic modulus of 0.182MPa, 26.8kPa, and a repair efficiency of 100% at 36h. The diisocyanate structure in the polyurethane elastomer prepared in Examples 2, 5 and 7 is more flexible than the corresponding diisocyanate structure in other embodiments, the molecular chain moves more easily, and the broken bonds have a higher probability of collision and bonding, so the corresponding repair efficiency is better. The number and density of hydrogen bonds in the polyurethane elastomer prepared in Example 1 are large, and the hydrogen bonds in the hard segment structure will lock the reversible disulfide bonds, and the repair efficiency is low. In Example 3, the molecular weight of the polyetheramine increases, the proportion of disulfide bonds and hydrogen bonds will continue to decrease, and the self-repair efficiency will decrease again. In Comparative Example 2, bis(2-hydroxyethyl) disulfide is replaced with an equal millimolar amount of 1,4-butanediol. There is no disulfide bond in the resin structure, and the synergistic effect of reversible covalent bonds and reversible non-covalent bonds is lost. Repair is only carried out by the action of hydrogen bonds, resulting in a decrease in self-healing performance. In Comparative Example 3, polyetheramine is replaced with 1,4-butanediol, and urea groups are not introduced. The density and number of hydrogen bonds are reduced, and the hydrogen bonds at the fracture surface cannot contact more effectively to reorganize to form a denser physical network. In addition, the probability of reversible SS bond collision at the fracture surface is also reduced, resulting in a sharp decrease in self-healing performance.

[0089] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A water-based photocurable multi-reversible room temperature self-healing elastomer, characterized in that: The invention comprises the following raw materials: 2,2-dimethylolpropionic acid, a neutralizing agent, a diisocyanate, a catalyst, a polyetheramine, a disulfide, a polymerization inhibitor and a capping agent, wherein the molar ratio of the 2,2-dimethylolpropionic acid to the disulfide is 7-14:4-8; The neutralizing agent is dimethylethanolamine or triethylamine; The diisocyanate is lysine diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, trimethyl hexamethylene diisocyanate or 1,6-hexamethylene diisocyanate; The disulfide is bis(2-hydroxyethyl) disulfide or dihydroxydiphenyl disulfide; The catalyst is dibutyltin dilaurate; the polyetheramine is at least one of polyetheramine PEA400 and polyetheramine PEA2000; the inhibitor is p-hydroxyanisole; The end-capping agent is hydroxyethyl acrylate, hydroxypropyl acrylate or hydroxyethyl methacrylate; The method for preparing the water-based photocurable multi-reversible room temperature self-healing elastomer comprises the following steps: 7-14 mmol of 2,2-dimethylol propionic acid is added to 17-90 mmol of solvent, and 5-7 mmol of neutralizer is added at a temperature of 25-50° C. After the reactant becomes clear and transparent, the temperature is raised to 50-70° C., and then 0.028-0.049 mmol of catalyst and 28-56 mmol of diisocyanate are added in sequence to react for 2-4 hours; The product is cooled to 0-10°C, 10-16 mmol of polyetheramine is added to react for 1-2 hours, the temperature is raised to room temperature to react for 1-3 hours, the temperature is raised to 35-55°C, 4-8 mmol of disulfide and 0.019-0.034 mmol of catalyst are added, the temperature is kept constant for 2-4 hours, the temperature is raised to 55-75°C, 0.0975-0.83 mmol of polymerization inhibitor, 0.028-0.049 mmol of catalyst and 14-28 mmol of end-capping agent are added, the temperature is kept constant for 3-6 hours, the system is finally cooled to 40°C, 4-9 mmol of neutralizing agent is added to react while stirring for 0.5-1 hour, and the solvent is removed to obtain a water-based light-cured multi-reversible room temperature self-healing elastomer resin; The water-based light-curable multiple reversible room temperature self-healing elastomer resin is dispersed at a speed of 1000 r / min for 5 to 8 minutes, then the speed is increased to 3000 r / min, and deionized water is dripped into the mixture to adjust the solid content of the system to 50%, and the mixture is dispersed for 20 to 40 minutes to obtain a water-based light-curable multiple reversible room temperature self-healing elastomer emulsion; 4 to 5 mmol of photoinitiator is added to the water-based photocurable multiple reversible room temperature self-healing elastomer emulsion, stirred evenly and then applied on a substrate or placed in a mold to dry the moisture, and irradiated with ultraviolet light to obtain the water-based photocurable multiple reversible room temperature self-healing elastomer.

2. A method for preparing the water-based photocurable multi-reversible room temperature self-healing elastomer according to claim 1, characterized in that: The following steps are involved: 7-14 mmol of 2,2-dimethylol propionic acid is added to 17-90 mmol of solvent, and 5-7 mmol of neutralizer is added at a temperature of 25-50° C. After the reactant becomes clear and transparent, the temperature is raised to 50-70° C., and then 0.028-0.049 mmol of catalyst and 28-56 mmol of diisocyanate are added in sequence to react for 2-4 hours; The product is cooled to 0-10°C, 10-16 mmol of polyetheramine is added to react for 1-2 hours, the temperature is raised to room temperature to react for 1-3 hours, the temperature is raised to 35-55°C, 4-8 mmol of disulfide and 0.019-0.034 mmol of catalyst are added, the temperature is kept constant for 2-4 hours, the temperature is raised to 55-75°C, 0.0975-0.83 mmol of polymerization inhibitor, 0.028-0.049 mmol of catalyst and 14-28 mmol of end-capping agent are added, the temperature is kept constant for 3-6 hours, the system is finally cooled to 40°C, 4-9 mmol of neutralizing agent is added to react while stirring for 0.5-1 hour, and the solvent is removed to obtain a water-based light-cured multi-reversible room temperature self-healing elastomer resin; The water-based light-curable multiple reversible room temperature self-healing elastomer resin is dispersed at a speed of 1000 r / min for 5 to 8 minutes, then the speed is increased to 3000 r / min, and deionized water is dripped into the mixture to adjust the solid content of the system to 50%, and the mixture is dispersed for 20 to 40 minutes to obtain a water-based light-curable multiple reversible room temperature self-healing elastomer emulsion; 4 to 5 mmol of photoinitiator is added to the water-based photocurable multiple reversible room temperature self-healing elastomer emulsion, stirred evenly and then applied on a substrate or placed in a mold to dry the moisture, and irradiated with ultraviolet light to obtain the water-based photocurable multiple reversible room temperature self-healing elastomer.

3. Application of the water-based photocurable multi-reversible room temperature self-healing elastomer according to claim 1 in the preparation of wearable strain sensors.

Images