Self-repairing polyurethane microcapsule as well as preparation method and application thereof

Abstract

The invention relates to a self-repairing polyurethane microcapsule as well as a preparation method and application thereof, and relates to the technical field of new materials. The microcapsule is mainly prepared from the following raw materials in parts by weight: 10 to 50 parts of polyisocyanate, 40 to 60 parts of oligomer polyol, 50 to 70 parts of a surfactant, 10 to 40 parts of a core material, 1 to 10 parts of a disulfide compound and 30 to 50 parts of a solvent. The self-repairing polyurethane microcapsule can recover the shape before damage under a heating condition, so that a wound is closed autonomously, and self-adaptive repairing of the damage is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to a self-repairing polyurethane microcapsule and a preparation method and application thereof. Background Art

[0002] Microcapsules are tiny particles composed of a target object (core material) wrapped with natural or synthetic polymers (wall materials). The wall material separates the core material from the external medium (such as light, oxygen and water, etc.) to protect the original physical and chemical properties of the core material, improve the stability of the core material and extend the shelf life of the product. By adjusting the wall material, core material and preparation method, microcapsules with different structures and properties can be obtained to meet different application requirements. Since Green's pioneering research in 1955, microcapsules have received great attention and have been widely used in many fields such as food processing, textiles, biomedicine, agriculture, electronics and construction, such as for the preparation of phase change energy storage materials, self-healing materials and photosensitive materials. Polyurethane is one of the most widely used polymer materials. Due to the variety of raw materials, diverse synthesis processes and processing methods, and a wide range of adjustable structures and properties, polyurethane products are rich in types and have been successfully used to prepare various microcapsule materials.

[0003] However, polyurethane microcapsules will inevitably suffer varying degrees of physical or chemical damage during the application process, thus affecting the physicochemical properties of the core material. If polyurethane microcapsules are endowed with self-healing properties, this problem can be effectively solved. So far, there have been few reports on self-healing polyurethane microcapsules, which is mainly related to the shape and structure of the microcapsules. Microcapsules have different shapes, because the core material they are coated with is liquid and spherical in most cases. This sphere is a curved surface structure with radial load and a certain curvature. When damaged by external force, cracks appear in the outer shell of the microcapsule and the microcapsule is deformed due to the shearing effect of the external force. Unlike plane cracks, this deformation makes it impossible for the curved surface cracks to close, which poses a great challenge to the self-healing of the microcapsules themselves. Therefore, how to make the curved surface cracks of microcapsules close autonomously is a key issue for microcapsules to achieve self-healing properties. Summary of the invention

[0004] In view of the above problems, the present invention provides a self-repairing polyurethane microcapsule, which can restore its shape before damage under heating conditions, allowing the wound to close autonomously, which is beneficial to the adaptive repair of the injury.

[0005] In order to achieve the above object, the present invention provides a self-repairing polyurethane microcapsule, which is mainly prepared from the following raw materials in parts by weight:

[0006]

[0007] The shape memory property of a polymer refers to its ability to restore a predetermined shape under specific conditions. After the shape memory material is deformed under certain conditions, it can be restored to a pre-set initial shape under specific external stimuli (such as temperature, light, humidity, pH value or electric field, etc.). Based on this, the inventor proposes to prepare microcapsules with polyisocyanates and oligomer polyols as the main raw materials, and introduce soft and hard segment structures into the polyurethane molecular structure by using polyisocyanates as hard segments and oligomer polyols as soft segments, giving the microcapsules shape memory properties, so that it can achieve wound autonomous closure under certain conditions after being damaged, and then repair the damage at the wound by diffusion rearrangement of the polyurethane molecular chain and dynamic covalent bonds or non-covalent bonds. At the same time, dynamic disulfide bonds are introduced into the molecular structure by disulfide compounds, while giving the microcapsules self-repairing properties, as chain extenders, participating in the reaction, adjusting the aforementioned soft and hard segment structures, and then regulating its shape memory properties. The operator can also control the number and density of disulfide bonds and hydrogen bonds by regulating disulfide compounds to achieve controllable structure and performance.

[0008] In one embodiment, the oligomer polyol includes at least one of polycaprolactone diol, polycarbonate diol, polytetramethylene glycol, polyoxypropylene diol or polyoxypropylene triol.

[0009] In one embodiment, the polyisocyanate includes at least one of isophorone diisocyanate, 1,6-hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane-4,4′-diisocyanate, xylylene diisocyanate, methylcyclohexyl diisocyanate, tetramethylxylylene diisocyanate, HDI trimer, isophorone diisocyanate trimer, TDI trimer or MDI trimer.

[0010] The above-mentioned HDI trimer is also known as hexamethylene diisocyanate trimer, the TDI trimer is also known as toluene diisocyanate trimer, and the MDI trimer is also known as hexamethylene diisocyanate trimer.

[0011] In one embodiment, the surfactant includes at least one of sodium dodecyl sulfate, gum arabic, cetyltrimethylammonium bromide, sodium dodecylbenzene sulfonate or sodium alginate.

[0012] In one embodiment, the core material includes at least one of n-tetradecane, n-octadecane, n-heptadecane or eicosane.

[0013] In one embodiment, the disulfide comprises at least one of 2-hydroxyethyl disulfide, 4,4-dithiodiylbis(4,1-phenylene)dimethanol, dithioglycolic acid, 2,2-dithiodipropionic acid, and bis(4-hydroxyphenyl)disulfide.

[0014] In one embodiment, the solvent includes at least one of chloroform, ethyl acetate, dichlorobenzene, and chlorobenzene.

[0015] The present invention also provides a method for preparing the self-repairing polyurethane microcapsule, comprising the following steps:

[0016] Preparation of polyurethane prepolymer: heating oligomer polyol, dehydrating, cooling, adding polyisocyanate, and performing polymerization reaction to obtain polyurethane prepolymer;

[0017] Preparation of polyurethane microcapsules: Mix a surfactant and water, stir to obtain a surfactant solution, dissolve a polyurethane prepolymer and a core material in a solvent to obtain a mixed solution, mix the mixed solution and the surfactant solution, stir, add a disulfide compound, react, and obtain polyurethane microcapsules.

[0018] In one embodiment, the preparation of polyurethane microcapsules further includes filtering, washing and drying after the reaction step.

[0019] In one embodiment, in the step of preparing the polyurethane prepolymer, the oligomer polyol is heated to 100-130° C., dehydrated for 2-3 hours under a vacuum degree of ≥0.08 MPa, cooled to below 60° C., polyisocyanate is added, and polymerization is carried out at 70-95° C. for 2-5 hours to obtain the polyurethane prepolymer;

[0020] In the step of preparing polyurethane microcapsules, a surfactant and water are mixed and stirred for 0.5-3 hours to obtain a surfactant solution, a polyurethane prepolymer and a core material are dissolved in a solvent to obtain a mixed solution, the mixed solution and the surfactant solution are mixed and stirred for 0.5-2 hours, a disulfide compound is added, and the reaction is carried out for 10-24 hours to obtain polyurethane microcapsules.

[0021] The present invention also provides the use of self-repairing polyurethane microcapsules in phase-change energy storage materials, self-repairing materials and photosensitive materials.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention discloses a self-repairing polyurethane microcapsule and a preparation method and application thereof. After being damaged and deformed, the self-repairing polyurethane microcapsule can restore the curved surface shape of the raw material under heating conditions by relying on its shape memory property, so that the wound closes autonomously and adaptive repair is achieved. The raw materials involved in the preparation method are cheap and easy to obtain, the synthesis process does not require special conditions and equipment, the synthesis process is easy to control, and the raw materials involved are industrial products that have been produced in large quantities, the process is simple, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a scanning electron microscope image of the morphology of the self-healing polyurethane microcapsules in Example 1;

[0025] Figure 2 This is a scanning electron microscope image of the self-repairing polyurethane microcapsule after cutting in Example 1;

[0026] Figure 3 This is a scanning electron microscope image of the self-repairing polyurethane microcapsules in Example 1 that recover to their original shape after heating;

[0027] Figure 4 This is a scanning electron microscope image of the self-repairing of the self-repairing polyurethane microcapsules in Example 1. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] source:

[0031] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0032] Example 1

[0033] A self-repairing polyurethane microcapsule and a preparation method thereof.

[0034] 1. Preparation of self-healing polyurethane microcapsules.

[0035] (1) Preparation of polyurethane prepolymer.

[0036] 60 parts of polycaprolactone diol (oligomer polyol) were heated to 130°C, and after dehydration for 2 hours with a vacuum degree maintained above 0.08 MPa, the temperature was lowered to below 60°C; then, 10 parts of 1,6-hexamethylene diisocyanate (polyisocyanate) were added, and the reaction system was reacted at 95°C for 2 hours to obtain a polyurethane prepolymer.

[0037] (2) Preparation of polyurethane microcapsules.

[0038] 50 parts of gum arabic (surfactant) and 600 parts of deionized water were reacted under stirring at room temperature for 0.5 hour to obtain a surfactant solution. The above-mentioned polyurethane prepolymer and 10 parts of n-tetradecane (core material) were dissolved in 50 parts of chlorobenzene (solvent) to obtain a mixed solution. The mixed solution was added to the surfactant solution and stirred for 0.5 hour. Then 1 part of 2-hydroxyethyl disulfide (disulfide compound) was added and the reaction was continued for 24 hours. Finally, the mixture was filtered, washed repeatedly with deionized water twice, and air-dried at room temperature for 48 hours to obtain polyurethane microcapsules.

[0039] 2. Self-healing performance test of polyurethane microcapsules.

[0040] The polyurethane microcapsules prepared in Example 1 are as follows Figure 1 As shown, the shape is spherical. When the polyurethane microcapsules are cut open with a blade, it can be seen that the microcapsules are deformed by shear force ( Figure 2 The damaged microcapsules were placed in a 60°C oven and heated for 10 hours. The morphology of the microcapsules was observed using a scanning electron microscope. It was found that the deformed microcapsules had recovered their original curved shape ( Figure 3 ). Further extending the heating time to 24 hours, the damaged microcapsules were completely repaired ( Figure 4 ).

[0041] Example 2

[0042] A self-repairing polyurethane microcapsule and a preparation method thereof.

[0043] 1. Preparation of self-healing polyurethane microcapsules.

[0044] (1) Preparation of polyurethane prepolymer.

[0045] 40 parts of polycaprolactone diol (oligomer polyol) were heated to 100°C, and after dehydration for 3 hours with a vacuum degree maintained above 0.08 MPa, the temperature was lowered to below 60°C; then, 50 parts of 1,6-hexamethylene diisocyanate (polyisocyanate) were added, and the reaction system was reacted at 70°C for 5 hours to obtain a polyurethane prepolymer.

[0046] (2) Preparation of polyurethane microcapsules.

[0047] 70 parts of gum arabic (surfactant) and 600 parts of deionized water were reacted under stirring at room temperature for 3 hours to obtain a surfactant solution. The above-mentioned polyurethane prepolymer and 40 parts of n-tetradecane (core material) were dissolved in 30 parts of chlorobenzene (solvent) to obtain a mixed solution. The mixed solution was added to the surfactant solution and stirred for 2 hours. Then 10 parts of 2-hydroxyethyl disulfide (disulfide compound) were added and the reaction was continued for 10 hours. Finally, the mixture was filtered, washed repeatedly with deionized water for 5 times, and air-dried at room temperature for 24 hours to obtain polyurethane microcapsules.

[0048] 2. Self-healing performance test of polyurethane microcapsules.

[0049] The polyurethane microcapsules prepared in Example 2 were spherical. The polyurethane microcapsules were cut open with a blade, and the microcapsules were deformed. The damaged microcapsules were placed in a 60°C oven and heated for 10 hours, and the microcapsules restored their original curved shape. The heating time was further extended to 24 hours, and the damaged microcapsules were completely repaired.

[0050] Example 3

[0051] A self-repairing polyurethane microcapsule and a preparation method thereof.

[0052] 1. Preparation of self-healing polyurethane microcapsules.

[0053] (1) Preparation of polyurethane prepolymer.

[0054] 50 parts of polytetrahydrofuran diol (oligomer polyol) were heated to 120°C, and after dehydration for 3 hours with a vacuum degree maintained above 0.08 MPa, the temperature was lowered to below 60°C; then, 50 parts of isophorone diisocyanate (polyisocyanate) were added, and the reaction system was reacted at 85°C for 3 hours to obtain a polyurethane prepolymer.

[0055] (2) Preparation of polyurethane microcapsules.

[0056] 50 parts of sodium dodecyl sulfate (surfactant) and 600 parts of deionized water were reacted under stirring at room temperature for 2 hours to obtain a surfactant solution. The above-mentioned polyurethane prepolymer and 20 parts of n-eicosane (core material) were dissolved in 40 parts of ethyl acetate (solvent) to obtain a mixed solution. The mixed solution was added to the surfactant solution and stirred for 1 hour. Then 5 parts of 4,4-disulfadiylbis(4,1-phenylene)dimethanol (disulfide compound) were added and the reaction was continued for 12 hours. Finally, the mixture was filtered, washed repeatedly with deionized water 4 times, and air-dried at room temperature for 24 hours to obtain polyurethane microcapsules.

[0057] 2. Self-healing performance test of polyurethane microcapsules.

[0058] The polyurethane microcapsules obtained in Example 3 were spherical. The polyurethane microcapsules were cut open with a blade, and the microcapsules were deformed. The damaged microcapsules were placed in a 60°C oven and heated for 10 hours, and the microcapsules restored their original curved shape. The heating time was further extended to 24 hours, and the damaged microcapsules were completely repaired.

[0059] Example 4

[0060] A self-repairing polyurethane microcapsule and a preparation method thereof.

[0061] 1. Preparation of self-healing polyurethane microcapsules

[0062] (1) Preparation of polyurethane prepolymer.

[0063] 45 parts of polytetrahydrofuran diol (oligomer polyol) were heated to 120°C, and after dehydration for 3 hours with a vacuum degree maintained above 0.08 MPa, the temperature was lowered to below 60°C; then, 30 parts of diphenylmethane-4,4′-diisocyanate (polyisocyanate) were added, and the reaction system was reacted at 90°C for 3 hours to obtain a polyurethane prepolymer.

[0064] (2) Preparation of polyurethane microcapsules.

[0065] 60 parts of gum arabic (surfactant) and 600 parts of deionized water were reacted under stirring at room temperature for 1 hour to obtain a surfactant solution, the above-mentioned polyurethane prepolymer and 30 parts of n-tetradecane (core material) were dissolved in 50 parts of ethyl acetate (solvent) to obtain a mixed solution, the mixed solution was added to the surfactant solution and stirred for 1 hour, and then 6 parts of 4,4-disulfadiylbis(4,1-phenylene)dimethanol (disulfide compound) were added and the reaction was continued for 10 hours. Finally, the polyurethane microcapsules were obtained after filtering, repeated washing with deionized water for 3 times, and air-dried at room temperature for 24 hours.

[0066] 2. Self-healing performance test of polyurethane microcapsules.

[0067] The polyurethane microcapsules prepared in Example 4 were spherical. The polyurethane microcapsules were cut open with a blade, and the microcapsules were deformed. The damaged microcapsules were placed in a 60°C oven and heated for 10 hours, and the microcapsules restored their original curved shape. The heating time was further extended to 24 hours, and the damaged microcapsules were completely repaired.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A self-repairing polyurethane microcapsule, characterized in that: It is mainly prepared from the following raw materials in parts by weight:

2. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The oligomer polyol includes at least one of polycaprolactone diol, polycarbonate diol, polytetramethylene glycol, polyoxypropylene diol or polyoxypropylene triol.

3. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The polyisocyanate includes at least one of isophorone diisocyanate, 1,6-hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane-4,4′-diisocyanate, xylylene diisocyanate, methylcyclohexyl diisocyanate, tetramethylxylylene diisocyanate, HDI trimer, isophorone diisocyanate trimer, TDI trimer or MDI trimer.

4. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The surfactant includes at least one of sodium dodecyl sulfate, gum arabic, cetyltrimethylammonium bromide, sodium dodecylbenzene sulfonate or sodium alginate.

5. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The core material includes at least one of n-tetradecane, n-octadecane, n-heptadecane or eicosane.

6. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The disulfide includes at least one of 2-hydroxyethyl disulfide, 4,4-dithiodiylbis(4,1-phenylene)dimethanol, dithioglycolic acid, 2,2-dithiodipropionic acid, and bis(4-hydroxyphenyl)disulfide.

7. The self-repairing polyurethane microcapsule according to claim 1, characterized in that: The solvent includes at least one of chloroform, ethyl acetate, dichlorobenzene and chlorobenzene.

8. The method for preparing the self-repairing polyurethane microcapsules according to any one of claims 1 to 7, characterized in that: The following steps are involved: Preparation of polyurethane prepolymer: heating oligomer polyol, dehydrating, cooling, adding polyisocyanate, and carrying out polymerization reaction to obtain polyurethane prepolymer; Preparation of polyurethane microcapsules: Mix a surfactant and water, stir to obtain a surfactant solution, dissolve a polyurethane prepolymer and a core material in a solvent to obtain a mixed solution, mix the mixed solution and the surfactant solution, stir, add a disulfide compound, react, and obtain polyurethane microcapsules.

9. The preparation method according to claim 8, characterized in that: In the step of preparing the polyurethane prepolymer, the oligomer polyol is heated to 100-130° C., dehydrated for 2-3 hours under a vacuum degree of ≥0.08 MPa, cooled to below 60° C., polyisocyanate is added, and polymerization reaction is carried out at 70-95° C. for 2-5 hours to obtain the polyurethane prepolymer; In the step of preparing polyurethane microcapsules, a surfactant and water are mixed and stirred for 0.5-3 hours to obtain a surfactant solution, a polyurethane prepolymer and a core material are dissolved in a solvent to obtain a mixed solution, the mixed solution and the surfactant solution are mixed and stirred for 0.5-2 hours, a disulfide compound is added, and the reaction is carried out for 10-24 hours to obtain polyurethane microcapsules.

10. Use of the self-repairing polyurethane microcapsule according to any one of claims 1 to 7 in phase change energy storage materials, self-repairing materials and photosensitive materials.

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