A method for preparing a super-tough polyurethane cross-linked network

Abstract

The present invention belongs to the field of polymer preparation and relates to a method for preparing a super-tough polyurethane cross-linked network. The method comprises the following steps: using isophorone diisocyanate and polypropylene glycol as raw materials, adipic acid dihydrazide chain extension, and diazoalkyl cross-linking to obtain a self-repairing polyurethane micro-cross-linked network based on multiple hydrogen bonds. The method for preparing the self-repairing polyurethane cross-linked network of the present invention is novel, adipic acid dihydrazide provides multiple hydrogen bonds, and diazoalkyl urea is used as a cross-linking agent to prepare a polyurethane elastomer with an amorphous hard domain structure. The prepared elastomer has ultra-high toughness and efficient self-repairing ability. The raw materials used in the present invention are relatively low in cost and have broad market prospects. The steps are simple, the operation is convenient, and the practicability is strong.

Description

Technical Field

[0001] The present invention relates to the field of elastomer self-repair, and in particular to a method for preparing a super-tough polyurethane cross-linked network with multiple hydrogen bonds. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Self-healing materials are materials that can self-recover after damage. The advent of self-healing materials not only increases the durability of materials but also significantly impacts their lifespan. Polyurethane, an emerging organic polymer known as the "fifth plastic," is widely used in a variety of fields, including construction, automotive, and aviation, due to its excellent stability, chemical resistance, resilience, sound insulation, thermal insulation, seismic resistance, and wear resistance, among other properties. However, materials operating in harsh environments inevitably experience some damage. Reversible bonds are a type of dynamic bond that can be interchanged under certain environmental conditions. Due to their dynamic nature, bonds can break and reassemble. Introducing dynamic bonds into polyurethane elastomers not only profoundly impacts the mechanical properties of polyurethane, but also potentially imparts self-healing properties, significantly extending the lifespan of polyurethane elastomers. Polyurethane is a polymer prepared by capping and chain-extending isocyanate groups with polyols or polyamines. By rationally controlling the soft and hard domains and spatial structure of the material, the material can be endowed with superior performance and functionality, introducing multiple hydrogen bonds into the polyurethane elastomer.

[0004] For self-healing elastomers, it remains a challenge to simultaneously possess high toughness, fast rebound, and efficient self-healing. Summary of the Invention

[0005] In order to prepare an elastomer with high toughness, fast rebound and high self-repairing efficiency, the present invention provides a design and preparation method of a super-tough polyurethane cross-linked network based on multiple hydrogen bonds. By rationally regulating the number of hydrogen bonds and the spatial structure of the polymer, the material is given ultra-high toughness, rebound resilience and self-repairing properties. In order to prepare a self-repairing polyurethane elastomer with high comprehensive performance, this experiment specifically selected polypropylene glycol as the soft segment. This is because polypropylene glycol is not easy to crystallize and has excellent fluidity. The side chain methyl group increases the entanglement between the segments, which is beneficial to energy dissipation. At the same time, adipic acid dihydrazide is selected as the chain extender. The rich carbonyl structure and the formed urea structure can greatly enhance the energy dissipation, and finally diazolidinyl urea was selected as the cross-linking agent. The covalent network structure enhances the ability of the elastomer to resist external forces. The carbonyl structure of the side chain can form hydrogen bonds, giving the elastomer excellent resilience. The free hydroxyl groups form weak hydrogen bonds, which improves the self-repairing ability of the elastomer. By controlling the ratio of adipic acid dihydrazide and diazoalkyl, the number of hydrogen bonds and the spatial structure of the polymer are controlled. The combined effect of physical bonds and chemical bonds and the mutual entanglement of soft segments give the material super toughness, fast rebound and excellent self-repairing performance. The present invention prepares an elastomer with super toughness, fast rebound and high self-repairing efficiency by reasonably regulating multiple hydrogen bonds and network structures.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a method for preparing a super-tough polyurethane cross-linked network, comprising:

[0008] isocyanate, polypropylene glycol and a catalyst are uniformly mixed in a solvent and reacted to obtain a prepolymer;

[0009] Chain extending the prepolymer and adipic acid dihydrazide to obtain a polymer;

[0010] The polymer is cross-linked with diazolidinyl urea to obtain the product.

[0011] The present invention prepares a polyurethane elastomer with super toughness, fast rebound and high self-repair efficiency by rationally adjusting the spatial structure and the number of hydrogen bonds. Due to its cheap and readily available raw materials, it is expected to achieve industrial production.

[0012] The second aspect of the present invention provides a super-tough polyurethane cross-linked network prepared by the above method.

[0013] The third aspect of the present invention provides applications of the above-mentioned super-tough polyurethane cross-linked network in the fields of construction, automobiles, and aviation.

[0014] The beneficial effects of the present invention are:

[0015] (1) Compared with most current self-healing polyurethane elastomers, this invention has excellent mechanical properties of 24-40MPa and also has super toughness of 240-630MJ / m 3 and a self-healing efficiency of up to 102%.

[0016] (2) Compared with most current self-healing polyurethane elastomers, this invention has excellent resilience. When the material is cyclically stretched to 1000% and kept at 20°C for 3 hours, the dissipated energy can be almost completely recovered.

[0017] (3) Compared with most current self-healing polyurethane elastomers, this invention has better thermal stability.

[0018] (4) Compared with most current self-healing polyurethane elastomers, the raw materials involved in this invention are cheaper and easier to achieve industrial production.

[0019] (5) The preparation method of the present invention is simple, easy to operate and highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1 is the molecular formula of the polymer of the present invention.

[0022] Figure 2 This is a cyclic stretching diagram of Example 4 of the present invention.

[0023] Figure 3 This is the thermogravimetric diagram of Example 4 of the present invention.

[0024] Figure 4 3 is a stress-strain diagram of the material before and after self-repair in Example 4 of the present invention. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0026] Explanation of terms

[0027] As used herein, "DMAC" refers to: dimethylacetamide;

[0028] “PPG” means: polypropylene glycol;

[0029] "IPDI" means: isophorone diisocyanate;

[0030] "DBTDL" means: dibutyltin dilaurate.

[0031] The invention discloses a method for preparing a super-tough polyurethane cross-linked network with multiple hydrogen bonds. The method uses isophorone diisocyanate, polypropylene glycol, adipic acid dihydrazide and diazoalkyl as raw materials, and polymerizes the raw materials under the catalytic condition of dibutyltin dilaurate to form a polyurethane elastomer network.

[0032] Polyurethane network.

[0033] A method for preparing a super-tough polyurethane cross-linked network with multiple hydrogen bonds, using isophorone diisocyanate, polypropylene glycol, adipic acid dihydrazide, and diazoalkyl as raw materials, and performing a polymerization reaction in the presence of a catalyst to generate a polyurethane network, the molecular formula of which is:

[0034]

[0035] The composite material of the present invention has a tensile strength of 24.8-38.7 MPa and a toughness of 240-625 MJ / m 3 , the material can exhibit a self-healing efficiency of 102% at 100°C.

[0036] The present invention selects a polyether with a side chain methyl group as a soft segment, and the material is not easy to crystallize.

[0037] The polyether molecular weight used in the present invention is 400-2000 g / mol polypropylene glycol soft segment.

[0038] The isocyanate selected in the present invention is an asymmetric diisocyanate.

[0039] The diisocyanate selected in the present invention is isophorone diisocyanate, which is characterized by an asymmetric structure, and the flexible cyclic structure gives the soft segment better fluidity.

[0040] The chain extender selected in the present invention is an amine-terminated chain extender.

[0041] The chain extender selected in the present invention is amino-terminated adipic acid dihydrazide, which has abundant carbonyl structures, thereby forming more hydrogen bonding sites, thereby greatly promoting the high toughness of the material.

[0042] The cross-linking agent selected by the present invention is a tetrahydroxy monomer with broad-spectrum antibacterial properties.

[0043] The cross-linking agent used in the present invention is diazolidinyl urea, which provides a covalent cross-linking network and hydrogen bonding sites.

[0044] The present invention also provides a method for preparing an excellent super-tough polyurethane material, and the specific preparation method is as follows:

[0045] First, asymmetric alicyclic isophorone diisocyanate and a certain molar amount of polypropylene glycol are reacted in the presence of a catalyst (dibutyltin dilaurate) at a ratio of 1:0.4-0.8 to form a prepolymer, and then adipic acid dihydrazide (IPDI: adipic acid dihydrazide = 1:0.1-0.6) is added and reacted at 30-100°C for 2-15 hours to produce a prepolymer, and finally diazolidinyl urea (IPDI: diazolidinyl urea = 1:0.1-0.8) is added and reacted at 30-100°C for 1-10 hours. Finally, the synthesized polymer is placed in an 80°C oven to obtain an elastomer with a tensile strength of 24-40 MPa, an elongation at break of 2100-3800%, and a self-healing efficiency of 85%.

[0046] Note: The elastomer must be kept in a nitrogen atmosphere throughout the preparation process and mechanically stirred at 100-400 r / min.

[0047] The elastomer prepared according to the experimental method has high transparency, which is as high as 80% to 90%.

[0048] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0049] In the following examples, the following test methods were used:

[0050] The tensile test was carried out in accordance with the national standard GB / T1024.2-2006 at a test speed of 100 mm / min at room temperature.

[0051] The cyclic tensile test was conducted in accordance with GB / T1024.2-2006 at a test speed of 100 mm / min at room temperature.

[0052] Example 1

[0053] Using DMAC as solvent, PPG (4g), IPDI (1.77g), and DBTDL (0.02g) were added to a 100ml three-necked flask. The mixture was mechanically stirred for 2h at 80°C under N2 atmosphere to obtain a colorless viscous solution, which was a prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.34g) was dispersed in DMAC (10ml) solvent, and the adipic acid dihydrazide dispersed in DMAC (10ml) was slowly added to the container and mechanically stirred for 7h under nitrogen atmosphere. After the reaction was completed, diazolidinyl urea (0.3g) dissolved in (5ml) DMAC was slowly added to the container and further reacted for 5h. After the reaction was completed, it was placed in a three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent was then poured into a PTFE mold and dried at 80°C. The high-toughness polyurethane had a stress of 24.5MPa and a strain of 2173%.

[0054] Example 2

[0055] Using DMAC as solvent, PPG (4g), IPDI (1.77g), and DBTDL (0.02g) were added to a 100ml three-necked flask and mechanically stirred for 2h at 80°C under N2 atmosphere to obtain a colorless viscous solution, which is the prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.41g) was dispersed in DMAC (10ml) solvent, and the adipic acid dihydrazide dispersed in DMAC (10ml) was slowly added to the container and mechanically stirred for 7h under nitrogen atmosphere. After the reaction, diazolidinyl urea (0.25g) dissolved in DMAC (5ml) was slowly added to the container and further reacted for 5h. After the reaction, it was placed in the three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent was then poured into a PTFE mold and dried at 80°C. The high-toughness polyurethane has a strain of 28.4MPa and a strain of 2845%.

[0056] Example 3

[0057] Using DMAC as solvent, PPG (4g), IPDI (1.77g), and DBTDL (0.02g) were added to a 100ml three-necked flask and mechanically stirred at 80°C under a nitrogen atmosphere for 2h to obtain a colorless viscous solution, which is the prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.49g) was dispersed in DMAC (10ml) solvent. The adipic acid dihydrazide dispersed in DMAC (10ml) was slowly added to the container and mechanically stirred under a nitrogen atmosphere for 7h. After the reaction, diazolidinyl urea (0.17g) dissolved in DMAC (5ml) was slowly added to the container and further reacted for 5h. After the reaction, the solution was placed in the three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent was then poured into a PTFE mold and dried at 80°C. The high-toughness polyurethane has a strength of 33.8MPa and a strain of 3350.

[0058] Example 4

[0059] Using DMAC as solvent, add PPG (4g), IPDI (1.77g), DBTDL (0.02g) to a 100ml three-necked flask, and mechanically stir for 2h at 80℃ and N2 atmosphere to obtain a colorless viscous solution, which is a prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.56g) is dispersed in DMAC (10ml) solvent, and the adipic acid dihydrazide dispersed in 10ml solvent is slowly added to the container, and mechanically stirred for 7h under nitrogen atmosphere. After the reaction is completed, diazolidinyl urea (0.14g) dissolved in DMAC (5ml) is slowly added to the container for further reaction for 5h. After the reaction is completed, it is placed in a three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent is then poured into a PTFE mold and dried at 80℃. The high-toughness polyurethane has a strength of 38.8MPa and a strain of 3760%. The specific test results are as follows Figure 2 、 Figure 3 、 Figure 4 shown.

[0060] Example 5

[0061] Using DMAC as solvent, PPG (4g), IPDI (1.77g), and DBTDL (0.02g) were added to a 100ml three-necked flask and mechanically stirred for 2h at 80°C under N2 atmosphere to obtain a colorless viscous solution, which is the prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.63g) was dispersed in DMAC (10ml) solvent. The adipic acid dihydrazide dispersed in DMAC (10ml) was slowly added to the container and mechanically stirred for 7h under nitrogen atmosphere. After the reaction, diazolidinyl urea (0.08g) dissolved in DMAC (5ml) was slowly added to the container and further reacted for 5h. After the reaction, it was placed in the three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent was then poured into a PTFE mold and dried at 80°C. The high-toughness polyurethane has a strain of 35.4MPa and a strain of 3556%.

[0062] Comparative Example 1

[0063] Using DMAC as solvent, PPG (4g), IPDI (1.77g), and DBTDL (0.02g) were added to a 100ml three-necked flask. The mixture was mechanically stirred for 2h at 80°C under N2 atmosphere to obtain a colorless viscous solution, which was a prepolymer. After obtaining the prepolymer, adipic acid dihydrazide (0.56g) was dispersed in DMAC (25ml) solvent, and adipic acid dihydrazide dispersed in DMAC (10ml) solvent was slowly added to the container and mechanically stirred for 7h under nitrogen atmosphere. After the reaction, pentaerythritol (0.08g) dissolved in DMAC (5ml) was slowly added to the container and further reacted for 5h. After the reaction, the mixture was placed in the three-necked flask for 12h to obtain a viscous DMAC solution of self-healing polyurethane. The solvent was then poured into a PTFE mold and dried at 80°C. The high-toughness polyurethane had a strain of 21MPa and a strain of 2057%.

[0064] See Table 1 for detailed data

[0065]

[0066] The polyurethane elastomer prepared by the present invention has excellent tensile strength, elongation at break and self-repairing properties, and the required raw materials are inexpensive, so it is expected to be industrially produced.

[0067] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or to replace portions thereof with equivalents. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a super-tough polyurethane cross-linked network, characterized in that: include: isocyanate, polypropylene glycol and a catalyst are uniformly mixed in a solvent and reacted to obtain a prepolymer; reacting the prepolymer with adipic acid dihydrazide at 30-100° C. for 2-15 hours to obtain a polymer; The polymer is reacted with diazolidinyl urea at 30-100° C. for 1-10 hours to obtain the product; The molar ratio of the isocyanate, polypropylene glycol, adipic acid dihydrazide, and diazolidinyl urea is 1:0.4-0.8:0.1-0.6:0.1-0.8; The entire preparation process was carried out in an inert atmosphere with mechanical stirring at 100-400 r / min.

2. The method for preparing a super-tough polyurethane cross-linked network according to claim 1, wherein: The isocyanate is an asymmetric diisocyanate.

3. The method for preparing a super-tough polyurethane cross-linked network according to claim 2, wherein: The isocyanate is isophorone diisocyanate.

4. The method for preparing a super-tough polyurethane cross-linked network according to claim 1, wherein: The catalyst is dibutyltin dilaurate; Alternatively, the solvent is dimethylacetamide.

5. The method for preparing a super-tough polyurethane cross-linked network according to claim 1, wherein: The molar ratio of the isocyanate to the catalyst is 1:0.4-0.

8.

6. The ultra-tough polyurethane cross-linked network prepared by the method according to any one of claims 1 to 5.

7. Application of the super-tough polyurethane cross-linked network according to claim 6 in the fields of construction, automobile and aviation.

8. The use according to claim 7, characterized in that The ultra-tough polyurethane cross-linked network is used to manufacture corrosion-resistant coatings, ion batteries or electronic skin.

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