Preparation method for synthesizing supramolecular polymer with stretchable and room-temperature self-repairing functions from lipoic acid

Abstract

The invention discloses a room-temperature self-repairing supramolecular elastomer polymer (TA-GDA-Zr < 4 + >) synthesized by taking natural small molecular lipoic acid (TA) as a monomer. Wherein lipoic acid (TA) is a key monomer and can provide dynamic disulfide bonds and carboxyl hydrogen bonds through thermal ring-opening polymerization, however, auto-polymerizable poly (TA) is metastable at room temperature, we use a glyceryl dimethacrylate (GDA) cross-linking agent to strengthen the network by quenching two free radicals at the end of PTA. Besides, zirconium (IV) ions are introduced into the network, and metal coordination bonds are formed between the zirconium ions and carboxyl groups to replace some weak hydrogen bonds, so that the TA, the GDA and the zirconium (IV) ions jointly form a thermodynamically stable supramolecular poly (TA-GDA-Zr < 4 + >) copolymer network. Based on the design, the elongation at break of the supramolecular polymer network is 267.3% (70: 1), the self-repairing rate at room temperature reaches 96.26%, and the transmittance can reach 96%. Therefore, an ideal stretching and self-repairing synergistic effect is achieved. Meanwhile, the fatigue problem of the polymer is solved, and the use efficiency is greatly improved. The preparation method of the self-repairing polymer is very simple, and the application range of the self-repairing polymer in the fields of flexible sensors, adhesives, self-healing materials, wearable and biodegradable devices and the like can be widened.

Description

Technical Field

[0001] The present invention relates to technologies applicable to flexible sensors, adhesives, self-healing materials, wearable and biodegradable devices, and to a preparation method for assembling natural small molecules into supramolecular polymers with stretchable and room temperature self-healing functions. Background Art

[0002] Modern materials require increasingly complex properties and multiple functionalities, and at the same time, ideal materials should be prepared through simple and low-energy routes derived from readily available, preferably bio-based, available raw materials. For artificial soft polymer materials, a variety of properties including plasticity, stretchability, self-healing, adhesion, and recyclability have been developed and achieved. Even in a comprehensive manner. These enhanced requirements have led to an increase in structural complexity and synthetic difficulty, which also increases the cost. Therefore, it is a crucial challenge to prepare polymer materials with comprehensive complex properties from bio-based raw materials through extremely simplified routes. To overcome this problem, the development of supramolecular polymers through the self-assembly of functional small molecules is an attractive solution. However, elaborate precursor synthesis is usually required to introduce the desired supramolecular bonds, and in many cases, supramolecular networks usually exhibit fragile mechanical properties. At the same time, typical supramolecular polymers usually require additional solvents to support the dynamic nature and strength of non-covalent interactions, resulting in gel networks rather than dry networks. There are still some difficulties and challenges in the current polymer materials: 1. How to reduce the difficulty and cost of synthesis; 2. How to prepare multifunctional comprehensive polymer materials; 3. How to reduce pollution during the synthesis and preparation process; 4. How to overcome the problem of cyclic fatigue during use; 5. How to prepare multi-performance polymer materials from bio-based raw materials through simple methods. Summary of the invention

[0003] In view of the shortcomings of existing preparations of polymer materials, the present invention designs and prepares a method for assembling natural small molecules into supramolecular polymers with stretchable and room-temperature self-healing functions, which can be applied to the fields of flexible sensors, adhesives, self-healing materials, wearable and biodegradable devices.

[0004] The preparation method thereof comprises the following steps: (1) Take natural small molecule (TA) as monomer, weigh 3g TA and add it into a glass bottle, add a magnet, place it in an oil bath at 150℃, and stir for 10-15min until the solid TA is completely melted into a yellow liquid with a certain viscosity; (2) Using glycerol dimethacrylate (GDA) as a crosslinking agent, weigh 20% of the total mass of GDA, add it to the molten TA, and continue stirring; (3) Using zirconium (IV) ions to provide metal coordination bonds, prepare a zirconium ion solution (200 mg / ml) dispersed in ethanol and select the optimal ratio of TA:Zr 4+ = (70:1), measure a certain amount of zirconium ion ethanol solution, add it to the molten TA, and continue stirring; (4) pouring the prepared solution into a polytetrafluoroethylene mold, allowing it to cool to room temperature, taking out the polymer strip, and conducting a mechanical property test; (5) Dye is added to the molten solution for dyeing, and then the solution is cut and spliced, and placed at room temperature for a certain period of time to observe and test its self-healing properties.

[0005] The advantages of the features of the present invention are: (1) Combined with TA ring opening to provide hydrogen bonds and disulfide bonds, the Michael addition reaction with GDA is completed, the carbon-carbon double bond disappears, the hydroxyl group disappears, and the disulfide bond splits. Poly (TA-GDA-Zr 4+ ) and the FTIR spectra of Poly(TA-GDA-Zr 4+ )’s Raman spectrum ( Figure 1 ).

[0006] (2) Select GDA content fixed at 20%, molar ratio TA:Zr 4+ =70:1 / 150:1 / 300:1 / 600:1 and the tensile properties of the polymer film without zirconium ions in the initial state and after 5 hours of self-repair at room temperature, the elongation at break of the best ratio is 267.30%, and the repair rate can reach 96.26%. ( Figure 2 ).

[0007] (3) Select GDA content fixed at 20%, molar ratio TA:Zr 4+ =70:1 / 150:1 / 300:1 / 600:1 and the shear performance of the polymer membrane without zirconium ions. The maximum shear strain of the optimal ratio is 1.15rad. As the zirconium ion content increases, the cross-linking points increase, the movement of the molecular chain segments is hindered, the molecular chain cannot slip, and brittle fracture is more likely to occur ( Figure 3 ).

[0008] (4) Use a blade to scratch the polymer film with the optimal ratio, then perform self-repair at room temperature, and use a microscope to observe the repair status of the scratch from 0h to 5h; dye the polymer, then cut and splice the polymer, repair it at room temperature for 5h, and then stretch it ( Figure 4 ).

[0009] (5) Optimal ratio of TA:Zr 4+ = (70:1) polymer transmittance diagram, the transmittance can reach 96% ( Figure 5 ). BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 .Poly(TA-GDA-Zr 4+ ) FTIR spectrum and Poly (TA-GDA-Zr 4+ )Raman spectrum; Figure 2 .Poly(TA-GDA-Zr 4+ )Tensile performance spectra before and after repair with different ratios; Figure 3 .Poly(TA-GDA-Zr 4+ )Shear performance diagram of different ratios; Figure 4 .Poly (TA-GDA-Zr under microscope 4+ ) scratch repair photos and dyed Poly (TA-GDA-Zr 4+ ) Self-healing performance photos; Figure 5 .Poly(TA-GDA-Zr 4+ )’s transmittance diagram. DETAILED DESCRIPTION Example

[0012] (1) Take natural small molecule (TA) as monomer, weigh 3g TA and add it into a glass bottle, add a magnet, place it in an oil bath at 150℃, and stir for 10-15min until the solid TA is completely melted into a yellow liquid with a certain viscosity; (2) Select a GDA ratio (0%-25%) and add it to TA, stir evenly, then pour it into a culture dish, cool it to room temperature, and observe the TA solution phenomenon; (3) When the optimal GDA content was 20%, TA did not depolymerize, and the TA and GDA contents were fixed, the effect of zirconium ion content on the polymer membrane was analyzed. Example

[0013] (1) Take natural small molecule (TA) as monomer, weigh 3g TA and add it into a glass bottle, add a magnet, place it in an oil bath at 150℃, and stir for 10-15min until the solid TA is completely melted into a yellow liquid with a certain viscosity.

[0014] (2) Using glycerol dimethacrylate (GDA) as a cross-linking agent, add 20% of GDA and stir for further 1-2 minutes.

[0015] (3) Using zirconium (IV) ions to provide metal coordination bonds, a zirconium ion solution (200 mg / ml) dispersed in ethanol was prepared to prepare a molar ratio of TA:Zr 4+ =70:1 / 150:1 / 300:1 / 600:1 polymer membrane, add the corresponding zirconium ion ethanol solution into TA, and stir for 1-2 minutes.

[0016] (4) Pour the prepared polymer solution into a polytetrafluoroethylene mold, cool it to room temperature, and test its mechanical properties.

[0017] (5) Polymer films with different proportions were cut and spliced, repaired at room temperature for 5 h, and then the mechanical properties after self-repair were tested.

[0018] (6) Select a polymer with the best ratio of TA:Zr4+ = (70:1), perform scratch treatment, and then perform self-repair at room temperature. Use a microscope to observe its repair status at 0h-5h.

[0019] (7) Select a polymer with the best ratio of TA:Zr4+ = (70:1), dye it with rhodamine, cut it open and splice it, repair it at room temperature for 5 hours, and then perform a tensile test.

[0020] (8) Select a polymer with the best ratio of TA:Zr4+ = (70:1) and use Shimadzu UV to test its transmittance, with glass as the baseline.

Claims

1. A method for preparing a supramolecular polymer with stretchable and room temperature self-healing functions by assembling natural small molecules, wherein the natural small molecule (TA) is a monomer, glycerol dimethacrylate (GDA) is a crosslinker, and zirconium (IV) ions provide metal coordination bonds. The room temperature test shows that it has excellent mechanical properties and self-healing properties. The preparation method comprises the following steps: (1) At a high temperature of 150°C, TA undergoes a thermal ring-opening reaction to form a primary linear main chain with disulfide bonds, which appears as a yellow liquid with a certain viscosity; (2) Use glycerol dimethacrylate (GDA) as a cross-linking agent, add it to the molten TA and continue stirring.

2. (3) Use zirconium (IV) ions to provide metal coordination bonds. Take a small amount of ethanol solution containing zirconium (IV) ions and add it to the molten TA and GDA, and continue stirring.

3. (4) Pour the evenly stirred solution into a polytetrafluoroethylene mold and allow to cool to room temperature.

4. The supramolecular polymer (TA-GDA-Zr) having stretchable and room temperature self-repairing function according to claim 1 4+ ), the best molar ratio of TA:Zr 4+ = (70:1), characterized in that, The Young's modulus is 0.13Mpa and the elongation at break is 267.3%, which shows excellent mechanical properties.

5. The supramolecular polymer (TA-GDA-Zr4+) with stretchable and room temperature self-healing function according to claim 1, the optimal ratio of TA:Zr 4+ = (70:1), characterized in that, The shear modulus is 0.76Mpa and the maximum shear strain is 1.15rad. As the number of cross-linking points increases, molecular motion is hindered and brittle fracture is more likely to occur.

6. The supramolecular polymer (TA-GDA-Zr4+) with stretchable and room temperature self-healing function according to claim 1, the optimal ratio of TA:Zr 4+ = (70:1), characterized in that, Its self-repair rate at room temperature can reach 96.26%, which has good self-repair effect.

7. The supramolecular polymer (TA-GDA-Zr4+) with stretchable and room temperature self-healing function according to claim 1, wherein the optimal ratio of TA:Zr 4+ = (70:1), characterized in that, Its transmittance is as high as 96%, which is excellent.

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