Electrically conductive self-healing poly(urethane-amide) and methods of making and using the same

Abstract

The application belongs to the field of high polymer materials, and particularly relates to a conductive self-repairing poly (urethane-amide) and a preparation method and application thereof. Under the protection of inert gas, macromolecular dihydric alcohol, diisocyanate, polyamide and / or block polyester amide, and chain extender are subjected to polymerization reaction in the presence of a catalyst, and the obtained poly (urethane-amide) is mixed with an ionic liquid to obtain the conductive self-repairing poly (urethane-amide). The conductive self-repairing poly (urethane-amide) provided by the application not only has adjustable mechanical properties, but also has self-repairing capability and good conductivity due to the multi-level hydrogen bonds between the ionic liquid and the polyamide molecular chain, and has self-repairing performance at 80 DEG C, and has application potential in the fields of biomedicine, intelligent sensing and electronic skin.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a conductive self-healing poly(urethane-amide) and its preparation method and application. Background Technology

[0002] Self-healing materials are intelligent materials that can spontaneously repair damage or repair damage under certain stimuli after being injured. In recent years, the design and development of self-healing materials has gradually become a research hotspot in the field of materials science, and it is expected to solve the problem of microcracks. There are many types of self-healing materials, including polyurethane, supramolecular polymers, and elastomers. Among them, polyurethane can synthesize unique soft and hard segments through the addition reaction between diols and diisocyanates. Its structure and properties can be achieved by adjusting the combination of macromolecular diols, diisocyanates, and chain extenders. In recent years, flexible sensors based on polyurethane have been gradually applied in fields such as electronic skin, supercapacitors, smart wearables, and biomedical devices.

[0003] The self-healing ability of polyurethane materials mainly originates from reversible disulfide bonds, hydrogen bonds, coordination bonds, and electrostatic interactions. However, while these weak interactions facilitate self-healing, they hinder the improvement of the material's mechanical properties; increased self-healing efficiency is often accompanied by a decrease in mechanical properties. To address these shortcomings, common modification strategies involve chemical and physical modifications. These strategies utilize microphase separation, synergistic effects of strong and weak interactions, and the introduction of nanofillers to design molecular chain chemical and condensed-state structures, thereby achieving a harmonious balance between excellent mechanical properties and efficient self-healing capabilities. For example, CN108503782A discloses a fully transparent, high-strength self-healing polyurethane elastomer. It uses polytetrahydrofuran as the soft segment and hydrogenated 4,4'-methylenediphenyl diisocyanate (HMDI) and 2,2'-dithiodiethanol (HEDS) as the hard segments. By controlling microphase separation, dynamic disulfide bonds are locked in the hard phase, resulting in a tensile strength as high as 25 MPa. When the temperature rises to 70°C, the disulfide bonds are activated, thus exhibiting self-healing capabilities. CN107325256A discloses a self-healing polymer material in which ureidopyrimidinone (UPy) is introduced into polyurethane. The material's self-healing ability is imparted by multiple hydrogen bonds in the urethane and ureidopyrimidinone units, resulting in a tensile strength as high as 40 MPa. However, none of these materials possess electrical conductivity.

[0004] Furthermore, while ionic liquids can provide a source of self-healing properties and possess excellent conductivity and thermal stability, they may exhibit problems such as easy migration, poor stability, poor miscibility with the matrix, and low conductivity when combined with a matrix. In summary, existing self-healing materials struggle to simultaneously achieve good self-healing performance, mechanical properties, and conductivity. Summary of the Invention

[0005] One objective of this invention is to provide a method for preparing a conductive self-healing poly(urethane-amide) that possesses excellent self-healing properties, mechanical properties, and electrical conductivity, specifically comprising the following steps:

[0006] S1. Under the protection of an inert gas, macromolecular diols, diisocyanates, polyamides and / or block polyesteramides, and chain extenders are polymerized in the presence of a catalyst to obtain poly(urethane-amide).

[0007] S2. The obtained poly(urethane-amide) is mixed with an ionic liquid to obtain conductive self-healing poly(urethane-amide).

[0008] The second objective of this invention is to provide a conductive self-healing poly(urethane-amide) prepared by the above method.

[0009] The third objective of this invention is to provide the application of the above-mentioned conductive self-healing (urethane-amide) in biomedicine, smart sensing and electronic skin.

[0010] The key to this invention lies in introducing polyamides and / or block polyesteramides into the traditional polyurethane molecular chain, thereby enabling the regulation of microphase separation and crystallization behavior of poly(urethane-amide), resulting in poly(urethane-amide) with good and adjustable mechanical properties. Furthermore, the introduction of polyamide segments increases the affinity between the poly(urethane-amide) matrix and ionic liquids, solving problems such as easy migration, poor stability, poor miscibility with the matrix, and low conductivity that may occur when ionic liquids are composited with the matrix. Simultaneously, the presence of multi-level hydrogen bonds between poly(urethane-amide) and ionic liquids, including hydrogen bonds between urethane units, polyamide segments, and amide-ionic liquid cations, provides a source of self-healing and imparts electrical conductivity to the material.

[0011] The conductive self-healing poly(urethane-amide) provided by this invention possesses excellent self-healing properties, mechanical properties, and electrical conductivity. Its tensile strength can reach 36.7 MPa, its elongation at break can reach 1292.5%, and its electrical conductivity can reach 3.3 × 10⁻⁶ MPa. -5 The self-healing efficiency can reach 91% at 80℃ (S / cm). Attached Figure Description

[0012] Figure 1 The chemical structure diagram of poly(urethane-amide) and 1 ¹H NMR spectra, where a is the chemical structure diagram, and b is the ¹H NMR spectrum of poly(urethane-amide) and PA6 prepared in Examples 1 and 4. 1 H NMR spectrum.

[0013] Figure 2GPC curves for poly(urethane-amide) prepared in Comparative Example 1 (curve a), Example 1 (curve b), and Example 4 (curve c).

[0014] Figure 3 The stress-strain curves are for the poly(urethane-amide) prepared in Examples 1-4 and the PCL-based polyurethane prepared in Comparative Example 1.

[0015] Figure 4 The infrared spectra of Examples 1 (curve a), 6 (curve b), 10 (curve c), and 11 (curve d) are shown.

[0016] Figure 5 The POM morphology of Examples 1, 6, 10 and 11 before and after self-healing at 80°C is shown.

[0017] Figure 6 The stress-strain curves of the conductive self-healing poly(urethane-amide) prepared in Example 6 before self-healing (curve a) and after self-healing at 80°C for 4 hours (curve b) are shown. Detailed Implementation

[0018] The method for preparing conductive self-healing poly(urethane-amide) provided by the present invention includes the following steps:

[0019] S1. Under the protection of an inert gas, macromolecular diols, diisocyanates, polyamides and / or block polyesteramides, and chain extenders are polymerized in the presence of a catalyst to obtain poly(urethane-amide).

[0020] S2. The obtained poly(urethane-amide) is mixed with an ionic liquid to obtain conductive self-healing poly(urethane-amide).

[0021] In this invention, step S1, the polymerization reaction can be carried out by first mixing macromolecular diol, diisocyanate, polyamide and / or block polyesteramide, and catalyst in any order for uniform polymerization, followed by prepolymerization, and then reacting the resulting prepolymer with a chain extender for chain extension. In one specific embodiment, the polymerization reaction is carried out by heating and dissolving macromolecular diol and polyamide and / or block polyesteramide in a solvent, adding diisocyanate and catalyst for prepolymerization, and then reacting the isocyanate-terminated prepolymer with a chain extender to obtain poly(urethane-amide).

[0022] In this invention, based on the total weight of the conductive self-healing poly(urethane-amide), the content of the poly(urethane-amide) is preferably 25-99 wt%, more preferably 50-95 wt%, such as 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 78 wt%, 80 wt%, 82 wt%, 85 wt%, 88 wt%, 90 wt%, 92 wt%, 95 wt%, or any value between them. The content of the ionic liquid is preferably 1-75 wt%, more preferably 5-25 wt%, such as 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, or any value between them.

[0023] In this invention, the molar ratio of the macromolecular diol, diisocyanate, and chain extender is preferably 1:(2.0-2.8):(0.5-2), more preferably 1:(2.2-2.4):(0.5-1.5). Based on 1 mol of the macromolecular diol, the amount of the diisocyanate is 2.0-2.8 mol, such as 2.0 mol, 2.1 mol, 2.2 mol, 2.3 mol, 2.4 mol, 2.5 mol, 2.6 mol, 2.7 mol, 2.8 mol, or any value between them; the amount of the chain extender is 0.5-2 mol, such as 0.5 mol, 0.8 mol, 1.0 mol, 1.2 mol, 1.5 mol, 1.8 mol, 2.0 mol, or any value between them.

[0024] In this invention, the total amount of the polyamide and block polyesteramide is such that the content of the polyamide segment in the poly(urethane-amide) is preferably 5 to 99 wt%, such as 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 78 wt%, 80 wt%, 82 wt%, 85 wt%, 88 wt%, 90 wt%, 92 wt%, 95 wt%, 99 wt%, or any value between them.

[0025] In this invention, the amount of catalyst used is preferably 0.001 to 20 mol% of the total molar amount of hydroxyl groups in the macromolecular diol and block polyesteramide, more preferably 0.05 to 1 mol%, such as 0.05 mol%, 0.1 mol%, 0.2 mol%, 0.5 mol%, 0.8 mol%, 1 mol%, or any value between them.

[0026] In this invention, by controlling the molecular weight of the polyamide segment and the composition of the two blocks in the block polyesteramide, the microphase separation and crystallization behavior of the poly(urethane-amide) can be regulated, so that the prepared poly(urethane-amide) has good and adjustable mechanical properties. The preferred mass ratio of the polyester segment to the polyamide segment in the block polyesteramide is (0.01–20):1, more preferably (0.01–10):1, such as 0.01:1, 0.1:1, 0.3:1, 0.5:1, 0.7:1, 0.9:1, 1:1, 2:1, 5:1, 7:1, 9:1, 10:1, or any value between them. The number-average molecular weight of the polyamide is preferably 100–30,000 g / mol, more preferably 200–10,000 g / mol, such as 200 g / mol, 500 g / mol, 700 g / mol, 800 g / mol, 1000 g / mol, 1500 g / mol, 1700 g / mol, 2000 g / mol, 2500 g / mol, 2700 g / mol, 3000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, or any value between them. The number-average molecular weight of the polyamide segment in the block polyesteramide is preferably 100–30000 g / mol, more preferably 200–10000 g / mol, such as 200 g / mol, 500 g / mol, 700 g / mol, 800 g / mol, 1000 g / mol, 1500 g / mol, 1700 g / mol, 2000 g / mol, 2500 g / mol, 2700 g / mol, 3000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, or any value between them.

[0027] In this invention, specific examples of the macromolecular diol include, but are not limited to, at least one of: polycaprolactone diol, polylactide diol, polyglycolic acid diol, polyethylene glycol diol, polytetrahydrofuran diol, polypropylene oxide diol, and polydimethylsiloxane diol. The number-average molecular weight of the macromolecular diol is preferably 500–20000 g / mol, more preferably 1000–10000 g / mol, such as 1000 g / mol, 2000 g / mol, 3000 g / mol, 5000 g / mol, 8000 g / mol, 10000 g / mol, or any value between them.

[0028] In this invention, specific examples of the diisocyanate include, but are not limited to, at least one of isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-methylene diphenyl diisocyanate, and hexamethylene diisocyanate.

[0029] In this invention, the chain extender is preferably C3-C4. 12 The diol, preferably a dithiodiol.

[0030] In this invention, specific examples of the catalyst include, but are not limited to, at least one of organometallic compounds, inorganic acids, and nucleophilic catalysts.

[0031] In this invention, the ionic liquid and poly(urethane-amide) have multi-level hydrogen bonds, providing a source of self-healing and imparting electrical conductivity to the material. Specific examples of the ionic liquid include, but are not limited to: 1-allyl-3-methylimidazolium chloride, 1-allyl-3-vinylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium chloride, 1-butylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-hydroxyethyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-vinyl-3-butylimidazolium chloride, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium bromide. At least one of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine salt, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate, 1-allyl-3-methylimidazolium acetate and 1-propyl-3-methylimidazolium acetate, preferably selected from at least one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-vinyl-3-butylimidazolium chloride, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine salt and 1-hexyl-3-methylimidazolium trifluoromethanesulfonate.

[0032] In this invention, the heating temperature in step S1 is preferably 50–200°C, such as 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, or any value between them; the heating time is preferably 1–30 min, such as 1 min, 3 min, 5 min, 8 min, 10 min, 15 min, 20 min, 25 min, 30 min, or any value between them; the prepolymerization temperature is preferably 50–200°C, such as 50°C, 80°C, 100°C, 110°C, 150°C, 180°C, or any value between them; the prepolymerization time is preferably 2–10 h, such as 2 h, 3 h, 5 h, 8 h, 10 h, or any value between them; the chain extension reaction temperature is preferably 60–120°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any value between them.

[0033] The present invention will be described in detail below through specific embodiments.

[0034] The raw materials involved in the following examples and comparative examples are as follows:

[0035] Polycaprolactone diol (PCL) was purchased from Heinz Company, grade P-69025+500g; diethylene glycol dithiocarbamate was purchased from Alfa Aesar Company, grade L11800.30; 1-allyl-3-methylimidazolium chloride was purchased from Lanzhou Institute of Chemical Physics, purity >99%; 1-butyl-3-methylimidazolium chloride was purchased from Lanzhou Institute of Chemical Physics, purity >99%; 1-hexyl-3-methyltetrafluoromethanesulfonate imidazolium was purchased from Lanzhou Institute of Chemical Physics, purity >99%.

[0036] Preparation example: Preparation of PA6 (di-terminated amino group)

[0037] Weigh 20g of caprolactam monomer, 2.4g of aminocaproic acid, and 5g of hexamethylenediamine, and add them to a three-necked flask under nitrogen protection. Vacuum the flask at room temperature for 30 minutes, and then place it in an oil bath at 180℃ under nitrogen protection for 6 hours. After the reaction is complete, cool the flask and grind the resulting polymer into powder.

[0038] The obtained polymer powder was washed with boiling water for 3.5 h, centrifuged, and then freeze-dried. The number-average molecular weight was calculated to be 800 g / mol by NMR, and it was denoted as PA6. 0.8k .

[0039] The obtained polymer powder was dissolved in hexafluoroisopropanol, precipitated in methanol, dried, and then dried in a vacuum oven at 80°C. The number-average molecular weight was calculated to be approximately 1700 g / mol using NMR spectroscopy, and it was designated as PA6. 1.7k .

[0040] Example 1: Based on PA6 0.8k / PCL preparation of poly(urethane-amide)

[0041] Weigh out 0.2g of PA6. 0.8k and 1.8g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80°C for 2 h. Then, under nitrogen protection, 14 mL of ultra-dry dimethyl sulfoxide was added and dissolved at 80°C for 5 min. After the solution became clear and transparent, 0.41 g of hexamethylene diisocyanate and 0.016 g of stannous octoate were added to a reaction tube under nitrogen protection, and the reaction was carried out at 80°C for 3 h. 0.159 g of diethylene glycol dithiocarbamate was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, added to a reaction flask under nitrogen protection, and reacted at 80°C for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40°C for 24 h before use, designated as PUA-1.

[0042] The obtained sample was dissolved in deuterated trifluoroacetic acid and analyzed by 1H NMR (1H NMR spectroscopy). 1 Structural analysis was performed using H NMR. Figure 1 Furthermore, the molecular weight and distribution of polymers were characterized by gel permeation chromatography. Figure 2 ).from Figure 1 It can be seen that the hydrogen chemical shifts at 3.61 and 2.78 ppm (j and f) belong to ε and α-H on the repeating unit of PA6, respectively, and the characteristic peaks at 4.28 and 2.54 ppm (e and a) are attributed to ε and α-H on the PCL molecular chain. The characteristic peaks of poly(urethane-amide) containing caprolactam and caprolactone repeating units indicate the successful introduction of PA6 into polyurethane. Figure 2 It can be seen that the molecular weight and distribution of poly(urethane-amide) synthesized based on different block polyesteramides are consistent, ranging from 10,000 to 20,000. The obtained samples were melt-pressed into dumbbell-shaped strips measuring 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness) at a melting temperature of 220℃ and a pressure of 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. PUA-1 showed a tensile strength of 20.6 MPa, a Young's modulus of 19.6 MPa, and an elongation at break of 973.5%. The results are shown in Table 1 and [Table data missing]. Figure 3 .

[0043] Example 2: Based on PA6 0.8k Preparation of poly(urethane-amide) using PCL-1:0.3 / PCL

[0044] PA6 0.8kBefore use, the product was dried in a vacuum oven at 80°C for 2 hours. 1.5 g was added to a reaction tube under nitrogen protection, and the reaction tube was pre-evacuated three times. The reaction tube was then evacuated at 80°C for 30 minutes, and 15 mL of N,N-dimethylformamide was added under nitrogen protection. Subsequently, 1.5 g of caprolactone (CLO) and 0.45 g of stannous octoate were added to the reaction tube, and the mixture was placed in an oil bath at 140°C for 24 hours. The product was dissolved in hexafluoroisopropanol, precipitated in methanol, and dried in a vacuum oven at 40°C for 24 hours to obtain triblock polyesteramide PA6. 0.8k -PCL-1:0.3 (NMR analysis, PA6) 0.8k The mass ratio of PCL to PCL is 1:0.3.

[0045] Weigh out 0.13g of PA6. 0.8k -PCL-1: 0.3 and 1.87 g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80°C for 2 h. Then, under nitrogen protection, 14 mL of ultra-dry dimethyl sulfoxide was added and dissolved at 80°C for 5 min. After the solution became clear and transparent, 0.43 g of hexamethylene diisocyanate and 0.016 g of stannous octoate were added to a reaction tube under nitrogen protection, and the reaction was carried out at 80°C for 3 h. 0.164 g of diethylene glycol dithiocarbamate was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, and added to a reaction flask under nitrogen protection, and reacted at 80°C for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40°C for 24 h before use, designated as PUA-2.

[0046] The obtained samples were melt-pressed to prepare dumbbell-shaped specimens with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. The tensile strength of PUA-2 was 20.0 MPa, the Young's modulus was 38.2 MPa, and the elongation at break was 1151.1%. The results are shown in Table 1 and [Table data missing]. Figure 3 .

[0047] Example 3: Based on PA6 0.8k -PCL-1:2 / PCL for the preparation of poly(urethane-amide)

[0048] PA6 0.8kBefore use, the product was dried in a vacuum oven at 80°C for 2 hours. 1 g was added to a reaction tube under nitrogen protection, and the tube was pre-evacuated three times. The reaction tube was then evacuated at 80°C for 30 minutes, and 10 mL of N,N-dimethylformamide was added under nitrogen protection. Subsequently, 2 g of CLO and 0.45 g of stannous octoate were added to the reaction tube, and the tube was placed in an oil bath at 140°C for 24 hours. The product was dissolved in hexafluoroisopropanol, precipitated in methanol, and dried in a vacuum oven at 40°C for 24 hours to obtain triblock polyesteramide PA6. 0.8k -PCL-1:2 (NMR analysis, PA6) 0.8k The mass ratio of PCL to PCL is 1:2.

[0049] Weigh out 0.3g of PA6. 0.8k -PCL-1:2 and 1.7g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80°C for 2 h. Then, under nitrogen protection, 14 mL of ultra-dry dimethyl sulfoxide was added and dissolved at 80°C for 5 min. After the solution became clear and transparent, 0.392 g of hexamethylene diisocyanate and 0.016 g of stannous octoate were added to a reaction tube under nitrogen protection, and reacted at 80°C for 3 h. 0.143 g of diethylene glycol dithiocarbamate was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, added to a reaction flask under nitrogen protection, and reacted at 80°C for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40°C for 24 h before use, designated as PUA-3.

[0050] The obtained samples were melt-pressed to prepare dumbbell-shaped specimens with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. The tensile strength of PUA-3 was 32.3 MPa, the Young's modulus was 33.3 MPa, and the elongation at break was 944.9%. The results are shown in Table 1 and [Table data missing]. Figure 3 .

[0051] Example 4: Based on PA6 0.8k -PCL-1:7 / PCL for the preparation of poly(urethane-amide)

[0052] PA6 0.8kBefore use, the product was dried in a vacuum oven at 80°C for 2 hours. 1 g was added to the reaction tube under nitrogen protection, and the tube was pre-evacuated three times. The reaction tube was then evacuated at 80°C for 30 minutes, and 10 mL of N,N-dimethylformamide was added under argon protection. Subsequently, 6 g of CLO and 0.45 g of stannous octoate were added to the reaction tube, and the tube was placed in an oil bath at 140°C for 24 hours. The product was dissolved in hexafluoroisopropanol, precipitated in methanol, and dried in a vacuum oven at 40°C for 24 hours to obtain triblock polyesteramide PA6. 0.8k -PCL-1:7 (NMR analysis showed PA6) 0.8k The mass ratio of PCL to PCL is 1:7.

[0053] Weigh 1g of PA6 0.8k -PCL-1: 7 and 1g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80℃ for 2 h. Then, 14 mL of ultra-dry dimethyl sulfoxide was added under nitrogen protection and dissolved at 80℃ for 5 min. After the solution became clear and transparent, 0.261 g of hexamethylene diisocyanate and 0.016 g of stannous octoate were added to the reaction tube under nitrogen protection, and reacted at 80℃ for 3 h. 0.100 g of dithiodiethylene glycol was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, added to a reaction flask under nitrogen protection, and reacted at 80℃ for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40℃ for 24 h before use, designated as PUA-4. The obtained sample was dissolved in deuterated trifluoroacetic acid, and... 1 H NMR ( Figure 1 Structural analysis was performed, and the molecular weight and distribution of the polymer were characterized by gel permeation chromatography (see [link to article]). Figure 2 ).

[0054] The obtained samples were melt-pressed to prepare dumbbell-shaped strips with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. The tensile strength of PUA-4 was 14.0 MPa, the Young's modulus was 144.6 MPa, and the elongation at break was 746.2%. The results are shown in Table 1 and [Table data missing]. Figure 3 .Depend on Figure 3 It can be seen that when the ratio of polyester segment to polyamide segment in block polyesteramide increases, poly(urethane-amide) changes from elastic to plastic.

[0055] Example 5: Based on PA6 1.7k Preparation of poly(urethane-amide) using PCL-1:0.3 / PCL

[0056] PA6 1.7kBefore use, the product was dried in a vacuum oven at 80°C for 2 hours. 1 g was added to the reaction tube under argon protection, and the tube was pre-evacuated three times. The reaction tube was then evacuated at 80°C for 30 minutes, and 10 mL of N,N-dimethylformamide was added under nitrogen protection. Subsequently, 1 g of CLO and 0.23 g of stannous octoate were added to the reaction tube, and the tube was placed in an oil bath at 140°C for 24 hours. The product was dissolved in hexafluoroisopropanol, precipitated in methanol, and dried in a vacuum oven at 40°C for 24 hours to obtain triblock polyesteramide PA6. 1.7k -PCL-1:0.3 (NMR analysis, PA6) 1.7k The mass ratio of PCL to PCL is 1:0.3.

[0057] Weigh out 0.12g of PA6. 1.7k -PCL-1: 0.3 and 1.88 g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80℃ for 2 h. Then, under nitrogen protection, 14 mL of ultra-dry dimethyl sulfoxide was added and dissolved at 110℃ for 5–10 min. After the solution became clear and transparent, 0.403 g of hexamethylene diisocyanate and 0.016 g of stannous octoate were added to a reaction tube under nitrogen protection, and reacted at 80℃ for 3 h. 0.154 g of diethylene glycol dithiocarbamate was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, added to a reaction flask under nitrogen protection, and reacted at 80℃ for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40℃ for 24 h before use, designated as PUA-5.

[0058] The obtained samples were melt-pressed to prepare dumbbell-shaped strips with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. The tensile strength of PUA-5 was 22.3 MPa, the Young's modulus was 70.8 MPa, and the elongation at break was 986.3%. The results are shown in Table 1. Compared with Example 2, while keeping the PA6 content unchanged, increasing the molecular weight of PA6 resulted in poly(urethane-amide) with lower tensile strength than the poly(urethane-amide) prepared in Example 2.

[0059] Examples 6-9: Preparation of PUA / AmimCl conductive self-healing polyurethane

[0060] 500 mg of PUA-1 to PUA-4 (Examples 1 to 4) and 166.7 mg of the ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) were dissolved in 6 mL of hexafluoroisopropanol, respectively. The solutions were poured into flat glass dishes, dried, and then pressed into thin films at 130 °C. After cooling to room temperature, the infrared spectra were measured. The infrared spectra of PUA-1 and PUA-1 / AmimCl samples are shown below. Figure 4 (Where a represents PUA-1 and b represents PUA-1 / AmimCl), the corresponding self-healing morphology is shown in [reference needed]. Figure 5 (The two images above and below correspond to the morphology of the same sample before and after restoration, respectively.) From Figure 4 It can be seen that 1622 and 1687cm -1 These vibrations are caused by the stretching vibrations of the amide group C=O (Amide I) in the PA6 molecular chain of poly(urethane-amide) and the hydrogen-bonded C=O in the hard segment urethane unit, located at 3320 and 3395 cm⁻¹, respectively. -1 The nearby absorption peaks are caused by hydrogen bonding and the stretching vibrations of free NH4+, respectively. The 1575 cm⁻¹ peak... -1 The characteristic peak at that location is caused by the stretching vibration of the C=N ring on the imidazole ring in the ionic liquid. After the addition of the ionic liquid, the hydrogen-bonded C=O (in the carbamate unit) disappears, possibly because the ionic liquid inserts into the hard segment, acting as a dilution agent. Figure 5 It can be seen that PUA-1 still has large cracks after self-healing for 5 minutes at 80℃, while PUA-1 / AmimCl almost completely disappears after self-healing for 5 minutes at 80℃, showing a significant self-healing effect.

[0061] The obtained samples were melt-pressed to prepare dumbbell-shaped strips with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Mechanical properties were then tested. The results are shown in Table 1. Notches were created on the PUA-1 / AmimCl samples at room temperature using a blade. After self-healing at 80℃ for 4 hours, the stress-strain curves of the samples before and after self-healing are shown below. Figure 6 As shown, a represents the stress-strain curve before self-healing, and b represents the stress-strain curve after self-healing. The self-healing efficiency (η) is determined by the ratio of the elongation at break before and after self-healing, calculated using the following formula: ε0 and ε t The elongation at break corresponds to the initial sample and the sample after a certain period of self-healing, respectively. From Figure 6 It can be concluded that the self-repair efficiency is approximately 91%.

[0062] The obtained sample was used to prepare a uniformly thick circular film with a radius of approximately 2 cm by melt pressing at a melting temperature of 130 °C and a pressure of 1 MPa. The conductivity of the sample was tested in an electrochemical workstation. The results are shown in Table 1.

[0063] Example 10: Preparation of PUA-1 / BmimCl conductive self-healing polyurethane

[0064] 500 mg of PUA-1 (Example 1) and 166.7 mg of the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) were weighed and dissolved in 6 mL of hexafluoroisopropanol. The solution was poured into a flat glass dish, dried, and then pressed into a thin film at 130 °C. After cooling to room temperature, the infrared spectrum was measured. Scratches were then created with a blade, and the self-healing morphology at 80 °C was observed under POM (Polymer Oxide Mold). The results are shown in Table 1. The infrared spectra are shown in Table 1. Figure 4 (Where c represents PUA-1 / BmimCl), the corresponding self-healing morphology is shown in [reference needed]. Figure 5 Different types of ionic liquids blended with poly(urethane-amide) exhibit varying self-healing effects, with PUA-1 / BmimCl showing a weaker self-healing effect than PUA-1 / AmimCl. The obtained samples were melt-pressed into dumbbell-shaped strips measuring 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness) at a melting temperature of 220℃ and a pressure of 1 MPa. Mechanical properties were then tested. The results are shown in Table 1.

[0065] The obtained sample was used to prepare a circular film with uniform thickness and a radius of approximately 2 cm by melt pressing. The melting temperature was 130℃ and the pressure was 1 MPa. The conductivity of the sample was tested in an electrochemical workstation, and the results are shown in Table 1.

[0066] Example 11: Preparation of PUA-1 / HmimOTf conductive self-healing polyurethane

[0067] Weigh 166.7 mg of the ionic liquid 1-hexyl-3-methyltetrafluoromethanesulfonate imidazolyl (HmimOTf) and 500 mg of PUA-1 (Example 1), dissolve them in 6 mL of hexafluoroisopropanol, pour the solution into a flat glass dish, let it dry, press it into a thin film at 130 °C, cool it to room temperature, and then measure the infrared spectrum. Figure 4 As shown (where d represents PUA-1 / HmimOTf). Scratches were created using a blade, and the self-healing morphology was observed at 80℃ under POM, as shown... Figure 5 As shown, the poly(urethane-amide) with added HmimOTf exhibited the worst self-healing effect. The obtained samples were melt-pressed into dumbbell-shaped strips measuring 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness) at a melting temperature of 220℃ and a pressure of 1 MPa. Mechanical properties were then tested. The results are shown in Table 1.

[0068] The obtained sample was used to prepare a circular film with uniform thickness and a radius of approximately 2 cm by melt pressing. The melting temperature was 130℃ and the pressure was 1 MPa. The conductivity of the sample was tested in an electrochemical workstation, and the results are shown in Table 1.

[0069] Comparative Example 1: Preparation of PCL-based polyurethane

[0070] Weigh out 3g of PCL (M n =2000 g / mol), added to a reaction flask under nitrogen protection, and vacuumed at 80℃ for 2 h. Then, 12 mL of ultra-dry dimethyl sulfoxide was added under nitrogen protection and dissolved at 80℃ for 5 min. After the solution became clear and transparent, 0.605 g of hexamethylene diisocyanate and 0.024 g of stannous octoate were added to the reaction tube under nitrogen protection, and reacted at 80℃ for 3 h. 0.231 g of diethylene glycol dithiocarbamate was weighed and dissolved in 1 mL of ultra-dry dimethyl sulfoxide, added to a reaction flask under nitrogen protection, and reacted at 80℃ for 24 h. The product was precipitated in 500 mL of deionized water, washed twice, filtered, lyophilized, and dried in a vacuum oven at 40℃ for 24 h before use, denoted as PU. The molecular weight and distribution of the polymer were characterized by gel permeation chromatography (see...). Figure 2 ).

[0071] The obtained samples were melt-pressed to prepare dumbbell-shaped strips with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness). The melting temperature was 220℃ and the pressure was 1 MPa. Tensile tests were performed using a universal testing instrument, and the average value of three samples was taken. The tensile strength of PU was 7.6 MPa, the Young's modulus was 102.1 MPa, and the elongation at break was 494.6%. The results are shown in Table 1 and [Table data missing]. Figure 3 .

[0072] Comparative Example 2: Preparation of PU / AmimCl-based blends

[0073] 166.7 mg of ionic liquid 1-allyl-3-methylimidazolium chloride and 500 mg of PU (Comparative Example 1) were weighed and dissolved in 6 mL of hexafluoroisopropanol. The solution was poured into a flat glass dish, dried, and then pressed into a thin film at 130 °C. After cooling to room temperature, the infrared spectrum was measured. The obtained sample was melt-pressed into dumbbell-shaped strips with dimensions of 35 mm (length) × 2 mm (neck width) × 0.15 mm (thickness) at a melting temperature of 220 °C and a pressure of 1 MPa. The mechanical properties were then tested. The results are shown in Table 1.

[0074] The obtained sample was used to prepare a circular film with uniform thickness and a radius of approximately 2 cm by melt pressing. The melting temperature was 130℃ and the pressure was 1 MPa. The conductivity of the sample was tested in an electrochemical workstation, and the results are shown in Table 1.

[0075] Table 1

[0076]

[0077] From Table 1 and Figure 3 The results show that the polymerization method provided by this invention offers a feasible strategy for preparing high-strength and conductive self-healing poly(urethane-amide). The poly(urethane-amide) prepared by solution polymerization has similar molecular weight and distribution. Compared with PCL-based polyurethane, poly(urethane-amide) exhibits improved tensile strength and elongation at break, and its mechanical properties are tunable. Furthermore, mixing poly(urethane-amide) with an ionic liquid to prepare a thin film sample, rich in multi-level hydrogen bonds, demonstrates self-healing properties at 80°C. In addition, the introduction of the ionic liquid imparts conductivity to the material, and the introduction of the polyamide segment improves conductivity compared to polyurethane / ionic liquid. This conductive self-healing poly(urethane-amide) holds promise for applications in biomedicine, smart sensing, and electronic skin.

[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing conductive self-healing poly(urethane-amide), characterized in that, The method includes the following steps: S1. Under the protection of an inert gas, a macromolecular diol, a diisocyanate, a polyamide and / or a block polyesteramide, and a chain extender are polymerized in the presence of a catalyst, wherein the chain extender is a C3~C12 dithiodiol, to obtain poly(urethane-amide). S2. The obtained poly(urethane-amide) is mixed with an ionic liquid to obtain conductive self-healing poly(urethane-amide); The ionic liquid is selected from 1-allyl-3-methylimidazolium chloride, 1-allyl-3-vinylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1-hexadecyl-3-methylimidazolium chloride, 1-butylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-hydroxyethyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1... At least one of the following: vinyl-3-butylimidazolium chloride, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate, 1-allyl-3-methylimidazolium acetate, and 1-propyl-3-methylimidazolium acetate.

2. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, Based on the total weight of the conductive self-healing poly(urethane-amide), the content of the poly(urethane-amide) is 25~99 wt%, and the content of the ionic liquid is 1~75 wt%.

3. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, The molar ratio of the macromolecular diol, diisocyanate and chain extender is 1:(2.0~2.8):(0.5~2).

4. The method for preparing conductive self-healing poly(urethane-amide) according to claim 3, characterized in that, The molar ratio of the macromolecular diol, diisocyanate and chain extender is 1:(2.2~2.4):(0.5~1.5).

5. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, The total amount of the polyamide and block polyesteramide is such that the content of the polyamide segment in the poly(urethane-amide) is 5~99 wt%.

6. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, The amount of catalyst used is 0.001~20 mol of the total molar amount of hydroxyl groups in the macromolecular diol and block polyesteramide.

7. The method for preparing conductive self-healing poly(urethane-amide) according to claim 6, characterized in that, The amount of catalyst used is 0.05~1 mol of the total molar amount of hydroxyl groups in the macromolecular diol and block polyesteramide.

8. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, The mass ratio of polyester segment to polyamide segment in the block polyesteramide is (0.01~20):

1.

9. The method for preparing conductive self-healing poly(urethane-amide) according to claim 8, characterized in that, The mass ratio of polyester segment to polyamide segment in the block polyesteramide is (0.01~10):

1.

10. The method for preparing conductive self-healing poly(urethane-amide) according to claim 1, characterized in that, The polyamide has a number-average molecular weight of 100-30000 g / mol; the polyamide segment in the block polyesteramide has a number-average molecular weight of 100-30000 g / mol.

11. The method for preparing conductive self-healing poly(urethane-amide) according to claim 10, characterized in that, The polyamide has a number-average molecular weight of 200-10000 g / mol; the polyamide segment in the block polyesteramide has a number-average molecular weight of 200-10000 g / mol.

12. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, The macromolecular diol is selected from at least one of polycaprolactone diol, polylactide diol, polyglycolic acid diol, polyethylene glycol diol, polytetrahydrofuran diol, polypropylene oxide diol, and polydimethylsiloxane diol.

13. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, The number-average molecular weight of the macromolecular diol is 500~20000 g / mol.

14. The method for preparing conductive self-healing poly(urethane-amide) according to claim 13, characterized in that, The number-average molecular weight of the macromolecular diol is 1000~10000 g / mol.

15. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, The diisocyanate is selected from at least one of isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-methylene diphenyl diisocyanate and hexamethylene diisocyanate.

16. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, The catalyst is selected from at least one of organometallic compounds, inorganic acids, and nucleophilic catalysts.

17. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, The ionic liquid is selected from at least one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-vinyl-3-butylimidazolium chloride, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, and 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine.

18. The method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, In step S1, the polymerization reaction is carried out by heating and dissolving macromolecular diols and polyamides and / or block polyesteramides in a solvent, adding diisocyanates and catalysts for prepolymerization, and then reacting the isocyanate-terminated prepolymer with a chain extender to obtain poly(urethane-amide). The heating conditions include a temperature of 50~200 ℃ and a time of 1~30 min; The prepolymerization conditions include a temperature of 50~200 ℃ and a time of 2~10 h; The chain extension reaction conditions include a temperature of 60~120 ℃ and a time of 1~48 h.

19. A method for preparing conductive self-healing poly(urethane-amide) according to any one of claims 1 to 11, characterized in that, In step S2, the mixing temperature is 10~100 ℃.

20. Conductive self-healing poly(urethane-amide) prepared by the method according to any one of claims 1 to 19.

21. The application of the conductive self-healing poly(urethane-amide) according to claim 20 in smart sensing, electronic skin and biomedical preparation.

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