Preparation method of high-strength high-temperature self-healing polymer

Abstract

The invention discloses a preparation method of a high-strength high-temperature self-healing polymer, and belongs to the technical field of functional materials. The preparation method comprises the following steps: dissolving polyvinylamine and carboxylated polycaprolactone in a water / tetrahydrofuran solvent to obtain a composite solution, and then drying to obtain the high-strength high-temperature self-healing polymer. Wherein the polyvinylamine accounts for 94%-98% of the total mass of the polyvinylamine and the carboxylated polycaprolactone. The method is low in cost and high in preparation speed. At a high temperature, high mechanical strength of the polymer is maintained, and self-healing of the material is realized at the same time.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-strength, high-temperature self-healing polymer, belonging to the field of functional materials technology. Background Technology

[0002] High-strength, high-temperature self-healing polymers can repair cracks and heal damage in high-temperature environments, exhibiting excellent high-temperature resistance, self-healing ability, and mechanical properties, and are widely used in aerospace, energy, electronics, and defense fields. However, traditional high-strength self-healing polymers tend to transform from a glassy state to a viscoelastic state at high temperatures, causing the material to soften and its mechanical strength and modulus to decrease significantly, leading to material failure.

[0003] Common high-temperature self-healing mechanisms include dynamic covalent bonds (Diels-Alder reaction, aromatic disulfide bonds, borate ester bonds, and imine bonds) and supramolecular interactions (high-temperature stable ionic interactions such as polyionic liquids, and high-bond-energy metal coordination bonds such as Fe). 3+ Cu 2+ (Compounds). However, the storage modulus of these polymers decreases from 1-10 GPa to 1-10 MPa at high temperatures (100-150℃). Although they have good self-healing efficiency, their mechanical strength drops significantly during the self-healing process, making them difficult to apply in practice. Some studies have also achieved self-healing of high-strength polymers at room temperature (25℃), which can maintain high mechanical strength during the healing process. However, once the temperature exceeds their glass transition temperature (50℃), the storage modulus rapidly decreases to 1 MPa (Science, 2018, 359(6371):72-76. and Proceedings of the National Academy of Sciences, 2020, 117(21):11299-11305.). Therefore, achieving self-healing of materials while maintaining high mechanical strength at high temperatures is a challenge. Summary of the Invention

[0004] [Technical Issues]

[0005] The technical problem to be solved by this invention is to achieve self-healing of the material while maintaining the high mechanical strength of the polymer at high temperatures.

[0006] [Technical Solution]

[0007] To address the above problems, the following technical solution is provided:

[0008] This invention provides a method for preparing a high-strength, high-temperature self-healing polymer, which involves dissolving and mixing polyvinylamine and carboxylated polycaprolactone in a water / tetrahydrofuran mixed solvent to obtain a composite solution; then drying the solution to obtain the high-strength, high-temperature self-healing polymer.

[0009] In the preparation method of the high-strength, high-temperature self-healing polymer of this invention, polyvinylamine (PVAm) and carboxylated polycaprolactone (CPCL) are selected as the polymer matrix. Polyvinylamine has a regular molecular structure with primary amine groups on its side chains. Intramolecular hydrogen bonds between these primary amine groups cause the polyethyleneamine molecular chains to fold in an orderly manner, forming crystalline regions and exhibiting high mechanical strength. Carboxylated polycaprolactone is also a crystalline polymer with carboxyl groups on its side chains. When the two are dissolved and mixed in a common solvent of water and tetrahydrofuran, the primary amine groups on the polyethyleneamine ionize, carrying a positive charge, while the carboxyl groups on the carboxylated polycaprolactone carry a negative charge. Through electrostatic attraction, new crystalline regions are formed, improving the mechanical strength of the polymer. At high temperatures, these crystalline regions partially melt, causing secondary relaxation in the polymer, enabling the material to self-heal; simultaneously, the presence of these crystalline regions maintains the mechanical strength of the material.

[0010] This invention is the first to discover that introducing ionic groups into crystalline polymers allows for the formation of new crystalline regions through electrostatic attraction, enabling the material to maintain high mechanical strength at high temperatures while achieving self-healing.

[0011] In one embodiment of the invention, the mass fraction of polyethyleneamine in the total mass of polyethyleneamine and carboxylated polycaprolactone is 94% or more and less than 100%. Preferably, it is 94%-98%. More preferably, it is 97%-98%.

[0012] In one embodiment of the present invention, the volume ratio of water to tetrahydrofuran in the water / tetrahydrofuran mixed solvent is 1:(1-5); specifically, 1:2 may be selected.

[0013] In one embodiment of the present invention, the total mass fraction of polyethyleneamine and carboxylated polycaprolactone relative to the water / tetrahydrofuran mixed solvent is 10wt%-20wt%. Specifically, 15wt% is optional.

[0014] In one embodiment of the present invention, the polyethyleneamine is commercially available, and the carboxylated polycaprolactone is synthesized in the laboratory.

[0015] In one embodiment of the present invention, the carboxylated polycaprolactone is synthesized by the following process:

[0016] Dimethylolpropionic acid and caprolactone are mixed and stirred at 120-150℃ for a period of time. After cooling, a white waxy solid is obtained, which is carboxylated polycaprolactone.

[0017] In one embodiment of the present invention, the drying temperature is 40-80°C. Specifically, 60°C may be selected.

[0018] In one embodiment of the present invention, the drying time is 5-40 hours, specifically 24 hours.

[0019] In one embodiment of the invention, the reaction is carried out under a nitrogen atmosphere.

[0020] In one embodiment of the present invention, the mass ratio of dimethylolpropionic acid to caprolactone is 1:4.

[0021] This invention provides a high-strength, high-temperature self-healing polymer based on the above preparation method.

[0022] In one embodiment of the present invention, the high temperature range is 100-150°C.

[0023] In one embodiment of the present invention, the self-healing time is 24 hours.

[0024] In one embodiment of the present invention, the above-mentioned polymer has potential applications in aerospace, energy, electronics and defense fields.

[0025] The beneficial effects of this invention are:

[0026] This invention describes a method for obtaining specific polyvinylamine-carboxylated polycaprolactone composites by controlling a certain component ratio, and preparing polymers with different mechanical strengths, moduli, and self-healing properties. Under specific formulation conditions, the resulting polymer exhibits the best performance, with a tensile strength of 70.4 MPa and a Young's modulus of 4.2 GPa. Simultaneously, it achieves self-healing at high temperatures (100°C) while maintaining high mechanical strength, with a storage modulus of 0.5 GPa, significantly higher than other high-temperature self-healing polymers (1-10 MPa). Attached Figure Description

[0027] Figure 1 This is a diagram showing the steps involved in the synthesis of carboxylated polycaprolactone.

[0028] Figure 2 This is a flowchart illustrating the preparation of a high-strength, high-temperature self-healing polymer. Polyvinylamine and carboxylated polycaprolactone in different proportions were mixed in a water / tetrahydrofuran solution to obtain a composite solution. The solution was then poured into a petri dish and dried in a 60°C oven for 24 hours.

[0029] Figure 3 To demonstrate ion-ion interaction diagrams using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS), the following diagrams are presented: (a) FTIR diagrams of polymers containing different mass fractions of polyethyleneamine (mass fraction refers to the percentage of polyethyleneamine in the total mass of polyethyleneamine and carboxylated polycaprolactone); (b) a diagram showing the calculated degree of ion-ion interaction; (c) an N1s XPS diagram of 97.83% PVAm; and (d) an N1s XPS diagram of 100% PVAm.

[0030] Figure 4Figures demonstrating the crystallinity of polymers using X-ray diffraction (XRD), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS) are shown. (a) shows the XRD patterns of polymers containing different mass fractions of polyvinylamine (PVAm); (b) shows the calculated crystallinity of polymers containing different mass fractions of PVAm; (c) shows the TEM image of 97.83% PVAm; (d) shows the calculated interplanar spacing of 97.83% PVAm; (e) shows a comparison of interplanar spacing calculated by XRD and TEM; and (f) shows the Guinier analysis of the SAXS image, calculating the grain size.

[0031] Figure 5 To demonstrate the polymeric relaxation plot of the polymer using dynamic thermomechanical analysis (DMA). (a) Figure shows the loss factor (tanθ) plot for polyvinylamine containing different mass fractions; (b) Figure shows the storage modulus plot for polyvinylamine containing different mass fractions; (c) Figure shows the stress relaxation plot for 97.83% PVAm; (d) Figure shows the activation energy (E). a )Calculation graph.

[0032] Figure 6 Figure 1 shows the mechanical properties of polymers containing different mass fractions of polyethyleneamine. (a) Figure 2 shows the stress-strain curves of polymers containing different mass fractions of polyethyleneamine; (b) Figure 3 shows the Young's modulus of polymers containing different mass fractions of polyethyleneamine.

[0033] Figure 7 This is a comparison chart of the storage modulus of the self-healing polymer obtained in this invention and other polymers reported in the literature at 100°C. Detailed Implementation

[0034] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0035] The synthesis steps of carboxylated polycaprolactone involved in the following examples are as follows: Figure 1 As shown, it is specifically prepared through the following process:

[0036] Weigh 5g of dimethylolpropionic acid and 20g of caprolactone, and place them in a 250mL three-necked flask under a nitrogen atmosphere. Maintain the reaction mixture at 120℃ with mechanical stirring at 60rpm for 2 hours. After cooling to room temperature, a white waxy solid, carboxylated polycaprolactone, is obtained.

[0037] The preparation of the high-strength, high-temperature self-healing polymer of this invention is as follows: Figure 2 As shown, the prepared composite solution is poured into a petri dish and dried to obtain a high-strength, high-temperature self-healing polymer.

[0038] The tensile strength test process is as follows: the polymer is cut into dumbbell shape (5cm long, 2cm wide, and 300μm thick), and stretched at a speed of 2mm / s using a universal mechanical testing instrument. The strength corresponding to the material breaking is the tensile strength, and the stress-strain curve is obtained.

[0039] The testing process for Young's modulus is as follows: Young's modulus is obtained by calculating the slope of the stress-strain curve.

[0040] Self-healing experiment: A dumbbell-shaped sample (5cm long, 2cm wide, and 300μm thick) was cut, and the two broken parts of the sample were brought into contact. The sample was then placed in an oven (100℃, 24 hours) and subjected to a tensile test at a speed of 2mm / s using a universal mechanical analyzer.

[0041] The self-healing efficiency is: tensile strength after healing / tensile strength of the original sample.

[0042] Example 1

[0043] A method for preparing a high-strength, high-temperature self-healing polymer:

[0044] According to the specified weight ratio, weigh out 94 parts of polyethyleneamine (equivalent to 9.400g) and 6 parts of carboxylated polycaprolactone, and dissolve them in water / tetrahydrofuran solvent (V). 水 V 四氢呋喃 In a mixture of 1:2, the total mass fraction of polyvinylamine and carboxylated polycaprolactone relative to the solvent is controlled at 15 wt%. After mixing, a composite solution is obtained. The composite solution is poured into a petri dish, and after the solvent evaporates and dries, a PVAm / CPCL polymer is formed, abbreviated as 94% PVAm.

[0045] Example 2

[0046] A method for preparing a high-strength, high-temperature self-healing polymer:

[0047] According to the specified weight ratio, weigh 95.24 parts of polyethyleneamine (equivalent to 9.524 g) and 4.76 parts of carboxylated polycaprolactone, and dissolve them in water / tetrahydrofuran solvent (V). 水 V 四氢呋喃 In a mixture of 1:2, the total mass fraction of polyvinylamine and carboxylated polycaprolactone relative to the solvent was controlled to be 15 wt%. The mixture was stirred to obtain a composite solution. The composite solution was poured into a petri dish and dried after the solvent evaporated to form a PVAm / CPCL polymer, abbreviated as 95.24% PVAm.

[0048] Example 3

[0049] A method for preparing a high-strength, high-temperature self-healing polymer:

[0050] According to the specified weight ratio, weigh 96 parts of polyethyleneamine (equivalent to 9.600g) and 4 parts of carboxylated polycaprolactone, and dissolve them in water / tetrahydrofuran solvent (V). 水 V 四氢呋喃 In a mixture of 1:2, the total mass fraction of polyvinylamine and carboxylated polycaprolactone relative to the solvent is controlled to be 15 wt%. The mixture is then stirred to obtain a composite solution. The composite solution is poured into a petri dish and allowed to evaporate and dry to form a PVAm / CPCL polymer, abbreviated as 96% PVAm.

[0051] Example 4

[0052] A method for preparing a high-strength, high-temperature self-healing polymer:

[0053] According to the specified weight ratio, weigh 97.83 parts of polyethyleneamine (equivalent to 9.783 g) and 2.17 parts of carboxylated polycaprolactone, and dissolve them in water / tetrahydrofuran solvent (V). 水 V 四氢呋喃 In a mixture of 1:2, the total mass fraction of polyvinylamine and carboxylated polycaprolactone relative to the solvent was controlled to be 15 wt%. The mixture was stirred to obtain a composite solution. The composite solution was poured into a petri dish and dried after the solvent evaporated to form a PVAm / CPCL polymer, abbreviated as 97.83% PVAm.

[0054] Figure 2 The polymer network structure of the PVAm / CPCL polymer of this invention is shown. After the addition of CPCL, the side groups (NH3) on the PVAm chains... + Through electrostatic interactions with the carboxyl groups (COO) of CPCL - The coupling restricts the mobility and arrangement of molecular chains, thereby altering the crystallinity. After complete drying, a PVAm / CPCL crystalline polymer with both original and newly formed crystalline regions was obtained.

[0055] Figure 3 The infrared spectrum (FTIR) and X-ray photoelectron spectroscopy (XPS) of the PVAm / CPCL polymer of the present invention are shown.

[0056] The formation of hydrogen bonds and ionic interactions affects the crystallinity of materials, as studied by FTIR ( Figure 3 (as shown in a). At approximately 1750 cm -1 The absorption peak at this point corresponds to the C=O stretching vibration of the carboxyl group. This characteristic peak appears in the spectrum after CPCL is added to the PVAm / CPCL polymer spectrum. When -COO... - and -NH3 + When ion pairs form, the electron cloud of the C=O bond shifts further toward the oxygen atom, thereby lowering the force constant and vibrational frequency, causing the C=O stretching vibration peak to drop from 1736 cm⁻¹. -1Redshifted to 1732cm -1 Between 1620-1690cm -1 Within the range, NH bending vibrations were observed. In the -COO range... - and -NH3 + After the ion pair forms, the electron density of the NH bond shifts towards the nitrogen atom, lowering the NH bending vibration frequency, which in turn causes the peak to shift to a lower wavenumber, from 1654 cm⁻¹. -1 Move to 1650cm -1 1522-1530cm -1 The absorption peaks within the range are attributed to -NH3 + Group. With increasing CPCL content, the electrostatic attraction within the ion pair weakens the force constant of the NH bond, lowering its vibrational frequency, thus causing the peak value to drop from 1530 cm⁻¹. -1 Redshift occurred to 1522cm -1 To further investigate the effect of CPCL content on the intensity of ion interactions, the infrared peaks of the -NH3 group were fitted, and the degree of ion interactions in different samples was quantitatively evaluated. Figure 3 b). The results showed that the ionic interactions in the PVAm / CPCL polymer gradually increased with the increase of CPCL content.

[0057] To further investigate the ion interactions in the PVAm / CPCL polymer, X-ray photoelectron spectroscopy (XPS) analysis was performed, and high-resolution N1s XPS spectra were obtained. Figure 3 c, 3d). A curve fitting of 97.83% PVAm yielded four peaks. The peaks in the 397-403 eV range were attributed to different states of the -NH2 group. The binding energy peak of the free -NH2 group appeared at 399.8 eV, while the hydrogen-bonded -NH2 group exhibited a shift to a lower binding energy due to the increased electron density on the nitrogen atom, with a corresponding peak at 399.1 eV. Protonation reduced the electron density, resulting in a relatively higher N1s binding energy. However, when the protonated -NH3 group is combined with a carboxylate group (-COO... - When ion pairs are formed, the electrostatic interaction of the ionic bond slightly increases the electron density around the nitrogen atom, causing its N1s binding energy to shift downward. Therefore, the peaks at 400.4 eV and 401.2 eV are attributed to the free -NH3 and the -NH3 ion pair. Thus, FTIR and XPS successfully verified the ionic interaction between PVAm and CPCL.

[0058] Figure 4 X-ray diffraction (XRD), projection electron microscopy (TEM), and small-angle X-ray scattering (SAXS) of the VAm / CPCL polymer of the present invention are shown.

[0059] To investigate the crystallization behavior of the PVAm / CPCL polymer, X-ray diffraction (XRD) tests were performed. In the XRD pattern ( Figure 4 a) The broad peak at approximately 25° belongs to the amorphous region of PVAm. The crystalline peaks at 32°, 18°, 21°, and 22° originate from PVAm and CPCL, respectively. In contrast, the distinctly sharp peaks at 23°, 40°, 47°, 53°, and 58° correspond to newly formed crystalline domains, while the intensity of the original crystalline PVAm peak at 32° increases significantly. This is because ionic interactions influence the crystallization behavior of the PVAm / CPCL polymer.

[0060] Through peak fitting ( Figure 4 b) Calculations showed that the crystallinity of 100% PVAm was 4.37%. With the addition of CPCL, the crystallinity of the PVAm / CPCL polymer first increased and then decreased, reaching a maximum of 17.47% for 97.83% PVAm. The mixing of CPCL and PVAm induced the ordered arrangement of molecular chains through ionic interactions, which was beneficial for the formation of crystalline regions. However, excessive CPCL caused overly strong ionic interactions, disrupting the ordered arrangement of polymer chains and reducing the mobility of molecular segments, thus limiting the crystallinity of the PVAm / CPCL polymer. More importantly, new crystalline peaks appeared in the XRD pattern after CPCL incorporation. To confirm the formation of new crystalline regions, Bragg's law (Equation 1) was applied to calculate the interplanar spacing of the peaks corresponding to different 2θ values.

[0061]

[0062] Where d is the interplanar spacing.

[0063] The calculations yielded six different interlayer spacings, indicating the existence of six distinct crystal domains. Figure 4 (AF in a).

[0064] Subsequently, the PVAm sample with the highest crystallinity (97.83%) (Example 4) was analyzed by high-resolution transmission electron microscopy (TEM). TEM results revealed five different crystal morphologies and their corresponding interlayer spacings (…). Figure 4 The c-4d crystal morphology was observed, while the sixth crystal form was not observed, possibly due to its coexistence with other crystal growths. It is noteworthy that the TEM data and XRD results ( Figure 4 e) Mutual verification. Crystal size was studied using small-angle X-ray scattering (SAXS), and the crystal size was determined by analyzing the SAXS data using Guinier fitting. The radius of gyration (Rg) was obtained by fitting the low-q region of the SAXS data. g ()( Figure 4 f, Equation 2).

[0065]

[0066] Where R g I represents the cyclotron radius, and I0 is the scattering intensity at zero angle (q=0).

[0067] Based on TEM observations, the crystal domains are approximated as spherical, and the crystal domain size (R) of the PVAm / CPCL polymer is calculated using Equation 3.

[0068]

[0069] The results showed that 97.83% of the PVAm samples had an R value of 86.252 nm, which is consistent with the crystal grain size observed in the transmission electron microscope images.

[0070] Figure 5 The polymeric relaxation map of the PVAm / CPCL polymer was demonstrated using dynamic thermomechanical analysis (DMA).

[0071] Dynamic mechanical analysis (DMA) was used to further investigate the relaxation of crystal domains and molecular mobility. The tanθ curves revealed temperature-dependent relaxation behavior. Figure 5 a). For 100% PVAm, the peak at approximately 40°C is attributed to localized chain segment movement within crystal defect regions or amorphous layers at grain boundaries, rather than overall relaxation. Because the crystal domains remain ordered, the material retains rigidity, with the storage modulus (E') gradually decreasing only due to localized movement. Figure 5 (b) The peak at 70 °C in the curves for 92.11% PVAm, 95.24% PVAm, and 97.83% PVAm corresponds to the enhanced fluidity of the amorphous phase after crystal melting, leading to a rapid decrease in E'. In the PVAm / CPCL polymer, a new tanθ peak appears at 110–130 °C, originating from the new crystal morphology. The 97.83% PVAm curve shows a second new peak at 94 °C, while other PVAm / CPCL polymers do not exhibit a significant peak at this position, which may be attributed to the higher proportion of newly formed crystalline regions in 97.83% PVAm. In contrast, the crystalline regions contained in other PVAm / CPCL combinations are insufficient to produce detectable relaxation peaks.

[0072] Stress relaxation tests performed using dynamic mechanical analysis (DMA) showed that the ratio of the relaxation modulus to the initial relaxation modulus gradually decreased over time. Figure 5 c). Substitute the characteristic relaxation time into the linearized Arrhenius equation (Equation 4) to calculate the activation energy.

[0073]

[0074] Where τ0 is the exponential factor, E a E is the activation energy, and R is the gas constant. Linear fitting yields E. a =28.2 kJ / mol, which does not correspond to α-relaxation of the material, but rather represents the activation energy of β-relaxation dominated by chain segment movement in some crystalline regions. The observed α-relaxation requires higher temperatures to completely melt the crystalline regions, but this sacrifices solid-state mechanical properties. Figure 5 d). At 100°C, the 100% PVAm sample exhibited complete stress relaxation (modulus dropped to zero), while the polymer containing CPCL maintained structural integrity under the same conditions. Notably, 97.83% PVAm maintained a storage modulus (E') of 0.5 GPa at 100°C. This behavior is attributed to partial relaxation within newly formed crystalline regions, with some thick crystalline layers or crystals with high structural perfection temporarily remaining unmelted. This phenomenon indicates that the material maintains a rigid glassy state during high-temperature relaxation without transitioning to a viscoelastic state, demonstrating practical engineering significance—that the material does not lose mechanical strength during self-healing, thus preventing structural damage.

[0075] Figure 6 The mechanical properties of polymers containing different mass fractions of polyvinylamine are shown. PVAm / CPCL forms a rigid material at room temperature with excellent mechanical properties. Stress-strain curves are also shown. Figure 6 a) shows that 97.83% PVAm exhibits the highest tensile strength of 70.4 MPa, while the tensile strengths of 100% PVAm, 95.24% PVAm, and 92.11% PVAm are 44.26 MPa, 39.24 MPa, and 24.66 MPa, respectively. Young's modulus ( Figure 6 b) shows that 97.83% PVAm has the highest modulus of 4283 MPa. These mechanical properties are associated with higher crystallinity, with well-ordered, tightly packed crystal domains providing robust structural support. The crystal domains also enhance strength, hardness, and modulus by restricting chain mobility by fixing the molecular chains to their lattice positions, thus preventing large-scale displacement / rearrangement. Adding excessive CPCL reduces hydrogen bonds between PVAm chains and decreases the material's crystallinity and tensile strength.

[0076] Compare with Example 1

[0077] The polyvinylamine in Example 4 is omitted, and other conditions or parameters are the same as in Example 4. The resulting polymer is a waxy crystalline substance that does not have mechanical strength.

[0078] Compare with Example 2

[0079] If the water / tetrahydrofuran in Example 4 is omitted and the two raw materials are directly mixed, and other conditions or parameters are the same as in Example 4, a uniform composite solution cannot be obtained, and therefore the polymer cannot be prepared.

[0080] Compare with Example 3

[0081] When the amount of polyethyleneamine added was adjusted to less than 94 parts, and other conditions or parameters were the same as in Example 4, due to the enhanced electrostatic interaction, precipitates appeared in the solution, and a uniform polymer could not be obtained.

[0082] Compare with Example 4

[0083] When the amount of polyethyleneamine added is adjusted to more than 98 parts, and other conditions or parameters are the same as in Example 4, due to the weak ionic phase interaction, a new crystal form cannot be formed, and the resulting polymer has a storage modulus of 0 at high temperature and cannot maintain high mechanical strength at high temperature.

[0084] Compare with Example 5

[0085] The carboxylated polycaprolactone in Example 4 is omitted, and other conditions or parameters are the same as in Example 4. Since no new crystal form is formed, pure polyethyleneamine has a storage modulus of 0 at 100°C and cannot maintain high mechanical strength at high temperatures.

[0086] Compare with Example 6

[0087] Compare with existing technology CN202410050072.0

[0088] A composite colloid, formulated by weight ratio, consists of 18 parts waterborne polyurethane, 72 parts polyethyleneamine, and 10 parts ammonia (28 wt%) (wherein polyethyleneamine accounts for 80% of the total mass of polyethyleneamine and waterborne polyurethane). The composite colloid is poured into a petri dish, and after the water evaporates and dries, a self-healing glassy crystalline polymer is formed. The resulting polymer has a low storage modulus at 100°C and cannot maintain high mechanical strength at high temperatures.

[0089] The preparation results of each embodiment and control example are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] In summary, introducing ionic groups into crystalline polymers allows for the formation of new crystalline regions through electrostatic attraction, enabling the polymer to maintain high mechanical strength while achieving self-healing at high temperatures. The ratio of polyethyleneamine to carboxylated polycaprolactone is crucial; the amount of polyethyleneamine added should be between 94 and 98 parts to ensure the formation of new crystal forms, thus allowing the polymer to maintain high mechanical strength and storage modulus during self-healing at 100°C.

[0094] Comparative Example 7

[0095] Finally, the present invention was also compared with other previously reported high-temperature self-healing polymers.

[0096] The polymer of this invention self-heals in its glassy state without α-relaxation, and 97.83% of PVAm retains high tensile strength and storage modulus. This behavior stems from persistent unmelted crystalline domains that provide structural reinforcement.

[0097] Furthermore, without α-relaxation, other previously reported polymers in their glassy state cannot withstand temperatures up to 100°C, especially above the glass transition temperature (T0). g At 50°C, the energy storage modulus decreases by approximately 1 MPa. However, the 97.83% PVAm of this invention exhibits an energy storage modulus approximately 500 times higher at 100°C, and maintains high mechanical properties during self-healing. Figure 7 ).

[0098] Figure 7 The relevant technical codes and corresponding literature information are shown in Table 2.

[0099] Table 2

[0100] serial number literature 23 Angew.Chem.Int.Ed.2021,60(14),7947-7955. 24 Chem.Mater.2023,35(2),682-691. 27 Proc.Natl.Acad.Sci.2020,117(21),11299-11305. 42 Chem.Eng.Res.Des.2018,136,431-446. 45 Chem.Eng.J. 2023, 466, 143179. 48 Compos.Sci.Technol.2022,219,109261. 50 Adv.Mater.2023,35(26),2300937.

[0101] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a high-strength, high-temperature self-healing polymer, characterized in that, The process involves dissolving polyvinylamine and carboxylated polycaprolactone in a water / tetrahydrofuran mixed solvent to obtain a composite solution; then drying it to obtain a high-strength, high-temperature self-healing polymer.

2. The method according to claim 1, characterized in that, The mass fraction of polyethyleneamine in the total mass of polyethyleneamine and carboxylated polycaprolactone is more than 94% and less than 100%.

3. The method according to claim 2, characterized in that, Polyvinylamine accounts for 94%-98% of the total mass of polyvinylamine and carboxylated polycaprolactone.

4. The method according to claim 3, characterized in that, Polyvinylamine accounts for 97-98% of the total mass of polyvinylamine and carboxylated polycaprolactone.

5. The method according to claim 1, characterized in that, The volume ratio of water to tetrahydrofuran in the water / tetrahydrofuran mixed solvent is 1:(1-5).

6. The method according to claim 1, characterized in that, The total mass fraction of polyethyleneamine and carboxylated polycaprolactone relative to the water / tetrahydrofuran mixed solvent is 10wt%-20wt%.

7. The method according to claim 1, characterized in that, The carboxylated polycaprolactone was synthesized via the following process: Dimethylolpropionic acid and caprolactone are mixed and stirred at 120-150℃ for a period of time. After cooling, a white waxy solid is obtained, which is carboxylated polycaprolactone.

8. The method according to any one of claims 1-7, characterized in that, The drying temperature is 40-80℃, and the time is 5-40 hours.

9. A high-strength, high-temperature self-healing polymer obtained by the method according to any one of claims 1-8.

10. The application of the high-strength, high-temperature self-healing polymer of claim 9 in the aerospace, energy, electronics and defense fields.

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