A shock-hardened polymer and a method of making and using the same

Abstract

The application discloses a preparation method and application of an impact-hardening polymer with self-sensing capability, and belongs to the technical field of functional polymer materials. The impact-hardening polymer is prepared from rigid molecules and long side-chain acrylate copolymerization; has the advantages of high hardening index and high transparency; the transparency can reach more than 85%, and the storage modulus can increase by 1831 times in the frequency range from 0.1 Hz to 100 Hz. The preparation method is simple; the rigid molecules containing double bonds and the long side-chain acrylate monomers are prepared through one-step photo-initiated free radical polymerization. Further, conductive salt is added to the impact-hardening material to prepare an intelligent impact-hardening polymer material integrating the hardening function and the self-sensing function, which can not only harden to resist impact deformation and absorb impact energy when suffering impact, but also realize the sensing capability of impact through the change of the electric signal such as the material resistance. The intelligent impact-hardening polymer material can be applied to the fields of flexible protective equipment, flexible electronic protection, human body protection and medical detection.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials technology, and in particular relates to a method for preparing and applying an impact-hardening polymer. Background Technology

[0002] Impact-hardened materials exhibit flexibility under low-frequency conditions, adapting to changes in the external environment. However, when subjected to high-speed impacts or shear forces, they undergo rapid structural changes, achieving rapid hardening and significantly enhancing their stiffness and strength. This increased stiffness and strength allows impact-hardened materials to effectively absorb and disperse impact energy. They embody the mechanical characteristic of being "soft against weak conditions and rigid against strong ones." This dynamic conversion between flexibility and rigidity makes them highly significant in flexible protective gear such as bulletproof vests, helmets, and protective gloves, as well as in flexible electronic protection fields such as shatterproof mobile phone screens, chip security, and battery safety protection.

[0003] Currently, research on impact-hardening materials largely focuses on polyborosiloxanes. Polyborosiloxanes are polymers with a unique structure containing numerous dynamic boron-oxygen covalent bonds. These dynamic covalent bonds can reversibly break and recombine under external force, thereby absorbing external energy and achieving impact resistance. However, the performance of existing polyborosiloxane materials still needs improvement; in the shear frequency range of 0.1 to 100 Hz, the increase in storage modulus is typically less than 1000 times, which limits their application in high-performance intelligent protection. The team of Wu Peiyi and Sun Shengtong at Donghua University proposed an impact-hardening supramolecular polymer; a supramolecular polymer system was constructed by the carboxyl group of polythiooctanoic acid and the guanidinium group of arginine through salt-bridge hydrogen bonding. Although this material exhibits a very high increase in storage modulus in the shear frequency range of 0.1 to 100 Hz, its yellow color limits its application in the protection of display devices.

[0004] Therefore, it is necessary to develop a new impact-hardening material to solve the problems existing in the current technology. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an impact-hardening material and its preparation method. The impact-hardening material prepared by this invention has colorless transparency and a high hardening index. Furthermore, a self-sensing impact-hardening material is developed based on this material.

[0006] A first aspect of the present invention provides an impact-hardening polymer, said polymer being a rigid molecular / long side-chain acrylate polymer.

[0007] An impact-hardening polymer is prepared by copolymerization of rigid molecules and long-side-chain acrylates;

[0008] Furthermore, the rigid molecule is selected from at least one of styrene, methyl methacrylate, isobornyl acrylate, and isobornyl methacrylate monomers;

[0009] Furthermore, the long-side-chain acrylate has the structure shown in Formula I.

[0010]

[0011] Furthermore, in Equation I, R is selected from... n is an integer between 2 and 18.

[0012] In some embodiments, the long-side-chain acrylate is selected from n-butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, and polyethylene glycol methyl ether acrylate monomer.

[0013] In some embodiments, the impact-hardening polymer has a molecular weight of Mn = 2-20 kg / mol.

[0014] In some embodiments, the impact-hardening polymer has a transparency of 85% or more of ultraviolet transmittance;

[0015] In some embodiments, the energy storage modulus G' of the impact hardening material increases by 50-2000 times in the frequency range from 0.1 Hz to 100 Hz; in some preferred embodiments, the energy storage modulus G' of the impact hardening material increases by 86-1831 times in the frequency range from 0.1 Hz to 100 Hz.

[0016] A second aspect of the present invention is to provide a method for preparing the impact-hardening polymer, characterized in that the rigid molecular monomer, the long side-chain acrylate monomer, and the photoinitiator are mixed, and the impact-hardening polymer is obtained by photoinitiated free radical polymerization.

[0017] Furthermore, the molar ratio of the rigid molecular monomer to the long side-chain acrylate monomer is 1:1 to 4:1.

[0018] Furthermore, the photoinitiator accounts for 1-10 wt% of the total polymer mass;

[0019] In some embodiments, the initiator is selected from one or a combination of photoinitiator 2959 or photoinitiator 1173;

[0020] In some embodiments, the photoinitiated free radical polymerization conditions are: ultraviolet light wavelength of 254-365 nm and irradiation time of 2-8 h. In some embodiments, the ultraviolet light wavelength is 254 or 365 nm.

[0021] Traditional protective materials, lacking real-time status monitoring and dynamic adjustment capabilities, struggle to cope with complex and ever-changing impact load environments. By imparting conductivity to impact-hardening materials, their ability to sense impact forces can be achieved. Based on the impact-hardening polymer provided in this invention, this invention further develops an impact-hardening polymer with self-sensing capabilities and its preparation method.

[0022] A third aspect of the present invention is to provide a method for preparing an impact-hardening polymer with self-sensing capability, wherein the impact-hardening polymer and a conductive salt are dissolved in a solvent, and then poured into a mold to evaporate the solvent. After the solvent evaporates, the impact-hardening polymer with self-sensing capability is obtained.

[0023] In a preferred embodiment, the preparation method of the self-sensing impact-hardening polymer of the present invention includes the following steps: dissolving the impact-hardening polymer and a conductive salt in tetrahydrofuran solvent, then pouring the solution into a mold and placing it in a drying oven to slowly evaporate the solvent at room temperature, and finally placing it in a vacuum oven to dry to obtain the self-sensing impact-hardening polymer.

[0024] Furthermore, the mass ratio of the impact-hardening polymer to the conductive salt is 4:1 to 32:1.

[0025] In some embodiments, the solvent is selected from one or a combination of tetrahydrofuran, dichloromethane, and N,N-dimethylformamide;

[0026] In some embodiments, the conductive salt is selected from at least one or a combination of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0027] A fourth aspect of the present invention is to provide a self-sensing impact-hardening polymer, which is prepared by a method for preparing the self-sensing impact-hardening polymer; when the self-sensing impact-hardening polymer is subjected to an impact, an electro-electrostatic inductive coupling effect is generated based on the contact between the impacting object and the interface of the impact-hardening polymer; the open-circuit voltage generated during the impact is collected and recorded by a digital source meter, and the open-circuit voltage is used as a sensing signal to realize the self-sensing of the external impact process.

[0028] A fifth aspect of the invention is to provide the application of the impact-curing polymer, or the impact-curing polymer with self-sensing capability;

[0029] Furthermore, the impact-hardening polymer can be applied to flexible protective gear, flexible electronic protective components, industrial and traffic protective devices, personal protective equipment, and medical testing.

[0030] The flexible protective gear includes, but is not limited to, personal protective equipment such as bulletproof vests, helmets, protective gloves, or joint protectors.

[0031] The flexible electronic protection components include, but are not limited to, electronic device protection components such as shatterproof mobile phone screens, chip packaging layers, or battery safety protection films.

[0032] Furthermore, based on the self-sensing capability of the aforementioned impact-hardening polymer, it can be applied to the fields of intelligent impact protection equipment, personal protective equipment, and medical testing devices. Further applications include protection for intelligent display devices, sports protection, and battery safety protection.

[0033] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0034] (1) The impact-hardening polymer provided by the present invention is obtained by copolymerization of rigid molecules and long side-chain acrylates; it has the significant advantages of high hardening index and high transparency; the transparency can reach more than 85%, and the storage modulus can increase by up to 1831 times in the frequency range from 0.1Hz to 100Hz.

[0035] (2) The present invention further provides a method for preparing impact-hardening polymers, which obtains impact-hardening polymer materials by one-step photoinitiated free radical polymerization of rigid monomers containing double bonds and long side-chain acrylate monomers. The preparation method is simple.

[0036] (3) The present invention further adds conductive salt to the impact hardening material to prepare an intelligent impact hardening polymer material that integrates hardening function and self-sensing function; when the material is subjected to impact, it can not only harden to resist impact deformation and absorb impact energy, but also sense the impact situation through changes in electrical signals. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the embodiments of the present application to explain the present application, but do not constitute a limitation thereof; in the drawings:

[0038] Figure 1 1H NMR spectrum of PS / PDEEA impact-hardened material;

[0039] Figure 2 UV transmittance of impact-hardened polymer materials;

[0040] Figure 3 Photographs demonstrating impact hardening behavior;

[0041] Figure 4 Shear frequency scans of PS / PDEEA impact hardening materials prepared with different initiator ratios;

[0042] Figure 5 Photograph of the impact-hardening polymer material prepared in Example 4;

[0043] Figure 6 Shear frequency scan of the PS / PHEA impact-hardening material prepared in Example 5;

[0044] Figure 7 Shear frequency scan of the PS / PHA impact hardening material prepared in Example 6. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification;

[0046] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0047] Example 1: Preparation of impact-hardening polymer materials:

[0048] 5.21 g styrene (50 mmol), 4.71 g ethoxyethyl acrylate (25 mmol), and 0.0990 g initiator 1173 (1 wt%) were shaken and mixed evenly. After deoxygenation by bubbling with N2 for 1 h, the mixture was injected into a sealed transparent glass mold for UV polymerization for 6 h to obtain PS / PDEEA impact-hardening polymer material.

[0049] like Figure 1 As shown, the impact-hardening polymer material prepared in Example 1 1 1H NMR analysis showed that the chemical shift peaks (ppm) were assigned as follows: 1.06 (3H, -CH3), 3.41 (2H, -CH2), 6.72 (25H, -Ph-H), proving that the PS / PDEEA copolymer was successfully prepared.

[0050] like Figure 2 As shown, the PS / PDEEA impact-curing polymer material prepared in Example 1 has a transparency of over 85% UV transmittance. As shown in Table 1, its number-average molecular weight M... n It is 12 kg / mol.

[0051] In addition, such as Figure 3As shown, slight pressure (such as finger pressure) can cause significant deformation in impact-hardened polymer materials; however, when a huge impact is applied, the impact-hardened polymer materials do not deform, indicating that they have rate sensitivity and impact hardening behavior.

[0052] like Figure 4 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 86 times from 0.1 Hz to 100 Hz.

[0053] Example 2: Preparation of impact-hardening polymer materials:

[0054] 5.21 g styrene (50 mmol), 4.71 g ethoxyethyl acrylate (25 mmol), and 0.2976 g initiator 1173 (3 wt%) were mixed by shaking and then bubbled with N2 to remove oxygen for 1 h. The mixture was then injected into a sealed transparent glass mold for UV polymerization for 6 h to obtain PS / PDEEA impact-hardening polymer material.

[0055] As shown in Table 1, its number-average molecular weight Mn is 6.7 kg / mol. Figure 4 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 256 times from 0.1 Hz to 100 Hz.

[0056] Example 3: Preparation of impact-hardening polymer materials:

[0057] 5.21 g styrene (50 mmol), 4.71 g ethoxyethyl acrylate (25 mmol), and 0.496 g initiator 1173 (5 wt%) were mixed by shaking and then bubbled with N2 to remove oxygen for 1 h. The mixture was then injected into a sealed transparent glass mold for UV polymerization for 6 h to obtain PS / PDEEA impact-hardening polymer material.

[0058] As shown in Table 1, their number-average molecular weight M n It is 5.8 kg / mol. For example... Figure 4 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 1122 times from 0.1 Hz to 100 Hz.

[0059] Example 4: Preparation of impact-hardening polymer materials:

[0060] 5.21 g styrene (50 mmol), 4.71 g ethoxyethyl acrylate (25 mmol), and 0.694 g initiator 1173 (7 wt%) were mixed evenly by shaking and then deoxygenated by bubbling with N2 for 1 h. The mixture was then injected into a sealed transparent glass mold for UV polymerization for 6 h to obtain PS / PDEEA impact-hardening polymer material.

[0061] As shown in Table 1, its number-average molecular weight Mn is 5.4 kg / mol. Figure 4 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 1831 times from 0.1 Hz to 100 Hz.

[0062] like Figure 5 As shown, the obtained impact-hardened polymer material also has a transparency of over 85% ultraviolet transmittance.

[0063] Example 5: Preparation of impact-hardening polymer materials:

[0064] 5.21 g of styrene (50 mmol), 4.61 g of 2-ethylhexyl acrylate (25 mmol), and 0.295 g of initiator 1173 (3 wt%) were mixed by shaking and then bubbled with N2 to remove oxygen for 1 h. The mixture was then injected into a sealed transparent glass mold for UV polymerization for 6 h to obtain PS / PHEA impact-hardening polymer material.

[0065] like Figure 6 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 359 times from 0.1 Hz to 100 Hz.

[0066] Example 6: Preparation of impact-hardening polymer materials:

[0067] 5.21 g styrene (50 mmol), 3.91 g hexyl acrylate (25 mmol), and 0.298 g initiator 1173 (3 wt%) were shaken and mixed evenly. After deoxygenation by bubbling with N2 for 1 h, the mixture was injected into a sealed transparent glass mold for ultraviolet light polymerization for 6 h to obtain PS / PHA impact-hardening polymer material.

[0068] like Figure 7 As shown, the frequency dependence of the impact polymer was characterized by rheology, and the storage modulus G' of the impact-hardened material increased by 566 times from 0.1 Hz to 100 Hz.

[0069] This invention constructs a single-electrode mode triboelectric nanogenerator (TENG) based on the conductivity of the PS / PDEEA copolymer / conductive salt composite system. Its sensing mechanism originates from the electro-electrostatic coupling effect induced by the contact between the impacting object and the impact-hardened polymer interface. The open-circuit voltage generated by the TENG sensor during the impact process is acquired and recorded using a digital source meter, and this open-circuit voltage is used as the sensing signal to achieve self-sensing of the external impact process.

[0070] Example 7: The preparation process of the self-sensing impact-curing polymer material is as follows:

[0071] 10g of the PS / PDEEA impact-curing polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt bis(trifluoromethanesulfonyl)imide (at a mass ratio of PS / PDEEA:LiTFSI of 6:1) was added. The mixture was then poured into a mold and the solvent was allowed to evaporate slowly at room temperature for 5 days. All the above steps were performed in a glove box. After the solvent had evaporated, the mixture was annealed in an 80°C vacuum oven to obtain the impact-curing polymer material with conductive properties.

[0072] Example 8: The preparation process of the self-sensing impact-curing polymer material is as follows:

[0073] 10g of the PS / PDEEA impact-curing polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt bis(trifluoromethanesulfonyl)imide (at a PS / PDEEA:LiTFSI mass ratio of 12:1) was added. The mixture was then poured into a mold and the solvent was allowed to evaporate slowly at room temperature for 5 days. All the above steps were performed in a glove box. After the solvent had evaporated, the mixture was annealed in an 80°C vacuum oven to obtain the impact-curing polymer material with conductive properties.

[0074] Example 9: The preparation process of the self-sensing impact-curing polymer material is as follows:

[0075] 10g of the PS / PDEEA impact-curing polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt bis(trifluoromethanesulfonyl)imide (at a mass ratio of PS / PDEEA:LiTFSI of 24:1) was added. The mixture was then poured into a mold and the solvent was allowed to evaporate slowly at room temperature for 5 days. All the above steps were performed in a glove box. After the solvent had evaporated, the mixture was annealed in an 80°C vacuum oven to obtain the impact-curing polymer material with conductive properties.

[0076] Table 1. Molecular weights of PS / PDEEA impact-hardening materials prepared with different initiator ratios.

[0077]

[0078] The preparation method proposed in this invention utilizes rigid molecules containing double bonds and long-side-chain acrylate monomers to prepare impact-hardening polymer materials via photoinitiated free radical polymerization. The resulting impact-hardening materials exhibit a high hardening index (G'). 100Hz / G' 0.1Hz =1831), and has a transparency of over 85% ultraviolet transmittance. Furthermore, traditional protective materials lack real-time status monitoring and dynamic adjustment capabilities, making them ill-suited for complex and variable impact load environments. This invention further develops an intelligent impact-hardening polymer material integrating hardening and self-sensing functions by adding conductive salts to the impact-hardening material. When subjected to impact, the material not only hardens to resist impact deformation and absorb impact energy, but also senses the impact through changes in electrical signals such as material resistance. It has broad application prospects in the field of protective materials, and is particularly suitable for intelligent impact protection equipment.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. An impact-hardening polymer with self-sensing capability, characterized in that, Based on the contact electro-electrostatic coupling effect between the impacting object and the impact-hardened polymer interface, the open-circuit voltage is used as the sensing signal to realize the self-sensing of the external impact process. The self-sensing impact-hardening polymer is prepared by dissolving the impact-hardening polymer and conductive salt in a solvent, then pouring the mixture into a mold to evaporate the solvent; the impact-hardening polymer is prepared by copolymerizing rigid molecules and long-side-chain acrylates; the molar ratio of the rigid molecules to the long-side-chain acrylates is 1:1 to 4:

1. The rigid molecule is selected from at least one of styrene, methyl methacrylate, isobornyl acrylate, and isobornyl methacrylate monomers; The long-chain acrylate is selected from 2-ethylhexyl acrylate, hexyl acrylate, and ethoxyethoxyethyl acrylate. The impact-hardening polymer has a molecular weight of M. n =2-20 kg / mol; The impact-hardening polymer has a transparency of over 85% ultraviolet transmittance; The storage modulus G' of the impact-hardening polymer increases by 86-1831 times in the frequency range from 0.1 Hz to 100 Hz.

2. The self-sensing impact-hardening polymer according to claim 1, characterized in that, The open-circuit voltage generated during the impact process is collected and recorded using a digital source meter.

3. The method for preparing the self-sensing impact-hardening polymer according to claim 1 or 2, characterized in that, By mixing the rigid molecule, long-side-chain acrylate, and photoinitiator, a photo-initiated free radical polymerization can be carried out to obtain an impact-hardening polymer. The impact-hardening polymer and conductive salt are dissolved in a solvent, and then poured into a mold to evaporate the solvent. After the solvent evaporates, the impact-hardening polymer with self-sensing capability is obtained.

4. The method for preparing the self-sensing impact-hardening polymer according to claim 3, characterized in that, The initiator is selected from one or a combination of photoinitiator 2959 or photoinitiator 1173.

5. The method for preparing the self-sensing impact-hardening polymer according to claim 3, characterized in that, The photoinitiator accounts for 1-10 wt% of the total polymer mass.

6. The method for preparing the self-sensing impact-hardening polymer according to claim 3, characterized in that, The ultraviolet light wavelength for photo-initiated free radical polymerization is 254-365 nm, and the irradiation time is 2-8 h. And / or, the mass ratio of impact-hardening polymer to conductive salt is 4:1 to 32:

1.

7. The method for preparing the self-sensing impact-hardening polymer according to claim 3, characterized in that, The solvent is selected from one or a combination of tetrahydrofuran, dichloromethane, and N,N-dimethylformamide.

8. The method for preparing the self-sensing impact-hardening polymer according to claim 3, characterized in that, The conductive salt is selected from at least one or a combination of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

9. The application of the self-sensing impact-hardening polymer as described in claim 1 or 2 in the preparation of intelligent impact protection equipment, human protective devices, and medical testing devices.

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