Impact hardening polymer as well as preparation method and application thereof

Abstract

The invention 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 by copolymerizing rigid molecules and long side chain acrylate; the advantages of high hardening index and high transparency are achieved; the transparency can reach 85% or above, and the storage modulus can be increased by 1831 times within the frequency range from 0.1 Hz to 100 Hz. The preparation method is simple; the photoinitiator is prepared from rigid molecules containing double bonds and a long-side-chain acrylate monomer through one-step photo-initiated free radical polymerization. The intelligent impact-hardening polymer material integrating a hardening function and a self-sensing function is prepared by adding the conductive salt into the impact-hardening material, and when the intelligent impact-hardening polymer material is impacted, the intelligent impact-hardening polymer material not only can be hardened to resist impact deformation and absorb impact energy, but also can realize the impact sensing capability through the change of electrical signals such as material resistance and the like. The method can be applied to the fields of flexible protection devices, flexible electronic protection, human body protection and medical detection.

Description

Technical Field

[0001] The invention belongs to the technical field of functional polymer materials, and in particular relates to a preparation method and application of an impact-hardening polymer. Background Art

[0002] Impact-hardening materials show flexibility under low-frequency conditions and can adapt to changes in the external environment. However, when subjected to high-speed impact or shear force, they can rapidly undergo structural changes and achieve rapid hardening, thereby significantly improving the stiffness and strength of the material. This increase in stiffness and strength enables impact-hardening materials to effectively absorb and disperse impact energy. It reflects the mechanical characteristics of "soft when weak and rigid when strong". This dynamic conversion between flexibility and rigidity makes it very important in the application of flexible protective equipment such as bulletproof vests, helmets, and protective gloves, as well as flexible electronic protection such as anti-shatter mobile phone screens, chip safety, and battery safety protection.

[0003] At present, the research on impact-hardening materials is mostly focused on polyborosiloxane materials. Polyborosiloxane is a polymer with a special structure, which contains a large number of boron-oxygen dynamic covalent bonds. These dynamic covalent bonds can undergo reversible breakage and recombination when subjected to external forces, thereby absorbing external energy and achieving the purpose of impact resistance. However, the performance of existing polyborosiloxane materials still needs to be improved. In the shear frequency range of 0.1 to 100 Hz, the increase in storage modulus is usually less than 1000 times; this limits its application in the field of high-performance intelligent protection to a certain extent. The Wu Peiyi / Sun Shengtong team of Donghua University proposed an impact-hardening supramolecular polymer; the supramolecular polymer system was constructed by the carboxyl group of polylipoic acid and the guanidine group of arginine through salt bridge hydrogen bonding. Although the storage modulus of this material is increased very much in the shear frequency range of 0.1 to 100 Hz, it appears yellow, which 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 prior art. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides an impact hardening material and a preparation method thereof. The impact hardening material prepared by the present invention has colorless transparency and a high hardening index; and based on this material, a self-sensing impact hardening material is further developed.

[0006] The first aspect of the present invention provides an impact hardening polymer, which is a rigid molecule / long side chain acrylate polymer.

[0007] An impact-hardening polymer made by copolymerizing a rigid molecule with a long side-chain acrylate;

[0008] Further, 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 a structure as shown in Formula I

[0010]

[0011] Furthermore, in Formula I, R is selected from n is an integer from 2 to 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 monomers.

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

[0014] In some embodiments, the transparency of the impact-hardening polymer is 85% or more in UV transmittance;

[0015] In some embodiments, the 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 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] The second aspect of the present invention is to provide a method for preparing the impact-hardening polymer, characterized in that the rigid molecule 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 molecule monomer to the long side chain acrylate monomer is 1:1-4:1.

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

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

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

[0021] Since traditional protective materials lack real-time status monitoring and dynamic adjustment capabilities, it is difficult to cope with complex and changeable impact load environments; by giving impact-hardening materials conductivity, their ability to sense impact external forces can be realized. Based on the impact-hardening polymer provided by the present invention, the present invention further develops an impact-hardening polymer with self-sensing ability and a preparation method thereof.

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

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

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

[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 of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate, or a combination thereof.

[0027] The fourth aspect of the present invention is to provide an impact-hardening polymer with self-sensing ability, which is prepared by the preparation method of the impact-hardening polymer with self-sensing ability; when the impact-hardening polymer with self-sensing ability is acted upon by an impact object, an electro-static induction coupling effect occurs based on the contact between the impact object and the interface of the impact-hardening polymer; the open circuit voltage generated during the impact process is collected and recorded by a digital source meter, and the open circuit voltage is used as a sensing signal to achieve self-sensing of the external impact process.

[0028] The fifth aspect of the present invention is to provide the impact hardening polymer, or the use of the impact hardening polymer with self-sensing ability;

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

[0030] The flexible protective equipment includes but is not limited to human protective equipment represented by bulletproof vests, helmets, protective gloves or joint protectors;

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

[0032] Furthermore, based on the self-sensing ability of the impact-hardening polymer with self-sensing ability, it can be applied to the field of intelligent impact protection equipment, human body protection, and medical detection devices. Furthermore, it can be applied to the protection of intelligent display equipment, sports protection, and battery safety protection.

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

[0034] (1) The impact-hardening polymer provided by the present invention is prepared 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 1831 times within the frequency range from 0.1 Hz to 100 Hz.

[0035] (2) The present invention further provides a method for preparing an impact-hardening polymer, wherein the impact-hardening polymer material is prepared by one-step photoinitiated free radical polymerization of a rigid monomer containing a double bond and a long side chain acrylate monomer, and 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 through changes in electrical signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0038] Figure 1 , NMR hydrogen spectrum of PS / PDEEA impact hardened material;

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

[0040] Figure 3 , photos demonstrating impact hardening behavior;

[0041] Figure 4 , shear frequency scanning diagram of PS / PDEEA impact hardening materials prepared with different initiator ratios;

[0042] Figure 5 , a photograph of the impact-hardening polymer material obtained in Example 4;

[0043] Figure 6 , shear frequency scanning diagram of the PS / PHEA impact hardening material prepared in Example 5;

[0044] Figure 7 , shear frequency scan diagram of the PS / PHA impact hardening material prepared in Example 6. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification;

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

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

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

[0049] like Figure 1 As shown, the impact hardening polymer material prepared in Example 1 1 H NMR showed that the chemical shift peaks (ppm) were assigned to: 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 in Table 1, the PS / PDEEA impact-hardening polymer material prepared in Example 1 has a UV transmittance of more than 85%. n It is 12kg / mol.

[0051] In addition, if Figure 3As shown, slight pressure (such as finger pressure) will cause the impact-hardening polymer material to produce a large deformation; but when a huge impact is applied, the impact-hardening polymer material will not deform, indicating that it has 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 86 times in the frequency range from 0.1 Hz to 100 Hz.

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

[0054] 5.21 g of styrene (50 mmol), 4.71 g of ethoxyethoxyethyl acrylate (25 mmol), and 0.2976 g of initiator 1173 (3 wt%) were shaken and mixed evenly, and then deoxygenated by bubbling with N2 for 1 hour. The mixture was then injected into a sealed transparent glass mold and subjected to UV polymerization for 6 hours to obtain a 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 256 times in the frequency range from 0.1 Hz to 100 Hz.

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

[0057] 5.21 g of styrene (50 mmol), 4.71 g of ethoxyethoxyethyl acrylate (25 mmol), and 0.496 g of initiator 1173 (5 wt%) were shaken and mixed evenly, and then deoxygenated by bubbling with N2 for 1 hour. The mixture was then injected into a sealed transparent glass mold and subjected to UV polymerization for 6 hours to obtain a PS / PDEEA impact-hardening polymer material.

[0058] As shown in Table 1, its number average molecular weight M n is 5.8kg / 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 1122 times in the frequency range from 0.1 Hz to 100 Hz.

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

[0060] 5.21 g of styrene (50 mmol), 4.71 g of ethoxyethoxyethyl acrylate (25 mmol), and 0.694 g of initiator 1173 (7 wt%) were shaken and mixed evenly, and then deoxygenated by bubbling with N2 for 1 hour. The mixture was then injected into a sealed transparent glass mold and subjected to UV polymerization for 6 hours to obtain a 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 in the frequency range from 0.1 Hz to 100 Hz.

[0062] like Figure 5 As shown, the prepared impact-hardening polymer material also has a transparency with an ultraviolet transmittance of more than 85%.

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

[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 shaken and mixed evenly, and then deoxygenated by bubbling with N2 for 1 hour. The mixture was then injected into a sealed transparent glass mold and subjected to UV polymerization for 6 hours to obtain a 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 in the frequency range from 0.1 Hz to 100 Hz.

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

[0067] 5.21 g of styrene (50 mmol), 3.91 g of hexyl acrylate (25 mmol), and 0.298 g of initiator 1173 (3 wt%) were shaken and mixed evenly, and then deoxygenated by bubbling with N2 for 1 hour. The mixture was then injected into a sealed transparent glass mold and subjected to UV polymerization for 6 hours to obtain a 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 566 times in the frequency range from 0.1 Hz to 100 Hz.

[0069] Based on the conductive properties of the PS / PDEEA copolymer / conductive salt composite system, the present invention constructs a single-electrode mode triboelectric nanogenerator (TENG), whose sensing mechanism originates from the contact electrification-electrostatic induction coupling effect between the impact object and the impact-hardened polymer interface. The open-circuit voltage generated by the TENG sensor during the impact process is collected and recorded by a digital source meter, and the open-circuit voltage is used as a sensing signal to realize self-sensing of the external impact process.

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

[0071] 10g of PS / PDEEA impact hardening polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt lithium bis(trifluoromethylsulfonyl)imide (PS / PDEEA: LiTFSI mass ratio was 6:1) was added, and then cast into a mold and the solvent was slowly evaporated at room temperature for 5 days. The above steps were all completed in a glove box. After the solvent evaporated, it was placed in a vacuum oven at 80°C for annealing to obtain an impact hardening polymer material with conductive properties.

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

[0073] 10g of PS / PDEEA impact-hardening polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt lithium bis(trifluoromethylsulfonyl)imide (PS / PDEEA: LiTFSI mass ratio was 12:1) was added, and then cast into a mold and the solvent was slowly evaporated at room temperature for 5 days. The above steps were all completed in a glove box. After the solvent evaporated, it was placed in a vacuum oven at 80°C for annealing to obtain an impact-hardening polymer material with conductive properties.

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

[0075] 10g of PS / PDEEA impact hardening polymer prepared in Example 1 was dissolved in tetrahydrofuran solvent, and conductive lithium salt lithium bis(trifluoromethylsulfonyl)imide (PS / PDEEA: LiTFSI mass ratio was 24:1) was added, and then cast into a mold and the solvent was slowly evaporated at room temperature for 5 days. The above steps were all completed in a glove box. After the solvent evaporated, it was placed in a vacuum oven at 80°C for annealing to obtain an impact hardening polymer material with conductive properties.

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

[0077]

[0078] The preparation method proposed in the present invention utilizes rigid molecules containing double bonds and long side chain acrylate monomers to prepare impact-hardening polymer materials through photoinitiated free radical polymerization, and the prepared impact-hardening polymer materials have a high hardening index (G' 100Hz / G' 0.1Hz =1831), and has a transparency with an ultraviolet transmittance of more than 85%. In addition, based on the current situation that traditional protective materials lack real-time status monitoring and dynamic adjustment capabilities, it is difficult to cope with complex and changeable impact load environments. The present invention further prepares an intelligent impact-hardening polymer material that integrates hardening function and self-sensing function by adding conductive salts to the impact-hardening material. When the material is subjected to impact, it can not only harden to resist impact deformation and absorb impact energy, but also realize the ability to perceive impact through changes in electrical signals such as material resistance. It has broad application prospects in the field of protective materials; it 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 rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. An impact-hardening polymer, characterized in that It is made by copolymerizing rigid molecules with long side chain acrylates; The rigid molecule is selected from at least one of styrene, methyl methacrylate, isobornyl acrylate, and isobornyl methacrylate monomers; The long side chain acrylate has a structure shown in Formula I In Formula I, R is selected from or n is an integer from 2 to 18.

2. The impact-hardening polymer according to claim 1, characterized in that The molecular weight of the impact-hardening polymer is M n =2-20kg / mol.

3. The impact-hardening polymer according to claim 1 or 2, characterized in that The transparency of the impact-hardening polymer is more than 85% of ultraviolet transmittance; The storage modulus G' of the impact hardening material increases by 50-2000 times in the frequency range from 0.1 Hz to 100 Hz.

4. The method for preparing the impact-hardening polymer according to any one of claims 1 to 3, characterized in that: The rigid molecule monomer, the long side chain acrylate monomer and the photoinitiator are mixed, and the free radical polymerization is initiated by light to obtain an impact hardening polymer; And / or, the molar ratio of the rigid molecule monomer to the long side chain acrylate monomer is 1:1-4:

1.

5. The method for preparing an impact-hardening polymer according to claim 4, characterized in that: The initiator is selected from one or a combination of photoinitiator 2959 or photoinitiator 1173; and / or, the photoinitiator accounts for 1-10wt% of the total mass of the polymer; And / or, the wavelength of ultraviolet light for photo-initiated free radical polymerization is 254-365 nm, and the illumination time is 2-8 h.

6. A method for preparing an impact-hardening polymer having self-sensing ability, characterized in that: The impact-hardening polymer according to any one of claims 1 to 3 and a conductive salt are dissolved in a solvent, and then poured into a mold to volatilize the solvent. After the solvent evaporates, an impact-hardening polymer with self-sensing ability can be obtained.

7. The method for preparing a self-sensing impact-hardening polymer according to claim 6, characterized in that: The mass ratio of the impact hardening polymer to the conductive salt is 4:1-32:

1.

8. The method for preparing a self-sensing impact-hardening polymer according to claim 6, characterized in that: The solvent is selected from one or a combination of tetrahydrofuran, dichloromethane, and N,N-dimethylformamide; And / or, the conductive salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate or a combination thereof.

9. The self-sensing impact-hardening polymer obtained by the method according to any one of claims 6 to 8, characterized in that: Based on the contact electrification-electrostatic induction coupling effect between the impact object and the interface of the impact-hardening polymer, the open-circuit voltage generated during the impact process is collected and recorded by a digital source meter, and the open-circuit voltage is used as a sensing signal to achieve self-perception of the external impact process.

10. Application of the impact-hardening polymer according to any one of claims 1 to 3 in flexible protective gear, sports protective equipment, flexible electronic protective components, industrial and traffic protective devices, human protection, and medical testing; Or, the use of the self-sensing impact-hardening polymer obtained by the method described in any one of claims 6 to 8 is applied to intelligent impact protection equipment, human body protection, and medical detection devices.

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