Epoxidized soybean oil-binary acid bio-based dynamic polymer, preparation method thereof and paper-based strain sensor packaged by epoxidized soybean oil-binary acid bio-based dynamic polymer

Abstract

The invention provides an epoxidized soybean oil-binary acid bio-based dynamic polymer, a preparation method thereof and a paper-based strain sensor packaged by the epoxidized soybean oil-binary acid bio-based dynamic polymer. The preparation method of the dynamic polymer comprises the following steps: (1) taking epoxidized soybean oil as an epoxy monomer, aliphatic dibasic acid as a flexible monomer and aromatic dibasic acid as a rigid monomer, and carrying out polymerization reaction in the presence of a transesterification catalyst to obtain a dynamic polymer prepolymer; the aliphatic binary acid comprises succinic acid, adipic acid and sebacic acid; (2) removing bubbles from the dynamic polymer prepolymer; and (3) carrying out thermal curing on the dynamic polymer prepolymer to obtain the epoxidized soybean oil-binary acid bio-based dynamic polymer. The epoxidized soybean oil-binary acid bio-based dynamic polymer has good mechanical properties and hydrophobicity, a paper-based strain sensor based on the epoxidized soybean oil-binary acid bio-based dynamic polymer also has good mechanical properties and hydrophobicity, and the sensor has certain application potential in the field of human motion monitoring.

Description

TECHNICAL FIELD

[0001] The present application relates to the cross field of bio-based materials and flexible sensing technology, in particular to an epoxy soybean oil-dibasic acid bio-based dynamic polymer, a preparation method thereof and a packaged paper-based strain sensor thereof. BACKGROUND

[0002] With the rapid development of Internet of Things and artificial intelligence, there is an increasing demand for low-cost, lightweight and environmentally friendly strain sensors in the fields of wearable devices, medical health monitoring, human-computer interaction interface and intelligent packaging. Paper-based materials, due to their natural biodegradability, flexibility, low cost and good biocompatibility, have become an ideal alternative to traditional polymer substrates (such as polydimethylsiloxane PDMS, polyurethane PU, etc.), and have shown unique advantages in the field of green electronics.

[0003] However, the inherent defects of pure paper materials seriously restrict their application: first, the poor electrical conductivity cannot meet the sensor signal transmission requirements; second, the limited mechanical properties make it difficult to adapt to the dynamic deformation scenarios of flexible electronics; third, the strong hygroscopicity easily leads to sensor performance drift or even failure. At present, the functional modification of paper-based materials is mainly achieved by loading conductive fillers (such as graphene, carbon nanotubes, etc.) or coating encapsulating materials, which can improve the electrical conductivity, mechanical properties and hydrophobicity to some extent, but most encapsulating materials rely on petroleum-based polymers (such as epoxy resin, etc.), which are non-degradable and pollute the environment, which is contrary to the development trend of green electronics under the current "double carbon" goal.

[0004] Therefore, it is urgent to develop new material systems to provide solutions to the above problems. Some researchers have introduced dynamic covalent bonds into thermosetting materials to form dynamic polymers. Dynamic polymer networks can respond to specific stimuli (such as light, heat, pH) to undergo bond exchange reactions and reorganization, maintaining the high performance of thermosetting materials and possessing the remoldability similar to thermoplastic materials. In addition, dynamic polymers are composed of dynamic covalent bonds, which have low bond energy and can quickly dissociate into oligomers or small molecules in a natural environment. Although existing dynamic polymers (especially bio-based systems) have shown potential in remoldability, renewability and degradability, there are still some problems when they are combined with paper-based strain sensors: the intrinsic defects of bio-based components result in insufficient mechanical properties, limited moisture resistance and poor synergy with paper-based substrates. SUMMARY

[0005] In view of the problems in the prior art, the present application aims to provide an epoxy soybean oil-dibasic acid bio-based dynamic polymer, a preparation method thereof and a paper-based strain sensor encapsulated with the epoxy soybean oil-dibasic acid bio-based dynamic polymer. The epoxy soybean oil-dibasic acid bio-based dynamic polymer has good mechanical properties and hydrophobicity, the paper-based strain sensor encapsulated with the epoxy soybean oil-dibasic acid bio-based dynamic polymer also has good mechanical properties and hydrophobicity, and the sensor has certain application potential in the field of human motion monitoring.

[0006] The present application is achieved by the following technical solutions: In a first aspect, the present application provides a preparation method of an epoxy soybean oil-dibasic acid bio-based dynamic polymer, comprising the following steps: (1) taking epoxy soybean oil (ESO) as an epoxy monomer, aliphatic dibasic acid as a flexible monomer and aromatic dibasic acid as a rigid monomer, and performing a polymerization reaction in the presence of an ester exchange catalyst to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer; the aliphatic dibasic acid includes succinic acid (SuA), adipic acid (AA) and sebacic acid (SeA) with different carbon chain lengths; (2) removing bubbles from the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer in a vacuum oven; (3) performing thermal curing on the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0007] Preferably, in step (1), the aromatic dibasic acid is 2,5-furandicarboxylic acid (FDCA).

[0008] Further, the molar ratio of succinic acid, adipic acid and sebacic acid in the aliphatic dibasic acid is 1:1:1.

[0009] Preferably, in step (1), the molar ratio of the epoxy groups in the epoxy soybean oil to the total amount of carboxyl groups in the aliphatic dibasic acid and the aromatic dibasic acid is 1:(0.5-1.5).

[0010] Preferably, in step (1), the molar ratio of the aliphatic dibasic acid to the aromatic dibasic acid is (1-9):(1-9).

[0011] Preferably, in step (1), the ester exchange catalyst is 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and the addition amount of the ester exchange catalyst is 0.5 wt% to 1.5 wt% of the total mass of the epoxy soybean oil, the aliphatic dibasic acid and the aromatic dibasic acid.

[0012] Preferably, in step (1), the polymerization reaction is specifically performed at 110-130℃ for 60-120 min.

[0013] Preferably, in step (2), the removing bubbles in the vacuum oven is: removing bubbles at 110-120℃ for 20-40 min.

[0014] Preferably, in step (3), the heat curing is specifically: curing at 130-140℃ for 2-4 h, and finally curing at 150-160℃ for 6-8 h.

[0015] In a second aspect, the present application provides an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared by the preparation method as described above.

[0016] In a third aspect, the present application further provides a paper-based strain sensor encapsulated by an epoxy soybean oil-dibasic acid bio-based dynamic polymer, comprising the epoxy soybean oil-dibasic acid bio-based dynamic polymer and a paper-based strain sensor, and the paper-based strain sensor is encapsulated in the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0017] In a fourth aspect, the present application provides a preparation method of the paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer, comprising the following steps: (a) Preparation of a paper-based strain sensor: first, a conductive paper is prepared by adopting plant fibers, carbon materials and water through a papermaking process; and then, the conductive paper is bonded with a wire to prepare the paper-based strain sensor.

[0018] (b) Immersing the paper-based strain sensor in an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer, and then, performing heat curing on the paper-based strain sensor after the immersion treatment, so as to finally obtain an encapsulated paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0019] Preferably, in step (a), the plant fibers can be selected from conifer pulp boards.

[0020] Preferably, in step (a), the carbon material is graphene, and the content of the graphene in the paper-based strain sensor is 10wt%-50wt%.

[0021] Preferably, in step (b), the heat curing is specifically: curing at 130-140℃ for 2-4 h, and finally curing at 150-160℃ for 6-8 h.

[0022] In a fifth aspect, the present application provides an application of the paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer in human motion monitoring.

[0023] Compared with the prior art, the present application has the following beneficial effects: The application takes biomass-derived epoxy soybean oil as an epoxy monomer, cooperates with flexible monomer aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and rigid monomer aromatic dibasic acid to construct a bio-based dynamic polymer containing hydroxyl-ester dynamic covalent bond, which has good mechanical properties (tensile strength is 1.045 MPa, elongation at break is 41.73 %) and hydrophobicity (hydrophobic angle is 102.4°). The epoxy soybean oil provides reactive epoxy groups and long chain structures, laying the foundation for the material basic toughness; the combination of succinic acid, adipic acid and sebacic acid in aliphatic dibasic acid cooperatively adjusts the flexibility of the chain segment through the difference in carbon chain length, compared with single aliphatic dibasic acid, which can not only avoid the toughness deficiency caused by short chain (succinic acid), but also improve the low strength problem caused by long chain (sebacic acid), and the long chain alkyl further enhances the hydrophobicity of the material; the aromatic dibasic acid further improves the rigidity and cooperatively improves the mechanical properties with the aliphatic unit, and its regular structure and aliphatic long chain together reduce the surface energy of the material and enhance the hydrophobicity. The reversibility of the hydroxyl-ester dynamic covalent bond ensures that the material has the above mechanical and hydrophobic properties, and also has certain processing remolding and self-repairing through dynamic reconstruction, further ensuring the performance stability and practicality. The use of biomass-derived raw materials also meets the green and environmentally friendly development concept.

[0024] The paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer has good mechanical properties (tensile strength is 19.2 MPa, elongation at break is 7.2 %) and hydrophobicity (hydrophobic angle is 99.6°), strain index GF=2.755, response time is 1.2 s, stability is greater than 1000 bending strain cycles, and can be successfully applied to the motion detection of human finger and wrist joints. It shows that it can be used as a wearable device and has wide application prospects in human motion monitoring and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The preparation flow chart of the epoxy soybean oil-dibasic acid bio-based dynamic polymer and the paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer in the embodiment 5 of the present application.

[0027] Figure 2 The Fourier transform infrared spectrum of the epoxy soybean oil-dibasic acid bio-based dynamic polymer in the embodiment 5 of the present application.

[0028] Figure 3 The stress and strain of the epoxidized soybean oil-diacid bio-based dynamic polymer in Example 5 of the present invention.

[0029] Figure 4 This refers to the water contact angle of the epoxidized soybean oil-diacid bio-based dynamic polymer in Example 5 of this invention.

[0030] Figure 5 The Fourier transform infrared spectra of the paper-based strain sensor encapsulated with epoxy soybean oil-diacid bio-based dynamic polymer in Embodiment 5 of the present invention before and after encapsulation. Figure 6 These are scanning electron microscope (SEM) images of the planar and cross-sectional aspects of the paper-based strain sensor encapsulated with an epoxidized soybean oil-diacarboxylic acid bio-based dynamic polymer in Embodiment 5 of the present invention, before and after encapsulation; a is a planar SEM of the paper-based strain sensor before encapsulation; b is a cross-sectional SEM of the paper-based strain sensor before encapsulation; c is a planar SEM of the paper-based strain sensor encapsulated with an epoxidized soybean oil-diacarboxylic acid bio-based dynamic polymer; d is a cross-sectional SEM of the paper-based strain sensor encapsulated with an epoxidized soybean oil-diacarboxylic acid bio-based dynamic polymer.

[0031] Figure 7 The stress and strain of the paper-based strain sensor encapsulated with epoxidized soybean oil-diacid bio-based dynamic polymer in Embodiment 5 of the present invention are shown before and after encapsulation.

[0032] Figure 8 The water contact angle of the paper-based strain sensor encapsulated with epoxidized soybean oil-diacid bio-based dynamic polymer in Embodiment 5 of the present invention before and after encapsulation.

[0033] Figure 9 This is a strain index diagram of the paper-based strain sensor encapsulated with epoxidized soybean oil-diacid bio-based dynamic polymer in Embodiment 5 of the present invention.

[0034] Figure 10 The response time is the paper-based strain sensor encapsulated with epoxidized soybean oil-diacid bio-based dynamic polymer in Example 5 of the present invention.

[0035] Figure 11 This represents 1000 cycles of the paper-based strain sensor encapsulated with epoxidized soybean oil-diacid bio-based dynamic polymer in Example 5 of this invention.

[0036] Figure 12 The paper-based strain sensor based on epoxy soybean oil-diacid bio-based dynamic polymer encapsulation, as described in Example 5 of this invention, is used to measure the rate of change in resistance of the finger (a) and wrist (b). The relationship curve of R / R0 over time. Detailed Implementation

[0037] The present application is herein described, by way of example only, with the comprehension that the advantages and utility thereof are not limited to specific embodiments described or suggested herein, but extend to whatever falls within the scope of the application. Although various specific embodiments of the present application are described in this specification, many other embodiments will occur to those of ordinary skill in the art, in view of the disclosure, without departing from the spirit of the application. Accordingly, the present application is not intended to be limited to the described and illustrated embodiments.

[0038] It should be understood that the process equipment or apparatus not specifically mentioned in the following examples are all conventional equipment or apparatus in the art.

[0039] It is to be understood that the terms "including", "comprising", "having" and their conjugates, denote an open ended inclusion of also other non- specifically mentioned items or steps which can be added to the ones explicitly stated or enhance the ones explicitly stated. It is also to be understood that the enumeration of identifiable methods steps does not preclude additional overall or sub-steps or materials being employed or involved in aiding with the invocations of the methods. Unless otherwise specified, the order of arrangement of the steps of the methods is merely a convenient tool to identify the steps of the methods, and is not intended to be limiting to the order of arrangement of the steps of the methods, nor to the scope of the application, which is to be determined with reference to the appended claims.

[0040] Reference Figure 1 In a preferred embodiment of the present application, the method for preparing the epoxy soybean oil-dibasic acid bio-based dynamic polymer comprises the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1: (0.5-1.5), and the molar ratio of the aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and the aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be (1-9):(1-9); wherein the molar ratio of succinic acid, adipic acid, and sebacic acid is 1:1:1; the above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 0.5 wt%-1.5 wt% of the total mass of the epoxy soybean oil and the dibasic acid is added, and heated and stirred at 110-130°C for 60-120 min to make the ester exchange catalyst react, so as to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0041] (2) The prepolymer is placed in a vacuum oven at 110-120°C for 20-40 min to remove bubbles.

[0042] (3) The prepolymer is poured into a polytetrafluoroethylene mold, and is cured in an oven (cured at 130-140°C for 2-4 h, and finally cured at 150-160°C for 6-8 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0043] Reference Figure 1 In one preferred embodiment of the present application, the paper-based strain sensor encapsulated with epoxy soybean oil-diacid bio-based dynamic polymer is prepared by the following steps: (a) Preparation of paper-based strain sensor: Firstly, a graphene paper with a graphene content of 10wt%~50wt% is prepared by a papermaking process using softwood pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip of 6 cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0044] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-diacid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by soaking is heat cured (cured at 130~140℃ for 2~4h, and finally cured at 150~160℃ for 6~8h) to obtain the paper-based strain sensor encapsulated with epoxy soybean oil-diacid bio-based dynamic polymer.

[0045] Example 1 The preparation method of the epoxy soybean oil-diacid bio-based dynamic polymer in this example includes the following steps: (1) The molar ratio of epoxy group and carboxyl group in the diacid is controlled to be 1:0.5. The molar ratio of aliphatic diacid (succinic acid, adipic acid, sebacic acid) and aromatic diacid (2,5-furandicarboxylic acid) is controlled to be 9:1. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)) with a mass of 0.5wt% of the total mass of epoxy soybean oil and diacid is added, heated and stirred at 110℃ for 120min to make it undergo polymerization reaction, and obtain the epoxy soybean oil-diacid bio-based dynamic polymer prepolymer.

[0046] (2) The epoxy soybean oil-diacid bio-based dynamic polymer prepolymer is removed from the vacuum oven at 110℃ for 40min to remove bubbles.

[0047] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 130℃ for 4h, and finally cured at 150℃ for 8h) to obtain the epoxy soybean oil-diacid bio-based dynamic polymer. Its tensile strength is 0.772 MPa, elongation at break is 36.727%, and hydrophobic angle is 100.7°.

[0048] The preparation method of the paper-based strain sensor in this example includes the following steps: (a) Preparation of paper-based strain sensor: Firstly, a graphene paper with 10wt% graphene content was prepared by a papermaking process using softwood pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking was cut into a sample of 6 cm x 1 cm, and the cut graphene paper was bonded with a wire by using a conductive copper tape, thereby preparing a graphene paper-based strain sensor.

[0049] (b) The graphene paper-based strain sensor was immersed in an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by soaking was heat cured (cured at 130°C for 4 h, and finally cured at 150°C for 8 h), and finally an epoxy soybean oil-dibasic acid bio-based dynamic polymer encapsulated paper-based strain sensor was obtained.

[0050] Example 2 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of this embodiment includes the following steps: (1) The molar ratio of epoxy group and carboxyl group in the dibasic acid is controlled to be 1:0.5. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be 5:5. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)) with a mass of 1wt% of the total mass of epoxy soybean oil and dibasic acid is added, heated and stirred at 120°C for 80 min to make it undergo a polymerization reaction, and an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is obtained.

[0051] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is placed in a vacuum oven at 110°C for 30 min to remove bubbles.

[0052] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140°C for 2 h, and finally cured at 150°C for 7 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. Its tensile strength is 1.022 MPa, the elongation at break is 33.021%, and the hydrophobic angle is 101.3°.

[0053] The preparation method of the paper-based strain sensor of this embodiment includes the following steps: (a) Preparation of paper-based strain sensor: Firstly, the needle-plywood board, graphene (5wt% water suspension) and deionized water were used to prepare the graphene paper with 30wt% graphene content by papermaking process. The graphene paper obtained by papermaking was cut into 6cm x 1 cm sample, and the cut graphene paper was bonded with the lead wire by using the conductive copper tape, so as to prepare the graphene paper-based strain sensor.

[0054] (b) The graphene paper-based strain sensor was immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by soaking was heat cured (cured at 140℃ for 2h, and finally cured at 150℃ for 7h), and finally the paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer was obtained.

[0055] Example 3 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present embodiment comprises the following steps: (1) The molar ratio of epoxy group and carboxyl group in the dibasic acid is controlled to be 1:0.5. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be 1:9. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and 1.5wt% of ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) is added, which is 1.5wt% of the total mass of epoxy soybean oil and dibasic acid, and heated and stirred at 130℃ for 60 min to make it polymerize to obtain the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0056] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer was removed from the vacuum oven at 120℃ for 20 min to remove bubbles.

[0057] (3) The prepolymer was poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140℃ for 3h, and finally cured at 160℃ for 6h) to obtain the epoxy soybean oil-dibasic acid bio-based dynamic polymer. The tensile strength is 1.038 MPa, the elongation at break is 24.091%, and the hydrophobic angle is 100.9°.

[0058] The preparation method of the paper-based strain sensor of the present embodiment comprises the following steps: (a) Preparation of paper-based strain sensor: Firstly, the graphene paper with 50wt% graphene content was prepared by papermaking process using softwood pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking was cut into a sample strip of 6cm x 1 cm, and the cut graphene paper was bonded with a wire by using a conductive copper tape, thereby preparing a graphene paper-based strain sensor.

[0059] (b) The graphene paper-based strain sensor was immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by soaking was heat cured (cured at 140°C for 3 h, and finally cured at 160°C for 6 h), and finally obtained a paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0060] Example 4 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present embodiment comprises the following steps: (1) The molar ratio of epoxy group and carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be 9:1. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 0.5wt% of the total mass of epoxy soybean oil and dibasic acid is added, heated and stirred at 130°C for 70 min to make it undergo polymerization reaction, and obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0061] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is removed from the vacuum oven at 120°C for 40 min to remove bubbles.

[0062] (3) Pour the prepolymer into a polytetrafluoroethylene mold and cure it in an oven (cured at 130°C for 2 h, and finally cured at 150°C for 7 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. Its tensile strength is 0.955 MPa, elongation at break is 34.443%, and hydrophobic angle is 99.5°.

[0063] The preparation method of the paper-based strain sensor of the present embodiment comprises the following steps: (a) Preparation of paper-based strain sensor: Firstly, the graphene paper with 20wt% graphene content was prepared by papermaking process using softwood pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking was cut into a sample strip of 6cm x 1 cm, and the cut graphene paper was bonded with a wire by using a conductive copper tape, thereby preparing a graphene paper-based strain sensor.

[0064] (b) The graphene paper-based strain sensor was immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor after soaking treatment was heat cured (cured at 130 °C for 2 h, and finally cured at 150 °C for 7 h), and finally obtained the paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0065] Example 5 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present embodiment comprises the following steps: (1) The molar ratio of epoxy group and carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be 7:3. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1wt% of the total mass of epoxy soybean oil and dibasic acid is added, heated and stirred at 120 °C for 100 min to make it undergo polymerization reaction, and obtain the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0066] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is reacted in a vacuum oven at 120 °C for 30 min to remove bubbles.

[0067] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140 °C for 2 h, and finally cured at 160 °C for 6 h) to obtain the epoxy soybean oil-dibasic acid bio-based dynamic polymer. Its tensile strength is 1.045 MPa, the elongation at break is 41.730%, and the hydrophobic angle is 102.4°.

[0068] The preparation method of the paper-based strain sensor of the present embodiment comprises the following steps: (a) Preparation of the paper-based strain sensor: First, the needle wood pulp board, graphene (5wt% water suspension) and deionized water are used to prepare the graphene paper with a graphene content of 40wt% by papermaking process. The graphene paper obtained by papermaking is cut into a sample strip of 6cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0069] (b) The graphene paper-based strain sensor was immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion was heat cured (cured at 140 °C for 3 h, and finally cured at 150 °C for 7 h) to obtain the paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0070] Example 6 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present application comprises the following steps: (1) The molar ratio of epoxy group and carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is controlled to be 2:8. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1.5wt% of the total mass of epoxy soybean oil and dibasic acid is added, heated and stirred at 110 °C for 120 min to make it undergo polymerization reaction to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0071] (2) The prepolymer is reacted in a vacuum oven at 110 °C for 40 min to remove bubbles.

[0072] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140 °C for 3 h, and finally cured at 150 °C for 7 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. Its tensile strength is 1.018 MPa, elongation at break is 35.311%, and hydrophobic angle is 101.1°.

[0073] The preparation method of the paper-based strain sensor of the present example comprises the following steps: (a) Preparation of the paper-based strain sensor: First, a graphene paper with a graphene content of 50wt% is prepared by a papermaking process using conifer pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip of 6cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0074] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat cured (cured at 140 °C for 3 h, and finally cured at 150 °C for 7 h) to obtain the paper-based strain sensor encapsulated by the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0075] Example 7 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present embodiment comprises the following steps: (1) The molar ratio of epoxy groups and carboxyl groups in the dibasic acid is regulated to be 1:1.5. The molar ratio of aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and aromatic dibasic acid (2,5-furandicarboxylic acid) is regulated to be 8:2. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 0.5wt% of the total mass of epoxy soybean oil and dibasic acid is added. The mixture is heated and stirred at 110°C for 110 min to make it undergo a polymerization reaction, thereby obtaining an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer.

[0076] (2) The prepolymer is placed in a vacuum oven at 120°C for 20 min to remove bubbles.

[0077] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 130°C for 4 h and finally cured at 150°C for 7 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. The tensile strength of the polymer is 0.896 MPa, the elongation at break is 37.536%, and the hydrophobic angle is 96.3°.

[0078] The preparation method of the paper-based strain sensor of the present embodiment comprises the following steps: (a) Preparation of the paper-based strain sensor: First, a needle-punched pulp board, graphene (5wt% aqueous suspension) and deionized water are used to prepare a graphene paper with a graphene content of 10wt% by a papermaking process. The graphene paper obtained by papermaking is cut into a sample strip with a size of 6cm×1 cm. The cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0079] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat-cured (cured at 130°C for 4 h and finally cured at 150°C for 7 h), thereby obtaining a paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer.

[0080] Example 8 The preparation method of the epoxy soybean oil-dibasic acid bio-based dynamic polymer of the present embodiment comprises the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1:1.5. The molar ratio of the aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and the aromatic dibasic acid (2,5-furan dicarboxylic acid) is controlled to be 6:4. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1wt% of the total mass of the epoxy soybean oil and the dibasic acid is added. The mixture is heated and stirred at 120℃ for 90 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer is obtained.

[0081] (2) The prepolymer is placed in a vacuum oven at 110℃ for 30 min to remove bubbles.

[0082] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140℃ for 2 h and finally cured at 150℃ for 8 h) to obtain an epoxy soybean oil-dibasic acid biobased dynamic polymer. The tensile strength thereof is 1.003 MPa, the elongation at break is 32.246%, and the hydrophobic angle is 95.8°.

[0083] The preparation method of the paper-based strain sensor of the present embodiment comprises the following steps: (a) Preparation of the paper-based strain sensor: First, a graphene paper with a graphene content of 30wt% is prepared by a papermaking process using conifer pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip with a size of 6cm×1 cm. The cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0084] (b) The graphene paper-based strain sensor is immersed in an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat-cured (cured at 140℃ for 2 h and finally cured at 150℃ for 8 h), and finally a paper-based strain sensor encapsulated based on an epoxy soybean oil-dibasic acid biobased dynamic polymer is obtained.

[0085] Example 9 The preparation method of the epoxy soybean oil-dibasic acid biobased dynamic polymer of the present application comprises the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1:1.5. The molar ratio of the aliphatic dibasic acid (succinic acid, adipic acid, sebacic acid) and the aromatic dibasic acid (2,5-furan dicarboxylic acid) is controlled to be 4:6. The molar ratio of succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1.5wt% of the total mass of epoxy soybean oil and dibasic acid is added. The mixture is heated and stirred at 130℃ for 70 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer is obtained.

[0086] (2) The prepolymer is placed in a vacuum oven at 120℃ for 20 min to remove bubbles.

[0087] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140℃ for 4h and finally cured at 160℃ for 6h) to obtain an epoxy soybean oil-dibasic acid biobased dynamic polymer. The tensile strength thereof is 1.014 MPa, the elongation at break is 31.556%, and the hydrophobic angle is 93.7°.

[0088] The preparation method of the paper-based strain sensor according to the embodiment of the application comprises the following steps: (a) Preparation of the paper-based strain sensor: first, a graphene paper with a graphene content of 40wt% is prepared by a papermaking process using conifer pulp board, graphene (5wt% water suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip with a size of 6cm×1cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0089] (b) The graphene paper-based strain sensor is immersed in an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor after immersion treatment is heat-cured (cured at 140℃ for 4h and finally cured at 160℃ for 6h), and finally a paper-based strain sensor encapsulated based on an epoxy soybean oil-dibasic acid biobased dynamic polymer is obtained.

[0090] Comparative Example 1 The preparation method of the epoxy soybean oil-dibasic acid biobased dynamic polymer in the present comparative example comprises the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of the aliphatic dibasic acid (succinic acid) and the aromatic dibasic acid (2,5-furan dicarboxylic acid) is controlled to be 7:3. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1 wt% of the total mass of the epoxy soybean oil and the dibasic acid is added. The mixture is heated and stirred at 120°C for 100 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is obtained.

[0091] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is placed in a vacuum oven at 120°C for 30 min to remove bubbles.

[0092] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140°C for 2 h and finally cured at 160°C for 6 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. The tensile strength thereof is 0.579 MPa, the elongation at break is 25.353%, and the hydrophobic angle is 91.3°.

[0093] The preparation method of the comparative example paper-based strain sensor includes the following steps: (a) Preparation of the paper-based strain sensor: First, a needle-punched pulp board, graphene (5 wt% aqueous suspension) and deionized water are used to prepare a graphene paper with a graphene content of 40 wt% by papermaking process. The graphene paper obtained by papermaking is cut into a sample strip of 6 cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0094] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor after immersion treatment is heat-cured (cured at 140°C for 2 h and finally cured at 160°C for 6 h), and finally a paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer is obtained.

[0095] Comparative Example 2 The preparation method of the comparative example epoxy soybean oil-dibasic acid bio-based dynamic polymer includes the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of the aliphatic dibasic acid (adipic acid) and the aromatic dibasic acid (2,5-furan dicarboxylic acid) is controlled to be 7:3. The monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1wt% of the total mass of the epoxy soybean oil and the dibasic acid is added. The mixture is heated and stirred at 120℃ for 100 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is obtained.

[0096] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is placed in a vacuum oven at 120℃ for 30 min to remove bubbles.

[0097] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140℃ for 2 h and finally cured at 160℃ for 6 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. The tensile strength thereof is 0.512 MPa, the elongation at break is 30.597%, and the hydrophobic angle is 97.9°.

[0098] The preparation method of the comparative example paper-based strain sensor includes the following steps: (a) Preparation of the paper-based strain sensor: First, a needle-punched pulp board, graphene (5wt% aqueous suspension) and deionized water are used to prepare a graphene paper with a graphene content of 40wt% by a papermaking process. The graphene paper obtained by papermaking is cut into a sample strip of 6cm×1 cm. The cut graphene paper is bonded with a conductive copper tape by using a conductive copper tape, thereby preparing a graphene paper-based strain sensor.

[0099] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat-cured (cured at 140℃ for 2 h and finally cured at 160℃ for 6 h), and finally a paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer is obtained.

[0100] Comparative Example 3 The preparation method of the comparative example epoxy soybean oil-dibasic acid bio-based dynamic polymer includes the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is controlled to be 1:1. The molar ratio of the aliphatic dibasic acid (sebacic acid) and the aromatic dibasic acid (2,5-furan dicarboxylic acid) is controlled to be 7:3. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1wt% of the total mass of the epoxy soybean oil and the dibasic acid is added. The mixture is heated and stirred at 120℃ for 100 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is obtained.

[0101] (2) The epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer is placed in a vacuum oven at 120℃ for 30 min to remove bubbles.

[0102] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140℃ for 2 h and finally cured at 160℃ for 6 h) to obtain an epoxy soybean oil-dibasic acid bio-based dynamic polymer. The tensile strength thereof is 0.432 MPa, the elongation at break is 32.556%, and the hydrophobic angle is 98.5°.

[0103] The preparation method of the comparative example paper-based strain sensor includes the following steps: (a) Preparation of the paper-based strain sensor: First, a graphene paper with a graphene content of 40wt% is prepared by a papermaking process using conifer pulp board, graphene (5wt% water suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip of 6cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0104] (b) The graphene paper-based strain sensor is immersed in the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat-cured (cured at 140℃ for 2 h and finally cured at 160℃ for 6 h), and finally a paper-based strain sensor encapsulated based on the epoxy soybean oil-dibasic acid bio-based dynamic polymer is obtained.

[0105] Comparative Example 4 The preparation method of the comparative example epoxy soybean oil-dibasic acid bio-based dynamic polymer includes the following steps: (1) The molar ratio of the epoxy group and the carboxyl group in the dibasic acid is 1:1. The molar ratio of the aliphatic dibasic acid succinic acid, adipic acid and sebacic acid is 1:1:1. The above monomers are mixed and an ester exchange catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene) with a mass of 1wt% of the total mass of epoxy soybean oil and dibasic acid is added, heated and stirred at 120°C for 100 min to make the polymerization reaction occur, and an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer is obtained.

[0106] (2) The epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer is removed from the vacuum oven at 120°C for 30 min to remove bubbles.

[0107] (3) The prepolymer is poured into a polytetrafluoroethylene mold and cured in an oven (cured at 140°C for 2 h and finally cured at 160°C for 6 h) to obtain an epoxy soybean oil-dibasic acid biobased dynamic polymer. Its tensile strength is 0.654 MPa, the elongation at break is 33.991%, and the hydrophobic angle is 100.6°.

[0108] The preparation method of the comparative example paper-based strain sensor includes the following steps: (a) Preparation of a paper-based strain sensor: First, a graphene paper with a graphene content of 40wt% is prepared by a papermaking process using softwood pulp board, graphene (5wt% aqueous suspension) and deionized water. The graphene paper obtained by papermaking is cut into a sample strip of 6cm x 1 cm, and the cut graphene paper is bonded with a conductive copper tape to prepare a graphene paper-based strain sensor.

[0109] (b) The graphene paper-based strain sensor is immersed in an epoxy soybean oil-dibasic acid biobased dynamic polymer prepolymer. Subsequently, the graphene paper-based strain sensor treated by immersion is heat cured (cured at 140°C for 2 h and finally cured at 160°C for 6 h), and finally a paper-based strain sensor encapsulated based on an epoxy soybean oil-dibasic acid biobased dynamic polymer is obtained.

[0110] Figure 2 The Fourier transform infrared spectrum of the epoxy soybean oil-dibasic acid biobased dynamic polymer prepared in Example 5. It can be seen that SuA, AA, SeA and FDCA appear characteristic peaks near 1701 cm -1 , which is the C=O stretching vibration peak in the carboxyl group. In addition, SuA is at 3047 cm -1 , AA is at 2966 cm -1 , SeA is at 2950 cm -1 , and FDCA is at 3151 cm -1occurred, which is the O-H stretching vibration peak in the carboxyl group. ESO characteristic peaks of the epoxy group occurred near 842 cm -1 After the polymerization reaction, the above characteristic peaks disappeared and the stretching vibration peak of the carbonyl C=O double bond in the ester bond occurred near 1735 cm -1 After the polymerization reaction, the above characteristic peaks disappeared and the stretching vibration peak of the carbonyl C=O double bond in the ester bond occurred near 1735 cm -1 The hydroxyl peak near 3500 cm -1 occurred, indicating that the epoxy soybean oil-dibasic acid bio-based dynamic polymer was successfully prepared.

[0111] Figure 3 The stress-strain diagram of the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 had a tensile strength of 1.045 MPa and an elongation at break of 41.730%.

[0112] Figure 4 The water contact angle of the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 was 102.4°.

[0113] Figure 5 The Fourier transform infrared spectra of the paper-based strain sensor packaged with the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 before and after packaging. The paper-based strain sensor packaged with the epoxy soybean oil-dibasic acid bio-based dynamic polymer did not have the characteristic peak of the epoxy group of the epoxy soybean oil near 842 cm -1 After the polymerization reaction, the above characteristic peaks disappeared and the stretching vibration peak of the carbonyl C=O double bond in the ester bond occurred near 1735 cm -1 After the polymerization reaction, the above characteristic peaks disappeared and the stretching vibration peak of the carbonyl C=O double bond in the ester bond occurred near 1735 cm -1 The graphene paper-based sensor did not have the corresponding characteristic peaks near 1735 cm -1 and 3500 cm -1 , indicating that the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer was cured in the graphene paper to form a crosslinked dynamic polymer.

[0114] Figure 6 The scanning electron microscope photos of the plane and cross-section of the paper-based strain sensor packaged with the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 before and after packaging. It can be seen that the epoxy soybean oil-dibasic acid bio-based dynamic polymer prepolymer penetrates into the fiber network pores and wraps the cellulose, and after thermal curing, the loose paper structure becomes more compact.

[0115] Figure 7Stress-strain of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 before and after encapsulation. It can be seen that the stress-strain (tensile strength of 19.2 MPa, elongation at break of 7.2 %) of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer encapsulation is significantly higher than that of paper-based strain sensor without encapsulation (tensile strength of 5 MPa, elongation at break of 2.7 %).

[0116] Figure 8 Water contact angle of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 before and after encapsulation. It can be seen that the water contact angle of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer encapsulation is 99.6°, which is greater than that of paper-based strain sensor without encapsulation (51.1°), because epoxy soybean oil-dibasic acid bio-based dynamic polymer has hydrophobicity.

[0117] Figure 9 The strain exponent GF of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 is 2.755.

[0118] Figure 10 The response time of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 is 1.2 s.

[0119] Figure 11 The paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 has almost no change in resistance change rate after 1000 bending cycle tests, still maintaining at 4%, indicating that the paper-based strain sensor has good cycle stability.

[0120] Figure 12 The resistance change rate of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 applied to fingers, wrists The resistance change rate of paper-based strain sensor based on epoxy soybean oil-dibasic acid bio-based dynamic polymer prepared in Example 5 applied to fingers, wrists

[0121] Therefore, the epoxy soybean oil-dibasic acid bio-based dynamic polymer has good mechanical properties and hydrophobic properties, and the application of the epoxy soybean oil-dibasic acid bio-based dynamic polymer in the packaging of the paper-based strain sensor can improve the performance of the paper-based strain sensor. The paper-based strain sensor obtained in Example 5 has good mechanical properties, a tensile breaking strength of 19.2 MPa, an elongation at break of 7.2%, and a surface hydrophobicity with a water contact angle of 99.6°. As a strain sensor, the strain index GF = 2.755, the response time is 1.2 s, the stability is greater than 1000 bending strain cycles, and the paper-based strain sensor can be successfully applied to the motion monitoring of joints such as fingers and wrists.

[0122] As can be seen from Comparative Example 5 and Comparative Examples 1-3, Comparative Example 1 uses only succinic acid to obtain a dynamic polymer with a significantly reduced breaking toughness relative to Example 5, Comparative Example 2 uses only adipic acid to obtain a dynamic polymer with a lower tensile strength and breaking toughness than Example 5, and Comparative Example 3 uses only sebacic acid to obtain a dynamic polymer with the most reduced tensile strength. Therefore, it is shown that the use of succinic acid, adipic acid, and sebacic acid in the aliphatic dibasic acid has a synergistic effect, ensuring that the obtained dynamic polymer has good tensile strength and breaking toughness.

[0123] The above content only illustrates the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.

Claims

1. A process for the preparation of an epoxy soybean oil-dibasic acid bio-based dynamic polymer, characterized in that, The method comprises the following steps: (1) performing a polymerization reaction in the presence of an ester exchange catalyst, using epoxy soybean oil as an epoxy monomer, aliphatic diacid as a flexible monomer, and aromatic diacid as a rigid monomer, to obtain an epoxy soybean oil-diacid bio-based dynamic polymer prepolymer; the aliphatic diacid comprises succinic acid, adipic acid, and sebacic acid; (2) removing bubbles from the epoxy soybean oil-diacid bio-based dynamic polymer prepolymer; (3) performing thermal curing on the epoxy soybean oil-diacid bio-based dynamic polymer prepolymer to obtain an epoxy soybean oil-diacid bio-based dynamic polymer.

2. The process for the preparation of an epoxy soybean oil-dibasic acid bio-based dynamic polymer according to claim 1, characterized in that, The aromatic diacid is 2,5-furan dicarboxylic acid.

3. The process for the preparation of an epoxy soybean oil-dibasic acid bio-based dynamic polymer according to claim 1, characterized in that, The molar ratio of the epoxy groups in the epoxy soybean oil to the total amount of carboxyl groups in the aliphatic diacid and the aromatic diacid is 1: (0.5-1.5).

4. The process for the preparation of epoxy soybean oil-dibasic acid bio-based dynamic polymer according to claim 1, characterized in that, The molar ratio of the aliphatic diacid to the aromatic diacid is (1-9):(1-9).

5. The process for the preparation of epoxy soybean oil-dibasic acid bio-based dynamic polymer according to claim 1, characterized in that, In step (1), the temperature of the polymerization reaction is 110-130°C, and the time is 60-120 min.

6. The process for the preparation of epoxy soybean oil-dibasic acid bio-based dynamic polymer according to claim 1, characterized in that, In step (3), the thermal curing is specifically as follows: first, curing at 130-140°C for 2-4 h, and then curing at 150-160°C for 6-8 h.

7. The epoxy soybean oil-diacid bio-based dynamic polymer obtained by the preparation method in any one of claims 1-7.

8. A paper-based strain sensor encapsulated with an epoxy soybean oil-dibasic acid bio-based dynamic polymer, characterized in that, The paper-based strain sensor is encapsulated in the epoxy soybean oil-diacid bio-based dynamic polymer.

9. The paper-based strain sensor encapsulated with bio-based dynamic polymer based on epoxidized soybean oil-dibasic acid of claim 8, wherein, The paper-based strain sensor comprises a paper base body and graphene loaded in the paper base body, and the content of the graphene in the paper-based strain sensor is 10wt%-50wt%.

10. Application of the paper-based strain sensor encapsulated based on the epoxy soybean oil-diacid bio-based dynamic polymer in claim 8 in human motion monitoring.

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