Biaxially-oriented reinforced polymer / carbon tube composite membrane as well as preparation method and application thereof

Abstract

The invention discloses a biaxially-oriented reinforced polymer / carbon tube composite membrane as well as a preparation method and application thereof. The preparation method of the biaxially oriented reinforced polymer / carbon tube composite membrane comprises the following steps: S1, mixing a modifier with polycaprolactone triol, then adding a cross-linking agent and a catalyst, and reacting to obtain modified polycaprolactone triol; s2, adding a carbon nanotube and the modified polycaprolactone triol into a solvent, and uniformly stirring and dispersing to obtain a carbon nanotube-modified polycaprolactone triol mixed solution; pouring the mixture into a mold, and drying and curing to obtain a carbon nanotube-modified polycaprolactone three-mellow tablet; and S3, putting the carbon nanotube-modified polycaprolactone three-mellow sheet into a stretcher, and carrying out transverse stretching and longitudinal stretching, so as to obtain the two-way stretching reinforced polymer / carbon tube composite membrane. Researches show that the biaxially oriented reinforced polymer / carbon tube composite membrane not only has better tensile property, but also has better electromechanical response property.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a biaxially stretched reinforced polymer / carbon tube composite film and a preparation method and application thereof. Background Art

[0002] Although various sensors have been developed, such as metal and semiconductor sensors, for monitoring human motion signals, these traditional sensors cannot cope with irregular large strain motion signals generated during exercise, such as stretching, bending and twisting of joints such as knees, elbows and wrists. Sensors assembled from conductive polymers with stretch-sensitive properties are wearable and flexible, and can accurately measure various complex strain motion signals of the human body.

[0003] However, at present, conductive composite materials have the problem of imbalance between electromechanical response performance and tensile performance, and the flexible substrates of composite materials are mostly made of petroleum-based monomers, which is not conducive to the sustainable use of resources. Therefore, it is urgent to develop bio-based conductive composite materials with good electromechanical response performance and tensile performance. Summary of the invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, the present invention provides a biaxially stretched reinforced polymer / carbon tube composite film and a preparation method and application thereof.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention first provides a method for preparing a biaxially stretched reinforced polymer / carbon tube composite film, which comprises the following steps:

[0007] S1. The modified substance is mixed with polycaprolactone triol, followed by adding a crosslinking agent and a catalyst to react to obtain a modified polycaprolactone triol; the modified substance is selected from vegetable oil;

[0008] S2. The carbon nanotubes and modified polycaprolactone triol are added to a solvent, stirred and dispersed to obtain a carbon nanotube - modified polycaprolactone triol mixture; then the carbon nanotube - modified polycaprolactone triol mixture is poured into a mold, dried and cured to obtain a carbon nanotube - modified polycaprolactone triol thick sheet;

[0009] S3. Place the carbon nanotube-modified polycaprolactone triol thick sheet into a stretching machine for transverse stretching and longitudinal stretching to obtain the biaxially stretched reinforced polymer / carbon nanotube composite film.

[0010] Vegetable oil is one of the most important renewable resources due to its wide availability, low cost and sustainability. Its saturated and unsaturated triester fatty acid structure provides abundant active chemical sites for the preparation of flexible substrates and functional derivatives with high mechanical properties; therefore, flexible polymer materials based on vegetable oil can be used as good substrates for conductive composite materials. Polycaprolactone triol has been widely used in tissue engineering, artificial skin, drug delivery systems and other fields due to its good biocompatibility and degradability. It can effectively improve the tensile properties of flexible substrates by using it as a soft segment. Carbon nanotubes have attracted widespread attention due to their high aspect ratio, low density, excellent conductivity and thermal stability; introducing CNT as a conductive filler into a flexible matrix is ​​conducive to the development of conductive composite materials with high sensitivity and electromechanical response stability.

[0011] Studies have shown that the biaxially stretched reinforced polymer / carbon nanotube composite film prepared by using vegetable oil as a modifier to modify polycaprolactone triol and further compounding it with carbon nanotubes has good tensile properties; in addition, it also has good electromechanical response performance.

[0012] Preferably, the mass ratio of the modified substance to the polycaprolactone triol is 10-20:80-90.

[0013] Most preferably, the mass ratio of the modified substance to the polycaprolactone triol is 15:85.

[0014] Preferably, in step S1, the amount of the cross-linking agent added is 1-5% of the total mass of the modified product and the polycaprolactone triol; and the amount of the catalyst added is 0.1-1% of the total mass of the modified product and the polycaprolactone triol.

[0015] Preferably, the cross-linking agent is cross-linking agent IPDI.

[0016] Preferably, the catalyst is catalyst DBTDL.

[0017] Preferably, the reaction in step S1 specifically refers to reacting at 60-70° C. for 3-6 hours;

[0018] Most preferably, the reaction in step S1 specifically refers to reacting at 65° C. for 5 hours.

[0019] Preferably, the modified substance in step S1 is epoxidized soybean oil.

[0020] Preferably, the modified substance in step S1 comprises epoxidized soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid.

[0021] The inventors discovered in their research that, in the process of preparing the biaxially stretched reinforced polymer / carbon tube composite film described in the present invention, the selection of the modifier plays an important role in the tensile properties of the biaxially stretched reinforced polymer / carbon tube composite film; the inventors surprisingly discovered in further research that when the modifier is selected from a combination of epoxy soybean oil and 3-(3,4-dihydroxyphenyl) propionic acid to prepare the biaxially stretched reinforced polymer / carbon tube composite film, its tensile properties are much higher than those of the biaxially stretched reinforced polymer / carbon tube composite film prepared using only epoxy soybean oil as the modifier.

[0022] Preferably, the mass ratio of the epoxy soybean oil to the 3-(3,4-dihydroxyphenyl)propionic acid is 50-60:40-50.

[0023] Most preferably, the mass ratio of epoxidized soybean oil to 3-(3,4-dihydroxyphenyl)propionic acid is 57:43.

[0024] Preferably, the modified product is prepared by the following method: mixing epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid, and stirring in an oil bath at 130-150° C. for 30-60 min.

[0025] The inventors also found in further research that the preparation process of the modified material is also very critical; in the preparation process of the biaxially stretched reinforced polymer / carbon tube composite film of the present invention, the modified material obtained by mixing epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid and further preparing it by oil bath can further improve the tensile properties of the prepared biaxially stretched reinforced polymer / carbon tube composite film, compared with the modified material obtained by directly adding the epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid.

[0026] Most preferably, the modified product is prepared by the following method: mixing epoxidized soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid, and stirring in an oil bath at 140° C. for 40 minutes.

[0027] Preferably, in step S2, the mass ratio of carbon nanotubes to modified polycaprolactone triol is 1-10:90-99.

[0028] Most preferably, in step S2, the mass ratio of carbon nanotubes to modified polycaprolactone triol is 7:93.

[0029] Preferably, in step S2, the ratio of the total mass of the carbon nanotubes and the modified polycaprolactone triol to the amount of the solvent is 1 g: 3-6 mL.

[0030] Most preferably, in step S2, the ratio of the total mass of the carbon nanotubes and the modified polycaprolactone triol to the amount of the solvent is 1 g:4 mL.

[0031] Preferably, in step S2, the carbon nanotubes are single-walled carbon nanotubes or multi-walled carbon nanotubes.

[0032] Preferably, in step S2, the solvent is tetrahydrofuran.

[0033] The present invention also provides a biaxially stretched reinforced polymer / carbon tube composite film prepared by the above preparation method.

[0034] The present invention also provides an application of the biaxially stretched reinforced polymer / carbon tube composite film in the preparation of a highly sensitive biosensor.

[0035] Beneficial effects: The present invention provides a novel method for preparing a biaxially stretched reinforced polymer / carbon tube composite film; studies have shown that the biaxially stretched reinforced polymer / carbon tube composite film prepared by the method of the present invention not only has good tensile properties, but also has good electromechanical response performance; therefore, using it to prepare a high-sensitivity biosensor has important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a graph showing the sensitivity coefficient experimental results of the biaxially stretched reinforced polymer / carbon tube composite film of the present invention.

[0037] Figure 2 This is a graph showing the cyclic durability test results of the biaxially stretched reinforced polymer / carbon tube composite film of the present invention.

[0038] Figure 3 This is a graph showing the results of an experiment on the electromechanical response signals of the biaxially stretched reinforced polymer / carbon tube composite film of the present invention for monitoring walking, uphill and downhill motion states. DETAILED DESCRIPTION

[0039] The present invention is further explained below in conjunction with specific examples, but the examples do not limit the present invention in any form.

[0040] Example 1 Preparation of biaxially stretched reinforced polymer / carbon tube composite film

[0041] S1. The modified substance is mixed with polycaprolactone triol, and then a crosslinking agent IPDI and a catalyst DBTDL are added, and the reaction is carried out at 65°C for 5 hours to obtain a modified polycaprolactone triol; wherein the amount of the crosslinking agent added is 2% of the total mass of the modified substance and the polycaprolactone triol; the amount of the catalyst added is 0.5% of the total mass of the modified substance and the polycaprolactone triol; the mass ratio of the modified substance to the polycaprolactone triol is 15:85, and the modified substance is epoxidized soybean oil;

[0042] S2. Add multi-walled carbon nanotubes and modified polycaprolactone triol to a solvent, stir for 1 hour, and ultrasonically vibrate for 30 minutes to uniformly disperse the carbon nanotubes and modified polycaprolactone triol to obtain a carbon nanotube-modified polycaprolactone triol mixed solution; then pour the carbon nanotube-modified polycaprolactone triol mixed solution into a polytetrafluoroethylene mold, and cure it in an oven at 70°C for 10 hours to obtain a carbon nanotube-modified polycaprolactone triol thick sheet; wherein the mass ratio of carbon nanotubes to modified polycaprolactone triol is 7:93; the total mass ratio of carbon nanotubes and modified polycaprolactone triol to the amount of solvent is 1g:4mL; the solvent is tetrahydrofuran; the carbon nanotubes are multi-walled carbon nanotubes;

[0043] S3. Place the carbon nanotube-modified polycaprolactone triol thick sheet into a stretching machine for transverse stretching and longitudinal stretching to prepare a biaxially stretched reinforced polymer / carbon nanotube composite film with a thickness of 20 μm.

[0044] Example 2 Preparation of biaxially stretched reinforced polymer / carbon tube composite film

[0045] S1. The modified product is mixed with polycaprolactone triol, and then a crosslinking agent IPDI and a catalyst DBTDL are added, and the mixture is reacted at 65° C. for 5 hours to obtain a modified polycaprolactone triol; wherein the amount of the crosslinking agent added is 2% of the total mass of the modified product and the polycaprolactone triol; the amount of the catalyst added is 0.5% of the total mass of the modified product and the polycaprolactone triol; the mass ratio of the modified product to the polycaprolactone triol is 15:85, and the modified product is a mixture of epoxy soybean oil and 3-(3,4-dihydroxyphenyl) propionic acid in a mass ratio of 57:43;

[0046] S2. Add multi-walled carbon nanotubes and modified polycaprolactone triol to a solvent, stir for 1 hour, and ultrasonically vibrate for 30 minutes to uniformly disperse the carbon nanotubes and modified polycaprolactone triol to obtain a carbon nanotube-modified polycaprolactone triol mixed solution; then pour the carbon nanotube-modified polycaprolactone triol mixed solution into a polytetrafluoroethylene mold, and cure it in an oven at 70°C for 10 hours to obtain a carbon nanotube-modified polycaprolactone triol thick sheet; wherein the mass ratio of carbon nanotubes to modified polycaprolactone triol is 7:93; the total mass ratio of carbon nanotubes and modified polycaprolactone triol to the amount of solvent is 1g:4mL; the solvent is tetrahydrofuran; the carbon nanotubes are multi-walled carbon nanotubes;

[0047] S3. Place the carbon nanotube-modified polycaprolactone triol thick sheet into a stretching machine for transverse stretching and longitudinal stretching to prepare a biaxially stretched reinforced polymer / carbon nanotube composite film with a thickness of 20 μm.

[0048] Example 3 Preparation of biaxially stretched reinforced polymer / carbon tube composite film

[0049] S1. The modified product is mixed with polycaprolactone triol, and then a crosslinking agent IPDI and a catalyst DBTDL are added, and the reaction is carried out at 65° C. for 5 hours to obtain a modified polycaprolactone triol; wherein the amount of the crosslinking agent added is 2% of the total mass of the modified product and the polycaprolactone triol; the amount of the catalyst added is 0.5% of the total mass of the modified product and the polycaprolactone triol; the mass ratio of the modified product to the polycaprolactone triol is 15:85;

[0050] S2. Add multi-walled carbon nanotubes and modified polycaprolactone triol to a solvent, stir for 1 hour, and ultrasonically vibrate for 30 minutes to uniformly disperse the carbon nanotubes and modified polycaprolactone triol to obtain a carbon nanotube-modified polycaprolactone triol mixed solution; then pour the carbon nanotube-modified polycaprolactone triol mixed solution into a polytetrafluoroethylene mold, and cure it in an oven at 70°C for 10 hours to obtain a carbon nanotube-modified polycaprolactone triol thick sheet; wherein the mass ratio of carbon nanotubes to modified polycaprolactone triol is 7:93; the total mass ratio of carbon nanotubes and modified polycaprolactone triol to the amount of solvent is 1g:4mL; the solvent is tetrahydrofuran; the carbon nanotubes are multi-walled carbon nanotubes;

[0051] S3. Place the carbon nanotube-modified polycaprolactone triol thick sheet into a stretching machine for transverse stretching and longitudinal stretching to prepare a biaxially stretched reinforced polymer / carbon nanotube composite film with a thickness of 20 μm.

[0052] The modified product described in step S1 is prepared by the following method: epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid are mixed in a mass ratio of 15:85, and stirred in an oil bath at 140° C. for 40 minutes to obtain the modified product.

[0053] Comparative Example 1 Preparation of Biaxially Stretched Reinforced Polymer / Carbon Tube Composite Film

[0054] S1. Adding a crosslinking agent IPDI and a catalyst DBTDL to polycaprolactone triol, reacting at 65°C for 5h, to obtain a polycaprolactone triol polymer; wherein the amount of the crosslinking agent added is 2% by mass of the polycaprolactone triol; and the amount of the catalyst added is 0.5% by mass of the polycaprolactone triol;

[0055] S2. Add multi-walled carbon nanotubes and polycaprolactone triol polymer to a solvent, stir for 1 hour, and ultrasonically vibrate for 30 minutes to uniformly disperse the carbon nanotubes-polycaprolactone triol polymer mixture; then pour the carbon nanotube-polycaprolactone triol polymer mixture into a polytetrafluoroethylene mold, and cure it in an oven at 70°C for 10 hours to obtain a carbon nanotube-polycaprolactone triol polymer thick sheet; wherein the mass ratio of carbon nanotubes to polycaprolactone triol polymer is 7:93; the total mass ratio of carbon nanotubes to polycaprolactone triol polymer to solvent is 1g:4mL; the solvent is tetrahydrofuran; the carbon nanotubes are multi-walled carbon nanotubes;

[0056] S3. Place the carbon nanotube-polycaprolactone triol polymer thick sheet into a stretching machine for transverse stretching and longitudinal stretching to prepare a biaxially stretched reinforced polymer / carbon nanotube composite film with a thickness of 20 μm.

[0057] Experimental Example 1 Tensile Properties Test

[0058] The tensile properties of the samples were characterized using a universal mechanical properties testing machine (MTS Systems (China) Co., Ltd.). The samples were cut into 20 mm × 10 mm × 1 mm specifications and tested at a tensile rate of 50 mm / min at room temperature. Five parallel experiments were set for each group of samples, and the final data were averaged; the test results are shown in Table 1.

[0059] The samples are biaxially stretched reinforced polymer / carbon tube composite films prepared in Examples 1 to 3 and Comparative Example 1.

[0060] Table 1. Mechanical properties test results of a biaxially stretched reinforced polymer / carbon tube flexible wearable sensor of the present invention

[0061]

[0062] It can be seen from the experimental data in Table 1 that the tensile strength and elongation at break of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 1 are significantly higher than those of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Comparative Example 1; this indicates that the biaxially stretched reinforced polymer / carbon tube composite film prepared by the present invention using vegetable oil as a modifier to modify polycaprolactone triol and further compounding it with carbon nanotubes has significantly higher tensile properties than the biaxially stretched reinforced polymer / carbon tube composite film prepared without adding vegetable oil.

[0063] It can be seen from the experimental data in Table 1 that the tensile strength and elongation at break of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 2 are much higher than those of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 1; this shows that in the preparation process of the biaxially stretched reinforced polymer / carbon tube composite film described in the present invention, the selection of the modifier plays an important role in the tensile properties of the biaxially stretched reinforced polymer / carbon tube composite film; the above study shows that when the modifier is selected from the combination of epoxy soybean oil and 3-(3,4-dihydroxyphenyl) propionic acid to prepare the biaxially stretched reinforced polymer / carbon tube composite film, its tensile properties are much higher than those of the biaxially stretched reinforced polymer / carbon tube composite film prepared using only epoxy soybean oil as the modifier.

[0064] It can be seen from the experimental data in Table 1 that the tensile strength and elongation at break of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 3 are further significantly higher than those of the biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 2; this shows that the preparation process of the modified product of the present invention is also very critical; in the preparation process of the biaxially stretched reinforced polymer / carbon tube composite film of the present invention, the modified product prepared by mixing epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid and further mixing them through an oil bath can further improve the tensile properties of the prepared biaxially stretched reinforced polymer / carbon tube composite film, compared with the modified product obtained by directly mixing epoxy soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid.

[0065] Experimental Example 2 Sensitivity Test

[0066] The biaxially stretched reinforced polymer / carbon tube composite film prepared in Example 3 was cut into rectangular strips, and conductive silver paste was evenly applied on both ends and dried at room temperature. Then, copper wires were connected to the parts coated with conductive silver paste at both ends, and finally wrapped with electrical insulating tape to obtain an assembled strain sensor.

[0067] The electromechanical properties of the strain sensor were measured using a digital multimeter (Keithley 2401) and a CHI760E workstation (CHInstruments, Austin, TX, USA). When a certain stress is applied to the flexible sensor, the resistance value of the sensor will change accordingly. The gauge factor (GF) is considered to be an important parameter for quantitatively evaluating the sensitivity of the sensor and represents the typical strain-to-resistance response law. GF can be expressed as the following equation

[0068]

[0069] where ΔR is the resistance change and Δε is the tensile strain.

[0070] Depend on Figures 1 to 3 It can be seen that the biaxially stretched reinforced polymer / carbon tube composite film prepared by the present invention has good electrochemical stability and signal response performance. After cycling 200 times under a strain of 10%, its resistance signal does not decay, and its sensitivity can reach up to 805.67 under a high strain of 92% to 100%. It can be seen that the sensor made of the biaxially stretched reinforced polymer / carbon tube composite film described in the present invention can have excellent recognition ability for different degrees of joint bending, can monitor local movement behavior of the human body, and can even detect changes in vocal cord vibration.

Claims

1. A method for preparing a biaxially stretched reinforced polymer / carbon tube composite film, characterized in that: The following steps are included: S1. The modified substance is mixed with polycaprolactone triol, followed by adding a crosslinking agent and a catalyst to react to obtain a modified polycaprolactone triol; the modified substance is selected from vegetable oil; S2. The carbon nanotubes and modified polycaprolactone triol are added to a solvent, stirred and dispersed to obtain a carbon nanotube - modified polycaprolactone triol mixture; then the carbon nanotube - modified polycaprolactone triol mixture is poured into a mold, dried and cured to obtain a carbon nanotube - modified polycaprolactone triol thick sheet; S3. Place the carbon nanotube-modified polycaprolactone triol thick sheet into a stretching machine for transverse stretching and longitudinal stretching to obtain the biaxially stretched reinforced polymer / carbon nanotube composite film.

2. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: The mass ratio of the modified substance to the polycaprolactone triol is 10-20:80-90; Most preferably, the mass ratio of the modified substance to the polycaprolactone triol is 15:

85.

3. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: In step S1, the amount of the cross-linking agent added is 1-5% of the total mass of the modified product and the polycaprolactone triol; the amount of the catalyst added is 0.1-1% of the total mass of the modified product and the polycaprolactone triol.

4. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: The reaction in step S1 specifically refers to reacting at 60-70° C. for 3-6 hours.

5. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: The modified substance described in step S1 is epoxidized soybean oil.

6. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: The modified product in step S1 comprises epoxidized soybean oil and 3-(3,4-dihydroxyphenyl)propionic acid.

7. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: In step S2, the mass ratio of carbon nanotubes to modified polycaprolactone triol is 1-10:90-99.

8. The method for preparing a biaxially stretched reinforced polymer / carbon tube composite film according to claim 1, characterized in that: In step S2, the ratio of the total mass of the carbon nanotubes and the modified polycaprolactone triol to the amount of the solvent is 1:3-6.

9. The biaxially stretched reinforced polymer / carbon tube composite film prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the biaxially stretched reinforced polymer / carbon tube composite film according to claim 9 in the preparation of a highly sensitive biosensor.

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