Dielectric enhanced sulfhydrylation multi-walled carbon nanotube / esterfication SBS elastomer composite film and preparation method thereof
By grafting ester compounds onto polybutadiene segments of SBS and combining them with thiolized multi-walled carbon nanotubes, the problems of low dielectric constant and easy damage of dielectric elastomer materials were solved, achieving efficient electro-induced deformation and self-repair effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG UNIV OF PETROCHEMICAL TECH
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing dielectric elastomer materials have low dielectric constants, require high-voltage electric fields to drive them, are prone to electrical breakdown, and suffer mechanical damage due to repeated expansion and contraction.
By grafting ester-containing compounds onto the polybutadiene segments of SBS through click chemistry and combining them with thiolized multi-walled carbon nanotubes, a thiolized multi-walled carbon nanotube/esterified SBS elastomer composite film is formed, which improves the dielectric constant and achieves self-healing.
It significantly improves the dielectric constant of the material, enhances its electrodeformation capability, and gives it self-healing ability, thus extending its service life.
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Figure CN122011454A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of SBS dielectric elastomer modification technology, and in particular to a dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film and its preparation method. Background Technology
[0002] Dielectric elastomers and polymers have many advantages, such as large electroinduced deformation, fast deformation recovery, good flexibility, high energy density, short response time, high conversion efficiency, light weight, and low manufacturing cost, and have broad application prospects in fields such as actuators, sensors, mechanical energy harvesting systems, soft robots, electronic skin, and artificial muscles. However, the application of dielectric elastomers and polymers is still limited by two major factors: (1) their dielectric constant is low (usually below 10), so high-voltage electric fields are often required to drive them to achieve the deformation requirements for practical use; (2) high driving electric fields and pre-stretching operations before use can easily cause electrical breakdown of the material, while repeated expansion and contraction during use inevitably cause mechanical damage to the material. Therefore, (1) how to improve the dielectric constant of the material to maximize the electroinduced deformation capability under limited driving electric field conditions and (2) how to enable the material to self-repair the damage caused by electric and mechanical fields to extend its service life are two important research topics in the field of dielectric elastomers.
[0003] Triblock polystyrene-butadiene-polystyrene (SBS) elastomers possess good deformability and high electric field breakdown strength, but their dielectric constant is only around 2. Notably, the polybutadiene segments of SBS contain double bonds, creating conditions for further functionalization and modification to improve performance. Therefore, grafting ester-containing compounds onto the polybutadiene segments of SBS via click chemistry can improve the dielectric constant while simultaneously enabling self-repair of material damage. Furthermore, multi-walled carbon nanotubes (MWCNTs), as commonly used dielectric-enhancing fillers, exhibit excellent conductivity, and their unique high aspect ratio facilitates the formation of numerous microcapacitor structures with relatively low filler content. Therefore, effective composite formation of MWCNTs with esterified SBS elastomers is expected to significantly improve the dielectric constant of the resulting composite material. Thiol-modification of MWCNTs is expected to increase the interfacial compatibility between MWCNTs and esterified SBS elastomers grafted with methyl mercaptoacetate. Summary of the Invention
[0004] The purpose of this invention is to provide a dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film and its preparation method. The composite film has a significantly improved dielectric constant compared to pure SBS film and has a certain self-healing ability.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film, comprising the following steps: Hydroxylated multi-walled carbon nanotubes, deionized water, anhydrous ethanol, polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (Pluronic F127 surfactant) and γ-mercaptopropyltriethoxysilane were mixed and then subjected to a thiolization reaction at 60-85°C with stirring for 20-24 h. The reaction product was washed and then dried at 70-80°C for 20-24 h to obtain thiolized multi-walled carbon nanotubes. SBS, methyl mercaptoacetate, 2,2-dimethoxy-2-phenylacetophenone (DMPA) UV initiator, and tetrahydrofuran were mixed and stirred at 20-30°C for 0.5-1 h to form a solution. The solution was then irradiated with 365 nm UV light (40-50 W) and stirred for 0.4-0.6 h to undergo a click chemical reaction to obtain esterified SBS. A mercaptoized multi-walled carbon nanotube / tetrahydrofuran suspension that had been sonicated for 0.4-0.6 h was then added to the reaction system and irradiated with 365 nm UV light (40-50 W) and stirred for another 0.4-0.6 h to obtain a composite material mixture. The composite material mixture was cast onto the surface of a glass plate and dried at 70-80°C for 20-24 hours to obtain a dielectric-reinforced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film.
[0006] Preferably, the ratio of the hydroxylated multi-walled carbon nanotubes, deionized water, anhydrous ethanol, Pluronic F127 surfactant, and γ-mercaptopropyltriethoxysilane is 1g: 20~60mL: 50~200mL: 0.05~0.2g: 0.5~2.5g.
[0007] Preferably, the ratio of SBS, methyl mercaptoacetate, DMPA violet initiator, tetrahydrofuran, and thiolated multi-walled carbon nanotube / tetrahydrofuran suspension is 5g: 20~25g: 0.05~0.20g: 30~70mL: 0.1~0.3g / 10~25mL.
[0008] The present invention also provides a dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film with certain self-healing ability prepared by the above preparation method. Attached Figure Description
[0009] Figure 1 Infrared test results of hydroxylated multi-walled carbon nanotubes and thiolized multi-walled carbon nanotubes prepared in Examples 1-3; Figure 2 XRD test results of hydroxylated multi-walled carbon nanotubes and mercaptolated multi-walled carbon nanotubes prepared in Examples 1-3; Figure 3 Thermogravimetric analysis results of hydroxylated multi-walled carbon nanotubes and thiolized multi-walled carbon nanotubes prepared in Examples 1-3; Figure 4 SEM images of the cross-section of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film prepared in Example 1. Figure 5 SEM images of the cross-section of the mercaptoized multi-walled carbon nanotube / esterified SBS elastomer composite film prepared in Example 3. Figure 6 The XRD test results are for the thin films prepared in Comparative Example 1, Example 1, Example 2 and Example 3; Figure 7 The infrared test results are for the thin films prepared in Comparative Example 1, Example 1, Example 2 and Example 3; Figure 8 The results of the proton nuclear magnetic resonance (NMR) spectra of the thin films prepared in Comparative Example 1 and Example 1 are shown. Figure 9 The results of self-healing tests are for the films prepared in Comparative Example 1 and Example 1; Figure 10 The dielectric constant test results are for the thin films prepared in Comparative Example 1, Example 1, Example 2 and Example 3. Detailed Implementation
[0010] The present invention will be further described in detail below with reference to specific preferred embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.
[0011] Example 1 1 g of hydroxylated multi-walled carbon nanotubes, 50 mL of deionized water, 100 mL of anhydrous ethanol, 0.05 g of Pluronic F127 surfactant, and 2.5 g of γ-mercaptopropyltriethoxysilane were mixed and subjected to a thiolization reaction at 85 °C with stirring for 24 h. The reaction product was washed and dried at 80 °C for 24 h to obtain thiolized multi-walled carbon nanotubes. Figure 1Infrared spectroscopy results show that the infrared spectra of hydroxylated multi-walled carbon nanotubes exhibit characteristic peaks of hydroxyl groups at 3427 cm⁻¹ and 1622 cm⁻¹, while the infrared spectra of mercapto-modified multi-walled carbon nanotubes show characteristic peaks of Si-O at 1086 cm⁻¹. The presence of hydroxyl groups facilitates the condensation reaction between multi-walled carbon nanotubes and hydrolyzed γ-mercaptopropyltriethoxysilane, thereby grafting mercapto groups onto multi-walled carbon nanotubes to obtain mercapto-modified multi-walled carbon nanotubes. Furthermore, in the mercapto-modification process of hydroxylated multi-walled carbon nanotubes, the Pluronic F127 surfactant mainly plays a role in effectively suspending and dispersing the hydroxylated multi-walled carbon nanotubes in a mixture of deionized water and anhydrous ethanol, thus enabling them to fully contact and react with γ-mercaptopropyltriethoxysilane. Figure 2 The XRD results show that thiolation modification did not significantly alter the crystal structure of carbon nanotubes. However, compared to hydroxylated multi-walled carbon nanotubes, the XRD pattern of thiolated multi-walled carbon nanotubes exhibited a new peak at 20.5 degrees, which can be attributed to the diffuse XRD peaks of amorphous silicon oxides. Figure 3 Thermogravimetric analysis (TGA) results under nitrogen atmosphere showed that the hydroxylated multi-walled carbon nanotubes (MWCNTs) experienced a weight loss of 3 wt.% at 900℃. This weight loss is likely due to the poor thermal stability of the hydroxyl groups on the MWCNTs. In contrast, the mercapto-modified MWCNTs exhibited a weight loss as high as 20 wt.% at 900℃, presumably due to the grafting of a large amount of thermally unstable γ-mercaptopropyltriethoxysilane onto the MWCNTs. In summary, the infrared, XRD, and TGA results indicate that the hydroxylated MWCNTs reacted effectively with γ-mercaptopropyltriethoxysilane, achieving mercapto-modification of the hydroxylated MWCNTs.
[0012] 5g SBS, 25g methyl mercaptoacetate, 0.15g DMPA UV initiator, and 40 mL tetrahydrofuran were mixed and stirred at 25°C for 1 h to form a solution. The solution was then subjected to click chemistry reaction under 365nm UV light (50W) and stirring for 0.5 h to obtain esterified SBS. A suspension of 0.1g mercaptoized multi-walled carbon nanotubes / 20 mL tetrahydrofuran that had been sonicated for 0.5 h was added to the reaction system, and the mixture was further irradiated under 365nm UV light (50W) and stirred for 0.5 h to obtain a composite material mixture.
[0013] The composite material mixture was cast onto the surface of a glass plate and dried at 80°C for 24 hours to obtain a dielectric-reinforced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film.
[0014] Example 2 The preparation of thiolized multi-walled carbon nanotubes is as described in Example 1.
[0015] 5g SBS, 25g methyl mercaptoacetate, 0.1g DMPA UV initiator, and 40 mL tetrahydrofuran were mixed and stirred at 25°C for 1 h to form a solution. The solution was then subjected to click chemistry reaction under 365nm UV light (50W) and stirring for 0.5 h to obtain esterified SBS. A suspension of 0.1g mercaptoized multi-walled carbon nanotubes / 20 mL tetrahydrofuran that had been sonicated for 0.5 h was then added to the reaction system, and the mixture was further irradiated under 365nm UV light (50W) and stirred for 0.5 h to obtain a composite material mixture.
[0016] The composite material mixture was cast onto the surface of a glass plate and dried at 80°C for 24 hours to obtain a dielectric-reinforced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film.
[0017] Example 3 The preparation of thiolized multi-walled carbon nanotubes is as described in Example 1.
[0018] 5g SBS, 25g methyl mercaptoacetate, 0.1g DMPA UV initiator, and 40 mL tetrahydrofuran were mixed and stirred at 25°C for 1 h to form a solution. The solution was then subjected to click chemistry reaction under 365nm UV light (50W) and stirring for 0.5 h to obtain esterified SBS. A suspension of 0.2g mercaptoized multi-walled carbon nanotubes / 20 mL tetrahydrofuran that had been sonicated for 0.5 h was then added to the reaction system, and the mixture was further irradiated under 365nm UV light (50W) and stirred for 0.5 h to obtain a composite material mixture.
[0019] The composite material mixture was cast onto the surface of a glass plate and dried at 80°C for 24 hours to obtain a dielectric-reinforced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film.
[0020] Comparative Example 1 Pure SBS is placed between two iron plates of a tablet press. After the two iron plates are clamped together, the tablet press is placed in the tablet press and pressed for 300 seconds at 165℃ and 20MPa to form a film, thus obtaining a pure SBS film.
[0021] Figure 4 and Figure 5The images show SEM images of the cross-sections of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite films prepared in Examples 1 and 3, respectively. Due to the good interfacial compatibility between the thiolized multi-walled carbon nanotubes and the esterified SBS elastomer grafted with methyl mercaptoacetate, the multi-walled carbon nanotubes are dispersed relatively uniformly in the esterified SBS matrix. The presence of low-conductivity esterified SBS between the high-conductivity thiolized multi-walled carbon nanotubes forms a microcapacitor structure, which is beneficial for improving the dielectric constant.
[0022] Figure 6 The XRD test results are shown for the films prepared in Comparative Example 1, Example 1, Example 2, and Example 3. It can be seen that compared with the pure SBS film, the XRD dispersion peaks of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film are broadened, which is likely due to the structural change caused by the grafting of methyl mercaptoacetate onto SBS. Furthermore, the characteristic XRD diffraction peaks of thiolized multi-walled carbon nanotubes are not observed in the XRD pattern of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film, which is likely due to the low content of thiolized multi-walled carbon nanotubes.
[0023] Figure 7 The infrared (IR) test results are shown for the films prepared in Comparative Example 1, Example 1, Example 2, and Example 3. It can be seen that, compared with the pure SBS film, the IR spectrum of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film shows a series of characteristic peaks from the ester groups of the methyl mercaptoacetate reactive monomer (C=O at 1728 cm⁻¹, C-O at 1272 cm⁻¹, and C-O-C at 1129 cm⁻¹), and the double bond peaks at 1644 cm⁻¹ and 964 cm⁻¹ are significantly weakened. These IR results indicate that a click chemical reaction occurred between the thiol groups of methyl mercaptoacetate and the double bonds of SBS, resulting in an esterified SBS matrix.
[0024] Figure 8 The results of the 1H NMR spectra of the films prepared in Comparative Example 1 and Example 1 are shown. It can be seen that, compared with the pure SBS film, the double bond hydrogen peaks (5.44 ppm, 5.40 ppm, 4.99 ppm) of the thiomethylene / esterified SBS elastomer composite film have essentially disappeared, and the intensities of the thiomethylene hydrogen peaks (3.25 ppm, 2.64 ppm) and the thiomethylene peak (2.77 ppm) are significantly enhanced. This further proves that the thiol group of methyl mercaptoacetate underwent a click chemical reaction with the double bond of SBS, resulting in an esterified SBS matrix.
[0025] Figure 9The results show the self-healing test results of the films prepared in Comparative Example 1 and Example 1. It can be seen that the pores punched in the pure SBS film did not shrink significantly after heat treatment at 110℃ for 5 hours, while the pores in the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film showed significant shrinkage after the same heat treatment. This indicates that the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film possesses a certain self-healing ability. This self-healing ability can be attributed to the reversible CH / π van der Waals interaction between the partially positively charged protons near the ester groups of esterified SBS and the partially negatively charged benzene rings on the polystyrene segments.
[0026] Figure 10 The dielectric constant test results are shown for the films prepared in Comparative Example 1, Example 1, Example 2, and Example 3. It can be seen that the dielectric constant of the thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film is significantly increased compared to the pure SBS film. The dielectric constants of Examples 1, 2, and 3 at 100 Hz are 8.36, 9.49, and 9.99, respectively, while the dielectric constant of Comparative Example 1 at 100 Hz is only 2.07. This increase in dielectric constant can be attributed to the dual dielectric enhancement effect of the polar methyl thioglycolate grafted units and the conductive multi-walled carbon nanotubes.
[0027] The thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film prepared by this invention has potential application value in fields such as actuators, sensors, mechanical energy harvesting systems, soft robots, electronic skin, and artificial muscles.
[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film, comprising the following steps: Hydroxylated multi-walled carbon nanotubes, deionized water, anhydrous ethanol, Pluronic F127 surfactant and γ-mercaptopropyltriethoxysilane were mixed and then subjected to a thiolation reaction at 60-85°C with stirring for 20-24 h. The reaction product was washed and then dried at 70-80°C for 20-24 h to obtain thiolated multi-walled carbon nanotubes. SBS, methyl mercaptoacetate, DMPA UV initiator, and tetrahydrofuran were mixed and stirred at 20-30°C for 0.5-1 h to form a solution. The solution was then irradiated with 365 nm UV light (40-50 W) and stirred for 0.4-0.6 h to undergo a click chemical reaction to obtain esterified SBS. A mercaptoized multi-walled carbon nanotube / tetrahydrofuran suspension that had been sonicated for 0.4-0.6 h was then added to the reaction system and irradiated with 365 nm UV light (40-50 W) and stirred for another 0.4-0.6 h to obtain a composite material mixture. The composite material mixture was cast onto the surface of a glass plate and dried at 70-80°C for 20-24 hours to obtain a dielectric-reinforced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film.
2. The preparation method according to claim 1, characterized in that, The ratio of the amount of hydroxylated multi-walled carbon nanotubes, deionized water, anhydrous ethanol, Pluronic F127 surfactant, and γ-mercaptopropyltriethoxysilane is 1g: 20~60mL: 50~200mL: 0.05~0.2g: 0.5~2.5g.
3. The preparation method according to claim 1, characterized in that, The ratio of SBS, methyl mercaptoacetate, DMPA violet initiator, tetrahydrofuran, and thiolated multi-walled carbon nanotube / tetrahydrofuran suspension is 5g: 20~25g: 0.05~0.20g: 30~70mL: 0.1~0.3g / 10~25mL.
4. The dielectric-enhanced thiolized multi-walled carbon nanotube / esterified SBS elastomer composite film with certain self-healing ability prepared by the preparation method according to claims 1, 2, and 3.