Anti-settling and stiffness-damping-adjustable magneto-rheological hydrogel and preparation method thereof

Abstract

This invention discloses a magnetorheological hydrogel with anti-settlement properties and adjustable stiffness and damping, and its preparation method. Micron-sized carbonyl iron powder is used as a filler, and acrylamide and acrylic acid are used as monomers to form an interpenetrating network. Under the influence of magnetic flux density, the carbonyl iron powder forms a chain-like structure within the interpenetrating network hydrogel matrix. The magnetorheological hydrogel of this invention allows for performance adjustment according to actual needs during preparation. The stiffness of the hydrogel composite material can be flexibly adjusted by changing the amount of magnetic particles, and the damping of the hydrogel composite material can be flexibly adjusted by changing the magnetic flux density, making it adaptable to different road conditions and driving requirements, thereby providing better suspension system control and ride comfort.

Description

Technical Field

[0001] This invention relates to a magnetorheological hydrogel with anti-settlement properties and adjustable stiffness and damping, belonging to the field of intelligent vibration reduction technology. Background Technology

[0002] The development of vehicle damping technology can be traced back to the early stages of automobile development in the late 19th and early 20th centuries. The earliest automobile suspension systems used a combination of springs and shock absorbers to reduce vehicle vibrations. However, traditional vehicle damping technology has some limitations. First, these systems typically have fixed damping characteristics and cannot be adjusted according to different driving conditions and road surfaces, thus affecting vehicle smoothness and ride comfort. Second, these traditional damping systems are made of metal, resulting in greater weight and size, increasing the overall load on the vehicle and also increasing costs. These drawbacks have, to some extent, limited the development and application of vehicle suspension systems.

[0003] However, in recent years, with the advancement of materials science and engineering technology, novel magnetic hydrogel materials and technologies have begun to be applied in the field of vehicle vibration damping, bringing new possibilities to vehicle vibration reduction. These magnetic hydrogel materials have many advantages, including adjustable damping characteristics, which can intelligently adjust the vehicle's vibration damping effect according to different road conditions, thereby improving driving smoothness and ride comfort. In addition, magnetic hydrogel materials are lighter and smaller than traditional metal materials, which can not only reduce the overall load on the vehicle but also has the potential to reduce manufacturing costs. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetic hydrogel with anti-settlement properties and adjustable stiffness and damping, and its preparation method.

[0005] To achieve its objectives, the present invention employs the following technical solution:

[0006] A magnetorheological hydrogel with anti-settling properties and adjustable stiffness and damping is characterized in that: the magnetorheological hydrogel uses micron-sized carbonyl iron powder as filler and forms an interpenetrating network with acrylamide and acrylic acid as monomers. Under the action of magnetic flux density, the carbonyl iron powder forms a chain structure in the interpenetrating network hydrogel matrix, thereby endowing the gel with unique magnetic properties.

[0007] The method for preparing the anti-settling and stiffness-damping magnetorheological hydrogel of the present invention comprises the following steps:

[0008] Step 1: Surface modification of carbonyl iron powder

[0009] 50g of micron-sized carbonyl iron powder, 6g of methacrylic acid and 50mL of ethanol were mixed evenly, and then 20g of vinyltrimethoxysilane was added. The mixture was ultrasonically dispersed evenly, and then 20g of vinyltrimethoxysilane and 25mL of ammonia were added. The mixture was mechanically stirred, and after repeated washing with anhydrous ethanol, the particles and solution were separated by magnet. The mixture was then dried by forced air to obtain silicon-coated carbonyl iron powder particles.

[0010] Step 2: Preparation of prepolymer

[0011] 3g of acrylamide was dissolved in deionized water to prepare a 50% (w / w) solution. A crosslinking agent and an initiator were added, and the polymerization reaction was carried out at 80°C for 20 min to obtain the PAM prepolymer.

[0012] Step 3: Preparation of interpenetrating network magnetic hydrogels

[0013] Dissolve 3g of acrylic acid in deionized water to prepare a 50% (w / w) solution, neutralize with sodium hydroxide solution, then mix with PAM prepolymer, stir evenly, add crosslinking agent and initiator, then add silicon-coated carbonyl iron powder particles, stir evenly, pour into a mold, and gel at a magnetic flux density of 200-900 mT for 15 min to obtain a magnetorheological hydrogel containing carbonyl iron powder and having an interpenetrating network structure.

[0014] Preferably, the volume of the added silicon-coated carbonyl iron powder particles accounts for 1-5 vol% of the total volume of acrylamide and acrylic acid, calculated as shown in the following formula, where m CIP With ρ CIP The mass and density of silicon-coated carbonyl iron powder particles, m 单总 With ρ 单总 The total mass and total density of acrylamide and acrylic acid.

[0015]

[0016] Preferably, the particle size of the micron-sized carbonyl iron powder is 2–5 μm.

[0017] Preferably, in step 2, the amount of crosslinking agent added accounts for 0.02-0.06% of the mass of acrylamide, and the amount of initiator added accounts for 0.2-0.8% of the mass of acrylamide.

[0018] Preferably, in step 3, the amount of crosslinking agent added accounts for 0.02-0.06% of the mass of acrylic acid, and the amount of initiator added accounts for 0.2-0.8% of the mass of acrylic acid.

[0019] Preferably, the initiator is one of potassium persulfate and ammonium persulfate.

[0020] Preferably, the crosslinking agent is one of N,N-methyleneacrylamide and ethylene glycol dimethacrylate.

[0021] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0022] 1. The magnetorheological hydrogel of the present invention can be adjusted in performance according to actual needs during preparation. The stiffness of the hydrogel composite material can be flexibly adjusted by changing the amount of magnetic particles, and the damping of the hydrogel composite material can be flexibly adjusted by changing the magnetic flux density, so as to adapt to different road conditions and driving needs, thereby providing better suspension system control and ride comfort.

[0023] 2. This invention employs an interpenetrating network structure and uses a magnetic field to cause carbonyl iron powder to form a chain-like structure within the network, effectively preventing the sedimentation of magnetic particles and ensuring the stability of the gel and its reliability for long-term use.

[0024] 3. The magnetic hydrogel prepared by this invention is lighter, consumes less energy, and has a lower cost than traditional metal shock absorbers. Attached Figure Description

[0025] Figure 1 The figures show the relationship between the hydrogel storage modulus and frequency for each embodiment and comparative example, where (a) represents samples with different CIP contents and (b) represents samples with different magnetic flux densities.

[0026] Figure 2 The figures show the relationship between the hydrogel loss factor and frequency for each embodiment and comparative example, where (a) represents samples with different CIP contents and (b) represents samples with different magnetic flux densities.

[0027] Figure 3 The graphs show the stress-strain relationship of the hydrogels in each embodiment and comparative example.

[0028] Figure 4 The swelling curves of the hydrogels in each embodiment and comparative example over time are shown.

[0029] Figure 5 The magnetic particles in the hydrogel samples of each embodiment and comparative example are shown in the state of their presence in the matrix. Detailed Implementation

[0030] To more clearly and understandably illustrate the purpose and content of this invention, the specific embodiments of this invention will be described in detail below with reference to examples. The following content is merely illustrative and explanatory of the invention, and those skilled in the art can modify the described specific embodiments or adopt similar methods, as long as they do not depart from the scope defined by the claims, they shall fall within the protection scope of this invention.

[0031] Example 1

[0032] This embodiment prepares a magnetorheological hydrogel with anti-settling properties and adjustable stiffness damping according to the following steps:

[0033] Step 1: Surface modification of carbonyl iron powder

[0034] 50g of micron-sized carbonyl iron powder, 6g of methacrylic acid and 50mL of ethanol were mixed evenly, and then 20g of vinyltrimethoxysilane was added. The mixture was ultrasonically dispersed for 45min, and then 20g of vinyltrimethoxysilane and 25mL of ammonia were added. The mixture was mechanically stirred, and after repeated washing with anhydrous ethanol, the particles and solution were separated by magnet. The mixture was then dried by forced air for 48h to obtain silicon-coated carbonyl iron powder particles.

[0035] Step 2: Preparation of prepolymer

[0036] 3g of acrylamide was dissolved in deionized water to prepare a 50% solution. 0.03% of N,N-methyleneacrylamide (a crosslinking agent) and 0.6% of ammonium persulfate (an initiator) were added. The mixture was polymerized at 80°C for 20 minutes to obtain the PAM prepolymer.

[0037] Step 3: Preparation of interpenetrating network magnetorheological hydrogels

[0038] 3g of acrylic acid was dissolved in deionized water to prepare a 50% (w / w) solution, which was then neutralized with sodium hydroxide solution. The solution was then mixed with PAM prepolymer and stirred until homogeneous. 0.04% (w / w) of N,N-methyleneacrylamide (a crosslinking agent) and 0.5% (w / w) of ammonium persulfate (an initiator) were added. 3 vol% and 5 vol% (w / w) of silicon-coated carbonyl iron powder particles (based on the total volume of acrylamide and acrylic acid) were added respectively. After uniform stirring, the mixture was poured into a mold and gelled at a magnetic flux density of 200 mT for 15 min to obtain a magnetorheological hydrogel containing carbonyl iron powder and having an interpenetrating network structure.

[0039] Example 2

[0040] This embodiment prepares a magnetorheological hydrogel with anti-settling properties and adjustable stiffness damping according to the following steps:

[0041] Step 1, same as in Example 1.

[0042] Step 2, same as in Example 1.

[0043] Step 3: Preparation of interpenetrating network magnetorheological hydrogels

[0044] 3g of acrylic acid was dissolved in deionized water to prepare a 50% (w / w) solution, which was then neutralized with sodium hydroxide solution. The solution was then mixed with PAM prepolymer and stirred until homogeneous. 0.04% (w / w) of N,N-methyleneacrylamide (a crosslinking agent) and 0.5% (w / w) of ammonium persulfate (an initiator) were added. 3 vol% (w / w) of silicon-coated carbonyl iron powder particles (based on the total volume of acrylamide and acrylic acid) were then added. After uniform stirring, the mixture was poured into a mold and gelled for 15 min at magnetic flux densities of 200 mT and 600 mT, respectively, to obtain a magnetorheological hydrogel containing carbonyl iron powder and having an interpenetrating network structure.

[0045] Comparative Example 1

[0046] This comparative example prepared a hydrogel according to the following steps:

[0047] Step 1, None

[0048] Step 2, same as in Example 1.

[0049] Step 3: Preparation of hydrogel

[0050] Dissolve 3g of acrylic acid in deionized water to prepare a 50% (w / w) solution. Neutralize with sodium hydroxide solution, then mix with PAM prepolymer and stir until homogeneous. Add 0.04% (w / w) of N,N-methyleneacrylamide (crosslinking agent) and 0.5% (w / w) of ammonium persulfate (initiator) to the acrylic acid. Do not add carbonyl iron powder particles. After stirring evenly, pour into a mold and gel directly for 15 minutes without magnetic field to obtain hydrogel.

[0051] Comparative Example 2

[0052] This comparative example prepared a hydrogel according to the following steps:

[0053] Step 1, same as in Example 1.

[0054] Step 2, same as in Example 1.

[0055] Step 3: Preparation of hydrogel

[0056] Dissolve 3g of acrylic acid in deionized water to prepare a 50% (w / w) solution. Neutralize with sodium hydroxide solution, then mix with PAM prepolymer and stir until homogeneous. Add 0.04% (w / w) of N,N-methyleneacrylamide (crosslinking agent) and 0.5% (w / w) of ammonium persulfate (initiator) based on the mass of acrylic acid. Then add 3 vol% (w / w) of silicon-coated carbonyl iron powder particles based on the total volume of acrylamide and potassium acrylate. After stirring evenly, pour into a mold and gel directly for 15 minutes without a magnetic field to obtain a hydrogel.

[0057] Figure 1(a) Comparison of the storage modulus of the samples obtained in Example 1 and Comparative Example 1. It can be seen that as the volume fraction of silicon-coated carbonyl iron powder particles (CIPs) increases, the storage modulus of the samples increases. The storage modulus of the samples with volume fractions of 0 vol%, 3 vol%, and 5 vol% are 6 kPa, 26 kPa, and 38 kPa, respectively. The continuous increase in storage modulus is due to the continuous increase of CIP particles, which makes the network structure of the magnetic hydrogel more dense. Figure 1 (b) Comparison of the storage modulus of the samples obtained in Example 2 and Comparative Example 2 shows that the storage modulus of the samples continuously increases with the increase of magnetic flux density. The storage moduli of the samples corresponding to 0 mT, 200 mT, and 600 mT are 16 kPa, 26 kPa, and 45 kPa, respectively. This is mainly because after applying a magnetic field, the CIP magnetic particles form a more regular chain structure in the hydrogel matrix, which plays a role in reinforcing the matrix and thus increasing the storage modulus of the hydrogel composite material. Therefore, the storage modulus of the magnetorheological hydrogel composite material can be changed by controlling the amount of CIP magnetic particles and the magnitude of the magnetic flux density, thereby achieving adjustable stiffness of the composite hydrogel.

[0058] Figure 2 (a) Comparison of the loss factors of the samples obtained in Example 1 and Comparative Example 1. It can be seen that as the volume fraction of CIPs increases, the loss factor of the sample increases. The loss factors of the samples with volume fractions of 0 vol%, 3 vol%, and 5 vol% are 0.07, 0.15, and 0.17, respectively. Figure 2 (b) Comparison of the loss factors of the samples obtained in Example 2 and Comparative Example 1 shows that the loss factor of the samples increases continuously with the increase of magnetic flux density. The storage moduli of the samples corresponding to 0 mT, 200 mT, and 600 mT are 0.05, 0.15, and 0.2, respectively. Therefore, the loss factor of the magnetorheological hydrogel composite material can be changed by controlling the amount of magnetic particles (CIP) and the magnitude of the magnetic flux density, thereby achieving adjustable damping of the composite hydrogel.

[0059] Figure 3 The figure shows the stress-strain relationship between the samples obtained in Example 1 (3 vol%, 200 mT), Example 2 (3 vol%, 600 mT), and Comparative Example 1 (0 vol%, 0 mT). The figure clearly shows that Example 1 (3 vol%, 200 mT) used the method of adding magnetic particles, and its elastic modulus was 1.5 MPa. Example 2 (3 vol%, 600 mT) achieved its elastic modulus by applying magnetic flux density, and its elastic modulus was 2.8 MPa. In contrast, Comparative Example 1 did not add CIP particles or apply magnetic flux density, therefore its elastic modulus was only 0.3 MPa. The samples in Examples 1 and 2 have better mechanical properties.

[0060] Figure 4 The swelling curve of the sample over time is shown, and Figure 5 This describes the state of the magnetic particles within the matrix. From Figure 4 It can be clearly observed that Example 1 (3 vol%, 200 mT) and Example 2 (3 vol%, 600 mT) exhibited better swelling properties and maintained good stability after swelling (see [link]). Figure 5 No sedimentation occurred in either Example 1 or Example 2. This is mainly because Examples 1 and 2 achieved a more stable interpenetrating network structure, and the magnetic particles were arranged in a chain-like structure and uniformly. In contrast, Comparative Example 2 (3 vol%, 0 mT) had poor stability and sedimentation occurred.

[0061] In summary, the hydrogel obtained by the two-step polymerization method has a denser network structure, excellent mechanical properties, and good stability, preventing particle sedimentation. The stiffness and damping characteristics of the hydrogel prepared in this invention can be controlled by adjusting the content of magnetic particles and the magnitude of magnetic flux density.

[0062] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a magnetorheological hydrogel with anti-settling properties and adjustable stiffness and damping, characterized in that: The magnetorheological hydrogel uses micron-sized carbonyl iron powder as a filler and forms an interpenetrating network with acrylamide and acrylic acid as monomers. Under the influence of magnetic flux density, the carbonyl iron powder forms a chain-like structure in the hydrogel matrix. The preparation method of the anti-settling and stiffness-damping magnetorheological hydrogel is carried out according to the following steps: Step 1: Surface modification of carbonyl iron powder 50g of micron-sized carbonyl iron powder, 6g of methacrylic acid and 50mL of ethanol were mixed evenly, and then 20g of vinyltrimethoxysilane was added. The mixture was ultrasonically dispersed evenly, and then 20g of vinyltrimethoxysilane and 25mL of ammonia were added. The mixture was mechanically stirred, and after repeated washing with anhydrous ethanol, the particles and solution were separated by magnet. The mixture was then dried by forced air to obtain silicon-coated carbonyl iron powder particles. Step 2: Preparation of prepolymer 3g of acrylamide was dissolved in deionized water to prepare a 50% (w / w) solution. A crosslinking agent and an initiator were added, and the polymerization reaction was carried out at 80°C for 20 min to obtain the PAM prepolymer. Step 3: Preparation of interpenetrating network magnetic hydrogels Dissolve 3g of acrylic acid in deionized water to prepare a 50% (w / w) solution, neutralize with sodium hydroxide solution, then mix with PAM prepolymer, stir evenly, add crosslinking agent and initiator, then add silicon-coated carbonyl iron powder particles, stir evenly and pour into a mold, gel at a magnetic flux density of 200-900 mT for 15 min to obtain a magnetorheological hydrogel containing carbonyl iron powder and having an interpenetrating network structure.

2. The preparation method according to claim 1, characterized in that: In step 3, the volume of the silicon-coated carbonyl iron powder particles added accounts for 1 to 5 vol of the total volume of acrylamide and acrylic acid.

3. The preparation method according to claim 1, characterized in that: The particle size of the micron-sized carbonyl iron powder is 2~5μm.

4. The preparation method according to claim 1, characterized in that: In step 2, the amount of crosslinking agent added is 0.02-0.06% of the mass of acrylamide, and the amount of initiator added is 0.2-0.8% of the mass of acrylamide.

5. The preparation method according to claim 1, characterized in that: In step 3, the amount of crosslinking agent added accounts for 0.02-0.06% of the mass of acrylic acid, and the amount of initiator added accounts for 0.2-0.8% of the mass of acrylic acid.

6. The preparation method according to claim 1, characterized in that: The initiator is one of potassium persulfate and ammonium persulfate.

7. The preparation method according to claim 2, characterized in that: The crosslinking agent is one of N,N-methyleneacrylamide and ethylene glycol dimethacrylate.

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