A photosensitive interface-based magnetically controlled coumarin soft actuator and its preparation and control methods.

Abstract

A photo-induced interface retention-based magnetically controlled coumarin soft actuator, its preparation method, and control method are disclosed. This belongs to the field of soft actuator technology. The soft actuator comprises a polymer matrix containing coumarin side groups and magnetic particles dispersed within the polymer matrix. The polymer matrix is ​​preferably a copolymer formed from acrylic monomers and coumarin-functionalized polymerizable monomers, and the magnetic particles are preferably Fe3O4 magnetic particles. Under the influence of an external magnetic field, the soft actuator can migrate, orient, or locate. Upon reaching the target region, 365 nm light irradiation causes photodimerization of the coumarin side groups, thereby enhancing its interfacial retention ability in the target region. This achieves orthogonal control where the magnetic field is responsible for migration and navigation, and the optical field is responsible for interface retention. This approach reduces the dependence of existing magnetically controlled soft materials on continuous external magnetic fields for maintaining their presence and provides a material basis for target retention, localized blocking, targeted release, and recyclable soft actuators.

Description

Technical Field

[0001] This invention belongs to the field of software execution technology, specifically relating to a magnetically controlled coumarin software actuator based on photo-induced interface fixation, and its preparation and control methods. Background Technology

[0002] Magnetically responsive soft materials, capable of remote control, non-contact actuation, and path navigation under the influence of external magnetic fields, hold promise for applications in directional migration in narrow channels, localized material transport, pinpoint sealing, and recyclable soft actuation. However, existing magnetically controlled soft materials typically rely on a continuous external magnetic field to remain stationary after reaching the target location. Once the magnetic field is removed, the material is prone to displacement, loss, or detachment from the interface, limiting its application in complex flow fields, narrow cavities, and multi-objective collaborative scenarios.

[0003] On the other hand, coumarin groups can undergo a [2+2] photodimerization reaction under 365 nm light irradiation, thereby increasing the cross-linking degree of the polymer network and potentially improving the material's interfacial retention ability at the target location. If this type of photoresponsive unit is introduced into a magnetically responsive soft material system, it is expected to establish an orthogonal control mode in which "the magnetic field is responsible for movement, and the light field is responsible for holding the target position".

[0004] While existing technologies encompass composite hydrogel solutions involving both magnetic components and coumarin photocrosslinking components, these solutions typically focus on piezoelectricity, conductivity, bioremediation, or general photocuring. Their material construction methods often involve combining magnetic fiber fragments with a photocrosslinkable hydrogel matrix. However, the technical objectives, configuration logic, and the need for interface retention control at the target location by the soft actuator are not aligned. Currently, there is a lack of specific solutions for constructing a soft actuator that can both migrate and remain at the target location after light exposure using an acrylic copolymer matrix containing coumarin side groups and directly dispersed magnetic particles.

[0005] Therefore, there is an urgent need to provide a magnetically controlled coumarin soft actuator and its control method that combines magnetic navigation capability and photo-induced interface retention capability, so as to achieve in-situ residence of the material at the target location and complete release, transfer or recycling when needed. Summary of the Invention

[0006] In order to solve the problem that existing magnetically controlled soft materials usually still rely on a continuous external magnetic field to maintain their position after reaching the target position, and are prone to displacement, loss or detachment from the interface after the magnetic field is removed, this invention provides a magnetically controlled coumarin soft actuator based on photo-induced interface fixation, as well as its preparation method and control method.

[0007] The technical solution adopted in this invention is:

[0008] A photosensitive interface-retained magnetically controlled coumarin soft actuator includes a polymer matrix containing coumarin side groups and magnetic particles dispersed in the polymer matrix. The soft actuator is in a migratory state before 365 nm illumination and transforms into a state with stronger interface retention capability after 365 nm illumination.

[0009] Furthermore, the migratable state is a fluid dynamic, semi-fluid dynamic, or low-modulus state; the state with stronger interface retention capability is a gel state, a weak gel state, or a high-modulus state.

[0010] Furthermore, the polymer matrix is ​​a copolymer formed by acrylic monomers and coumarin-functionalized polymerizable monomers, wherein the coumarin-functionalized polymerizable monomer is 7-(2-methacryloyloxyethoxy)-4-methylcoumarin.

[0011] Furthermore, the magnetic particles are Fe3O4 nanoparticles, Fe3O4 components in magnetic fluid, or a combination thereof. The magnetic particles are directly added to the polymer matrix precursor system in the form of a dispersion or magnetic fluid, and after stirring and / or ultrasonic treatment, a homogeneous magnetically controlled coumarin precursor system is formed.

[0012] A method for preparing a photosensitive coumarin-based magnetically controlled soft actuator includes the following steps:

[0013] S1. Preparation of 7-(2-hydroxyethoxy)-4-methylcoumarin;

[0014] S2. Preparation of 7-(2-methacryloyloxyethoxy)-4-methylcoumarin from 7-(2-hydroxyethoxy)-4-methylcoumarin;

[0015] S3. The acrylic monomer is copolymerized with the 7-(2-methacryloyloxyethoxy)-4-methylcoumarin under the action of a free radical initiator to obtain a polymer containing coumarin side groups;

[0016] S4. The polymer is added to an aqueous system to form a polymer precursor system;

[0017] S5. Add magnetic particle dispersion or magnetic fluid to the polymer precursor system, and stir and / or sonicate to uniformly disperse the magnetic components to obtain a magnetically controlled coumarin precursor system.

[0018] S6. The precursor system is kept in a transferable state for direct use, or after molding, it is irradiated with 365 nm light to form a soft actuator with interface dwell capability.

[0019] Furthermore, in S1, 4-methylumbelliferone reacts with ethylene carbonate in DMF in the presence of anhydrous potassium carbonate to prepare 7-(2-hydroxyethoxy)-4-methylcoumarin.

[0020] Furthermore, in S2, 7-(2-hydroxyethoxy)-4-methylcoumarin is co-dissolved with triethylamine in DMF, and methacryloyl chloride is added dropwise and reacted under ice bath conditions to prepare 7-(2-methacryloyloxyethoxy)-4-methylcoumarin.

[0021] A control method for a magnetically controlled coumarin soft actuator based on photosensitive interface fixation includes the following steps:

[0022] S1. Under conditions without 365 nm illumination, an external magnetic field is applied to cause the software execution unit according to any one of claims 1 to 4 to migrate to the target region;

[0023] S2. Apply 365 nm illumination to the target area to improve the interface dwell capability of the software execution unit at the target location.

[0024] Furthermore, after step S2, the external magnetic field is removed, and the software execution unit remains stationary in the target area.

[0025] Furthermore, the coumarin side group is at least partially cleaved after being exposed to 254 nm light.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention does not simply mix the coumarin-modified unit as an external photocrosslinking component with other hydrogel matrices. Instead, it first copolymerizes the coumarin-functionalized monomer MAEMC with acrylic acid AA to form a polymer matrix P (AA-r-MAEMC) containing coumarin side groups. This allows the coumarin functional groups to be embedded in the main chain as side groups in a copolymerization manner, which is more conducive to directly triggering the matrix state switching at the target position by 365nm light.

[0028] 2. This invention constructs magnetically responsive soft materials by directly dispersing Fe3O4 magnetic particles or magnetic fluid in a polymer precursor system. This eliminates the need to first prepare electrospun fiber fragments and break them up before embedding them into a hydrogel matrix. The material configuration is simpler and more suitable for forming continuous, transferable soft precursors.

[0029] 3. In this invention, the 365 nm light illumination is not just a photocuring step in the general sense, but is used to trigger the photodimerization of coumarin side groups in the target area, so that the software actuator switches from a migratory state to a state with stronger interface dwell capability, realizing orthogonal control in which "magnetic field is responsible for migration and navigation, and light field is responsible for target position fixation".

[0030] 4. The present invention focuses on solving the problems of target site retention, local blockage and recyclable soft execution in scenarios such as planar interface, inclined interface, curved interface, narrow channel inner wall or wet interface. The application logic is different from the magnetic response photocurable hydrogel solution with piezoelectric conductive osteogenic repair as the core objective.

[0031] 5. This invention can be implemented along a continuous path of “4-methylumbelliferone → HMC → MAEMC → P(AA-r-MAEMC) → magnetically controlled coumarin precursor system → magnetic navigation / 365 nm immobilization”, with a clear correspondence between chemical preparation and material construction, which facilitates subsequent implementation.

[0032] 6. This invention can reduce the dependence of existing magnetically controlled soft materials on continuous external magnetic fields to maintain their presence, and provides a material basis for target retention, local blocking, fixed-point release and recyclable soft execution. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the preparation routes of HMC, MAEMC and P(AA-r-MAEMC) in this invention;

[0034] Figure 2 This is a schematic diagram of the light response mechanism of the software execution unit of the present invention;

[0035] Figure 3 This is a physical image of the software actuator of the present invention undergoing sol-gel conversion under ultraviolet light irradiation at 365 nm and 254 nm.

[0036] Figure 4 These are SEM images of different regions of the software execution unit of this invention;

[0037] Figure 5 This is a schematic diagram illustrating the process by which the software execution unit of the present invention achieves magnetic navigation and photosensitive interface fixation in the target area. Detailed Implementation

[0038] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.

[0039] The soft actuator of the present invention can migrate, orient, or position itself under the action of an external magnetic field, and achieve photo-induced interface fixation after reaching the target area by 365 nm light illumination.

[0040] This invention constructs a polymer matrix containing coumarin side groups and directly disperses magnetic particles within it, enabling the resulting soft actuator to migrate, orient, or position itself under the influence of an external magnetic field. Once it reaches the target region, photodimerization of the coumarin side groups is induced by 365nm light illumination, thereby enhancing the soft actuator's interfacial residence capability in the target region. This establishes an orthogonal control mode where "the magnetic field is responsible for migration and navigation, and the optical field is responsible for target position interfacial fixation."

[0041] This invention introduces polymerizable coumarin functional monomers into the backbone of acrylic polymers to construct a polymer matrix containing coumarin side groups. Magnetic particles are then directly dispersed within this polymer precursor system, thereby establishing a software execution system with the core functions of "external magnetic field for migration and positioning, and 365 nm light illumination for target location interface fixation." This technical solution focuses on controlling the switching of the software actuator from a migratory state to a state with stronger interface retention in the target region, rather than magneto-piezoelectricity, conductivity, or osteogenic repair.

[0042] The software actuator of the present invention includes a polymer matrix containing coumarin side groups; and magnetic particles dispersed in the polymer matrix;

[0043] The soft actuator is in a migratory state before 365 nm illumination and transforms into a state with stronger interface retention capability after 365 nm illumination. The migratory state can be a fluid dynamic, semi-fluid dynamic, or low modulus state; the state with stronger interface retention capability can be a gel state, weak gel state, or high modulus state.

[0044] The software actuator can be strip-shaped, block-shaped, sheet-shaped, column-shaped, film-shaped, or droplet-shaped.

[0045] The operation process is as follows: the soft actuator can migrate, orient, or position itself under the action of an external magnetic field, and after reaching the target area, the coumarin side groups undergo photodimerization reaction under 365 nm light, thereby improving the interfacial residence ability of the soft actuator in the target area.

[0046] The polymer matrix is ​​a copolymer formed by acrylic monomers and coumarin-functionalized polymerizable monomers. Preferably, the coumarin-functionalized polymerizable monomer is 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (MAEMC); the copolymer is preferably P(AA-r-MAEMC).

[0047] The 7-(2-methacryloyloxyethoxy)-4-methylcoumarin is prepared by reacting 7-(2-hydroxyethoxy)-4-methylcoumarin (HMC) with methacryloyl chloride; the 7-(2-hydroxyethoxy)-4-methylcoumarin is prepared by reacting 4-methylumbelliferone with ethylene carbonate.

[0048] The magnetic particles are Fe3O4 nanoparticles, Fe3O4 components in magnetofluids, or a combination thereof.

[0049] Instead of first forming fibers or fragments and then combining them with hydrogels, the magnetic particles are directly added to the polymer matrix precursor system in the form of dispersions or magnetic fluids, and then subjected to stirring and / or ultrasonic treatment to form a homogeneous magnetically controlled coumarin precursor system. This is more conducive to the formation of a continuous, transferable soft precursor.

[0050] like Figure 1 As shown, the method for preparing a software executable includes the following steps:

[0051] S1. Preparation of 7-(2-hydroxyethoxy)-4-methylcoumarin (HMC);

[0052] S2. Preparation of 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (MAEMC) from 7-(2-hydroxyethoxy)-4-methylcoumarin (HMC);

[0053] S3. The acrylic monomer (AA) is copolymerized with 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (MAEMC) under the action of a free radical initiator to obtain a polymer containing coumarin side groups;

[0054] S4. The polymer is added to an aqueous system to form a polymer precursor system;

[0055] S5. Add magnetic particle dispersion or magnetic fluid to the polymer precursor system, and stir and / or sonicate to uniformly disperse the magnetic components to obtain a magnetically controlled coumarin precursor system;

[0056] S6. The precursor system is kept in a transferable state for direct use, or after molding, it is irradiated with 365 nm light to form a soft actuator with interface dwell capability.

[0057] In S1, 4-methylumbelliferone and ethylene carbonate react in DMF (N,N-dimethylformamide) in the presence of anhydrous potassium carbonate to prepare 7-(2-hydroxyethoxy)-4-methylcoumarin.

[0058] In S2, 7-(2-hydroxyethoxy)-4-methylcoumarin (HMC) and triethylamine are co-dissolved in DMF, and methacryloyl chloride is added dropwise under ice bath conditions to react and prepare 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (MAEMC).

[0059] In S3, acrylic acid and MAEMC are copolymerized with toluene under the initiation of AIBN (azobisisobutyronitrile) to obtain P(AA-r-MAEMC).

[0060] In S5, the amount of magnetic particles added is 0.1 wt% to 10 wt% of the total mass of the precursor system.

[0061] In S6, the 365 nm light intensity is 50–150 mW / cm², and the irradiation time is 10–90 min.

[0062] like Figures 2-5 As shown, the control method for the software execution unit of the present invention includes the following steps:

[0063] S1. Under conditions without 365 nm illumination, an external magnetic field is applied to cause the software actuator to migrate to the target region;

[0064] S2. After the software execution unit reaches the target area, 365 nm light is applied to the target area to improve the interface dwell capability of the software execution unit at the target location.

[0065] After step S2, the external magnetic field is removed, and the software actuator remains stationary in the target area, exhibiting a higher stationary capability in the target area compared to when the 365 nm illumination is not applied.

[0066] The target area is a planar interface, an inclined interface, a curved interface, the inner wall of a narrow channel, or a wet interface.

[0067] The coumarin side groups are at least partially cleaved upon 254 nm light irradiation, thereby increasing the fluidity or reducing the modulus of the soft actuator, making it possible for subsequent release, re-migration or recycling.

[0068] Example 1: Synthesis of HMC

[0069] 0.05 mol of 4-methylumbelliferone and 0.05 mol of ethylene carbonate were dissolved in 50 mL of DMF, followed by the addition of 0.1 mol of anhydrous potassium carbonate. The reaction mixture was placed under argon protection and stirred at 100 °C for 10 h. After the reaction was complete, the mixture was poured into a large amount of 0 °C ice water to precipitate the product. The precipitate was then filtered and washed three times with deionized water. The crude product was purified by recrystallization from ethanol and dried in a vacuum drying oven to obtain a white solid powder, namely 7-(2-hydroxyethoxy)-4-methylcoumarin (HMC).

[0070] In this embodiment, HMC serves as a precursor to the subsequent polymerizable coumarin monomer MAEMC, and its successful preparation provides a foundation for the subsequent construction of acrylic copolymers containing coumarin side groups.

[0071] Example 2: Synthesis of MAEMC

[0072] HMC (0.01 mol) and triethylamine (0.02 mol) were co-dissolved in 20 mL of DMF, and argon gas was introduced under ice bath conditions at 0 °C. Subsequently, a DMF solution of methacryloyl chloride (0.02 mol) in 10 mL was added dropwise to the cooled mixture. After the addition was complete, the ice bath was removed, and the reaction system was stirred continuously at room temperature for 12 h. After the reaction was completed, insoluble salts were removed by vacuum filtration, and the filtrate was concentrated by rotary evaporation. The crude product was recrystallized from ethanol and dried under vacuum to obtain a white solid powder, namely 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (MAEMC).

[0073] In this embodiment, MAEMC has both polymerizable double bonds and coumarin photoresponsive groups, which can be introduced into the polymer backbone in the form of side groups during subsequent free radical copolymerization.

[0074] Example 3: Synthesis of P(AA-r-MAEMC)

[0075] Acrylic acid (0.13 mol) and MAEMC (0.013 mol) were dissolved in 50 mL of toluene, and 1 wt% AIBN (based on the total monomer mass) was added as an initiator. The mixture was heated to 80 °C and magnetically stirred for 12 h under an argon atmosphere. After polymerization, the system was cooled to room temperature, and the resulting liquid was added dropwise to excess supercooled chloroform for precipitation. The resulting polymer was vacuum dried to constant weight, and the target copolymer P(AA-r-MAEMC) was finally collected.

[0076] In this embodiment, by copolymerizing MAEMC with AA, the coumarin functional groups can be uniformly embedded in the acrylic polymer chain in the form of copolymer side groups, providing a matrix basis for subsequent interface fixation triggered by 365 nm light.

[0077] Example 4: Preparation of Magnetically Controlled Coumarin Precursor System and Soft Actuator

[0078] Weigh the P(AA-r-MAEMC) copolymer obtained in Example 3, add it to the aqueous phase system and stir to dissolve, thus obtaining the polymer precursor system. Then add Fe3O4 magnetic particle dispersion or magnetic fluid, and sonicate to uniformly disperse the magnetic components, thus obtaining the magnetically controlled coumarin precursor system.

[0079] In some embodiments, the resulting precursor system can be used directly in a migrateable state; in other embodiments, it can be injected into a mold or a predetermined region and then irradiated with 365 nm ultraviolet light for 10–90 min, preferably at 50–150 mW / cm². 2 Irradiation under certain conditions for 60 minutes is performed to form a soft actuator with a predetermined shape and interface dwell capability.

[0080] In this invention, the magnetic particles are not first prepared as fibers or fragments and then compounded with other hydrogels, but are directly dispersed in the P(AA-r-MAEMC) precursor system, thereby forming a magnetically controlled coumarin soft actuator capable of overall migration and overall fixation.

[0081] Example 5: Verification of magnetic navigation and photo-induced interface adhesion

[0082] The magnetically controlled coumarin precursor system or soft actuator prepared in Example 4 is placed near a simulated channel, planar interface, inclined interface, curved interface, narrow channel inner wall or wet interface, and the material is driven to migrate to the designated position by an external magnetic field. After reaching the target position, the target area is irradiated with 365 nm light to change the material from a migratory state to a state with stronger interface retention ability.

[0083] In some embodiments, the material remains in the target region after the external magnetic field is removed, thus achieving in-situ fixation after magnetic navigation. In other embodiments, 254 nm light irradiation can be continued to break down at least some of the coumarin dimerization crosslinking points, thereby achieving release, re-migration, or recovery.

[0084] As described above, the 365 nm illumination in this invention is not merely a general photocuring step, but is used to trigger a material state switch in the target area, thereby improving the interface retention capability.

[0085] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A magnetically controlled coumarin soft actuator based on photosensitive interface fixation, characterized in that: The polymer matrix includes a coumarin side group; and magnetic particles dispersed in the polymer matrix. The software actuator is in a mobile state before 365 nm illumination, and transforms into a state with stronger interface dwell capability after 365 nm illumination.

2. The magnetically controlled coumarin soft actuator based on photosensitive interface fixation according to claim 1, characterized in that: The migratable state is a fluid dynamic, semi-fluid dynamic, or low-modulus state; the state with stronger interface retention ability is a gel state, weak gel state, or high-modulus state.

3. The magnetically controlled coumarin soft actuator based on photosensitive interface fixation according to claim 2, characterized in that: The polymer matrix is ​​a copolymer formed by acrylic monomers and coumarin-functionalized polymerizable monomers, wherein the coumarin-functionalized polymerizable monomer is 7-(2-methacryloyloxyethoxy)-4-methylcoumarin.

4. The magnetically controlled coumarin soft actuator based on photosensitive interface fixation according to claim 1, characterized in that: The magnetic particles are Fe3O4 nanoparticles, Fe3O4 components in magnetic fluid, or a combination thereof. The magnetic particles are directly added to the polymer matrix precursor system in the form of dispersion or magnetic fluid, and after stirring and / or ultrasonic treatment, a homogeneous magnetically controlled coumarin precursor system is formed.

5. A method for preparing a magnetically controlled coumarin soft actuator based on photo-induced interface immobilization, characterized in that: Includes the following steps: S1. Preparation of 7-(2-hydroxyethoxy)-4-methylcoumarin; S2. Preparation of 7-(2-methacryloyloxyethoxy)-4-methylcoumarin from 7-(2-hydroxyethoxy)-4-methylcoumarin; S3. The acrylic monomer is copolymerized with the 7-(2-methacryloyloxyethoxy)-4-methylcoumarin under the action of a free radical initiator to obtain a polymer containing coumarin side groups; S4. The polymer is added to an aqueous system to form a polymer precursor system; S5. Add magnetic particle dispersion or magnetic fluid to the polymer precursor system, and stir and / or sonicate to uniformly disperse the magnetic components to obtain a magnetically controlled coumarin precursor system. S6. The precursor system is kept in a transferable state for direct use, or after molding, it is irradiated with 365 nm light to form a soft actuator with interface dwell capability.

6. The method for preparing a magnetically controlled coumarin soft actuator based on photo-induced interface fixation according to claim 5, characterized in that: In S1, 4-methylumbelliferone and ethylene carbonate react in DMF (N,N-dimethylformamide) in the presence of anhydrous potassium carbonate to prepare 7-(2-hydroxyethoxy)-4-methylcoumarin.

7. The method for preparing a magnetically controlled coumarin soft actuator based on photo-induced interface retention according to claim 6, characterized in that: In S2, 7-(2-hydroxyethoxy)-4-methylcoumarin and triethylamine are co-dissolved in DMF, and methacryloyl chloride is added dropwise under ice bath conditions to react and prepare 7-(2-methacryloyloxyethoxy)-4-methylcoumarin.

8. A control method for a magnetically controlled coumarin soft actuator based on photosensitive interface fixation, characterized in that: Includes the following steps: S1. Under conditions without 365 nm illumination, an external magnetic field is applied to cause the software execution unit according to any one of claims 1 to 4 to migrate to the target region; S2. Apply 365 nm illumination to the target area to improve the interface dwell capability of the software execution unit at the target location.

9. The control method for a magnetically controlled coumarin soft actuator based on photosensitive interface fixation according to claim 8, characterized in that: After step S2, the external magnetic field is removed, and the software execution unit remains stationary in the target area.

10. The control method for a magnetically controlled coumarin soft actuator based on photosensitive interface holding according to claim 9, characterized in that: The coumarin side group was at least partially cleaved after being exposed to 254 nm light.

Images