A near-infrared light-responsive gradient hydrogel induced by self-floating silicone, and its preparation method and application

Abstract

The present invention relates to a near-infrared light-responsive gradient hydrogel induced by self-floating of silicone, and a preparation method and application thereof. Specifically, a near-infrared light-responsive gradient hydrogel actuator induced by self-floating of silicone with good tensile properties, fast driving speed and reusability is disclosed. Self-made silicone macromolecular cross-linking agents with photoinitiating properties, thermosensitive monomers, photothermal converters, hydrogen donors and cosolvents of different formulas are placed in a polytetrafluoroethylene mold, and a gradient hydrogel is prepared by one-step green LED photopolymerization. The present invention utilizes an organosilicon cross-linking agent with strong initiating ability and self-floating properties to effectively promote the autonomous formation of composition gradients and structural gradients inside the hydrogel, resulting in a change in shrinkage stress from top to bottom. The hydrogel actuator of the present invention has fast driving ability and reversible cycle characteristics, has good reusability, can significantly improve utilization rate, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of flexible intelligent driving materials, and in particular to a near-infrared light-responsive gradient hydrogel induced by self-floating silicone, and a preparation method and application thereof. Background Art

[0002] With the development of society and technological advancement, smart materials such as biomimetic soft materials and soft robots have attracted much attention. Smart responsive materials include light-responsive materials, heat-responsive materials, chemical-responsive materials, and pH-responsive materials. In response to an applied stimulus, the material's microscopic molecular structure changes, resulting in corresponding macroscopic responses, such as changes in shape, color, electrical conductivity, and thermal conductivity. Among these, smart materials capable of remote control are particularly important. Near-infrared light actuators, stimulated by near-infrared light, undergo internal structural changes, causing morphological changes or mechanical responses, enabling controllable deformations such as macroscopic bending, grasping, walking, and jumping. Near-infrared light offers advantages such as remote triggering, adjustable intensity, fast switching, high spatiotemporal precision, and contactlessness. Compared to traditional light-responsive hydrogels, near-infrared gradient hydrogels have become a research hotspot due to their faster response / recovery speeds and significant deformation capabilities. Although recent reports have focused on optimizing the performance of near-infrared hydrogel actuators by constructing gradient structures, existing fabrication methods still face numerous challenges, such as the time-consuming, high-temperature, high-pressure operation, and the application of external magnetic or electric fields. In view of this, developing a simple, efficient, green, environmentally friendly, mild and stable method for preparing gradient hydrogels to prepare gradient hydrogels that can meet on-demand spatiotemporal actuation and rapid response has become an urgent need and important direction of current research.

[0003] In order to overcome the shortcomings of the prior art, the present invention proposes a near-infrared light-responsive gradient hydrogel induced by self-floating of silicone, and its preparation method and application. The gradient hydrogel utilizes a silicone cross-linking agent with strong initiation ability and self-floating properties to effectively promote the autonomous formation of composition gradients and structural gradients inside the hydrogel, resulting in a change in shrinkage stress from top to bottom. This design not only improves the motion performance of the actuator, but also enhances its reliability and stability in practical applications. In addition, the preparation method of the present invention is simple and efficient, and gradient hydrogels can be prepared by one-step green LED photopolymerization. The gradient hydrogel has a gradient distribution of cross-linking degree and components from the top layer to the bottom layer. This new near-infrared light-responsive gradient hydrogel and its preparation method provide new ideas and methods for the development of the field of smart materials, and have broad application prospects and potential. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned technologies, the present invention proposes a near-infrared light-responsive gradient hydrogel induced by self-floating silicone, and its preparation method and application. The method is green and simple, and the prepared gradient hydrogel has a fast response, is reusable and has good tensile properties.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a near-infrared light-responsive gradient hydrogel induced by self-floating of silicone. The precursor solution of the near-infrared light-responsive gradient hydrogel induced by self-floating of silicone consists of a silicone macromolecular cross-linker with photoinitiating properties, a thermosensitive monomer, a photothermal conversion agent, a hydrogen donor and a cosolvent.

[0007] Preferably, the structural formula of the organosilicon macromolecular crosslinking agent having photoinitiation properties is:

[0008]

[0009] X is independently selected from: acrylate group, methacrylate group;

[0010] n=7-25.

[0011] Preferably, the temperature-sensitive monomer is one or a combination of two or more of N-isopropylacrylamide, N,N-dimethylacrylamide, dimethylaminoethyl methacrylate, and N-vinylcaprolactam; preferably, the temperature-sensitive monomer is N-isopropylacrylamide.

[0012] Preferably, the photothermal conversion agent is a photothermal organic eutectic, polydopamine, polypyrrole, polyaniline, indocyanine green, graphene oxide, gold nanoparticles, or a combination of two or more thereof; the photothermal organic eutectic is composed of a donor 2,5-di(2-naphthyl)thiophene or a donor 2,5-di(1,1'-biphenyl-4-yl)thiophene and an acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone; the molar ratio of the donor to the acceptor in the photothermal organic eutectic is 1.1 to 2.

[0013] Preferably, the hydrogen donor is selected from one or more tertiary amine compounds; and the cosolvent is one or a combination of two or more of 1,4-dioxane, tetrahydrofuran, methanol, and ethanol.

[0014] Preferably, the organosilicon macromolecular cross-linking agent with photoinitiating properties accounts for 0.5-3 mol% of the total moles of the temperature-sensitive monomer.

[0015] Preferably, the photothermal conversion agent accounts for 5-15 wt% of the total mass of the thermosensitive monomer; the hydrogen donor accounts for 0.5-3 mol% of the total molar mass of the thermosensitive monomer; and the cosolvent accounts for 1-10 wt% of the total mass of the thermosensitive monomer.

[0016] A second aspect of the present invention provides a method for preparing a near-infrared light-responsive gradient hydrogel induced by self-floating silicone, comprising the following steps:

[0017] Different solutions of a photoinitiated organosilicon macromolecular crosslinker, a thermosensitive monomer, a photothermal converter, a hydrogen donor, and a cosolvent precursor were injected into a polytetrafluoroethylene mold and allowed to stand for 0.5-2 hours. Subsequently, polymerization was initiated under LED light, and the cosolvent was removed by deionized water treatment to produce a gradient hydrogel.

[0018] Preferably, the LED light wavelengths are 365nm, 385nm, 395nm and 405nm, and the light intensity is 100mW / cm 2 , the irradiation time is 10-60min.

[0019] The third aspect of the present invention provides an application of a near-infrared light-responsive gradient hydrogel induced by self-floating silicone in light-driven operation. The near-infrared light-responsive gradient hydrogel induced by self-floating silicone is applied to intelligent bionic materials, soft robots, light actuators, and microfluidic valves.

[0020] The above technical solution has the following beneficial effects:

[0021] 1. The method for preparing the silicone self-floating induced near-infrared light-responsive gradient hydrogel of the present invention is green and simple.

[0022] 2. The near-infrared light-responsive gradient hydrogel induced by self-floating silicone prepared by the present invention has excellent tensile properties.

[0023] 3. The organosilicon self-floating, near-infrared light-responsive gradient hydrogel prepared by this invention can be intelligently driven under near-infrared light irradiation and exhibits excellent reversible cycling properties. This has potential applications in fields such as biomimetic hydrogels and soft robotics. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the preparation process of gradient hydrogel;

[0025] Figure 2 The atomic percentages of the top and bottom layers of the gradient hydrogel prepared in Example 1;

[0026] Figure 3 This is the SEM image of the gradient hydrogel prepared in Example 1;

[0027] Figure 4 Temperature changes of the gradient hydrogel prepared in Example 1 under irradiation with 980nm near-infrared light of different powers;

[0028] Figure 5The stress-strain curves of the gradient hydrogels prepared in Examples 1-4;

[0029] Figure 6 This is a photograph of the deformation of the gradient hydrogel prepared in Example 1 under near-infrared light stimulation;

[0030] Figure 7 This is the reversible cycling curve of the gradient hydrogel prepared in Example 3 recovered under near-infrared light and water. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to specific embodiments and test examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] The raw materials used in the following examples are as follows:

[0033] Silicone macromolecular crosslinkers with photoinitiator properties:

[0034]

[0035] X is independently selected from: acrylate group (1), methacrylate group (2);

[0036] n=7-25.

[0037] Thermosensitive monomers: N-isopropylacrylamide (NIPAAM), N,N-dimethylacrylamide (DEA), dimethylaminoethyl methacrylate (DMAEMA), N-vinylcaprolactam (NVCMA).

[0038] Photothermal conversion agent: photothermal organic eutectic (donor 2,5-di(2-naphthyl)thiophene and acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone in a molar ratio of 1:1 to form eutectic NFQ; donor 2,5-di(1,1'-biphenyl-4-yl)thiophene and acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone in a molar ratio of 1:1 to form eutectic DFQ), polydopamine (PDA), polypyrrole (PPy), polyaniline (PANI), indocyanine green (ICG), graphene oxide (GO), gold nanoparticles (AuNPs), and silver nanoparticles (AgNPs).

[0039] Hydrogen donor: ethyl 4-dimethylaminobenzoate (EDB), triethylamine (Et3N), etc.

[0040] Cosolvents: 1,4-dioxane, tetrahydrofuran, methanol, ethanol.

[0041] [Example 1]

[0042] Preparation of near-infrared gradient hydrogel 1.

[0043] 10 mmol of NIPAAM, 1 mol% (relative to the molar amount of NIPAAM) of PA-Si 25-1 , 10 wt% (relative to the mass of NIPAAM) NFQ, 1 mol% (relative to the molar amount of NIPAAM) EDB and 5 wt% (relative to the mass of NIPAAM) 1,4-dioxane were ultrasonically dissolved and placed in a 20 mm × 2 mm × 0.5 mm polytetrafluoroethylene mold. 2 The near-infrared gradient hydrogel 1 was prepared by irradiating the water with 405 nm LED light for 10 min and replacing the cosolvent. Figure 1 shown.

[0044] [Example 2-4]

[0045] Preparation of near-infrared gradient hydrogels 2-4.

[0046] Repeat the steps of Example 1, except that PA-Si 25-1 The addition amount of the hydrogels was different, and the addition amount and hydrogel number are shown in Table 1.

[0047] Table 1. PA-Si used in Examples 2-4 25-1 Amount of addition

[0048] Formula and number Example 2 Example 3 Example 4 <![CDATA[PA-Si 25-1 Addition amount (mol%)]]> 0.5 2 3 Hydrogel No. 2 3 4

[0049] [Examples 5-6]

[0050] Preparation of near-infrared gradient hydrogels 5-6.

[0051] The steps of Example 1 were repeated, except that the amount of NFQ added was different. The amount added and the gradient hydrogel number are shown in Table 2.

[0052] Table 2. Addition amount of NFQ used in Examples 5-6

[0053] Formula and number Example 5 Example 6 NFQ addition amount (wt%) 5 15 Hydrogel No. 5 6

[0054] [Examples 7-9]

[0055] Preparation of near-infrared gradient hydrogels 7-9.

[0056] The steps of Example 1 were repeated, except that the photothermal conversion agent was different. The specific type and gradient hydrogel number are shown in Table 3.

[0057] Table 3. Photothermal conversion agents used in Examples 7-9

[0058] Formula and number Example 7 Example 8 Example 9 Photothermal conversion agent DFQ PPy GO Hydrogel No. 8 9 10

[0059] Test Example 1

[0060] The purpose of this test example is to illustrate that the self-floating property of the organic silicone in the gradient hydrogel 1 prepared in Example 1 induces the hydrogel composition to be distributed in a gradient from the top layer to the bottom layer.

[0061] The present invention uses energy dispersive spectroscopy (EDS) technology to characterize the element gradient distribution in the gradient hydrogel 1. Figure 2 As shown in FIG, the atomic percentage of silicon (Si) element gradually increases from the bottom to the top of the hydrogel. 25-1 It is the only component of silicon in gradient hydrogel, which indicates that PA-Si 25-1 A gradient concentration distribution spontaneously formed inside the hydrogel. This is attributed to the PA-Si 25-1 Unique self-buoyancy characteristics.

[0062] Test Example 2

[0063] The purpose of this test example is to further illustrate that the cross-linking degree of the hydrogel in the gradient hydrogel 1 prepared in Example 1 changes gradually from the top layer to the bottom layer.

[0064] The cross section of the freeze-dried hydrogel 1 was observed using a JSM-5610LV scanning electron microscope. Figure 3 It can be seen that the cross-linked network structure from the top layer to the bottom layer is distributed in a gradient, which indicates that the cross-linking degree of the hydrogel is distributed in a gradient from the top layer to the bottom layer.

[0065] Test Example 3

[0066] The purpose of this test example is to illustrate that the gradient hydrogels 1, 7, 8, and 9 prepared in Examples 1, 7, 8, and 9 have good photothermal conversion effects.

[0067] Under irradiation with 980nm near-infrared light of different powers, the temperature change of the gradient hydrogel 1 was monitored using a thermocouple, as shown in FIG. Figure 4 As shown. At 1W / cm 2 Table 4 shows the temperature changes of hydrogels 7, 8, and 9 under irradiation with 980 nm near-infrared light of different power for different times.

[0068] Table 4. Temperature of hydrogel 7-9 prepared in Example 7-9 under different time of near-infrared light irradiation

[0069]

[0070] Test Example 4

[0071] The purpose of this test case is to illustrate the PA-Si 25-1 The addition of will improve the tensile properties of the gradient hydrogels 1-4 prepared in Examples 1-4.

[0072] Gradient hydrogels 1-4 were prepared into dumbbell-shaped hydrogel strips of 35 mm × 2 mm × 2 mm. The tensile stress and strain of gradient hydrogels 1-4 were tested at 25°C using an Instron electronic universal testing machine at a tensile speed of 10 mm / min. Figure 5 It can be seen that when PA-Si 25-1 When the content increased from 0.5 mol% to 3 mol% (relative to the amount of NIPAAM), the fracture stress of the gradient hydrogel increased by 2 times from 650 kPa to 1491 kPa, and the fracture strain increased by more than 3 times from 185% to 615%, indicating that the gradient hydrogels 1-4 have excellent tensile properties.

[0073] Test Example 5

[0074] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has fast driving capability.

[0075] The wavelength is 980nm and the light intensity is 1.5W / cm 2 The near-infrared light was irradiated at a distance of 3 cm from the spline and the near-infrared light driving process of the hydrogel was recorded using a camera. Figure 6 It can be seen that gradient hydrogel 1 can bend 200° within 25 s, which indicates that gradient hydrogel 6 has fast actuation capability.

[0076] Test Example 6

[0077] The purpose of this test example is to illustrate that the gradient hydrogel 3 prepared in Example 3 has fast driving capability and reusability.

[0078] Figure 7 The results show that the gradient hydrogel 3 prepared in Example 3 bends after 1 minute of near-infrared light irradiation, then returns to a flat state after 30 minutes of immersion in water. Furthermore, the gradient hydrogel 3 maintains excellent reversible cycling properties after 10 cycles. This indicates that the gradient hydrogel 3 has excellent reusability.

[0079] In addition, other hydrogels of the present invention can be synthesized according to the methods in the examples, which will not be described in detail here.

[0080] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0081] The above results indicate that the organosilicon self-floating induced near-infrared light-responsive gradient hydrogel provided by the present invention has the characteristics of good mechanical properties, rapid response and reusability.

Claims

1. A near-infrared light-responsive gradient hydrogel induced by self-floating silicone, characterized in that: The precursor solution of the organic silicon self-floating induced near-infrared light-responsive gradient hydrogel is composed of an organic silicon macromolecular cross-linking agent with photoinitiating properties, a thermosensitive monomer, a photothermal conversion agent, a hydrogen donor and a cosolvent; The structural formula of the organosilicon macromolecular crosslinking agent with photoinitiation performance is: X is independently selected from: acrylate group, methacrylate group; n＝7-25。 2. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 1, characterized in that: The temperature-sensitive monomer is one or a combination of two or more of N-isopropylacrylamide, N,N-dimethylacrylamide, dimethylaminoethyl methacrylate, and N-vinylcaprolactam.

3. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 2, characterized in that: The temperature-sensitive monomer is N-isopropylacrylamide.

4. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 1, characterized in that: The photothermal conversion agent is a photothermal organic eutectic, polydopamine, polypyrrole, polyaniline, indocyanine green, graphene oxide, gold nanoparticles, and a combination of two or more thereof; the photothermal organic eutectic is composed of a donor 2,5-di(2-naphthyl)thiophene or a donor 2,5-di(1,1'-biphenyl-4-yl)thiophene and an acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone; and the molar ratio of the donor to the acceptor in the photothermal organic eutectic is 1.1 to 2.

5. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 1, characterized in that: The hydrogen donor is selected from one or more tertiary amine compounds; the cosolvent is one or a combination of two or more of 1,4-dioxane, tetrahydrofuran, methanol, and ethanol.

6. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 1, characterized in that: The organosilicon macromolecular cross-linking agent with photoinitiating properties accounts for 0.5-3 mol% of the total moles of the temperature-sensitive monomers.

7. The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 1, characterized in that: The photothermal conversion agent accounts for 5-15 wt% of the total mass of the thermosensitive monomer; the hydrogen donor accounts for 0.5-3 mol% of the total molar mass of the thermosensitive monomer; and the cosolvent accounts for 1-10 wt% of the total mass of the thermosensitive monomer.

8. The method for preparing the organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to any one of claims 1 to 7, characterized in that: The steps include: Different formula solutions of organosilicon macromolecular crosslinking agent with photoinitiating properties, thermosensitive monomer, photothermal conversion agent, hydrogen donor and cosolvent precursor are injected into a polytetrafluoroethylene mold and left to stand for 0.5-2 hours. Subsequently, polymerization is initiated under LED light, and the cosolvent is removed by deionized water treatment to produce a gradient hydrogel.

9. The method for preparing the organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to claim 8, characterized in that: The LED light wavelengths are 365nm, 385nm, 395nm and 405nm, and the light intensity is 100mW / cm 2 , the irradiation time is 10-60min.

10. Use of the organosilicon self-floating induced near-infrared light-responsive gradient hydrogel according to any one of claims 1 to 7, characterized in that: The organosilicon self-floating induced near-infrared light-responsive gradient hydrogel is applied to intelligent bionic materials, soft robots, light drivers, and microfluidic valves.

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