Organic silicon self-floating induced near-infrared light response gradient hydrogel as well as preparation method and application thereof

Abstract

The invention relates to an organic silicon self-floating induced near-infrared light response gradient hydrogel as well as a preparation method and application thereof, and particularly discloses an organic silicon self-floating induced near-infrared light response gradient hydrogel driver which is relatively good in tensile property, high in driving speed and reusable. The preparation method comprises the following steps: putting an organic silicon macromolecular cross-linking agent, a temperature-sensitive monomer, a photo-thermal conversion agent, a hydrogen donor and a cosolvent, which are homemade according to different formulas and have photo-initiation performance, into a polytetrafluoroethylene mold, and carrying out one-step green LED photopolymerization, so as to prepare the gradient hydrogel. According to the invention, the organic silicon cross-linking agent with relatively strong initiation capability and self-floating characteristic is utilized to effectively promote the autonomous formation of composition gradient and structural gradient in the hydrogel, so that the shrinkage stress change from top to bottom is caused. The hydrogel driver provided by the invention has rapid driving capability and reversible cycle characteristic, has good reusability, can significantly improve the utilization rate, and has wide 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 of organic silicon, and a preparation method and application thereof. Background Art

[0002] With the development of society and the progress of science and technology, smart materials such as bionic 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. Under the stimulation of the applied stimulus, the microscopic molecular structure of the material changes, and then makes corresponding macroscopic responses, such as changes in shape, color, electrical conductivity, and thermal conductivity. Among them, smart materials that can achieve remote control are particularly important. The internal structure of the near-infrared light actuator changes under the stimulation of near-infrared light, causing the material to change morphology or mechanical response, achieving controllable deformation, such as macroscopic bending, grasping, walking, and jumping. In addition, near-infrared light has the advantages of remote triggering, adjustable intensity, fast switching, high spatiotemporal precision, and contactlessness. Compared with traditional photoresponsive hydrogels, near-infrared gradient hydrogels have become a research hotspot due to their faster response / recovery speed and significant deformation ability. Although relevant reports in recent years have been devoted to optimizing the performance of near-infrared hydrogel actuators by constructing gradient structures, existing manufacturing methods still face many challenges. For example, time-consuming, high-temperature, high-pressure operations, external magnetic fields or electric fields are required. In view of this, developing a simple, efficient, green, environmentally friendly, mild and stable method for preparing gradient hydrogels in order 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 a preparation method and application thereof. The gradient hydrogel utilizes a silicone cross-linking agent with strong initiation ability and self-floating characteristics 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 a gradient hydrogel can be prepared by one-step green LED photopolymerization. The gradient hydrogel has a gradient distribution of crosslinking 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 view of the problems existing in the above-mentioned technologies, the present invention proposes a near-infrared light-responsive gradient hydrogel induced by self-floating of silicone and a preparation method and application thereof. 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 an organosilicon macromolecular cross-linking agent 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 performance 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, silver 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; and 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; the co-solvent is one or a combination of two or more of 1,4-dioxane, tetrahydrofuran, methanol and ethanol.

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

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

[0016] The 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 organosilicon macromolecular crosslinkers with photoinitiation properties, thermosensitive monomers, photothermal conversion agents, hydrogen donors and cosolvent precursors were injected into the polytetrafluoroethylene mold and left to stand for 0.5-2 hours. Subsequently, polymerization was initiated under LED light, and the cosolvent was removed by deionized water treatment to obtain 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 of silicone in light-driven operation. The near-infrared light-responsive gradient hydrogel induced by self-floating of 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 near-infrared light-responsive gradient hydrogel induced by self-floating of silicone is green and simple.

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

[0023] 3. The organic silicon self-floating induced near-infrared light-responsive gradient hydrogel prepared by the present invention can be intelligently driven under near-infrared light irradiation and has good reversible cyclicity. It has application potential in the fields of bionic hydrogels and soft robots. 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 a SEM image of the gradient hydrogel prepared in Example 1;

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

[0028] Figure 5This is the stress-strain curve of the gradient hydrogel prepared in Example 1-4;

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

[0030] Figure 7 This is the reversible cycle 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 in conjunction with 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 used to limit the present invention.

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

[0033] Silicone macromolecular crosslinker 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 (the molar ratio of donor 2,5-di(2-naphthyl)thiophene and acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone is 1:1 to form eutectic NFQ; the molar ratio of donor 2,5-di(1,1'-biphenyl-4-yl)thiophene and acceptor 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone is 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 and heated at 100 mW / cm 2 The near-infrared gradient hydrogel 1 was prepared by irradiating the water with 405 nm LED light for 10 min to displace the cosolvent. Figure 1 shown.

[0044] [Example 2-4]

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

[0046] The steps of Example 1 were repeated except that PA-Si 25-1 The addition amount is 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 hydrogels7-9.

[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 silicon 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 the figure, 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 the 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 degree of crosslinking 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 hydrogel 1, hydrogel 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 by a thermocouple. Figure 4 As shown. At 1W / cm 2 Table 4 shows the temperature changes of hydrogels 7, 8 and 9 under irradiation with 980nm near-infrared light of different power for different time periods.

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

[0069]

[0070] [Test Example 4]

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

[0072] Gradient hydrogel 1-4 was prepared into dumbbell-shaped hydrogel strips of 35 mm × 2 mm × 2 mm. The tensile stress and strain of gradient hydrogel 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 hydrogel 1-4 has good 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 a camera was used to record the near-infrared light-driven process of the hydrogel. 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 It is shown that the gradient hydrogel 3 prepared in Example 3 bends after irradiation with near-infrared light for 1 minute, then recovers to be flat after being immersed in water for 30 minutes, and still has good reversible cycle characteristics after 10 cycles. This shows that the gradient hydrogel 3 has good 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, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0081] The above results indicate that the near-infrared light-responsive gradient hydrogel induced by self-floating of silicone 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 consists of an organic silicon macromolecular cross-linking agent with light-initiating properties, a thermosensitive monomer, a photothermal conversion agent, a hydrogen donor and a cosolvent.

2. The near-infrared light-responsive gradient hydrogel induced by self-floating silicone according to claim 1, characterized in that: The structural formula of the organosilicon macromolecular crosslinking agent with photoinitiating properties is: X is independently selected from: acrylate group, methacrylate group; n＝7-25。 3. 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; preferably, 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, silver 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; 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 co-solvent 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 crosslinking agent with photoinitiating properties accounts for 0.5-3 mol% of the total mole of the temperature-sensitive monomer.

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 5-15wt% of the total mass of the thermosensitive monomer; the hydrogen donor accounts for 0.5-3mol% of the total molar mass of the thermosensitive monomer; and the cosolvent accounts for 1-10wt% of the total mass of the thermosensitive monomer.

8. The method for preparing the near-infrared light-responsive gradient hydrogel induced by self-floating silicone according to any one of claims 1 to 7, characterized in that: The steps include: Different solutions of organosilicon macromolecular crosslinkers with photoinitiation properties, thermosensitive monomers, photothermal conversion agents, hydrogen donors and cosolvent precursors were injected into the polytetrafluoroethylene mold and left to stand for 0.5-2 hours. Subsequently, polymerization was initiated under LED light, and the cosolvent was removed by deionized water treatment to obtain a gradient hydrogel.

9. The method for preparing the near-infrared light-responsive gradient hydrogel induced by self-floating silicone 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. The use of the near-infrared light-responsive gradient hydrogel induced by self-floating silicone 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, optical drivers, and microfluidic valves.

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