Polysiloxane self-migration induced multi-stimulation response and programmable gradient hydrogel as well as preparation method and application thereof

Abstract

The invention relates to a polysiloxane self-migration induced multi-stimulus response and programmable gradient hydrogel as well as a preparation method and application thereof. The invention relates to a hydrogel driver, and particularly discloses a polysiloxane self-migration induced gradient hydrogel driver which is quick in response, reusable, better in tensile property, multi-stimulation response and programmable in complex deformation capability. The preparation method comprises the following steps: putting a polysiloxane cross-linking agent, a temperature-sensitive monomer, spiropyrane coordinated up-conversion nanoparticles, a photoinitiator and a cosolvent in different formulas into a polytetrafluoroethylene mold, and carrying out one-step green LED polymerization to prepare the gradient hydrogel. The polysiloxane cross-linking agent is utilized to effectively promote autonomous formation of composition gradient and structure gradient in the hydrogel, and shrinkage stress change from top to bottom is caused. The hydrogel driver disclosed by the invention has the capabilities of rapid driving, reversible circulation, multiple stimulation response and programmable complex deformation, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the field of flexible intelligent driving materials, and in particular to a polysiloxane self-migration-induced multi-stimulus-responsive and programmable gradient hydrogel, and a preparation method and application thereof. Background Art

[0002] In recent years, gradient hydrogels have been widely studied as a special class of smart materials, owing to the unique gradient structural characteristics exhibited by natural biological systems. However, with technological advances and increasing demand, gradient hydrogels with a unidirectional actuation mode are no longer able to meet the current higher requirements for biomimetic smart actuators. Against this backdrop, programmable complex deformation gradient hydrogel actuators have emerged. These actuators achieve complex deformations in hydrogels through controllable gradient structural design, demonstrating great application potential and providing an important research direction for the development of next-generation smart actuators. In traditional preparation processes, hydrogels can be patterned or gradient structures with different directions can be introduced through a series of sophisticated manipulation methods such as layer-by-layer assembly, electric field induction, or 3D printing, thereby endowing them with complex deformation capabilities. However, these processes generally require complex preparation processes or demanding instrumentation, which to some extent limits their development and application. Furthermore, biomimetic hydrogels that respond to a single stimulus are increasingly unable to meet the complex and diverse application scenarios. In contrast, multi-stimulus-responsive hydrogels, as a class of functional smart materials capable of responding to multiple external stimuli, show broad application prospects. Therefore, there is an urgent need to develop a simple and convenient strategy to construct multi-responsive, programmable gradient hydrogels.

[0003] In order to overcome the shortcomings of the prior art, the present invention proposes a polysiloxane self-migration-induced multi-stimulus-responsive and programmable gradient hydrogel, as well as a preparation method and application thereof. The preparation method of the present invention is convenient and efficient, and can utilize the spontaneous upward surface migration characteristics of the polysiloxane crosslinker to prepare a series of reversibly driven, multi-stimulus-responsive and programmable dual-gradient hydrogels with the help of mask LED photopolymerization. By adjusting the static conditions of the photosensitive precursor solution and the size of the photopolymerization mask, the autonomous formation of the internal composition gradient and structural gradient of the hydrogel is effectively promoted, giving it complex deformation capabilities. This design not only improves the motion performance of the actuator, but also enhances its durability and stability in practical applications. This new multi-stimulus-responsive and programmable dual-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 polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel and its preparation method and application. The method is green and simple. The prepared gradient hydrogel is fast-responsive, reusable, has good tensile properties, is responsive to multiple stimulus sources, and has programmable complex deformation capabilities.

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

[0006] The first aspect of the present invention provides a polysiloxane self-migration-induced multi-stimulus-responsive and programmable gradient hydrogel, wherein the precursor solution of the polysiloxane self-migration-induced multi-stimulus-responsive and programmable gradient hydrogel consists of a polysiloxane crosslinker, a thermosensitive monomer, spiropyran-coordinated upconversion nanoparticles, a photoinitiator and a cosolvent.

[0007] Preferably, the structural formula of the polysiloxane crosslinking agent is:

[0008]

[0009] R1 and R2 are the same or different and are independently selected from C1-C 12 Alkyl, N, O, S heteroatom substituted C1-C 12 Alkyl, C1-C 12 alkoxy, or a combination thereof;

[0010] R3 and R4 are the same or different and are independently selected from C3-C 12 alkyl and alkoxy, or a combination thereof;

[0011] M is independently selected from: hydrogen, methyl;

[0012] n=3-50.

[0013] Preferably, the temperature-sensitive monomer is selected from 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.

[0014] Preferably, the structural formula of the spiropyran of the spiropyran-coordinated upconversion nanoparticles is:

[0015] X is independently selected from: hydrogen or methoxy;

[0016] The upconversion nanoparticles of the spiropyran-coordinated upconversion nanoparticles are selected from NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@NaYF4:Yb 3+ ,Tm 3+、LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@LiYF4:Yb 3+ ,Tm 3+ One or a combination of two or more of the above, preferably the upconversion nanoparticles are LiYF4@LiYF4:Yb 3+ ,Tm 3+ .

[0017] Preferably, the photoinitiator is selected from one or a combination of two or more of α-hydroxyketones, α-aminoketones, α-oxyacyl oxime esters, and acylphosphine photoinitiators; the cosolvent is selected from one or a combination of two or more of 1,4-dioxane, tetrahydrofuran, methanol, and ethanol.

[0018] Preferably, the polysiloxane crosslinking agent accounts for 0.5-2 mol% of the total moles of the temperature-sensitive monomer.

[0019] Preferably, the spiropyran-coordinated upconversion nanoparticles account for 1-5 wt% of the total mass of the thermosensitive monomer; the photoinitiator accounts for 0.5-2 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.

[0020] The second aspect of the present invention provides a method for preparing a polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel, comprising the following steps:

[0021] Different solutions of a polysiloxane crosslinker, a thermosensitive monomer, spiropyran-coordinated upconversion nanoparticles, a photoinitiator, and a cosolvent precursor were injected into a polytetrafluoroethylene mold and allowed to stand for 0.5-1.5 hours. Subsequently, polymerization was initiated under LED light, and the cosolvent was removed by deionized water treatment to produce a gradient hydrogel.

[0022] Preferably, the LED light wavelengths are 365nm, 385nm, 395nm and 405nm, and the light intensity is 100mW / cm 2 , the irradiation time is 2-5min.

[0023] The third aspect of the present invention provides a polysiloxane self-migration-induced multiple stimulus response and programmable gradient hydrogel application in light driving, wherein the polysiloxane self-migration-induced multiple stimulus response and programmable gradient hydrogel are applied to intelligent bionic materials, soft robots and light actuators.

[0024] The above technical solution has the following beneficial effects:

[0025] 1. The method of the present invention for preparing polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel is green and simple, and the prepared hydrogel has excellent tensile properties.

[0026] 2. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel prepared by the present invention is driven under thermal stimulation, ultraviolet light irradiation and near-infrared light irradiation, and has good reversible cyclicity.

[0027] 3. By adjusting the static conditions of the photosensitive precursor solution and the mask size, the present invention can programmatically design the gradient hydrogel's response shape to thermal or near-infrared light stimulation. This gradient hydrogel has potential applications in fields such as biomimetic hydrogels and soft robotics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the preparation process of gradient hydrogel;

[0029] Figure 2 The silicon atomic percentage of the top and bottom layers of the gradient hydrogels prepared in Examples 1-4;

[0030] Figure 3 SEM images of the gradient hydrogels prepared in Examples 1-4;

[0031] Figure 4 Temperature changes of the gradient hydrogel prepared in Example 1 under irradiation with 980nm near-infrared light of different powers;

[0032] Figure 5 The stress-strain curves of the gradient hydrogels prepared in Examples 1 and 5-7;

[0033] Figure 6 This is a photograph of the deformation of the gradient hydrogel prepared in Example 1 under thermal stimulation;

[0034] Figure 7 This is a photograph of the deformation of the gradient hydrogel prepared in Example 1 under ultraviolet light stimulation;

[0035] Figure 8 This is a photograph of the deformation of the gradient hydrogel prepared in Example 1 under near-infrared light stimulation;

[0036] Figure 9 This is the reversible cycling curve of the gradient hydrogel prepared in Example 1 under near-infrared light on-off;

[0037] Figure 10 These are photos of the programmable complex deformation of the gradient hydrogels prepared in Examples 10-13 under thermal and near-infrared light stimulation. DETAILED DESCRIPTION

[0038] 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.

[0039] The raw materials used in the following examples are as follows:

[0040] Polysiloxane crosslinker:

[0041]

[0042] R1 and R2 are the same or different and are independently selected from C1-C 12 Alkyl, N, O, S heteroatom substituted C1-C 12 Alkyl, C1-C 12 alkoxy, or a combination thereof;

[0043] R3 and R4 are the same or different and are independently selected from C3-C 12 alkyl and alkoxy, or a combination thereof;

[0044] n = 3-50;

[0045] Preferred

[0046] Thermosensitive monomers: N-isopropylacrylamide (NIPAAM), N,N-dimethylacrylamide (DEA), dimethylaminoethyl methacrylate (DMAEMA), N-vinylcaprolactam (NVCMA); preferably NIPAAM.

[0047] Upconversion nanoparticles: NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@NaYF4:Yb 3+ ,Tm 3+ 、LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@LiYF4:Yb 3+ ,Tm 3+ ; LiYF4@LiYF4:Yb is preferred 3+ ,Tm 3 + .

[0048] Spiropyran: SPMA2 is preferred.

[0049] Photoinitiator: 2-hydroxy-2-methylphenylacetone (1173), methyl benzoylformate (MBF), 2,4,6-trimethylbenzoylphenylphosphonate (TPO), ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L), etc.

[0050] Cosolvents: 1,4-dioxane, tetrahydrofuran, methanol, ethanol.

[0051] [Example 1]

[0052] Preparation of gradient hydrogel 1.

[0053] Take LiYF4@LiYF4:Yb 3+ ,Tm 3+ The oleic acid-removed upconversion nanoparticles (RUC) were then added with 20 mL of anhydrous ethanol solution containing 10 mmol of SPMA2 (10 mg) and stirred in the dark at room temperature for 48 hours. The mixture was then centrifuged at 4000 rpm for 30 minutes, collected, and washed three times with 10 mL of anhydrous ethanol to obtain M2UC.

[0054] At 25 °C, 5 mmol of NIPAAM and 1 mol% of SiMA were added. 19-2 , 3wt% M2UC, 1mol% TPO, 800μL 1,4-dioxane and 200μL H2O were mixed to prepare a photosensitive precursor solution. Subsequently, the solution was injected into a polytetrafluoroethylene mold with a size of 15mm×2mm×0.5mm and allowed to stand for 1h. Then, at 405nm (100mW / cm 2 ) was irradiated under an LED light source for 5 min to replace the cosolvent in water to obtain gradient hydrogel 1.

[0055] [Example 2-4]

[0056] Prepare gradient hydrogels 2-4.

[0057] The steps of Example 1 were repeated, except that the photosensitive precursor solution was left standing for a different time. The standing time and hydrogel number are shown in Table 1.

[0058] Table 1. Standing time of photosensitive precursor solution of Example 2-4

[0059] Standing time and number Example 2 Example 3 Example 4 Standing time (h) 0 0.5 1.5 Hydrogel No. 2 3 4

[0060] [Examples 5-7]

[0061] Prepare gradient hydrogels 5-7.

[0062] The steps of Example 1 were repeated except that SiMA 19-2 The addition amount of the hydrogels was different, and the addition amount and hydrogel number are shown in Table 2.

[0063] Table 2. SiMA used in Examples 5-7 19-2 Amount of addition

[0064] Formula and number Example 5 Example 6 Example 7 <![CDATA[SiMA 19-2 Addition amount (mol%)]]> 0.5 1.5 2 Hydrogel No. 5 6 7

[0065] [Examples 8-9]

[0066] Preparation of gradient hydrogels 8-9.

[0067] The steps of Example 1 were repeated, except that the amount of M2UC added was different. The amount added and the gradient hydrogel number are shown in Table 3.

[0068] Table 3. Addition amount of M2UC used in Examples 8-9

[0069] Formula and number Example 8 Example 9 <![CDATA[Addition amount of M2UC (wt%)]]> 1 2 Hydrogel No. 8 9

[0070] [Examples 10-13]

[0071] Prepare gradient hydrogels 10-13.

[0072] The steps of Example 1 were repeated, except that the static conditions of the photosensitive solution were different. The specific types and gradient hydrogel numbers are shown in Table 4.

[0073] Table 4. Static conditions for Examples 10-13

[0074]

[0075] Test Example 1

[0076] The purpose of this test example is to illustrate that the spontaneous migration performance of polysiloxane in the gradient hydrogel 1-4 prepared in Example 1-4 induces the hydrogel composition to be distributed in a gradient from the top layer to the bottom layer.

[0077] The present invention uses energy dispersive spectroscopy (EDS) technology to characterize the element gradient distribution in the gradient hydrogels 1-4. 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, and as the static time of the photosensitive precursor solution increases, the atomic percentage of silicon element in the top layer of the hydrogel gradually increases, while that in the bottom layer decreases. 19-2 It is the only component of silicon in gradient hydrogel, which indicates that SiMA 19-2A gradient concentration distribution spontaneously formed inside the hydrogel.

[0078] Test Example 2

[0079] The purpose of this test example is to further illustrate that the cross-linking degree of the hydrogel in the gradient hydrogel 1-4 prepared in Examples 1-4 changes gradually from the top layer to the bottom layer.

[0080] The cross sections of the freeze-dried hydrogels 1-4 were observed using a JSM-5610LV scanning electron microscope (SEM). Figure 3 It can be seen that the cross-linked network structure of hydrogel 1 shows a gradient distribution from the top layer to the bottom layer. The pore size near the top layer is smaller, while the pore size near the bottom layer is larger, approximately twice that of the top layer. This indicates that the cross-linking degree of the hydrogel is gradient from the top layer to the bottom layer. In addition, with increasing standing time, the average pore size near the top layer gradually decreases, while the average pore size near the bottom layer gradually increases, and the difference in pore size between the top and bottom layers increases. These results confirm the existence of a gradient cross-linking structure in the hydrogel and that the gradient cross-linking degree of the hydrogel can be effectively controlled by adjusting the standing time of the photosensitive precursor solution.

[0081] Test Example 3

[0082] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has a good photothermal conversion effect.

[0083] Under irradiation with 980nm near-infrared light of different powers, the temperature change of the gradient hydrogel 1 was monitored using a thermocouple. Figure 4 As shown in the figure, as the near-infrared light power increases, the temperature change (ΔT) of gradient hydrogel 1 also increases. While keeping other experimental conditions unchanged, the near-infrared light power and the temperature change of the hydrogel show a good positive correlation. This shows that by adjusting the near-infrared light power, the temperature of the gradient hydrogel after photothermal conversion can be effectively controlled.

[0084] Test Example 4

[0085] The purpose of this test case is to illustrate the 19-2 The addition of will improve the tensile properties of the gradient hydrogels 1 and 5-7 prepared in Examples 1 and 5-7.

[0086] Gradient hydrogels 1 and 5-7 were prepared into dumbbell-shaped hydrogel strips of 35 mm × 2 mm × 2 mm. The tensile stress and strain of gradient hydrogels 1 and 5-7 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 SiMA 19-2When the content of NIPAAM increased from 0.5 mol% to 2 mol%, the fracture strain increased from 252% to 950%, and the fracture stress increased from 291 kPa to 1105 kPa. In summary, the introduction of polysiloxane chains significantly improved the flexibility of the hydrogels, and the gradient hydrogels 1, 5-7 had excellent tensile properties.

[0087] Test Example 5

[0088] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has thermal response driving ability.

[0089] The driving process of the hydrogel in 60℃ hot water was recorded by a camera. Figure 6 As the temperature of gradient hydrogel 1 increases from 40°C to 60°C, the final deformation angle of the hydrogel increases from 261° to 480°, and the average thermal response deformation rate increases from 26.1° / s to 120° / s. This demonstrates that gradient hydrogel 8 has rapid thermal response actuation capabilities.

[0090] Test Example 6

[0091] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has ultraviolet light driving capability.

[0092] The wavelength is 365nm and the light intensity is 0.16W / cm 2 The UV light was irradiated at a distance of 3 cm from the spline and the UV-driven process of the hydrogel was recorded with a camera. Figure 7 It can be seen that under ultraviolet light irradiation, the gradient hydrogel 1 undergoes bending deformation. After turning off the ultraviolet light, the hydrogel gradually recovers under visible light irradiation, which indicates that the hydrogel undergoes reversible driving under ultraviolet and visible light irradiation.

[0093] Test Example 7

[0094] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has near-infrared light driving capability.

[0095] The wavelength is 980nm and the light intensity is 3W / 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 8 It can be seen that gradient hydrogel 1 can bend 555° within 30 seconds, which indicates that gradient hydrogel 8 has the ability to be driven by fast near-infrared light.

[0096] Test Example 8

[0097] The purpose of this test example is to illustrate that the gradient hydrogel 1 prepared in Example 1 has fast driving capability and reusability.

[0098] Figure 9 It shows that the gradient hydrogel 1 prepared in Example 1 undergoes obvious deformation under near-infrared light irradiation. After the light source is turned off, the hydrogel gradually recovers. In addition, the gradient hydrogel exhibits stable repeatability in at least 10 deformation cycles, which indicates that the gradient hydrogel has excellent reversible driving ability.

[0099] Test Example 9

[0100] The purpose of this test example is to illustrate that the gradient hydrogel 10-13 prepared in Examples 10-13 has fast driving capability.

[0101] like Figure 10 As shown, after being immersed in hot water, gradient hydrogel 10 quickly exhibited the shape of a "7"; while gradient hydrogel 11 quickly exhibited a lollipop shape after being immersed in 60°C water. In addition, gradient hydrogel 12 quickly exhibited hook shapes with different degrees of curling after being immersed in hot water. After being placed in 20°C water, the splines gradually recovered. Similarly, under near-infrared light irradiation, the programmed gradient hydrogels 10, 11, and 13 can exhibit a "9", "lollipop" and "dumbbell" shape, respectively, with remote control complex response characteristics. And after turning off the light source, the splines can gradually return to their initial shape. In summary, by adjusting the static conditions of the photosensitive precursor solution and the mask size, temperature and near-infrared light responsive programmable gradient hydrogels were successfully constructed.

[0102] 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.

[0103] 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.

[0104] The above results indicate that the gradient hydrogel induced by spontaneous migration of polysiloxane provided by the present invention has the characteristics of good mechanical properties, rapid response, reusability, multi-stimulus response and programmability.

Claims

1. A polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel, characterized in that: The precursor solution of the polysiloxane self-migration-induced multi-stimulus response and programmable gradient hydrogel consists of a polysiloxane crosslinker, a thermosensitive monomer, spiropyran-coordinated upconversion nanoparticles, a photoinitiator and a cosolvent.

2. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The structural formula of the polysiloxane crosslinking agent is: R1 and R2 are the same or different and are independently selected from C1-C 12 Alkyl, N, O, S heteroatom substituted C1-C 12 Alkyl, C1-C 12 alkoxy, or a combination thereof; R3 and R4 are the same or different and are independently selected from C3-C 12 alkyl and alkoxy, or a combination thereof; M is independently selected from: hydrogen, methyl; n＝3-50。 3. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The temperature-sensitive monomer is selected from 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 polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The structural formula of the spiropyran of the spiropyran-coordinated upconversion nanoparticles is independently selected from: X is independently selected from: hydrogen, methoxy; The upconversion nanoparticles of the spiropyran-coordinated upconversion nanoparticles are selected from NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@NaYF4:Yb 3+ ,Tm 3+ 、LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@LiYF4:Yb 3+ ,Tm 3+ 、LiYF4@NaYF4:Yb 3+ ,Tm 3+ 、NaYF4@LiYF4:Yb 3+ ,Tm 3+ One or a combination of two or more of the above, preferably the upconversion nanoparticles are LiYF4@LiYF4:Yb 3 + ,Tm 3+ .

5. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The photoinitiator is selected from one or a combination of two or more of α-hydroxy ketones, α-amino ketones, α-oxyacyl oxime esters, and acylphosphine photoinitiators; the cosolvent is selected from one or a combination of two or more of 1,4-dioxane, tetrahydrofuran, methanol, and ethanol.

6. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The polysiloxane crosslinking agent accounts for 0.5-2 mol% of the total moles of the temperature-sensitive monomer.

7. The polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to claim 1, characterized in that: The spiropyran-coordinated upconversion nanoparticles account for 1-5 wt% of the total mass of the thermosensitive monomer; the photoinitiator accounts for 0.5-2 mol% of the total molar amount of the thermosensitive monomer; and the cosolvent accounts for 1-10 wt% of the total mass of the thermosensitive monomer.

8. A method for preparing a polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to any one of claims 1 to 7, characterized in that: The steps include: Different solutions of a polysiloxane crosslinker, a thermosensitive monomer, spiropyran-coordinated upconversion nanoparticles, a photoinitiator, and a cosolvent precursor were injected into a polytetrafluoroethylene mold and allowed to stand for 0.5-1.5 hours. Subsequently, polymerization was initiated under LED light, and the cosolvent was removed by deionized water treatment to produce a gradient hydrogel.

9. The method for preparing polysiloxane self-migration-induced multi-stimulus responsive and programmable 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 2-5min.

10. A use of the polysiloxane self-migration-induced multi-stimulus responsive and programmable gradient hydrogel according to any one of claims 1 to 7, characterized in that: The polysiloxane self-migration-induced multiple stimulus responses and programmable gradient hydrogel are applied to intelligent biomimetic materials, soft robots and light actuators.

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