Preparation method and application of pH-responsive hydrogel

Abstract

The present invention relates to the field of hydrogel technology, and in particular to a preparation method and application of a pH responsive hydrogel, the preparation method comprising the following steps: S1, adding pretreated corn starch to deionized water to obtain solution A; S2, adding itaconic acid and ammonium persulfate to deionized water, subsequently, adding acrylic acid, after complete mixing, continuing to add N, N-methylenebisacrylamide and d-limonene, stirring completely to obtain solution B; S3, sodium alginate and modified silica are added to deionized water and stirred to obtain solution C; S4, A, B, C are mixed and thermally cross-linked; S5, the dry gel obtained in step S4 is put into ammonium fluoride and acetic acid for processing, and then dried. The hydrogel prepared by the present invention has high mechanical strength, is uniformly cross-linked, and is sensitive to pH responsiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogels, and in particular to a preparation method and application of a pH-responsive hydrogel. Background Art

[0002] With the rapid development of sensor technology and medical devices, flexible wearable sensors have become a transformative innovation in healthcare monitoring. Unlike traditional sensors, which are often limited by their bulk and rigidity, flexible wearable sensors have attracted widespread attention due to their lightweight design, exceptional flexibility, and superior deformation and bending properties. These properties make them ideal for monitoring physiological signals during human movement and detecting characteristic changes in body fluids such as sweat and wound exudate.

[0003] Hydrogels, organic three-dimensional networks formed by hydrogen bonding, physical crosslinking, or chemical crosslinking of polymer chains, are gaining increasing prominence in fields such as cosmetics, biotechnology, agriculture, and medicine. Their excellent biocompatibility, mechanical properties, high water content, and biodegradability make them particularly suitable for advanced applications. Furthermore, their sensitivity to stimuli such as pH and temperature makes hydrogels a key material for smart flexible sensors. The application of hydrogel-based flexible sensors in textiles and wearable devices has broad potential applications.

[0004] The key to hydrogels' application in these wearable devices lies in their sensitive pH response. Furthermore, since the human body is often in motion, the mechanical strength of the hydrogel directly affects the lifespan of flexible wearable devices. To this end, we developed a hydrogel with high pH responsiveness and high strength suitable for direct application to human skin. Summary of the Invention

[0005] In order to solve the problems existing in the above background technology, the purpose of the present invention is to provide a preparation method and application of pH-responsive hydrogel.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a pH-responsive hydrogel, the preparation method comprising the following steps:

[0008] S1. Add the pretreated corn starch to deionized water, heat and stir at 80-85°C for 0.5-1h, then cool to 50°C while continuing to stir to obtain solution A;

[0009] S2. Itaconic acid and ammonium persulfate are added to deionized water, followed by acrylic acid. After thorough mixing, N,N-methylenebisacrylamide and d-limonene are added, and the mixture is stirred thoroughly to obtain a solution B.

[0010] S3, adding sodium alginate and modified silicon dioxide into deionized water and stirring uniformly to obtain solution C;

[0011] S4. Solution C and solution B are sequentially added to solution A to obtain a mixture, and then 1 mol / L sodium hydroxide solution is added to the mixture to adjust the pH of the solution to 10.5-11. The mixture is continuously stirred at 50° C. for 5-15 hours, ultrasonically defoamed, and poured into a mold, and polymerized at 75-80° C. for 3-4 hours to obtain a xerogel;

[0012] S5. Place the xerogel obtained in step S4 into a mixed solution of ammonium fluoride with a sufficient concentration of 0.2-0.8 mol / L and 0.1-0.3 mol / L acetic acid for reaction for 2-12 hours, perform ultrasonic treatment during the reaction at an ultrasonic frequency of 15-30 kHz, and then centrifuge and filter. The product is repeatedly rinsed with sufficient deionized water and dried at low temperature at 20° C. to obtain a pH-responsive hydrogel.

[0013] The preparation method of the modified silicon dioxide comprises the following steps:

[0014] S101, activating mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica in a toluene solution containing γ-aminopropyltriethoxysilane, reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.;

[0015] S102, dispersing the mesoporous silica treated in step S101 into a 0.1-1 mol / L calcium chloride solution and soaking for 6-24 hours, centrifugally filtering, and vacuum drying the product at 50° C.;

[0016] S103. Disperse the mesoporous silica treated in step S102 into deionized water, then add dopamine, add 25% by mass ammonia water to adjust the pH to 8.5, continuously introduce air, react for 6 to 12 hours, centrifuge and filter the product, and vacuum dry at 50° C. to obtain modified silica.

[0017] Furthermore, the mass ratio of γ-aminopropyltriethoxysilane, mesoporous silica and toluene in step S101 to the calcium chloride solution in step S102 is 1:12:(70-90):(150-200);

[0018] Furthermore, the mass ratio of dopamine and deionized water in step S103 to the mesoporous silica in step S101 is 1:(200-350):(2-6).

[0019] Furthermore, the mass ratio of the pretreated corn starch to the deionized water in the solution A of step S1 is 1:(10-20).

[0020] Furthermore, the mass ratio of d-limonene, itaconic acid, acrylic acid and deionized water in the solution B of step S2 is 1:(2-3):(5-6):(15-25), and the mass ratio of N,N-methylenebisacrylamide, ammonium persulfate and acrylic acid is 1:5:1000.

[0021] Furthermore, the mass ratio of modified silica, sodium alginate and deionized water in solution C of step S3 is 1:(4-6):(20-30); the mass ratio of pretreated starch in step S1, acrylic acid in step S2 and sodium alginate in step S3 is 1:(1.5-3):(1.5-3).

[0022] Furthermore, the mass ratio of the anti-hemolytic acid solution added in step S4 to the mass of the deionized water in solution A, solution B and solution C is 1:10.

[0023] Furthermore, the preparation method of the pretreated corn starch comprises the following steps:

[0024] S201, dispersing corn starch in deionized water solution, heating to 70-95°C, and gelatinizing for 1-2 hours;

[0025] S202, freeze-drying the corn starch treated in step S101 for 12-24 hours at a freeze-drying temperature of -30 to -100°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

[0026] Furthermore, in step S201, the mass ratio of corn starch to deionized water is 1:(20-30).

[0027] A method for preparing a pH-responsive hydrogel and the application of the hydrogel prepared in smart textiles.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. In the present invention, starch is pretreated to form a uniformly cross-linked starch molecular network during the cross-linking process. Simultaneously, the present invention adds modified silica, and the slowly released calcium ions provide more cross-linking sites for sodium alginate, thereby improving the mechanical properties of the hydrogel.

[0030] 2. The hydrogel prepared in the present invention has excellent and uniform bonding effect between sodium alginate, starch and acrylic acid. The formed hydrogel has many and uniform pores and has excellent pH sensitive response. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a process flow chart for preparing pH-responsive hydrogels in the present invention;

[0032] Figure 2 This is a process flow chart for preparing modified silicon dioxide in the present invention;

[0033] Figure 3 The present invention is a process flow chart for preparing pretreated corn starch;

[0034] Figure 4 1 is the swelling diagram of the pH-responsive hydrogel prepared in Example 1 of the present invention at different pH values;

[0035] Figure 5 This is an electron microscope image of the pH-responsive hydrogel prepared in Example 1 of the present invention before water absorption;

[0036] Figure 6 This is an electron microscope image of the pH-responsive hydrogel prepared in Example 1 of the present invention after absorbing water;

[0037] Figure 7 FT-IR spectra of PAA / SH / SA, PAA / SA hydrogel, SH and SA in the present invention. DETAILED DESCRIPTION

[0038] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] See also Figure 1-7 , the present invention provides a technical solution:

[0040] Example 1

[0041] A method for preparing a pH-responsive hydrogel, the preparation method comprising the following steps:

[0042] S1. Add 3.2 g of pretreated corn starch to 38 g of deionized water, heat and stir at 82° C. for 0.8 h, then cool to 50° C. while continuing to stir to obtain solution A;

[0043] S2. 3.25 g of itaconic acid and 0.036 g of ammonium persulfate were added to 25 g of deionized water, followed by 7.2 g of acrylic acid. After thorough mixing, 0.0072 g of N,N-methylenebisacrylamide and 1.3 g of d-limonene were added, and the mixture was stirred thoroughly to obtain Solution B.

[0044] S3, adding 6.8 g of sodium alginate and 1.35 g of modified silicon dioxide to 33.8 g of deionized water and stirring uniformly to obtain solution C;

[0045] S4. Solution C and solution B were sequentially added to solution A to obtain a mixture, and then 1 mol / L sodium hydroxide solution was added to the mixture to adjust the pH of the mixture to 10.8. The mixture was continuously stirred at 50° C. for 8 h, ultrasonically defoamed, poured into a mold, and polymerized at 78° C. for 3.5 h to obtain a xerogel.

[0046] S5. The xerogel obtained in step S4 is placed in a mixed solution of ammonium fluoride and acetic acid with a sufficient concentration of 0.6 mol / L and reacted for 3 h. During the reaction, ultrasonic treatment is performed at an ultrasonic frequency of 25 kHz. The product is then centrifuged and filtered. The product is repeatedly rinsed with sufficient deionized water and dried at 20° C. to obtain a pH-responsive hydrogel.

[0047] The preparation method of the modified silica comprises the following steps:

[0048] S101, activating 3.6 g of mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica into a toluene solution containing γ-aminopropyltriethoxysilane (0.3 g) and toluene (25.6 g), reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.;

[0049] S102, dispersing the mesoporous silica treated in step S101 into 54 g of a 0.2 mol / L calcium chloride solution, soaking the solution for 10 hours, centrifuging and filtering, and vacuum drying the product at 50° C.;

[0050] S103, dispersing the mesoporous silica treated in step S102 into 180 g of deionized water, then adding 0.72 g of dopamine, and adjusting the pH to 8.5 by adding 25% by mass ammonia water, continuously introducing air, reacting for 8 h, centrifuging the product, and vacuum drying at 50° C. to obtain modified silica;

[0051] The preparation method of the above-mentioned pretreated starch comprises the following steps:

[0052] S201, dispersing 5.8 g corn starch into 140 g deionized water solution, heating to 80° C., and gelatinizing for 1.5 h;

[0053] S202, freeze-drying the corn starch treated in step S101 for 18 hours at a freeze-drying temperature of -75°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

[0054] Example 2

[0055] A method for preparing a pH-responsive hydrogel, the preparation method comprising the following steps:

[0056] S1. Add 4.4 g of pretreated corn starch to 44 g of deionized water, heat and stir at 80° C. for 0.5 h, then cool to 50° C. while continuing to stir to obtain solution A;

[0057] S2. Add 2.64 g of itaconic acid and 0.033 g of ammonium persulfate to 19.8 g of deionized water, then add 6.6 g of acrylic acid. After thorough mixing, add 0.0066 g of N,N-methylenebisacrylamide and 1.32 g of d-limonene. Stir thoroughly to obtain Solution B.

[0058] S3, adding 6.6 g of sodium alginate and 1.65 g of modified silicon dioxide to 33 g of deionized water and stirring uniformly to obtain solution C;

[0059] S4, adding solution C and solution B to solution A in sequence to obtain a mixture, then adding 1 mol / L sodium hydroxide solution to the mixture to adjust the pH of the mixture to 10.5, stirring the mixture continuously at 50° C. for 5 h, ultrasonically defoaming the mixture, pouring the mixture into a mold, and polymerizing at 75° C. for 3 h to obtain a xerogel;

[0060] S5. Place the xerogel obtained in step S4 into a mixed solution of ammonium fluoride and acetic acid at a sufficient concentration of 0.2 mol / L for 2 h, perform ultrasonic treatment at a frequency of 15 kHz during the reaction, and then centrifuge and filter. The product is repeatedly rinsed with sufficient deionized water and dried at 20° C. to obtain a pH-responsive hydrogel.

[0061] The preparation method of the modified silica comprises the following steps:

[0062] S101, activating 3.6 g of mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica into a toluene solution containing γ-aminopropyltriethoxysilane (0.3 g) and toluene (21 g), reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.;

[0063] S102, dispersing the mesoporous silica treated in step S101 into 45 g of a 0.1 mol / L calcium chloride solution, soaking the solution for 6 hours, centrifuging and filtering, and vacuum drying the product at 50° C.;

[0064] S103, dispersing the mesoporous silica treated in step S102 into 360 g of deionized water, then adding 1.8 g of dopamine, and adjusting the pH to 8.5 by adding 25% by mass ammonia water, continuously introducing air, reacting for 6 h, centrifuging the product, and vacuum drying at 50° C. to obtain modified silica;

[0065] The preparation method of the above-mentioned pretreated starch comprises the following steps:

[0066] S201, disperse 6.2g corn starch into 124g deionized water solution, heat to 70°C, and gelatinize for 1h;

[0067] S202, freeze-drying the corn starch treated in step S101 for 12 hours at a freeze-drying temperature of -30°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

[0068] Example 3

[0069] A method for preparing a pH-responsive hydrogel, the preparation method comprising the following steps:

[0070] S1. Add 2.4 g of pretreated corn starch to 48 g of deionized water, heat and stir at 85° C. for 1 h, then cool to 50° C. while continuing to stir to obtain solution A;

[0071] S2. Add 2.4 g of itaconic acid and 0.036 g of ammonium persulfate to 30 g of deionized water, then add 7.2 g of acrylic acid. After thorough mixing, add 0.0072 g of N,N-methylenebisacrylamide and 1.2 g of d-limonene. Stir thoroughly to obtain Solution B.

[0072] S3, adding 7.2 g of sodium alginate and 1.2 g of modified silicon dioxide to 36 g of deionized water and stirring uniformly to obtain solution C;

[0073] S4, adding solution C and solution B to solution A in sequence to obtain a mixture, then adding 1 mol / L sodium hydroxide solution to the mixture to adjust the pH of the mixture to 11, stirring the mixture continuously at 50° C. for 15 h, ultrasonically defoaming the mixture, pouring the mixture into a mold, and polymerizing at 80° C. for 4 h to obtain a xerogel;

[0074] S5. The xerogel obtained in step S4 is placed in a mixed solution of ammonium fluoride and acetic acid with a sufficient concentration of 0.8 mol / L and reacted for 12 h. During the reaction, ultrasonic treatment is performed at an ultrasonic frequency of 30 kHz. The product is then centrifuged and filtered. The product is repeatedly rinsed with sufficient deionized water and dried at 20° C. to obtain a pH-responsive hydrogel.

[0075] The preparation method of the modified silica comprises the following steps:

[0076] S101, activating 3.6 g of mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica into a toluene solution containing γ-aminopropyltriethoxysilane (0.3 g of γ-aminopropyltriethoxysilane) and 27 g of toluene, reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.;

[0077] S102, dispersing the mesoporous silica treated in step S101 into 60 g of 1 mol / L calcium chloride solution, soaking for 24 hours, centrifuging and filtering, and vacuum drying the product at 50° C.;

[0078] S103, dispersing the mesoporous silica treated in step S102 into 210 g of deionized water, then adding 0.6 g of dopamine, and adjusting the pH to 8.5 by adding 25% by mass ammonia water, continuously introducing air, reacting for 12 h, centrifuging the product, and vacuum drying at 50° C. to obtain modified silica;

[0079] The preparation method of the above-mentioned pretreated starch comprises the following steps:

[0080] S201, dispersing 4.2 g corn starch into 126 g deionized water solution, heating to 95° C., and gelatinizing for 2 h;

[0081] S202, freeze-drying the corn starch treated in step S101 for 24 hours at a freeze-drying temperature of -100°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

[0082] Example 4

[0083] A method for preparing a pH-responsive hydrogel, the preparation method comprising the following steps:

[0084] S1. Add 3.2 g of pretreated corn starch to 46 g of deionized water, heat and stir at 80° C. for 0.6 h, then cool to 50° C. while continuing to stir to obtain solution A;

[0085] S2. 1.3 g of itaconic acid and 0.032 g of ammonium persulfate were added to 25 g of deionized water, followed by 6.4 g of acrylic acid. After thorough mixing, 0.0064 g of N,N-methylenebisacrylamide and 3.3 g of d-limonene were added, and the mixture was stirred thoroughly to obtain Solution B.

[0086] S3, adding 6.6 g of sodium alginate and 1.3 g of modified silicon dioxide to 31 g of deionized water and stirring uniformly to obtain solution C;

[0087] S4. Solution C and solution B were sequentially added to solution A to obtain a mixture, and then 1 mol / L sodium hydroxide solution was added to the mixture to adjust the pH of the mixture to 11. The mixture was continuously stirred at 50° C. for 12 h, ultrasonically defoamed, poured into a mold, and polymerized at 77° C. for 3.6 h to obtain a xerogel.

[0088] S5. Place the xerogel obtained in step S4 into a mixed solution of ammonium fluoride and acetic acid at a sufficient concentration of 0.6 mol / L for 8 h, perform ultrasonic treatment at a frequency of 20 kHz during the reaction, and then centrifuge and filter. The product is repeatedly rinsed with sufficient deionized water and dried at 20° C. to obtain a pH-responsive hydrogel.

[0089] The preparation method of the modified silica comprises the following steps:

[0090] S101, activating 3.6 g of mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica into a toluene solution containing γ-aminopropyltriethoxysilane (0.3 g of γ-aminopropyltriethoxysilane) and 24 g of toluene, reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.;

[0091] S102, dispersing the mesoporous silica treated in step S101 into 51 g of a 0.4 mol / L calcium chloride solution, soaking the solution for 18 hours, centrifuging and filtering, and vacuum drying the product at 50° C.;

[0092] S103, dispersing the mesoporous silica treated in step S102 into 320 g of deionized water, then adding 1.3 g of dopamine, and adjusting the pH to 8.5 by adding 25% by mass ammonia water, continuously introducing air, reacting for 10 h, centrifuging the product, and vacuum drying at 50° C. to obtain modified silica;

[0093] The preparation method of the above-mentioned pretreated starch comprises the following steps:

[0094] S201, disperse 5.4 g corn starch into 130 g deionized water solution, heat to 85°C, and gelatinize for 1.2 h;

[0095] S202, freeze-drying the corn starch treated in step S101 for 15 hours at a freeze-drying temperature of -60°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

[0096] Comparative Example 1

[0097] The difference between Comparative Example 1 and Example 1 is that the pretreated corn starch added in step S1 is replaced with ordinary corn starch, and the remaining steps are exactly the same as in Example 1.

[0098] Comparative Example 2

[0099] The difference between Comparative Example 2 and Example 1 is that step S102 is completely eliminated, and the remaining steps are exactly the same as those in Example 1.

[0100] Comparative Example 3

[0101] The difference between Comparative Example 3 and Example 1 is that step S103 is completely eliminated, and the remaining steps are exactly the same as those in Example 1.

[0102] Comparative Example 4

[0103] The difference between Comparative Example 4 and Example 1 is that the addition of sodium hydroxide solution in step S4 is cancelled, and the remaining steps are exactly the same as those in Example 1.

[0104] Comparative Example 5

[0105] The difference between Comparative Example 5 and Example 1 is that the addition of modified silicon dioxide in step S3 is completely eliminated, and the remaining steps are exactly the same as those in Example 1.

[0106] In order to evaluate the mechanical properties of the hydrogels prepared in the present invention, the hydrogels prepared in Examples 1-4 and Comparative Examples 1-5 were subjected to tensile strength tests. The test results are shown in Table 1 below:

[0107] Table 1: Tensile strength test of hydrogels prepared in Examples 1-4 and Comparative Examples 1-5

[0108]

[0109] It can be seen from the data in Table 1 above that the addition of modified silicon dioxide and the pretreatment of corn starch in the present invention can effectively increase the tensile strength of the hydrogel and greatly improve the mechanical properties.

[0110] In order to evaluate the pH sensitivity of the hydrogel prepared in the present invention, the equilibrium swelling degree of the hydrogel prepared in Example 1 was measured under different pH conditions. Figure 4 As shown in the figure, with the increase of pH value, the equilibrium swelling degree of the hydrogel gradually increases. It is worth noting that at pH = 12, the swelling degree reaches 9200%, which is 23 times higher than 400% at pH = 2, indicating that the hydrogel prepared by the present invention is extremely sensitive to pH.

[0111] Figure 5 This is an electron microscope image of the hydrogel prepared in Example 1 of the present invention before swelling. It can be seen that the surface of the hydrogel prepared in the present invention has a large number of pores and the pore distribution is very uniform; Figure 6This is an electron micrograph of the hydrogel prepared in Example 1 of the present invention after swelling at 25° C. for 6 hours. The internal pore diameter is significantly increased, indicating that the hydrogel has good swelling properties.

[0112] The FT-IR spectra of the hydrogel (comprising polyacrylic acid PAA, starch SH, sodium alginate SA), PAA / SA hydrogel, SH and SA of the present invention are as follows: Figure 7 The SA FTIR spectrum shows absorption peaks at 3478, 1622, and 1416 cm-1, corresponding to the asymmetric and symmetric stretching vibration peaks caused by -OH stretching vibration and -COOH, respectively; the SH FTIR spectrum shows absorption peaks at 3458 cm-1, corresponding to the asymmetric and symmetric stretching vibration peaks caused by -OH stretching vibration and -COOH, respectively. -1 There is an obvious broad absorption peak at 1162 and 1023 cm -1 The characteristic absorption peak at 3392 cm-1 is attributed to the COC group. It is worth noting that compared with SH and SA, the characteristic absorption peaks at 1572, 1453, 1704 and 2923 cm-1 of the FTIR spectrum of PAA / SH / SA hydrogel increased significantly; this enhancement is due to the formation of a large number of NH, Cn, C=O and -CH2 groups through grafting and cross-linking polymerization; in addition, the FTIR spectrum of PAA / SA also showed similar changes; for PAA / SH / SA hydrogel, since grafting and cross-linking polymerization mainly occurred in -OH groups, the peak intensity at 3392 cm-1 weakened, and compared with SH and SA, due to the increase in the number of hydrogen bonds, the OH peak shifted to a lower wavelength; these modifications confirmed the successful grafting and cross-linking polymerization of SH, SA and PAA in the present invention.

[0113] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a pH-responsive hydrogel, characterized in that: The preparation method comprises the following steps: S1. Add the pretreated corn starch to deionized water, heat and stir at 80-85°C for 0.5-1h, then cool to 50°C while continuing to stir to obtain solution A; S2. Itaconic acid and ammonium persulfate are added to deionized water, followed by acrylic acid. After thorough mixing, N,N-methylenebisacrylamide and d-limonene are added, and the mixture is stirred thoroughly to obtain a solution B. S3, adding sodium alginate and modified silicon dioxide into deionized water and stirring uniformly to obtain solution C; S4. Solution C and solution B are sequentially added to solution A to obtain a mixture, and then 1 mol / L sodium hydroxide solution is added to the mixture to adjust the pH of the solution to 10.5-11. The mixture is continuously stirred at 50° C. for 5-15 hours, ultrasonically defoamed, and poured into a mold, and polymerized at 75-80° C. for 3-4 hours to obtain a xerogel; S5. Place the xerogel obtained in step S4 into a mixed solution of ammonium fluoride with a sufficient concentration of 0.2-0.8 mol / L and 0.1-0.3 mol / L acetic acid for reaction for 2-12 hours, perform ultrasonic treatment during the reaction at an ultrasonic frequency of 15-30 kHz, then centrifuge and filter, repeatedly rinse the product with sufficient deionized water, and dry it at 20° C. to obtain a pH-responsive hydrogel; The preparation method of the modified silicon dioxide comprises the following steps: S101, activating mesoporous silica at 110° C. for 2 h, dispersing the activated mesoporous silica in a toluene solution containing γ-aminopropyltriethoxysilane, reacting for 3 h, and then filtering the product and drying it in vacuo at 30° C.; S102, dispersing the mesoporous silica treated in step S101 into a 0.1-1 mol / L calcium chloride solution and soaking for 6-24 hours, centrifugally filtering, and vacuum drying the product at 50° C.; S103, dispersing the mesoporous silica treated in step S102 into deionized water, then adding dopamine, and adjusting the pH to 8.5 by adding 25% by mass ammonia water, continuously introducing air, reacting for 6-12 hours, centrifuging the product, and vacuum drying at 50° C. to obtain modified silica; The mass ratio of modified silica, sodium alginate and deionized water in solution C of step S3 is 1:(4-6):(20-30); the mass ratio of pretreated starch in step S1, acrylic acid in step S2 and sodium alginate in step S3 is 1:(1.5-3):(1.5-3).

2. The method for preparing the pH-responsive hydrogel according to claim 1, wherein: The mass ratio of γ-aminopropyltriethoxysilane, mesoporous silica and toluene in step S101 to the calcium chloride solution in step S102 is 1:12:(70-90):(150-200).

3. The method for preparing the pH-responsive hydrogel according to claim 1, wherein: The mass ratio of dopamine and deionized water in step S103 to the mesoporous silica in step S101 is 1:(200-350):(2-6).

4. The method for preparing the pH-responsive hydrogel according to claim 1, wherein: The mass ratio of the pretreated corn starch to deionized water in the solution A of step S1 is 1:(10-20).

5. The method for preparing the pH-responsive hydrogel according to claim 1, wherein: The mass ratio of d-limonene, itaconic acid, acrylic acid and deionized water in the solution B of step S2 is 1:(2-3):(5-6):(15-25), and the mass ratio of N,N-methylenebisacrylamide, ammonium persulfate and acrylic acid is 1:5:1000.

6. The method for preparing the pH-responsive hydrogel according to claim 1, wherein: The preparation method of the pretreated corn starch comprises the following steps: S201, dispersing corn starch in deionized water solution, heating to 70-95°C, and gelatinizing for 1-2 hours; S202, freeze-drying the corn starch treated in step S101 for 12-24 hours at a freeze-drying temperature of -30 to -100°C, and grinding the obtained freeze-dried powder through a 200-mesh sieve to obtain pretreated corn starch.

7. The method for preparing the pH-responsive hydrogel according to claim 6, wherein: In step S201, the mass ratio of corn starch to deionized water is 1:(20-30).

8. Use of the hydrogel prepared by the method for preparing a pH-responsive hydrogel according to any one of claims 1 to 7 in smart textiles.

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