Preparation method and application of hydrogel with temperature self-adaptation and antifreeze functions

Abstract

The present invention relates to the technical field of intelligent building materials, and in particular to a method for preparing a hydrogel with temperature self-adaptation and antifreeze functions and its application. The present invention prepares the hydrogel by adding tetramethylethylenediamine to a hydrogel precursor solution, stirring the solution, and introducing the solution into a gel mold for low-temperature gelation. The present invention determines whether the demoulded hydrogel has local characteristics by initially comparing a light intensity variation curve of the reflected light intensity in the mold cavity as it changes with a scanning trajectory with a pre-stored sample reference curve. The present invention selects a feedback adjustment method for the preparation of the hydrogel by determining the local characteristic manifestation category of the hydrogel. Thus, the present invention realizes the detection of local characteristics by effective technical means during the large-scale continuous production process of the hydrogel, and the targeted feedback adjustment of the preparation process based on the detection results, thereby improving the quality stability and thermal response characteristics of the continuous production of the hydrogel.

Description

Technical Field

[0001] The present invention relates to the technical field of building intelligent materials, and in particular to a preparation method and application of a hydrogel with temperature self-adaptation and antifreeze functions. Background Art

[0002] In the field of modern materials science, hydrogels, as polymer materials with unique properties, have long attracted much attention. With the growing demand for smart materials in the construction industry, the development of hydrogels with special functions for application in the construction field has become a research hotspot. Traditional building materials have relatively simple functions when responding to changes in ambient temperature, making it difficult to meet the increasing requirements of energy conservation and intelligence. Materials with temperature-adaptive functions can automatically adjust their own performance according to changes in ambient temperature, which is of great significance for improving the energy efficiency and comfort of buildings. At the same time, in cold regions or low-temperature environments, the antifreeze performance of building materials is also crucial to prevent the degradation or even damage of material performance caused by low temperatures.

[0003] In the preparation research of hydrogels, how to accurately control their internal structure and performance uniformity has always been a challenge. Previous preparation methods often find it difficult to effectively detect and regulate local non-uniformity problems that may occur in the hydrogel molding process, which may lead to unstable performance of the final product in actual applications or fail to meet expected requirements. Local structural differences may affect key indicators such as the thermal response characteristics and mechanical properties of the hydrogel, thereby affecting its reliability and durability in application scenarios such as building smart windows. Therefore, there is an urgent need for a preparation method that can monitor local property changes in the hydrogel preparation process in real time and perform feedback adjustment accordingly, so as to improve the quality and performance stability of the hydrogel, so that it can be better used in fields with high material performance requirements such as building smart windows, thereby promoting the development of building materials towards intelligence and high performance.

[0004] For example, Chinese patent publication number: CN116769085A, the invention discloses the preparation of an intermediate interlayer hydrogel for a smart window with solar spectrum modulation, the invention uses aldehyde compounds to graft-modify polyvinyl alcohol, the obtained product is placed in a saturated sodium bicarbonate solution for termination reaction, the precipitated white solid is removed from impurities, and vacuum freeze-dried to obtain white particles, namely modified polyvinyl alcohol material; the modified polyvinyl alcohol material is dissolved, ultrasonically treated, defoamed, centrifuged, cast, and then placed in a closed saturated lithium chloride salt solution environment to evaporate the solvent, and the soaked water is removed after the solvent is completely evaporated to obtain a transparent hydrophobic associating phase change gel material formed by physical cross-linking, and finally the gel material is sandwiched between two glass plates and sealed with silica gel plates on all sides to prevent water evaporation, thereby obtaining a thermally responsive smart window with solar spectrum modulation capability.

[0005] The following problems also exist in the prior art:

[0006] The existing technology cannot use effective technical means to detect local properties during the large-scale continuous production of hydrogels, and cannot perform targeted feedback adjustments to the preparation process based on the detection results, affecting the quality stability and thermal response characteristics of the continuous production of hydrogels. Summary of the Invention

[0007] To this end, the present invention provides a method for preparing a hydrogel with temperature self-adaptation and antifreeze functions and its application, so as to overcome the problems that the existing technology cannot detect local properties through effective technical means during the large-scale continuous production of hydrogels, and cannot perform targeted feedback adjustment of the preparation process based on the detection results.

[0008] To achieve the above objectives, the present invention provides a method for preparing a hydrogel with temperature self-adaptation and antifreeze functions, comprising:

[0009] Adding polyvinyl alcohol to deionized water and mixing well to obtain a homogeneous polyvinyl alcohol solution;

[0010] Adding N-isopropylacrylamide, glycerol, acrylamide, N,N′-methylenebisacrylamide, potassium persulfate and the homogeneous polyvinyl alcohol solution to deionized water, respectively, and stirring the mixture in an oil bath for a first preset stirring time to obtain a hydrogel precursor solution;

[0011] adding tetramethylethylenediamine to the hydrogel precursor solution and stirring the solution; introducing the solution after stirring for a second preset stirring time into a gel mold for low-temperature gelation and demolding to produce a hydrogel; and scanning the demolded gel mold with a light beam to plot a light intensity variation curve of the reflected light intensity in the mold cavity as a function of the scanning trajectory;

[0012] Determining whether the demoulded hydrogel has local morphological characteristics based on a preliminary comparison result of the light intensity variation curve with a pre-stored sample reference curve;

[0013] Comparing the light intensity change curve with the sample reference curve again to screen a characteristic performance curve segment in the light intensity change curve, and determining the local property performance category of the hydrogel according to the scanning trajectory corresponding to the characteristic performance curve segment;

[0014] The feedback regulation method for hydrogel preparation is selected according to the local property expression category, including:

[0015] adjusting an introduction rate of the solution into the gel mold according to introduction information of the gel mold, wherein the introduction information is determined according to a distance between an edge of the contour of the gel mold and a solution introduction port;

[0016] Alternatively, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

[0017] Furthermore, the process of drawing the light intensity variation curve includes:

[0018] Scanning the demoulded gel mold with a light beam of preset light intensity along a preset scanning trajectory;

[0019] The reflected light intensity of the light beam reflected from the mold cavity is obtained through a receiver, and a correlation relationship between the reflected light intensity and the scanning trajectory is established;

[0020] Drawing the light intensity variation curve according to the associated reflected light intensity and the scanning trajectory;

[0021] The rectangular coordinate system where the light intensity variation curve is located has the reflected light intensity as the vertical axis and the distance between the current light beam scanning position and the light beam scanning starting position as the horizontal axis.

[0022] Furthermore, the process of pre-storing the sample reference curve includes:

[0023] Scanning the gel mold several times with the light beam of the preset light intensity, and drawing several light intensity test change curves according to the reflected light intensity obtained from each scan;

[0024] A plurality of light intensity test variation curves are fitted into the sample reference curve and stored in the sample database.

[0025] Furthermore, determining whether the demoulded hydrogel has localized characteristics includes:

[0026] determining a degree of coincidence between the light intensity variation curve and the sample reference curve;

[0027] If the degree of overlap satisfies the characteristic determination condition, it is determined that the demoulded hydrogel has local property characteristics;

[0028] The characteristic determination condition is that the degree of overlap is less than a preset degree of overlap reference value.

[0029] Furthermore, the process of screening characteristic performance curve segments includes:

[0030] dividing the light intensity variation curve into a plurality of curve segments;

[0031] Determine the degree of overlap between each sub-curve segment and the corresponding sample reference curve segment, and select the sub-curve segment corresponding to the minimum overlap value as the characteristic performance curve segment.

[0032] Furthermore, the local properties of the hydrogels are classified into the following categories:

[0033] If the scanning track corresponding to the characteristic performance curve segment has an edge area track, determining that the local property performance category of the hydrogel is the first local property performance category;

[0034] If the scanning track corresponding to the characteristic performance curve segment does not have an edge area track, determining that the local property performance category of the hydrogel is the second local property performance category;

[0035] The edge area track is a track segment in the edge area of ​​the gel mold in the pre-set scanning track.

[0036] Furthermore, the feedback regulation methods selected for hydrogel preparation include:

[0037] If the local property performance category of the hydrogel is the first local property performance category, adjusting the introduction rate of the solution into the gel mold according to the introduction information of the gel mold;

[0038] If the local property performance category of the hydrogel is the second local property performance category, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

[0039] Furthermore, the introduction rate is positively correlated with the maximum distance between the contour edge of the gel mold and the solution introduction port.

[0040] Furthermore, the first preset stirring time and the second preset stirring time are negatively correlated with the degree of overlap between the light intensity variation curve and the sample reference curve.

[0041] Furthermore, the present invention also provides an application of a hydrogel with temperature self-adaptation and antifreeze functions, which is used as a thermochromic material in building smart windows.

[0042] Compared with the prior art, the beneficial effect of the present invention lies in that the present invention prepares the hydrogel by adding tetramethylethylenediamine to the hydrogel precursor solution for stirring and introducing it into the gel mold for low-temperature gelation, and draws a light intensity change curve of the reflected light intensity in the mold cavity as the scanning trajectory changes by scanning the demolded gel mold with a light beam, and determines whether the demolded hydrogel has local characteristics based on the initial comparison result of the light intensity change curve with the pre-stored sample reference curve, and determines the local characteristic performance category of the hydrogel by screening the characteristic performance curve segment in the light intensity change curve, and selects the feedback adjustment method for the hydrogel preparation according to the local characteristic performance category, thereby realizing the detection of local characteristic characteristics by effective technical means in the large-scale continuous production process of the hydrogel, and carrying out targeted feedback adjustment of the preparation process according to the detection results, thereby improving the quality stability and thermal response characteristics of the continuous production of the hydrogel.

[0043] In particular, the present invention performs a light beam scan on the gel mold after demolding to draw a light intensity change curve of the reflected light intensity in the mold cavity as the scanning trajectory changes. During the preparation process of the hydrogel, local unevenness and other property differences may appear inside it. It is difficult to quickly detect the uniformity of the internal structure during large-scale continuous production. It is understandable that during the preparation process of the hydrogel, due to various factors, such as uneven mixing of raw materials, insufficient stirring, temperature distribution differences and objective factors of the mold, local property differences may appear inside the hydrogel, resulting in differences in the residual components of the hydrogel prepared each time by demolding in the mold cavity. The difference in residual components will cause the reflected light to present different reflection directions, resulting in differences in the intensity of the reflected light received by the receiver. The present invention draws a light intensity change curve of the reflected light intensity in the mold cavity as the scanning trajectory changes, thereby realizing rapid detection of local property differences in the large-scale continuous production process of the hydrogel.

[0044] In particular, the present invention determines whether the demolded hydrogel has localized characteristics by initially comparing the light intensity variation curve with a pre-stored sample reference curve, thereby accurately detecting whether the hydrogel has localized unevenness. If the light intensity variation curve has a low degree of overlap with the sample reference curve, this indicates that the hydrogel may have residual components in certain local areas and abnormal internal adhesion. By establishing a sample reference curve during the production process, continuously produced hydrogels can be produced and tested according to the same quality standards, ensuring the consistency and stability of product quality.

[0045] In particular, the present invention divides the light intensity change curve into several curve segments, analyzes the difference between the light intensity change curve and the sample reference curve in more detail, and selects the sub-curve segments corresponding to the minimum overlap as characteristic performance curve segments, focusing more accurately on the changes in the local area, thereby realizing accurate detection of local property characteristics during the large-scale continuous production process of hydrogels.

[0046] In particular, the present invention divides local property performance categories by judging whether there is an edge area track in the scanning track corresponding to the characteristic performance curve segment. It can be understood that in the edge area of ​​the mold, the flow, heat exchange and other conditions of the solution may be different from those inside the mold. These differences may cause the hydrogel to form different local properties at the edge and inside. When the scanning track corresponding to the characteristic performance curve segment involves the edge area track, it is classified into the first local property performance category; otherwise, it is classified into the second local property performance category, thereby improving the scientific nature of targeted optimization of the preparation process based on the detection results.

[0047] In particular, the present invention adjusts the introduction rate of the solution into the gel mold to be negatively correlated with the maximum distance between the contour edge of the gel mold and the solution introduction port. It can be understood that in the process of introducing the solution into the gel mold, if local property differences appear and are concentrated in the edge area, then the flow conditions of the solution will have a major impact on the formation of the hydrogel in the mold. In the area close to the solution introduction port, the flow rate, flow rate and other factors of the solution are different from those in the area far from the introduction port. The greater the maximum distance between the contour edge of the gel mold and the solution introduction port, the slower the solution flows in this area, and problems such as edge gaps and structural differences are prone to occur. By increasing the solution introduction rate in the farther edge area, the filling gaps in the edge area can be avoided, and the negative impact of local edge defects on the overall performance can be reduced. Furthermore, targeted feedback adjustment of the preparation process based on the test results is achieved, thereby improving the quality stability and thermal response characteristics of continuous production of hydrogels.

[0048] In particular, in the process of introducing the solution into the gel mold of the present invention, if local property differences occur and are not concentrated in the edge area, it indicates that the distribution of the internal components of the solution itself is uneven. When the overlap between the light intensity change curve and the sample reference curve is low, the cross-linking degree of the hydrogel can be improved by extending the stirring time, so that the hydrogel forms a uniform three-dimensional network structure and reduces internal structural defects. Furthermore, targeted feedback adjustment of the preparation process is achieved according to the test results, thereby improving the quality stability and thermal response characteristics of the continuous production of hydrogels. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a step diagram of a method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention;

[0050] Figure 2 This is a scanning electron microscope image of a hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention;

[0051] Figure 3 This is a diagram showing the antifreeze point test of the hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention;

[0052] Figure 4 This is a phase transition temperature test diagram of a hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention;

[0053] Figure 5 This is a logic flow chart for determining whether a demoulded hydrogel has localized characteristics according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0055] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0056] It should be noted that, in the description of the present invention, terms such as "upper", "lower", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0057] See also Figure 1 As shown, it is a step diagram of a method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention. A method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to the present invention comprises:

[0058] Step S1, adding polyvinyl alcohol to deionized water and mixing them evenly to obtain a homogeneous polyvinyl alcohol solution;

[0059] Step S2: adding 3.43 g of N-isopropylacrylamide, 4 g of glycerol, 0.55 g of acrylamide, 0.038 g of N,N′-methylenebisacrylamide, 0.2 g of potassium persulfate, and 6 g of homogeneous polyvinyl alcohol solution to 15 mL of deionized water, respectively, and stirring the mixture in a 40° C. oil bath for a first preset stirring time to obtain a hydrogel precursor solution;

[0060] Specifically, in the embodiment of the present invention, the first preset stirring time is 1 hour.

[0061] Step S3, adding 100 μL of tetramethylethylenediamine to the hydrogel precursor solution and stirring, introducing the solution after stirring for a second preset stirring time into a gel mold for low-temperature gelation and demolding to produce a hydrogel, and performing a light beam scanning on the demolded gel mold to plot a light intensity variation curve of the reflected light intensity in the mold cavity as a function of the scanning trajectory;

[0062] Specifically, in the embodiment of the present invention, the second preset stirring time is 30 seconds.

[0063] Specifically, the present invention does not limit the specific structure of the gel mold, which is well known to those skilled in the art and will not be described in detail here. The gel mold after demolding can be scanned with a light beam by a laser unit that integrates a light emitter and a receiver. This technology is widely used in the field of engineering measurement and will not be described in detail here.

[0064] Step S4, determining whether the demoulded hydrogel has local morphological characteristics based on the initial comparison result of the light intensity variation curve and the pre-stored sample reference curve;

[0065] In implementation, the sample reference curve may be pre-stored in a data storage device, which will not be described in detail here.

[0066] Step S5, comparing the light intensity variation curve with the sample reference curve again to screen a characteristic performance curve segment in the light intensity variation curve, and determining the local property performance category of the hydrogel according to the scanning trajectory corresponding to the characteristic performance curve segment;

[0067] Step S6, selecting a feedback regulation method for hydrogel preparation according to the local property performance category, including:

[0068] adjusting an introduction rate of the solution into the gel mold according to introduction information of the gel mold, wherein the introduction information is determined according to a distance between an edge of the contour of the gel mold and a solution introduction port;

[0069] Alternatively, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

[0070] In practice, the distance between the contour edge of the gel mold and the solution inlet can be measured and calculated in advance. The distance between the contour edge of the gel mold and the solution inlet is the distance between each contour point on the contour edge of the gel mold and the solution inlet.

[0071] See also Figure 2 As shown, it is a scanning electron microscope image of the hydrogel with temperature self-adaptation and antifreeze functions of an embodiment of the present invention. An appropriate amount of hydrogel sample is selected and immersed in liquid nitrogen until completely frozen, and then placed in a freeze dryer for freeze drying for 72 hours until the hydrogel is completely dry. The freeze-dried sample is immersed in liquid nitrogen for brittle fracture, and the polymer microstructure is observed on the cross section. The hydrogel sample exhibits a dense porous structure, indicating the feasibility of the method for preparing a hydrogel with temperature self-adaptation and antifreeze functions.

[0072] See also Figure 3As shown in FIG, which is an antifreeze point test diagram of a hydrogel with temperature self-adaptation and antifreeze functions according to an embodiment of the present invention, the antifreeze function test process of the hydrogel sample according to the embodiment of the present invention is as follows: weigh an appropriate amount of the hydrogel sample in a crucible, and heat it from -40°C to 20°C at a speed of 5°C / min. Figure 3 As shown, the antifreeze point of the hydrogel sample is -16.54°C, indicating that the hydrogel sample prepared by the above preparation method has excellent antifreeze function.

[0073] See also Figure 4 As shown in FIG, which is a phase transition temperature test diagram of a hydrogel with temperature self-adaptation and antifreeze function according to an embodiment of the present invention, the process of conducting a thermal response temperature test on a hydrogel sample according to this embodiment includes: weighing an appropriate amount of the hydrogel sample into a crucible and heating it from 10°C to 50°C at a rate of 5°C / min. Figure 4 As shown, the phase transition temperature of the hydrogel sample starts at 21.41°C and the peak temperature is 24.04°C, indicating that the hydrogel sample has a lower thermal response temperature.

[0074] Specifically, the process of drawing the light intensity variation curve includes:

[0075] Scanning the demoulded gel mold with a light beam of preset light intensity along a preset scanning trajectory;

[0076] The reflected light intensity of the light beam reflected from the mold cavity is obtained through a receiver, and a correlation relationship between the reflected light intensity and the scanning trajectory is established;

[0077] Drawing the light intensity variation curve according to the associated reflected light intensity and the scanning trajectory;

[0078] The rectangular coordinate system where the light intensity variation curve is located has the reflected light intensity as the vertical axis and the distance between the current light beam scanning position and the light beam scanning starting position as the horizontal axis.

[0079] In practice, the pre-set scanning trajectory is a beam scanning route trajectory planned by those skilled in the art in the mold cavity, and the preset light intensity of the beam can be 350 lm, which will not be described in detail here.

[0080] Specifically, the present invention performs a light beam scan on the gel mold after demolding to draw a light intensity change curve of the reflected light intensity in the mold cavity as the scanning trajectory changes. During the preparation process of the hydrogel, local unevenness and other property differences may appear inside it. It is difficult to quickly detect the uniformity of the internal structure during large-scale continuous production. It is understandable that during the preparation process of the hydrogel, due to various factors, such as uneven mixing of raw materials, insufficient stirring, temperature distribution differences and objective factors of the mold, local property differences may appear inside the hydrogel, resulting in differences in the residual components of the hydrogel prepared each time by demolding in the mold cavity. The difference in residual components will cause the reflected light to present different reflection directions, resulting in differences in the intensity of the reflected light received by the receiver. The present invention realizes the rapid detection of local property differences in the large-scale continuous production process of the hydrogel by drawing a light intensity change curve of the reflected light intensity in the mold cavity as the scanning trajectory changes.

[0081] Specifically, the process of pre-storing the sample reference curve includes:

[0082] Scanning the gel mold several times with the light beam of the preset light intensity, and drawing several light intensity test change curves according to the reflected light intensity obtained from each scan;

[0083] A plurality of light intensity test variation curves are fitted into the sample reference curve and stored in the sample database.

[0084] Specifically, see Figure 5 As shown, it is a logic flow chart for determining whether a demolded hydrogel has local characteristics according to an embodiment of the present invention. Determining whether a demolded hydrogel has local characteristics includes:

[0085] determining a degree of coincidence between the light intensity variation curve and the sample reference curve;

[0086] If the degree of overlap does not satisfy the characteristic determination condition, it is determined that the demoulded hydrogel does not have the local characteristic feature;

[0087] If the degree of overlap satisfies the characteristic determination condition, it is determined that the demoulded hydrogel has local property characteristics;

[0088] The characteristic determination condition is that the degree of overlap is less than a preset degree of overlap reference value.

[0089] In implementation, the preset coincidence reference value can be obtained based on the historical production data of products with the same specifications, and the average coincidence value of the light intensity change curve in the historical data is calculated, and the average coincidence value is determined as the coincidence reference value. Preferably, the coincidence reference value is 0.92.

[0090] Specifically, the present invention determines whether the demolded hydrogel has local property characteristics by initially comparing the light intensity change curve with a pre-stored sample reference curve. This can accurately detect whether the hydrogel has local unevenness. If the light intensity change curve has a low degree of overlap with the sample reference curve, it indicates that the hydrogel may have residual components in certain local areas and its internal adhesion may be abnormal. By establishing a sample reference curve during the production process, continuously produced hydrogels can be produced and tested according to the same quality standards, ensuring the consistency and stability of product quality.

[0091] Specifically, the process of screening characteristic performance curve segments includes:

[0092] dividing the light intensity variation curve into a plurality of curve segments;

[0093] Determine the degree of overlap between each sub-curve segment and the corresponding sample reference curve segment, and select the sub-curve segment corresponding to the minimum overlap value as the characteristic performance curve segment.

[0094] Specifically, the present invention divides the light intensity change curve into several curve segments, analyzes the difference between the light intensity change curve and the sample reference curve in more detail, and selects the sub-curve segments corresponding to the minimum overlap as characteristic performance curve segments, focusing more accurately on the changes in the local area, thereby realizing accurate detection of local property characteristics during the large-scale continuous production process of hydrogels.

[0095] Specifically, the categories of local properties of hydrogels include:

[0096] If the scanning track corresponding to the characteristic performance curve segment has an edge area track, determining that the local property performance category of the hydrogel is the first local property performance category;

[0097] If the scanning track corresponding to the characteristic performance curve segment does not have an edge area track, determining that the local property performance category of the hydrogel is the second local property performance category;

[0098] The edge area track is a track segment in the edge area of ​​the gel mold in the pre-set scanning track.

[0099] In practice, the area between a loop line 3 cm away from the edge of the gel mold and the edge of the gel mold can be defined as the gel mold edge area.

[0100] Specifically, the present invention divides local property performance categories by judging whether there is an edge area track in the scanning track corresponding to the characteristic performance curve segment. It can be understood that in the edge area of ​​the mold, the flow, heat exchange and other conditions of the solution may be different from those inside the mold. These differences may cause the hydrogel to form different local properties at the edge and inside. When the scanning track corresponding to the characteristic performance curve segment involves the edge area track, it is classified into the first local property performance category; otherwise, it is classified into the second local property performance category, thereby improving the scientific nature of targeted optimization of the preparation process based on the test results.

[0101] Specifically, the feedback regulation methods selected for hydrogel preparation include:

[0102] If the local property performance category of the hydrogel is the first local property performance category, adjusting the introduction rate of the solution into the gel mold according to the introduction information of the gel mold;

[0103] If the local property performance category of the hydrogel is the second local property performance category, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

[0104] Specifically, the introduction rate is positively correlated with the maximum distance between the contour edge of the gel mold and the solution introduction port.

[0105] Specifically, the present invention adjusts the introduction rate of the solution into the gel mold to be negatively correlated with the maximum distance between the contour edge of the gel mold and the solution introduction port. It can be understood that in the process of introducing the solution into the gel mold, if local property differences appear and are concentrated in the edge area, then the flow conditions of the solution will have a major impact on the formation of the hydrogel in the mold. The flow rate, flow rate and other factors of the solution in the area close to the solution introduction port are different from those in the area far from the introduction port. The greater the maximum distance between the contour edge of the gel mold and the solution introduction port, the slower the solution flows in this area, and problems such as edge gaps and structural differences are prone to occur. By increasing the solution introduction rate in the farther edge area, the filling gaps in the edge area can be avoided, and the negative impact of local edge defects on the overall performance can be reduced. Furthermore, targeted feedback adjustment of the preparation process based on the test results is achieved, thereby improving the quality stability and thermal response characteristics of continuous production of hydrogels.

[0106] Specifically, the first preset stirring time and the second preset stirring time are negatively correlated with the degree of overlap between the light intensity variation curve and the sample reference curve.

[0107] Specifically, in the process of introducing the solution into the gel mold of the present invention, if local property differences occur and are not concentrated in the edge area, it indicates that the internal distribution of the solution itself is uneven. When the overlap between the light intensity change curve and the sample reference curve is low, the cross-linking degree of the hydrogel can be improved by extending the stirring time, so that the hydrogel forms a uniform three-dimensional network structure and reduces internal structural defects. Furthermore, targeted feedback adjustment of the preparation process is achieved according to the test results, thereby improving the quality stability and thermal response characteristics of the continuous production of hydrogels.

[0108] Specifically, the hydrogel with temperature self-adaptation and antifreeze functions of the present invention is used as a thermochromic material in building smart windows.

[0109] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0110] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrogel with temperature self-adaptation and antifreeze functions, characterized in that: include: Adding polyvinyl alcohol to deionized water and mixing well to obtain a homogeneous polyvinyl alcohol solution; Adding N-isopropylacrylamide, glycerol, acrylamide, N,N′-methylenebisacrylamide, potassium persulfate and the homogeneous polyvinyl alcohol solution to deionized water, respectively, and stirring the mixture in an oil bath for a first preset stirring time to obtain a hydrogel precursor solution; adding tetramethylethylenediamine to the hydrogel precursor solution and stirring the solution; introducing the solution after stirring for a second preset stirring time into a gel mold for low-temperature gelation and demolding to produce a hydrogel; and scanning the demolded gel mold with a light beam to plot a light intensity variation curve of the reflected light intensity in the mold cavity as a function of the scanning trajectory; determining whether the demoulded hydrogel has local morphological characteristics based on a preliminary comparison result of the light intensity variation curve with a pre-stored sample reference curve; Comparing the light intensity change curve with the sample reference curve again to screen a characteristic performance curve segment in the light intensity change curve, and determining the local property performance category of the hydrogel according to the scanning trajectory corresponding to the characteristic performance curve segment; The feedback regulation method for hydrogel preparation is selected according to the local property expression category, including: adjusting an introduction rate of the solution into the gel mold according to introduction information of the gel mold, wherein the introduction information is determined according to a distance between an edge of the contour of the gel mold and a solution introduction port; Alternatively, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

2. The method for preparing a hydrogel with temperature self-adaptation and antifreeze function according to claim 1, characterized in that: The process of drawing the light intensity variation curve includes: Scanning the demoulded gel mold with a light beam of preset light intensity along a preset scanning trajectory; The reflected light intensity of the light beam reflected from the mold cavity is obtained through a receiver, and a correlation relationship between the reflected light intensity and the scanning trajectory is established; Drawing the light intensity variation curve according to the associated reflected light intensity and the scanning trajectory; The rectangular coordinate system where the light intensity variation curve is located has the reflected light intensity as the vertical axis and the distance between the current light beam scanning position and the light beam scanning starting position as the horizontal axis.

3. The method for preparing a hydrogel with temperature self-adaptation and antifreeze function according to claim 2, characterized in that: The process of pre-storing sample reference curves includes: Scanning the gel mold several times with the light beam of the preset light intensity, and drawing several light intensity test change curves according to the reflected light intensity obtained from each scan; A plurality of light intensity test variation curves are fitted into the sample reference curve and stored in the sample database.

4. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 3, characterized in that: Determining whether the demoulded hydrogel has localized characteristics includes: determining a degree of coincidence between the light intensity variation curve and the sample reference curve; If the degree of overlap satisfies the characteristic determination condition, it is determined that the demoulded hydrogel has local property characteristics; The characteristic determination condition is that the degree of overlap is less than a preset degree of overlap reference value.

5. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 4, characterized in that: The process of screening characteristic performance curve segments includes: dividing the light intensity variation curve into a plurality of curve segments; Determine the degree of overlap between each sub-curve segment and the corresponding sample reference curve segment, and select the sub-curve segment corresponding to the minimum overlap value as the characteristic performance curve segment.

6. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 5, characterized in that: The categories of localized properties of hydrogels include: If the scanning track corresponding to the characteristic performance curve segment has an edge area track, determining that the local property performance category of the hydrogel is the first local property performance category; If the scanning track corresponding to the characteristic performance curve segment does not have an edge area track, determining that the local property performance category of the hydrogel is the second local property performance category; The edge area track is a track segment in the edge area of ​​the gel mold in the pre-set scanning track.

7. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 6, characterized in that: Selected feedback control methods for hydrogel preparation include: If the local property performance category of the hydrogel is the first local property performance category, adjusting the introduction rate of the solution into the gel mold according to the introduction information of the gel mold; If the local property performance category of the hydrogel is the second local property performance category, the first preset stirring time and the second preset stirring time during the stirring process are adjusted according to the initial comparison result.

8. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 7, characterized in that: The introduction rate is positively correlated with the maximum value of the distance between the contour edge of the gel mold and the solution introduction port.

9. The method for preparing a hydrogel with temperature self-adaptation and antifreeze functions according to claim 7, characterized in that: The first preset stirring time and the second preset stirring time are negatively correlated with the degree of overlap between the light intensity variation curve and the sample reference curve.

10. Use of the hydrogel with temperature self-adaptation and antifreeze function prepared by the method for preparing the hydrogel with temperature self-adaptation and antifreeze function according to any one of claims 1 to 9, characterized in that: Used as thermochromic material in building smart windows.

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