Liquid crystal elastomer transient curing in-situ infrared spectrum testing tool and testing method

Abstract

The invention discloses a liquid crystal elastomer transient curing in-situ infrared spectrum testing tool and a testing method, which are used for realizing on-line, in-situ and quantitative monitoring on a chemical structure of a liquid crystal elastomer sample in a transient curing process. By adopting the oppositely arranged potassium bromide wafers and adjusting the number of the annular polytetrafluoroethylene isolation sheets arranged between the two potassium bromide wafers, the sample amount can be adjusted, so that the better test dynamic range of various active groups can be obtained at the same time. According to the testing method, changes of various active components in the transient curing process can be obtained on line in situ, the fastest response rate is 22 infrared spectrograms per second, and the testing method can be used for researching the activity, kinetics and mechanism of the liquid crystal elastomer multi-component transient curing reaction; through contrastive analysis of infrared spectrum peak displacement and intensity change in the curing process and research of curing rate test, stability rules and the like, an optimization thought is provided for a liquid crystal elastomer polymer polymerization process.

Description

Technical Field

[0001] The present invention relates to the field of infrared spectroscopy testing of liquid crystal elastomers, and particularly to a transient curing in-situ infrared spectroscopy testing tooling and testing method for liquid crystal elastomers. Background Art

[0002] Liquid crystal elastomers are a type of moderately cross-linked liquid crystal polymer network, whose molecular structure is composed of liquid crystal units and flexible chain segments, and have broad application prospects in the fields of soft robots, artificial organs, flexible wearables, and optical anti-counterfeiting, etc., and are also at the forefront of research on functional polymer materials and new intelligent materials.

[0003] Currently, the widely used liquid crystal elastomers are liquid crystal monomers containing flexible groups and another monomer containing flexible groups. Under the action of an initiator, a moderately cross-linked linear polymer network structure is formed. This moderately cross-linked process, i.e., the curing process, is that liquid crystal monomers such as terminal C═C bonds react with a cross-linkable and curable component containing another active group (such as -SH bond) under the action of an initiator to form a moderately cross-linked and cured liquid crystal polymer network.

[0004] The curing activity of the terminal group C═C bond of liquid crystal monomers is manifested in:

[0005] (1) Reacting with -SH bond, the C═C double bond opens, one end forms a C-S bond, and the other end C is saturated by the H on the -SH bond. The effect is that the molecular chain grows and a network structure is formed.

[0006] (2) Cross-linking and curing with the terminal group C═C bond of another molecule to form a C-C bond, the molecular chain grows, and even cross-linking between molecular chains forms a "bridge" to form a molecular network structure.

[0007] Both of the above cross-linking and curing reactions will cause changes in mechanical properties. By adjusting the chemical properties of liquid crystal monomers and components containing -SH bonds, the mechanical properties of liquid crystal elastomers can be regulated. Therefore, studying the reaction kinetics and mechanism of active groups such as C═C bond and -SH bond during the curing process can master the mechanical property law at the microscopic level, and further achieve the mechanical property design of liquid crystal elastomers.

[0008] Since the cross-linking and curing process of liquid crystal elastomers only takes a few seconds, there is still a lack of in-situ testing methods for studying transient curing at the microscopic molecular scale. Currently, the research mainly focuses on mechanical properties research, such as testing of samples that have been cured by dynamic thermomechanics. Therefore, the curing process cannot be studied at the molecular design level.

[0009] The existing infrared in-situ curing testing methods include thermal curing monitoring, which has low resolution for the transient curing process and lacks tooling preparation and data processing methods for obtaining the variation law of the amount value of active groups. Nuclear magnetic resonance technology also cannot obtain the molecular dynamics process of the transient curing process due to its slow response rate. Summary of the Invention

[0010] In view of this, in order to overcome the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a liquid crystal elastomer transient curing in-situ infrared spectroscopy test tooling and test method to solve the problem of the kinetic study of the reaction process of the transient cross-linking and curing active components in the research process of the existing liquid crystal elastomer formulations and processes.

[0011] To achieve the above object, the present invention adopts the following technical solutions: A liquid crystal elastomer transient curing in-situ infrared spectroscopy test method includes clamping a liquid sample between two potassium bromide wafers, and using a clip to clamp the wafers to seal the liquid sample so that when tested vertically, the absorbance value will not change due to flow; at the same time, several annular polytetrafluoroethylene spacer sheets are placed between the two potassium bromide wafers to adjust the sample amount between the wafers, and by controlling the sample thickness, the infrared absorbance values of all active groups in the system are made to be within a better linear range (0.2 - 2); the potassium bromide wafers do not absorb ultraviolet light and have no infrared absorption, and have the "transparent" characteristics in the infrared and ultraviolet regions, so that the sample cell does not produce any chemical background and there is no interference in excitation and testing.

[0012] An infrared and ultraviolet light transmissive sealed sample cell with adjustable sample amount, which has no absorption of infrared light and ultraviolet light, can obtain infrared absorbance values within a good linear range, and is used for curing kinetics calculation and research. On the basis of initially exploring the curing rate and time, ultraviolet light intensity, and analyzing the infrared characteristic absorption of active single components, the test parameters, sample cell settings, and the intensity of the curing-exciting ultraviolet light reaching the sample are set. During the test, the ultraviolet light and the fast scanning program are started simultaneously, and a series of infrared absorption spectra of the transient curing process induced by ultraviolet light are in-situ online tested. By observing the change of the intensity of the active characteristic groups over time, the reaction kinetic curve of the active components during the curing process is obtained.

[0013] The present invention provides a liquid crystal elastomer transient curing in-situ infrared spectroscopy test tooling, which is characterized in that it includes two opposed potassium bromide wafers clamped by a fixture, infrared light and ultraviolet light can pass through the potassium bromide wafers, and one or more annular polytetrafluoroethylene spacer sheets are arranged between the two potassium bromide wafers to adjust the distance between the two potassium bromide wafers so as to adjust the sample amount between the two potassium bromide wafers, and the fixture clamps the two potassium bromide wafers in a sealed state to prevent the leakage of the sample to be tested.

[0014] Further, two annular polytetrafluoroethylene spacer sheets are arranged between the two potassium bromide wafers.

[0015] Further, the potassium bromide wafer is a circular wafer with a diameter of 25 mm and a thickness of 5 mm; the outer diameter of the annular polytetrafluoroethylene spacer sheet is 25 mm, the inner diameter is 20 mm, and the thickness is 0.1 mm.

[0016] The present invention also provides a method for in-situ infrared spectroscopy testing of transient curing of liquid crystal elastomers using the in-situ infrared spectroscopy testing tooling for transient curing of liquid crystal elastomers, which comprises the following steps:

[0017] S1: Pre-test the infrared spectrum of each component in the liquid crystal elastomer sample, analyze the infrared characteristic absorption of the active groups, and determine the characteristic peaks and baseline positions of the active groups with obvious signals and not interfered by other components;

[0018] S2: Determine the sample amount: Absorb the sample and drop it on a potassium bromide wafer, add a circular polytetrafluoroethylene spacer, then cover it with another potassium bromide wafer, and clamp the two potassium bromide wafers with a fixture to be in a sealed state to prevent sample leakage; Adjust the sample amount by adjusting the number of the spacers so that the infrared absorbance values of the reactive groups and the product groups are in the linear range of 0.2 - 2 to conform to the Lambert-Beer quantitative law;

[0019] S3: Determine the rapid scanning test parameters of the infrared spectrum so that the test parameters respond synchronously with the curing process of the specimen, where:

[0020] (1) Acquisition mode: The ordinate is in the absorbance display format. First, acquire the background and then acquire the sample.

[0021] (2) Optical component parameters: Light mirror rate: 0.1581 - 6.3290, Gain: 1 - 8.

[0022] (3) Series acquisition parameters: Select the total test time, which is consistent with the curing time;

[0023] S4: Use an ultraviolet light intensity detector, an ultraviolet lamp, an infrared spectrum rapid detector, and rapid test control software to test the in-situ infrared spectrum of the curing reaction process of the specimen initiated by ultraviolet light;

[0024] S5: On the static infrared spectrum, cure the reactive groups of the reaction to generate a curve of the peak position absorption intensity - time of the reaction groups.

[0025] Further, in step S1, each active group respectively has characteristic infrared absorption peaks including stretching vibration and bending vibration. After superimposing the spectra according to the formulation ratio, further determine the characteristic peaks of the data processing active groups.

[0026] Further, the wavelength of the ultraviolet light source for exciting the curing reaction is 200 - 400 nm, and the wavelength of the infrared light source for infrared testing is 2.5 μm - 25 μm. The two do not interfere with each other. The infrared light passes through the sample and enters the detector, and the ultraviolet light irradiates the sample at a certain angle and distance.

[0027] Further, in step S4, the test mode of the infrared spectrum rapid detector is the rapid scanning mode, the ordinate of the spectrogram is in absorbance format, the sample gain, resolution, and step size are set to be synchronized with the curing reaction process, and at the same time, the rapid scanning program and the ultraviolet lamp are started.

[0028] Further, in step S4, the ultraviolet light from the ultraviolet lamp irradiates the sample position at a certain angle and distance. The ultraviolet light intensity detector is placed at the sample position in advance to record the ultraviolet light intensity, and the air background is collected in advance. The test tooling is vertically fixed in the infrared test optical path, and the infrared light vertically irradiates the sample cell and passes through it into the infrared spectrum rapid detector. The transmitted infrared light contains the infrared absorption information of the sample. When the test is completed, the rapid test control software provides several infrared absorption spectrograms.

[0029] Further, in step S5, according to the characteristic peaks and baseline positions of the active groups analyzed in step S1, the infrared absorption spectrograms obtained in step S4 are integrated under a certain baseline and region to obtain the active group absorbance intensity-time curve.

[0030] Further, the liquid crystal elastomer sample contains 85.5% liquid crystal monomer, 13% dithiol, 0.5% photoinitiator Irg184, and 1% chloroform by mass.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention uses a ultraviolet light source for initiating curing, a test tooling, an infrared light source, an infrared spectrum rapid response detector, and a rapid test control software to realize the on-line, in-situ, and quantitative monitoring of the chemical structure of the transient curing process of the sample.

[0033] (2) The test tooling of the present invention uses two opposed potassium bromide wafers, which are clamped by a fixture. The infrared light and ultraviolet light can pass through the potassium bromide wafers, and one or more annular polytetrafluoroethylene spacer sheets are arranged between the two potassium bromide wafers, so that the distance between the two potassium bromide wafers can be adjusted, thereby adjusting the sample addition amount between the two potassium bromide wafers, and thus a good linear range of the infrared absorbance value of the active group can be obtained for curing kinetics calculation and research.

[0034] (3) According to the transient curing characteristics, the present invention sets the infrared spectrum test parameters to achieve synchronous response with the curing process.

[0035] (4) The liquid crystal elastomer transient curing in-situ infrared spectrum test tooling and test method of the present invention can in-situ and on-line obtain the changes of multiple active components in the transient curing process, and the fastest response rate is 22 infrared spectra per second, which can be used to study the transient curing reaction activity, kinetics, and mechanism of liquid crystal elastomers with multiple components. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the working principle of the embodiment of the present invention.

[0037] Figure 2 It is a schematic diagram of a potassium bromide wafer and a polytetrafluoroethylene spacer of the embodiment of the present invention.

[0038] Figure 3 It is the infrared 100% transmission curve of the potassium bromide wafer of the embodiment of the present invention.

[0039] Figure 4 It is the ultraviolet 100% transmission curve of the potassium bromide wafer of the embodiment of the present invention.

[0040] Figure 5 It is the characteristic infrared absorption at 2547 cm of the curing component containing -SH active groups in the embodiment of the present invention -1 .

[0041] Figure 6 It is the curing component containing terminal C=C groups in the embodiment of the present invention, at 1635 cm -1 is the stretching vibration of terminal C=C, 987 cm -1 , 905 cm -1 is the -CH bending vibration on terminal C=C.

[0042] Figure 7 It is the infrared spectrum of the ultraviolet initiator Irg184 in the embodiment of the present invention.

[0043] Figure 8 It is the solvent for preparing the sample in the embodiment of the present invention, with a usage amount of 1%, and the sample is sealed during testing, which has no influence on the infrared absorption of active groups.

[0044] Figure 9 It is the static infrared absorption spectrum of the liquid crystal elastomer before curing in the embodiment of the present invention.

[0045] Figure 10 It is the peak intensity integral diagram of the C=C terminal group selection at 1606 cm of the liquid crystal monomer in the embodiment of the present invention -1 .

[0046] Figure 11 It is the peak intensity integral diagram of the -SH bond selection at 2547 cm of the thiol in the embodiment of the present invention -1 .

[0047] Figure 12 It is the peak intensity integral diagram of the saturated -CH bond selection at 2963 cm of the embodiment of the present invention -1 .

[0048] Figure 13The spectrogram provided by the 120 - second control software for the test of the embodiment of the present invention.

[0049] Figure 14 The characteristic infrared absorption intensity - time curve graph of the SH, terminal C═C, and product - CH groups during the curing process of the liquid crystal elastomer for the embodiment of the present invention.

[0050] In the figure: 1 - potassium bromide wafer; 2 - circular polytetrafluoroethylene spacer; 3 - fixture. Detailed implementation manners

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0052] The present invention provides a method for testing the in - situ infrared spectrum of the transient curing of liquid crystal elastomers, which preliminarily explores the ultraviolet light intensity, curing time, and analyzes the infrared characteristic absorption of the curing active groups to determine the intensity of the ultraviolet light reaching the sample, infrared test parameters, the number of spacers, and the data processing method. During the test, the ultraviolet light and the fast - scanning program are started simultaneously to obtain a series of infrared absorption spectrograms of the curing process induced by the ultraviolet light, and the reaction kinetic curve of the active components during the curing process is obtained by analyzing the change of the intensity of the active characteristic groups with time.

[0053] The following further explains the specific content of the present invention in detail with reference to the embodiments.

[0054] As Figure 1 and 2 shown, this embodiment provides a test tool for the in - situ infrared spectrum of the transient curing of liquid crystal elastomers. A potassium bromide wafer is used as the substrate, and two circular polytetrafluoroethylene spacers are placed between the wafers to adjust the capacity between the wafers, so as to obtain a spectrogram with high signal intensity, and it is fixed on a Fourier transform infrared spectrometer with a fixture. The reason for choosing the potassium bromide wafer is that it has a very wide infrared transmission range, especially in the mid - infrared region. The light source selects ultraviolet light with a wavelength of 365 nm, and the ultraviolet light power is about 15 mW / cm -1 .

[0055] Figure 3 shows the infrared transmission curve of the potassium bromide wafer. Its transmission range usually ranges from about 4000 cm−1 to 400 cm−1, which means that it can effectively transmit most of the infrared spectral regions and is less affected by the selected ultraviolet light source in this experiment and will not affect the experimental results. Figure 4 shows the ultraviolet transmission curve of the potassium bromide wafer.

[0056] Prepare a fresh sample of the liquid crystal elastomer curing system. The sample of this example contains 85.5% liquid crystal monomer, 13% dithiol, 0.5% photoinitiator Irg184 and 1% chloroform by mass. After dissolving the dithiol and photoinitiator with a small amount of solvent chloroform (about 1%), then add the liquid crystal monomer and stir evenly.

[0057] A method for testing the in-situ infrared spectrum of transient curing of liquid crystal elastomers, which comprises the following steps:

[0058] S1: Pre-test the infrared spectra of single-component liquid crystal monomer, dithiol, photoinitiator, and chloroform in the liquid crystal elastomer sample, analyze the infrared characteristic absorption of active groups, and determine the characteristic peaks and baseline positions of the active groups with obvious signals and not interfered by other components; each active group has characteristic infrared absorption peaks such as stretching vibration and bending vibration. After superimposing the spectra according to the formula ratio, the characteristic peaks of the data processing active groups can be further determined.

[0059] Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 To test the infrared spectra of each component in the sample, among which Figure 5 shows the characteristic infrared absorption of the curing component containing -SH active groups in the embodiment of the present invention at 2547 cm -1 , Figure 6 shows the curing component containing terminal C=C groups in the embodiment of the present invention. At 1635 cm -1 is the stretching vibration of terminal C=C, 987 cm -1 , 905 cm -1 is the -CH bending vibration on terminal C=C; Figure 7 is the infrared spectrum of the ultraviolet photoinitiator Irg184 (1-hydroxycyclohexyl phenyl ketone) in the embodiment of the present invention. The change in infrared absorption intensity due to the structural change after the addition of 0.5% has no significant effect on the active groups. Figure 8 shows the solvent used for preparing the sample in the embodiment of the present invention, with a usage amount of 1%, and the sample is sealed during testing, which has no effect on the infrared absorption of the active groups. Analyze the infrared spectra of its monomers respectively, and then combine with the spectra after polymerization to observe the peak position changes.

[0060] S2: Determine the sample amount: Pipette the sample to be measured onto a potassium bromide wafer, add a circular polytetrafluoroethylene spacer, then cover it with another potassium bromide wafer, and clamp the two potassium bromide wafers with a fixture to be in a sealed state to prevent sample leakage; adjust the sample amount by adjusting the number of the spacers so that the infrared absorbance values of the peak heights of reactive groups such as -SH bonds, C=C or -NCO and product groups such as -CH, amide bonds, etc. are in the linear range of 0.2 - 2 to conform to the Lambert-Beer quantitative law; if the group is consumable during the curing reaction, the sample amount can be increased to make its absorbance value larger; if the group is a product, the sample amount can be adjusted to make its absorbance value far lower than 2, leaving room for growth. In this embodiment, two spacers are used. Figure 9 The static infrared absorption spectrogram before curing of the liquid crystal elastomer according to the embodiment of the present invention is shown, and the infrared absorption of the active components is within the linear range of 0.2 - 2, and the infrared absorption of the product group -CH is 1.2, far lower than the upper limit of the linear range.

[0061] S3: Set the infrared spectrum fast scanning test parameters of the infrared spectrum MCT (mercury cadmium telluride type) fast response detector so that the test parameters respond synchronously with the curing process of the sample, where:

[0062] (1) Acquisition mode: The ordinate is in the absorbance display format. First, collect the background and then collect the sample.

[0063] (2) Optical component parameters: Light mirror rate: 0.1581 - 6.3290, Gain: 1 - 8.

[0064] The number of scans is optional from 1 to 32 times. The more scans, the slower the test speed. The resolution is optional from 1 to 32 cm -1 Optional. The higher the resolution, the slower the test speed.

[0065] (3) Series acquisition parameters: Select the total test time, which is the same as the curing time or can be slightly longer.

[0066] The parameters can be tried to estimate the number of spectrograms measured per unit time and whether it matches the curing rate. The larger the light mirror rate, the smaller the number of scans, and the larger the resolution value, the faster the test speed. The fastest response rate of the MCT detector under the control software is 22 infrared spectrograms.

[0067] S4: Use an ultraviolet light intensity detector, an ultraviolet lamp, an infrared spectrum fast detector and fast test control software to test the in-situ infrared spectrogram of the curing reaction process of the sample initiated by ultraviolet light. The specific operation is as follows:

[0068] The test mode of the infrared spectrum rapid detector is the fast scan mode, the ordinate of the spectrum is in absorbance format, the sample gain, resolution and step size are set to be synchronized with the curing reaction process, the infrared aperture and detector attenuation are both default values, and the fast scan program and ultraviolet lamp are started simultaneously. In this implementation, the aperture selects medium resolution, the sample gain is 1.0, the step size is 0.6147, the acquisition range is from 400.1569 to 4000.1230, the acquisition duration is 31 s, and a total of 49 spectra are generated during the process. Each spectrum is scanned once to synchronize with the polymerization reaction rate. Among them, if the polymerization time is long, the parameters can be appropriately adjusted, such as increasing the step size and decreasing the resolution, etc.

[0069] Place an ultraviolet light intensity detector at the sample cell. The ultraviolet light from the ultraviolet lamp irradiates the sample position at a certain angle and distance. Place the ultraviolet light intensity detector at the sample position in advance to record the ultraviolet light intensity and collect the air background in advance. The number of scans during collection is the same as that during fast scanning. Put the sample clamp in place and start the ultraviolet lamp and fast scan program simultaneously. The test tooling is vertically fixed in the infrared test optical path, and the infrared light vertically irradiates the sample cell and passes through it into the infrared spectrum rapid detector. The transmitted infrared light contains the infrared absorption information of the sample. When the test is completed, the fast test control software provides several infrared absorption spectra.

[0070] S5: Curing reactive groups on the static infrared spectrum to generate a curve of the peak position absorption intensity - time of the reactive groups.

[0071] Determine the baseline and integration range of the curing reactive groups such as C=C, -SH, and the generated group -CH, etc. on the static infrared spectrum. Generally, the baseline selection should not be affected by the absorption peaks of other components and should be selected as flat as possible. The integration range is generally symmetric on both sides of the highest peak, and the cut-off ends are at the bottom of the peak and separated from other peak shapes. Integrate the absorption intensity of the same group at the same baseline and integration range respectively to obtain the intensity - time curve.

[0072] It should be noted that the ultraviolet light source (wavelength 200 - 400 nm) used to stimulate the curing reaction and the infrared light source (wavelength 2.5 μm - 25 μm) used for testing in the test tooling do not interfere with each other. The infrared light passes through the sample and enters the detector, and the ultraviolet light irradiates the sample at a certain angle and distance.

[0073] After the test is completed, in-situ spectra during the polymerization process are obtained. Figure 10 , 11, 12 are respectively the partial thumbnail views of their corresponding peak positions. Figure 10 For the full spectrum after the polymerization of the liquid crystal elastomer, it should be observed that the peak position changes during the reaction mainly concentrate on the C=C peak at 1606 cm -1 the -SH peak at 2547 cm -1 and the peak at 2963 cm -1The C-H peak, baseline 2215~2106 cm -1 , integration range 1622~1590 cm -1 , and the absorbance at the peak height is 1.2. Figure 11 Select 2547 cm for the -SH bond of thiol -1 Peak intensity integration, baseline 3806~2626 cm -1 , integration range 2626~2525 cm -1 , and the absorbance at the peak height is 0.28. Figure 12 Select 2963 cm for the saturated -CH bond -1 Peak intensity integration, baseline 3993~2617 cm -1 , integration range 3029~2838 cm -1 , and the absorbance at the peak height is 0.3.

[0074] Generate a curve of the absorption intensity - time of the reaction group peaks, Figure 13 For the 120 - second test, the control software gives 336 spectra, 2.8 spectra per second. As Figure 13 shown, during the polymerization process, it is observed that the C=C peak and -SH peak gradually decay while the C-H peak strengthens. The dynamic changes between the peak positions can be clearly observed, thereby realizing in-situ analysis of the polymerization process. Figure 14 A two-dimensional graph of the peak position changing with time is plotted, and it is found that the peak position changes mainly concentrate in the first 20 s before the reaction, proving that the polymerization reaction rate is relatively high and almost complete polymerization has been achieved in the early stage of the reaction. Through analysis, the light intensity and duration of subsequent experiments can also be optimized to make it more efficient.

[0075] The test method of the present invention can obtain in-situ and online the changes of various active components during the transient curing process. The fastest response rate is 22 infrared spectra per second, which can be used to study the reactivity, kinetics, and mechanism of the multi-component transient curing reaction of liquid crystal elastomers; by comparing and analyzing the infrared spectral peak displacement and intensity changes during the curing process, study the curing rate test and stability rules, etc., providing an optimization idea for the polymerization process of liquid crystal elastomer polymers.

[0076] It should be noted that the above-described embodiments are only the preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several modifications, improvements, and equivalent replacements can be made to the present invention, and these modifications, improvements, and equivalent replacements are also considered to fall within the protection scope of the claims of the present invention.

Claims

1. A liquid crystal elastomer transient curing in-situ infrared spectroscopy test tool, characterized in that: The invention comprises two opposed potassium bromide wafers which are clamped by a clamp, infrared light and ultraviolet light can penetrate the potassium bromide wafers, and one or more annular polytetrafluoroethylene spacers are arranged between the two potassium bromide wafers for adjusting the distance between the two potassium bromide wafers so as to adjust the sample amount between the two potassium bromide wafers. The clamp clamps the two potassium bromide wafers in a sealed state to prevent the side leakage of the sample to be tested.

2. The liquid crystal elastomer transient curing in-situ infrared spectroscopy testing tool according to claim 1, characterized in that: Two annular polytetrafluoroethylene spacers are arranged between the two potassium bromide wafers.

3. The liquid crystal elastomer transient curing in-situ infrared spectroscopy testing tool according to claim 1, characterized in that: The potassium bromide wafer is a circular wafer with a diameter of 25 mm and a thickness of 5 mm; the annular polytetrafluoroethylene isolation sheet has an outer diameter of 25 mm, an inner diameter of 20 mm and a thickness of 0.1 mm.

4. A method for testing liquid crystal elastomer transient curing in-situ infrared spectroscopy using the liquid crystal elastomer transient curing in-situ infrared spectroscopy testing tool as claimed in claim 1, characterized in that: The steps include: S1: Pre-test the infrared spectrum of a single component in the liquid crystal elastomer sample, analyze the infrared characteristic absorption of the active group, and determine the characteristic peak and baseline position of the active group with obvious signals and no interference from other components; S2: Determine the sample amount: Pipette the sample and drop it on a potassium bromide wafer, add a ring-shaped polytetrafluoroethylene spacer, and then cover it with another potassium bromide wafer, and clamp the two potassium bromide wafers with a clamp in a sealed state to prevent the sample from leaking sideways; adjust the sample amount by adjusting the number of the spacers, so that the infrared absorbance values ​​of the reactive groups and the product groups are in the linear range of 0.2 to 2, so as to comply with the Lambert-Beer quantitative law; S3: Determine infrared spectrum rapid scanning test parameters so that the test parameters respond synchronously with the sample curing process, wherein: (1) Collection mode: The vertical axis is in absorbance display format, first collect the background and then collect the sample. (2) Optical component parameters: Mirror speed: 0.1581~6.3290, Gain: 1~8. (3) Series acquisition parameters: select the total test time, which is consistent with the curing time; S4: using an ultraviolet light intensity detector, an ultraviolet lamp, an infrared spectrum rapid detector and a rapid test control software to test an in-situ infrared spectrum of the curing reaction process of the sample induced by ultraviolet light; S5: Curing the reactive groups on the static infrared spectrum to generate a curve of the peak absorption intensity of the reactive groups-time.

5. The method for testing transient curing of liquid crystal elastomer by in-situ infrared spectroscopy according to claim 4, characterized in that: In step S1, each active group has characteristic infrared absorption peaks including stretching vibration and bending vibration. After superimposing the spectra according to the formula ratio, the characteristic peaks of the active groups are further determined for data processing.

6. The method for testing transient curing of liquid crystal elastomer by in-situ infrared spectroscopy according to claim 4, characterized in that: The wavelength of the ultraviolet light source used to stimulate the curing reaction is 200-400nm, and the wavelength of the infrared light source used for infrared testing is 2.5μm-25μm. The two do not interfere with each other. The infrared light passes through the sample into the detector, and the ultraviolet light irradiates the sample at a certain angle and distance.

7. The method for testing transient curing of liquid crystal elastomer by in-situ infrared spectroscopy according to claim 4, characterized in that: In step S4, the test mode of the infrared spectrum rapid detector is the rapid scanning mode, the spectrum ordinate is in absorbance format, the sample gain, resolution and step length are set to be synchronized with the curing reaction process, and the rapid scanning program and ultraviolet lamp are started at the same time.

8. The in-situ infrared spectroscopy testing method for transient curing of liquid crystal elastomer according to claim 4 or 7, characterized in that: In step S4, the ultraviolet light from the ultraviolet lamp is irradiated to the sample position at a certain angle and distance, and an ultraviolet light intensity detector is placed at the sample position in advance to record the ultraviolet light intensity, and the air background is collected in advance; the test tooling is vertically fixed in the infrared test light path, and the infrared light vertically irradiates the sample pool and passes through into the infrared spectrum rapid detector. The transmitted infrared light contains the infrared absorption information of the sample. When the test is completed, the rapid test control software provides several infrared absorption spectrum graphs.

9. The method for testing transient curing of liquid crystal elastomer by in-situ infrared spectroscopy according to claim 4, characterized in that: In step S5, according to the characteristic peak and baseline position of the active group analyzed in step S1, the infrared absorption spectrum obtained in step S4 is integrated under a certain baseline and region to obtain an absorbance intensity-time curve of the active group.

10. The method for testing transient curing of liquid crystal elastomer by in-situ infrared spectroscopy according to claim 4, characterized in that: The liquid crystal elastomer sample contained 85.5% by mass of a liquid crystal monomer, 13% by mass of a dithiol, 0.5% by mass of a photoinitiator Irg184, and 1% by mass of chloroform.

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