Visual detection method for topological freezing transition temperature of glass-like polymer

Abstract

The invention belongs to the technical field of detection and analysis, and particularly relates to a glassy-like polymer topological freezing transition temperature visual detection method, which comprises the following steps: preparing a photonic crystal film on a substrate, and preparing a glassy-like polymer on the photonic crystal film to obtain a substrate coated with a composite film; then soaking the substrate coated with the composite film in fluorescein containing ester bonds to obtain a substrate covered with a fluorescein composite film, and finally judging the topological freezing transition temperature (Tv) of the glass-like polymer according to the fluorescence color change condition under ultraviolet irradiation. The Tv can be visually detected according to the fluorescence color change condition under ultraviolet irradiation, and expensive spectrum detection equipment is not needed.

Description

Technical Field

[0001] This invention belongs to the field of detection and analysis technology, specifically relating to a method for visually detecting the topological freeze transition temperature of glassy polymers. Background Technology

[0002] Glass-like polymers are dynamically covalently cross-linked compounds with a topological freeze transition temperature (T0). v The temperature above T is the critical temperature for topological phase transitions in glassy polymers. v At this temperature, the glass-like polymer exhibits fluidity, allowing for reprocessing and recycling; when the temperature is below T... v At this time, the glass-like polymer exhibits a frozen state, similar to traditional thermosetting resins, and can be used normally.

[0003] T is measured under external force using a rheometer or dynamic mechanical analyzer. v (Nat. Commun. 2018, 9, 1906) Additional local forces can affect the crosslinking breakage rate and effective activation energy, which may lead to changes in the required T value. v The value changes. Ji et al. doped aggregation-induced emission (AIE) into glassy polymers, and because the fluorescence intensity of the AIE luminescent material changes at T... v The fluorescence intensity changes significantly, therefore T can be detected by observing the change in fluorescence intensity. v (Nat. Commun. 2019, 10, 3165) This method requires doping AIE into a glassy polymer and detecting T using a fluorescence spectrometer. v Furthermore, the added AIE must have aggregation-induced emission effect, and such fluorescent substances are generally complex to synthesize and expensive.

[0004] Patent application number 202410236717X discloses a method for detecting the topological freeze transition temperature (TFT) of a glassy polymer. This method involves preparing a substrate coated with a double-layer film (PCV) based on a bottom layer of photonic crystal (PC) and an upper layer of glassy polymer, and then performing in-situ detection. PC has a photonic bandgap; when the photonic coating is heated, the intensity and position of the reflection peak of the PCV change significantly. Therefore, the TFT of the glassy polymer can be easily obtained intuitively through changes in the PCV peak intensity and / or peak position. v However, it cannot visualize the detection of T. v Precision testing equipment is still required. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by providing a method for visually detecting T based on changes in fluorescence color under ultraviolet irradiation. vA visual detection method for the topological freeze transition temperature of glassy polymers that does not require expensive spectroscopic detection equipment.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for visually detecting the topological freeze transition temperature of a glassy polymer, the method comprising:

[0008] Fabrication of photonic crystal films on a substrate;

[0009] An ester-bonded glass-like polymer was prepared on the photonic crystal film to obtain a matrix coated with the composite film;

[0010] The substrate coated with the composite film is immersed in a fluorescein containing ester bonds to obtain a substrate covered with a fluorescein composite film; the composite film is heated, and the topological freezing transition temperature of the glass-like polymer is determined based on the change in fluorescence color under ultraviolet irradiation.

[0011] Preferably, determining the topological freeze transition temperature of the glass-like polymer based on the change in fluorescence color under ultraviolet irradiation means taking the temperature at which the fluorescence color changes under ultraviolet irradiation as the topological freeze transition temperature of the glass-like polymer.

[0012] Preferably, the fluorescein containing ester bonds includes: Rhodamine B fluorescein, diacetic acid fluorescein, and 5-carboxyfluorescein.

[0013] Preferably, the photonic crystal coating is prepared using SiO2 nanosphere dispersion as raw material, and the particle size of the SiO2 nanosphere is 165-300 nm.

[0014] Preferably, the preparation steps of the photonic crystal coating include: weighing SiO2 nanospheres and ethanol in the required ratio, mixing and ultrasonically dispersing to obtain a SiO2 nanosphere dispersion; placing one end of the substrate into the dispersion and drying to obtain a photonic crystal film.

[0015] Preferably, the mass ratio of the SiO2 nanospheres to the volume ratio of ethanol is 0.06 g : 15 mL.

[0016] Preferably, the glass-like polymer is prepared from dodecanoic acid, bisphenol A diglycidyl ether, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene as raw materials.

[0017] Preferably, the preparation step of preparing a glass-like polymer on a photonic crystal film includes:

[0018] Dodecanoic acid and bisphenol A diglycidyl ether were placed in a muffle furnace and kept at 155°C for 30 minutes.

[0019] The catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene was placed in the blank space at the other end of the matrix. A mixture of dodecanoic acid and bisphenol A diglycidyl ether was dropped onto the catalyst. The blank space at the other end of the matrix was tilted upwards at 4° and then placed back into the muffle furnace. The furnace was kept at 155° for 20 min.

[0020] After tilting the blank part of the other end of the substrate downwards at an 11° angle, place it back into the muffle furnace, hold it at 155°C for 20 minutes, and then hold it at 140°C for 8 hours.

[0021] The substrate was placed in a high-pressure reactor at room temperature and nitrogen gas was introduced. The reactor was kept at 140℃ and 2.6 MPa for 6 hours to obtain a substrate coated with a composite membrane.

[0022] Preferably, the molar ratio of dodecanoic acid, bisphenol A diglycidyl ether, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene is 10:9.5:1.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention discloses a method for visually detecting the topological freeze transition temperature of a glassy polymer. First, a photonic crystal film is prepared on a substrate. Then, an ester-bonded glassy polymer is prepared on the photonic crystal film, resulting in a substrate coated with the composite film. Subsequently, the substrate coated with the composite film is immersed in a fluorescein containing ester bonds, resulting in a substrate covered with a fluorescein composite film. The composite film is then heated. Finally, the topological freeze transition temperature of the glassy polymer is determined based on the change in fluorescence color under ultraviolet irradiation. Since when the temperature is higher than T... v At this time, fluorescein containing ester bonds can undergo dynamic transesterification with ester bonds in glassy polymers, thereby enabling it to exhibit T0... v The fluorescence color changes over time. Compared to existing technologies that dope glass-like polymers with aggregation-induced emission (AIE) and require a precise fluorescence spectrometer to achieve this, T… v For detection, this method uses a more common and inexpensive fluorescein, which only needs to contain ester bonds. Moreover, it enables visual detection without the need for a precision fluorescence spectrometer, greatly reducing detection requirements and offering advantages such as accuracy, low cost, and non-destructiveness. Attached Figure Description

[0025] Figure 1 The fluorescence images of PC0VF1-PC5VF1 and PC4V prepared in Example 1 under ultraviolet light irradiation show the changes with temperature.

[0026] Figure 2 The fluorescence images of PC0VF2-PC5VF2 prepared in Example 2 under ultraviolet light irradiation show the changes with temperature.

[0027] Figure 3 The fluorescence images of PC0VF3-PC2VF3 and PC4VF3 prepared in Example 3 under ultraviolet light irradiation show the changes with temperature.

[0028] Figure 4 The fluorescence images of PC4VF4, PC2VF5, PC2VF6 and PC1VF6 prepared in Example 4 under ultraviolet light irradiation show the changes with temperature.

[0029] Figure 5 The fluorescence spectrum of PC0VF2 prepared in Example 2 was obtained by in-situ monitoring using a spectrometer.

[0030] Figure 6 The study investigated the variation of the highest peak intensity with temperature obtained by in-situ monitoring of PC0VF2 prepared in Example 2 using a spectrometer.

[0031] Figure 7 The fluorescence spectrum of PC4VF2 prepared in Example 2 was obtained by in-situ monitoring using a spectrometer.

[0032] Figure 8 The study investigated the variation of the highest peak intensity with temperature obtained by in-situ monitoring of PC4VF2 prepared in Example 2 using a spectrometer. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0034] Example 1:

[0035] A method for visually detecting the topological freeze transition temperature of glassy polymers, comprising the following steps:

[0036] Step 1: Prepare a photonic crystal coating (PC) on the substrate.

[0037] Take 0.06g of SiO2 nanospheres and 15mL of ethanol and place them in a beaker for ultrasonic dispersion to obtain a SiO2 nanosphere dispersion.

[0038] After placing one end of a clean glass slide into a beaker containing a dispersion, the entire slide is placed in an oven and kept at 65°C for 17 hours to dry, thus obtaining PC (one end of the glass slide surface is a PC film, and the other end is blank).

[0039] Five types of PC with different band gaps were prepared from five SiO2 nanospheres with different particle sizes (165nm, 190nm, 260nm, 280nm, and 300nm, respectively), and were designated as PC1-PC5.

[0040] Step 2: Prepare the substrate (PCV) coated with the composite coating.

[0041] Weigh 0.068g of dodecanoic acid and 0.094g of bisphenol A diglycidyl ether and place them in a beaker. Put the mixed sample into a muffle furnace and heat it to 155℃ and keep it at that temperature for 30 minutes to melt and mix the dodecanoic acid and bisphenol A diglycidyl ether.

[0042] Weigh 0.004 g of catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene and place it in the blank space of a PC glass slide. While it is still hot, drop the mixed sample in the beaker onto the catalyst. Tilt the blank part of the glass slide upward at 4° and put it back into the muffle furnace. Continue to keep it at 155° for 20 min.

[0043] After removal, tilt the glass slide 11° downwards with the blank part facing down and return it to the muffle furnace for another 20 minutes at 155°C. This step aims to obtain a uniform composite film. Then, hold it at 140°C for 8 hours. It should be noted that the tilt angle of the glass slide only affects the thickness of the glass-like polymer film and does not affect its temperature (T). v value.

[0044] The composite membrane was placed in a high-pressure reactor at room temperature, nitrogen gas was introduced into the reactor, and the temperature was raised to 140 °C to reach a pressure of 2.6 MPa. The mixture was held at this temperature for 6 hours to obtain PCV. It is worth noting that by changing the heating temperature of the high-pressure reactor, different T values ​​can be obtained from the same three raw materials. v Glass-like polymers.

[0045] The five composite membranes composed of five types of PC are designated as PC1V-PC5V, while the composite membrane without PC is designated as PC0V.

[0046] Step 3: Prepare a composite membrane (PCVF) coated with fluorescein.

[0047] The obtained PC1V-PC5V were immersed in a Rhodamine B fluorescein toluene solution for 16 hours to obtain PCVF; the concentration of the fluorescein toluene solution was 2 × 10⁻⁶. -4 g / mL;

[0048] The five composite membranes impregnated with fluorescein are abbreviated as PC1VF1-PC5VF1, while the composite membrane without PC but impregnated with fluorescein is denoted as PC0VF1.

[0049] Step 4: Detect the T value of PCVF v

[0050] The PCVF was placed on a temperature-controlled platform, with the temperature maintained between room temperature (25℃) and 40-150℃. The temperature was increased by 10℃ and held for 10 minutes at each temperature to ensure the PCVF film was fully heated. Images were taken under UV light (2×15 Watt, 365nm) at each temperature, including an additional image taken at 95℃. The fluorescence of the PCVF film under UV light was observed as a function of temperature; the temperature at which the color changed was defined as T. v .

[0051] Example 2:

[0052] This embodiment is the same as Embodiment 1, except that:

[0053] In step three, the Rhodamine B fluorescein toluene solution was replaced with diacetic acid fluorescein toluene solution. The five composite membranes soaked in fluorescein were abbreviated as PC1VF2-PC5VF2, and the composite membrane without PC but soaked in fluorescein was denoted as PC0VF2.

[0054] Example 3:

[0055] This embodiment is the same as Embodiment 1, except that:

[0056] In step one, three types of PC with different band gaps were prepared from three SiO2 nanospheres with different particle sizes (165nm, 190nm, and 280nm, respectively), and were designated as PC1, PC2, and PC4.

[0057] In step three, the rhodamine B fluorescein toluene solution is replaced with a 5-carboxyfluorescein aqueous solution, with a concentration of 2 × 10⁻⁶. -4 g / mL; the three composite membranes soaked in fluorescein are abbreviated as PC1VF3, PC2VF3, and PC4VF3, respectively, while the composite membrane without PC but soaked in fluorescein is denoted as PC0VF3.

[0058] Example 4:

[0059] This embodiment is the same as Embodiment 1, except that:

[0060] In step three, PC4V was soaked in a coumarin 6 fluorescein toluene solution, PC2V was soaked in a fluorescein isothiocyanate toluene solution, PC2V was soaked in a food coloring red 105 fluorescein toluene solution, and PC1V was soaked in a food coloring red 105 fluorescein toluene solution. After soaking for 16 hours, PC4VF4, PC2VF5, PC2VF6, and PC1VF6 were obtained, respectively.

[0061] Performance testing:

[0062] 1. The changes in fluorescence images of the PCVF obtained in Examples 1 to 3 under ultraviolet light irradiation with temperature are as follows: Figures 1 to 3 As shown, from Figures 1 to 3 As can be seen, the PCVF films immersed in Rhodamine B, fluorescein diacetate, and 5-carboxyfluorescein all gradually changed color within the temperature range of 90-100℃. Especially for PC1VF2-PC5VF2 immersed in fluorescein diacetate, the fluorescence color change was significant around 95℃. Therefore, 95℃, the midpoint of the 90-100℃ temperature range, was taken as the Tg for the glassy polymer. v value.

[0063] The reason why the color change occurs in the 90-100℃ temperature range is that: (1) The experimental environment is not a completely ideal environment. It is affected by external factors such as environment and weather, and there will be slight fluctuations between different measurement results. (2) The fluorescence color is gradual. The gradual change does not mean that the change is immediate and very obvious at a certain temperature. Rather, it means that the fluorescence color of the film gradually begins to change at 90-100℃. This color change is more obvious above 100℃, and it is obviously unchanged below 90℃. Different ester bond fluoresceins and different particle sizes of bottom photonic crystals will not affect the T of glass-like polymers. v .

[0064] exist Figure 1 In the study, PC4V (unimmersed fluorescein) did not fluoresce at different temperatures and its color remained consistently blue-violet. This blue-violet color corresponds to the background color under UV light, demonstrating that without fluorescein immersion, the T-phase of the glassy polymer cannot be detected by the change in fluorescence color under UV irradiation. v .

[0065] 2. The fluorescence image of the PCVF obtained in Example 4 under ultraviolet light irradiation changes with temperature as follows: Figure 4 As shown, the fluorescence color remains unchanged. This is because the structural formulas of coumarin 6, fluorescein isothiocyanate, and food coloring Red 105 are different from those of rhodamine B, diacetate fluorescein, and 5-carboxyfluorescein. The first three fluoresceins do not have ester bonds, and when the temperature is higher than T... v At these temperatures, they cannot undergo dynamic ester exchange with glassy polymers, therefore the fluorescence color remains unchanged. However, for the latter three fluorophores with ester bonds, when the temperature is above T... v At that time, they can undergo dynamic transesterification with glassy polymers, thus in T v The fluorescence color changes with temperature, therefore, based on this principle, it is possible to achieve T... v Visual detection. Theoretically, glassy polymers containing ester bonds and any fluorescein containing ester bonds can be visualized using the method described in this invention to detect T. v Visual detection.

[0066] 3. In-situ monitoring of PC0VF2 and PC4VF2 was performed using a spectrometer. In-situ fluorescence spectra were recorded at each temperature, and the change in the peak intensity of the spectra with temperature was observed. The fluorescence spectrum of PC0VF2 and the change in peak intensity with temperature are shown below. Figure 5 , Figure 6 As shown, the fluorescence intensity is relatively low and does not change significantly with temperature. The fluorescence spectrum of PC4VF2 and the variation of the peak intensity with temperature are shown below. Figure 7 , Figure 8 As shown, the fluorescence intensity is very high, which is due to the photonic crystal at the bottom layer of PC4VF2 enhancing the fluorescence. Furthermore, the fluorescence intensity changes at around 95°C, which further confirms the accuracy and effectiveness of the visualization detection method described in this invention.

Claims

1. A method for visualizing the topological freezing transition temperature of a glass-like polymer, comprising: preparing a photonic crystal film on a substrate; preparing an ester bond-containing glass-like polymer on the photonic crystal film to obtain a substrate coated with a composite film; immersing the substrate coated with the composite film in an ester bond-containing fluorescein to obtain a substrate covered with a fluorescein composite film; and determining the topological freezing transition temperature of the glass-like polymer according to the change in fluorescent color under ultraviolet irradiation. The topological freezing transition temperature of the glass-like polymer is determined by taking the temperature corresponding to the change in fluorescent color under ultraviolet irradiation as the topological freezing transition temperature of the glass-like polymer. The ester bond-containing fluorescein includes rhodamine B fluorescein, fluorescein diacetate, and 5-carboxyfluorescein. The photonic crystal coating is prepared using a 100-700 nm SiO2 nanosphere dispersion liquid as a raw material. The preparation steps of the photonic crystal coating include weighing SiO2 nanospheres and ethanol in a desired ratio, mixing and ultrasonic dispersing to obtain a SiO2 nanosphere dispersion liquid, and drying the substrate in the dispersion liquid to obtain a photonic crystal film. The mass of the SiO2 nanospheres to the volume of the ethanol is (0.01 g-0.1 g):(7-30 mL).

2. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 1, characterized in that: The glass-like polymer is prepared using dodecanedioic acid, bisphenol A diglycidyl ether, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene as raw materials.

3. A method for visualizing the topologically frozen transition temperature of a vitrimer according to claim 1 or 2, characterized in that: The preparation steps of the glass-like polymer on the photonic crystal film include placing dodecanedioic acid and bisphenol A diglycidyl ether in a muffle furnace at 155°C for 30 min, placing the catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene in the blank on the other end of the substrate, dropping the mixture of dodecanedioic acid and bisphenol A diglycidyl ether onto the catalyst, and tilting the blank on the other end of the substrate upward by 4° before returning it to the muffle furnace for continued 155°C incubation for 20 min.

4. The method for visualizing the topologically frozen transition temperature of a vitrimer according to claim 1 or 2, characterized in that: The blank on the other end of the substrate is then tilted downward by 11° before being returned to the muffle furnace for 155°C incubation for 20 min and then 140°C incubation for 8 h.

5. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 4, characterized in that: The substrate is then placed in a high-pressure reaction kettle and purged with nitrogen at 140°C and 2.6 MPa for 6 h to obtain a substrate coated with a composite film.

6. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 5, wherein: The molar ratio of dodecanedioic acid, bisphenol A diglycidyl ether, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene is (15-5):(15-5):

1.

7. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 1 or 2, characterized in that: The temperature of the high-pressure kettle can be 50-180°C, the pressure can be 0.5-4 MPa, and the incubation time can be 2-10 h.

8. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 7, characterized in that: ​ ​ ​ ​ ​ 9. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 8, characterized in that: ​ 10. The method of visualizing the topologically frozen transition temperature of a vitrimer according to claim 8, wherein: ​

Images