Method for rapidly testing phase diagram of polymer solution by fusing test data and theoretical model

Abstract

The invention belongs to the technical field of polymer physical characterization and basic research, and relates to a polymer solution phase diagram rapid test method fusing test data and a theoretical model. The method is further provided based on the polymer solution phase diagram universal mathematical model provided by the invention, and comprises the steps of polymer solution sample preparation, phase transition temperature measurement, experimental result fusion of a theoretical model and polymer solution phase diagram drawing. The method can greatly shorten the surveying and mapping period of the polymer solution phase diagram and realize rapid drawing of the high-quality polymer solution phase diagram.

Description

Technical Field

[0001] This invention belongs to the field of polymer physics characterization and basic research technology, specifically, it relates to a rapid testing method for polymer solution phase diagrams that integrates test data and theoretical models. Background Technology

[0002] Phase transitions in polymer solutions are closely related to industrial production. For example, in solution polymerization and solution processing, the practical application of adjusting solvent properties and temperature to control the structure or properties of polymers is very common. Drawing polymer solution phase diagrams is of great significance for guiding and solving practical application problems.

[0003] Currently, methods for plotting polymer solution phase diagrams using testing instruments include laser light scattering, optical microscopy, and thermal analysis. However, accurately plotting polymer solution phase diagrams using only experimental methods is quite difficult. Firstly, polymer solution phase diagrams exhibit a significant chain length dependence, requiring the polymer samples used for phase diagram plotting to have a narrow chain length distribution. Secondly, to construct a complete phase diagram, it is typically necessary to prepare a series of polymer solution samples with different volume fractions and measure the temperature dependence of each solution sequentially. The phase diagram construction process is extremely time-consuming and requires a large quantity of polymer samples with narrow molecular weight distributions. To date, high-quality phase diagrams of polymer solutions are still relatively rare in the literature. Summary of the Invention

[0004] To address the technical problems of existing polymer solution phase diagram testing techniques, such as the large quantity of narrow molecular weight distribution samples and the long time required for phase diagram mapping, the present invention aims to provide a universal theoretical model for polymer solution phase diagrams. Based on a small amount of accurate data measurement and supplemented by a data fitting algorithm of the theoretical model, efficient drawing of polymer solution phase diagrams can be achieved.

[0005] This invention provides a rapid testing method for polymer solution phase diagrams that integrates test data and theoretical models, comprising the following steps:

[0006] (1) Prepare multiple polymer solutions with different volume fractions, wherein at least two polymer solutions have a volume fraction higher than the critical volume fraction of the polymer, and at least two polymer solutions have a volume fraction lower than the critical volume fraction of the polymer;

[0007] (2) Obtain the phase transition temperature T of each polymer solution;

[0008] (3) Plot multiple numerical points with the phase transition temperature T and volume fraction φ of the polymer solution as the horizontal and vertical axes, and fit them using Formula 1 and Formula 2 to obtain the phase diagram of the polymer solution.

[0009] The fitting method includes: for numerical points where the volume fraction of the polymer solution is lower than the critical volume fraction, Formula 1 is used for fitting; for numerical points where the volume fraction of the polymer solution is higher than the critical volume fraction, Formula 2 is used for fitting.

[0010] Formula 1

[0011]

[0012] Formula 2

[0013]

[0014] In Formulas 1 and 2, α1, α2, β, and Δ are fixed parameters independent of the properties of the polymer system and the polymer chain length, N represents the degree of polymerization of the polymer chain, and T... C and φ c Φ0, Φ1, and Φ2 represent the critical temperature and critical volume fraction of the polymer solution, respectively; T represents the phase transition temperature of the polymer solution; φ represents the volume fraction of the polymer solution; and Φ0, Φ1, and Φ2 are unknown parameters that are not chain length dependent.

[0015] The beneficial effects of this invention are: based on the universal mathematical model of polymer solution phase diagram proposed in this invention, a rapid testing method for polymer solution phase diagrams that integrates test data and theoretical models is provided, which can significantly reduce the mapping cycle of polymer solution phase diagrams and realize the rapid drawing of high-quality polymer solution phase diagrams.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram illustrating the principle of a static small-angle laser light scattering instrument for measuring phase transition temperature in one embodiment of the present invention.

[0019] In the figure, 1. Laser source; 2. Laser beam expander; 3. First lens; 4. Constant temperature heater; 5. First slit; 6. Second lens; 7. Second slit; 8. Scattered light signal detector; 9. Sample cell; 10. Temperature control component; 11. Computer.

[0020] Figure 2 This invention provides a curve showing the variation of small-angle laser light scattering signal intensity of samples of different concentrations in a polymer solution system with system temperature, as one embodiment of the invention.

[0021] Figure 3This invention provides a comparison between a phase diagram curve obtained by fusing measured phase transition points of a polymer solution with theoretical models and literature data, as part of one embodiment of the invention.

[0022] Figure 4 This invention provides a curve showing the variation of small-angle laser light scattering signal intensity of samples of different concentrations in a polymer solution system with system temperature, as another embodiment of the invention.

[0023] Figure 5 This invention provides a comparison between the phase diagram curve obtained by fusing the measured phase transition point of a polymer solution with a theoretical model and literature data, which is another embodiment of the invention. Detailed Implementation

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] This invention provides a universal theoretical model for polymer solution phase diagrams, which integrates test data with the theoretical model to enable rapid plotting of polymer solution phase diagram curves.

[0026] Previous theoretical studies on polymer solution phase diagrams have shown that linear polymers exhibit the following universal scaling relationship near the critical volume fraction of the polymer solution:

[0027] |ψ-ψ c |=ψ0(εN b ) β

[0028] Among them, dimensionless factor φ is the volume fraction of the polymer solution. c R is the critical volume fraction of the polymer solution. C It is a parameter related to the critical volume fraction of a polymer solution.

[0029] Based on the above universal scaling relationship, this invention proposes a universal mathematical model applicable to a wide range of volume fractions in polymer solution phase diagrams, including the following equations:

[0030] Low concentration side:

[0031]

[0032] High concentration side:

[0033]

[0034] For a given polymer solution system, α1, α2, β, Δ, and N are all known constants. Among them, α1, α2, β, and Δ are fixed parameters, independent of the polymer system properties and polymer chain length; α1 = -0.22, α2 = 0.014, β = 0.326, and Δ = 0.501. N represents the degree of polymerization of the polymer chain. Φ0, Φ1, and Φ2 are unknown parameters, not dependent on chain length, but only related to the system properties; their specific values ​​can be obtained through fitting. T C and φ c These represent the critical temperature and critical volume fraction of the polymer solution, respectively. For a polymer solution system with a given chain length, theoretically, it is only necessary to prepare 2-3 sets of solutions with different volume fractions around the critical point, measure their respective phase transition temperatures, and substitute them into the above mathematical model to draw the phase diagram of the polymer solution.

[0035] Volume fraction, which is the ratio of the volume of polymer solute to the volume of its organic solvent (V solute / V solvent), can be calculated using the formula V = m / ρ (volume = mass / density).

[0036] This invention is proposed based on the above theoretical model.

[0037] This invention provides a rapid testing method for polymer solution phase diagrams that integrates test data and theoretical models, comprising the following steps:

[0038] (1) Prepare multiple polymer solutions with different volume fractions, wherein at least two polymer solutions have a volume fraction higher than the critical volume fraction of the polymer, and at least two polymer solutions have a volume fraction lower than the critical volume fraction of the polymer;

[0039] (2) Obtain the phase transition temperature T of each polymer solution;

[0040] (3) Plot multiple numerical points with the phase transition temperature T and volume fraction φ of the polymer solution as the horizontal and vertical axes, and fit them using Formula 1 and Formula 2 to obtain the phase diagram of the polymer solution.

[0041] The fitting method includes: for numerical points where the volume fraction of the polymer solution is lower than the critical volume fraction, Formula 1 is used for fitting; for numerical points where the volume fraction of the polymer solution is higher than the critical volume fraction, Formula 2 is used for fitting.

[0042] Formula 1

[0043]

[0044] Formula 2

[0045]

[0046] In Formulas 1 and 2, α1, α2, β, and Δ are fixed parameters independent of the properties of the polymer system and the polymer chain length, N represents the degree of polymerization of the polymer chain, and T... C and φ c Φ0, Φ1, and Φ2 represent the critical temperature and critical volume fraction of the polymer solution, respectively. T represents the phase transition temperature of the polymer solution, φ represents the volume fraction of the polymer solution, and Φ0, Φ1, and Φ2 are unknown parameters that are not dependent on chain length and are only related to the properties of the solution system.

[0047] According to the present invention, α1, α2, β, and Δ are fixed parameters that are independent of the properties of the polymer system and the polymer chain length, and can be determined as α1 = -0.22, α2 = 0.014, β = 0.326, and Δ = 0.501; Φ0, Φ1, and Φ2 can be obtained by fitting.

[0048] For polymer solution phase diagram construction, theoretically, more test points are more beneficial to the accuracy of the phase diagram. However, in practice, more test points obviously require more time. In addition, some polymer solutions with extreme concentrations are difficult to detect. Achieving relatively accurate phase diagram construction with the fewest possible test points would have significant practical value. The greatest advantage of the method in this invention is that it can achieve high-quality and accurate phase diagram construction using only 5-6 polymer solutions' test data.

[0049] According to a preferred embodiment of the present invention, the phase transition temperature is measured by a static small-angle laser light scattering instrument, which includes the following components arranged in sequence: a laser source, a laser beam expander, a first lens, a temperature-controlled sample cell, and a small-angle confocal diode detection system;

[0050] The small-angle confocal diode detection system includes a second lens with a first collimation system and a scattered light signal detector with a second collimation system.

[0051] The aforementioned equipment enables accurate measurement of phase transition temperatures.

[0052] According to the present invention, the phase diagram instrument can use any available laser light source to provide an incident signal for the system. Preferably, the laser light source is a helium-neon laser red light source with a wavelength of 632.8 nm and / or a green light source with a wavelength of 532 nm.

[0053] The temperature-controlled sample cell is set up for precise temperature control of the sample. According to a preferred embodiment, the temperature-controlled sample cell includes: a sample container, a constant temperature heater, and a temperature control component.

[0054] The sample container is used to hold the solution sample to be tested.

[0055] The constant temperature heater serves as a solid medium for sample temperature control and provides a laser detection pathway;

[0056] The temperature control component is used for precise temperature control of the thermostatic heater.

[0057] The sample container can be made of various materials suitable for optical detection of solutions, preferably an optical-grade quartz sealed bottle or a quartz capillary tube. There are no specific size limitations for the sample container; different sizes can be selected according to experimental requirements.

[0058] According to the present invention, the purpose of the constant temperature heater is to serve as a solid medium for sample temperature control and to provide a laser detection path.

[0059] From the perspective of providing a laser detection path, the constant-temperature heater is placed perpendicular to the optical path, with a through-hole parallel to the optical path and a non-through-hole in the vertical direction serving as a sample slot for placing the sample container. This invention does not have specific requirements for the specific structure of the sample slot; it can be customized according to the type and size of the sample container to ensure a tight fit between the sample container and the inner wall of the sample slot, resulting in good heat transfer. According to a specific embodiment of this invention, the sample slot is square, and the sample container is a quartz square bottle.

[0060] From the perspective of the solid medium used for sample temperature control, the thermostatic heater has several interconnected flow channels inside. The inlet and outlet of the flow channels are located on both sides of the thermostatic heater. The heat medium from the temperature control component enters the flow channel from the lower inlet and circulates back to the temperature control component from the upper outlet on the other side.

[0061] The thermostatic heater of the present invention can be single-channel or multi-channel.

[0062] According to one embodiment of the present invention, the isothermal heater is a multi-channel isothermal heater, and the phase imager can achieve high-throughput detection. Specifically, the multi-channel isothermal heater is fixed on a precision parallel moving stage controlled by a computer and driven by a stepper motor. The position of the multi-channel isothermal heater is controlled by the stepper motor. The positioning of the channel isothermal heaters allows the laser to be focused onto the center of the sample solution to be tested through a first lens. Through the repeated reciprocating motion of the multi-channel isothermal heaters in the horizontal direction, the laser sequentially scans the sample container in each channel, realizing automated acquisition of high-throughput signals. Therefore, the phase imager of the present invention preferably also includes a computer and a precision parallel moving stage.

[0063] The number of channels can be set as needed. Specifically, the multi-channel isothermal heater can have 3 to 30 channels for accommodating sample containers, preferably 5 to 8. It can simultaneously monitor the phase transition patterns of multiple polymer solution systems during temperature changes. The size of the multi-channel isothermal heater is determined based on the number of samples placed simultaneously.

[0064] According to the present invention, the material of the constant temperature heater is preferably a high thermal conductivity material, more preferably stainless steel, copper or aluminum, and even more preferably brass.

[0065] In addition to the aforementioned components, the temperature-controllable sample cell is also equipped with thermocouples, heat-resistant pipelines, and insulation sleeves. The constant-temperature heater is externally covered with fire-resistant and heat-insulating foam to ensure accurate temperature control. The heat transfer medium, heat-resistant pipelines, and insulation sleeves can be matched according to the actual experimental temperature.

[0066] In this invention, the thermocouple serves as a temperature probe. During use, its temperature sensing port is immersed in a sealed control group container containing only the pure solvent of the test system to monitor the internal temperature of the sample cell in real time. According to one specific embodiment, the thermocouple's temperature sensing port is immersed in the sealed control group container containing only the pure solvent of the test system, and the internal temperature of the sample cell is fed back to the data processing module via a data transmission line, recording the measured temperature inside the sample cell in real time.

[0067] According to one specific embodiment of the present invention, the temperature control component includes a heated and cooled oil bath-constant temperature circulator and a heat transfer medium. The heated and cooled oil bath-constant temperature circulator used in this invention has a wide heating range of -50 to 300°C, and its temperature control accuracy can be controlled within ±0.01°C. The heated and cooled oil bath-constant temperature circulator is commercially available, for example, from Ulbo.

[0068] The phase diagram instrument of the present invention adopts a 2f-2f confocal optical path. The second lens is set on the other side of the temperature-controllable sample cell (specifically a constant temperature heater) at an angle of 3 to 10° with the incident light direction, and the horizontal distance between the center of the lens and the center of the sample cell is fixed at twice the focal length. The scattered light signal detector is set behind the second lens at twice the focal length.

[0069] The scattered light signal detector described in this invention is preferably a photodiode.

[0070] According to a preferred embodiment of the present invention, the small-angle confocal diode detection system further includes a signal and data processing module. By recording the composition and temperature corresponding to the signal abrupt changes at phase transition points, the module performs software calculations to obtain the phase diagram of the polymer solution system, thus shortening the experimental time. Specifically, the software obtains the phase diagram by fitting a formula using the input parameters of temperature and composition.

[0071] To ensure the accuracy of the test, during installation, the centers of the heights of all components located on the laser optical path are kept at the same horizontal level.

[0072] According to the test method of the present invention, the sample preparation step (1) further includes maintaining the prepared polymer solution in a homogeneous state for subsequent detection. The sample preparation method varies slightly for different sample containers.

[0073] According to one embodiment of the present invention, using a quartz bottle as a sample container, the method for preparing the polymer solution includes the following steps:

[0074] Step (1): Calculate the mass of polymer sample and organic solvent required for the target volume fraction of the test system based on the volume of the quartz bottle.

[0075] Step (2): Based on the calculation results, accurately weigh the polymer sample and organic solvent, put them into a quartz bottle and seal it; a tetrafluoroethylene sealing ring can be used to seal the sample bottle cap in time to prevent the organic solvent from evaporating;

[0076] Step (3) involves heating in an oil bath and waiting for the sample to dissolve into a homogeneous system.

[0077] According to another embodiment of the present invention, a quartz capillary tube is used as the sample container, and the method for preparing the polymer solution includes the following steps:

[0078] Step (1): Accurately weigh the polymer sample and organic solvent, mix them, heat and dissolve them to prepare a high-concentration polymer solution mother liquor;

[0079] Step (2): Connect the inlet and outlet of the microfluidic chip using a pump tube with a suitable inner diameter, and connect the other end of the pump tube to the microsyringe and the quartz capillary port respectively.

[0080] Step (3): Set the flow rate of different injection ports of the microsyringe according to the experimental requirements;

[0081] Step (4): The polymer solution mother liquor, organic solvent and carrier solvent are injected into each microchannel inlet respectively. By controlling the flow rate and injection time, the polymer droplets that finally flow into the quartz capillary form the target concentration gradient.

[0082] Step (5) involves sealing the quartz capillary containing several polymer droplets to be tested and placing it in a suitable temperature environment to keep each droplet in a stable homogeneous state.

[0083] According to the present invention, the method for obtaining the phase transition temperature using the phase diagram instrument includes the following steps:

[0084] (1) Place one or more sample containers containing polymer solutions in the sample bath of a temperature-controlled sample cell;

[0085] (2) Start the device. The laser beam is focused to the center of the sample container by the laser beam expander and the first lens. After being scattered by the sample, the incident laser is focused again by the second lens through the first collimation system. Finally, it enters the scattered light signal detector through the second collimation system for data acquisition and processing.

[0086] (3) Control the temperature during the test process, collect the scattered light signal of each sample at each temperature, and obtain the phase transition temperature parameters of each sample.

[0087] More specifically, the method for obtaining the phase transition temperature includes the following steps:

[0088] Step (1): Preheat the temperature-controlled sample cell in advance so that the polymer solution can still maintain a stable homogeneous state after the sample container is placed in the sample cell.

[0089] Step (2): Place the sample container into the sample cell and adjust the sample cell height so that the laser is focused at the center height of the polymer solution in the sample cell.

[0090] Step (3): After standing for a period of time, once the temperature of the sample solution is consistent with the temperature in the tank measured by the thermocouple, start the programmed heating / cooling at a constant rate.

[0091] Step (4): Detect the scattered light signal and record the measured temperature of the sample cell. When the temperature of the polymer solution system reaches a certain temperature range, the scattered light signal will increase from zero to strong. When the scattered light signal reaches its maximum value, the experiment ends.

[0092] Step (5): Plot the temperature-dependent scattered light signal intensity change curve, and take the measured temperature corresponding to the moment when the scattered light signal intensity changes abruptly as the phase transition temperature of the polymer solution sample with this composition.

[0093] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0094] In the examples, the phase transition temperature of the polymer solution was measured using a static small-angle laser light scattering instrument, as follows: Figure 1 As shown. The static small-angle laser light scattering instrument includes: a laser source 1, a laser beam expander 2, a first lens 3, a temperature-controlled sample cell, a second lens 6 with a first slit 5, and a scattered light signal detector 8 with a second slit 7. Specifically,

[0095] On the optical platform, install the laser light source 1 (a 632.8nm helium-neon laser red light source or a 532nm green light source), the laser beam expander 2, and the first lens 3 in sequence to form the incident light portion of the light source. Adjust the height of each component so that their centers are at the same horizontal level.

[0096] A temperature-controlled sample cell is installed at the focal length of the incident light lens to focus the incident light at the center of the sample cell. The temperature-controlled sample cell includes: an optical-grade square quartz sealed bottle, a constant-temperature heater 4, a temperature control component 10 (including a heating / cooling oil bath-constant-temperature circulator and a heat transfer medium), a thermocouple, heat-resistant pipelines, and an insulation sleeve. The constant-temperature heater 4 is externally covered with fire-resistant and heat-insulating foam. The constant-temperature heater 4 is made of brass and is placed perpendicular to the light path. It has a through-hole parallel to the light path and a non-through-hole in the vertical direction for placing the sample container in a sample slot 9. The size of the sample slot 9 allows the sample container to fit tightly against the inner wall of the sample slot 9. The constant-temperature heater has several interconnected flow channels inside, with the inlet and outlet of each channel located on opposite sides of the heater. The heat transfer medium enters the flow channel from the lower inlet via the heating / cooling oil bath-constant-temperature circulator and pipelines, and circulates back to the heating / cooling oil bath-constant-temperature circulator from the upper outlet and pipelines on the other side. The heating and cooling oil bath-thermal circulator used was purchased from Ulbo, with a heating range of -50 to 300℃ and a temperature control accuracy of ±0.01℃.

[0097] On the optical platform, in the direction of the scattered light from the constant-temperature heater, a first slit 5, a second lens 6, a second slit 7, a scattered light signal detector 8, and a signal processing module are installed to form a 2f-2f confocal detection system and a signal collection system. The height of each component is adjusted so that their centers are at the same horizontal level. The second lens 6, which includes the first slit 5, forms an angle of 3–10° with the incident light.

[0098] Example 1

[0099] Polystyrene standard, weight-average molecular weight M w =8.90×10 4 g / mol, molecular weight distribution M w / M n =1.03; cyclohexane was selected as the solvent.

[0100] First, different masses of polystyrene were added to seven square quartz bottles (7.5mm × 10mm). Then, a certain amount of cyclohexane solution was added to each bottle. After precise weighing, the volume fractions of the seven polystyrene / cyclohexane solutions were calculated to be 4.20 × 10⁻⁶. -3 V / V, 1.00×10 -2 V / V, 2.35×10 -2 V / V, 8.80×10 -2 V / V, 1.26×10 -1 V / V, 1.87×10 -1 and 2.27×10 -1 V / V.

[0101] A 60℃ oil bath heating method is used to allow the polystyrene macromolecular chains to fully swell and dissolve in cyclohexane solvent, forming a stable homogeneous solution.

[0102] After the sample has completely dissolved, turn on the temperature control component 10 to stabilize the temperature of the constant temperature heater 4 at around 30°C.

[0103] Take a completely dissolved polymer solution sample from the oil bath, wipe the bottle clean, and place the quartz bottle into the sample tank 9. Then adjust the height of the thermostatic heater 4 so that the laser is focused at the center height of the solution in the thermostatic heater 4.

[0104] After standing for 20 minutes, the temperature control component 10, controlled by computer 11, begins to cool down at a constant rate of 0.1℃ / min.

[0105] The scattered light signal detector 8 and the temperature control component 10's measured temperature recording module are simultaneously activated. As the temperature drops to a certain range, the scattered signal gradually increases in strength, starting from nothing. Once the scattered light signal appears and reaches its maximum value, the scattered light signal detector 8 and the temperature control component 10's measured temperature recording module are deactivated, and the recorded data is saved.

[0106] Plot the temperature-dependent scattered light signal intensity variation curve of the sample to obtain the phase transition temperature parameter, and simultaneously record the composition parameters of the sample.

[0107] Repeat the above experimental procedure for collecting phase transition points using polystyrene / cyclohexane solution samples of different volume fractions until all seven volume fractions of polystyrene / cyclohexane solution samples have been measured. The measurement results are as follows: Figure 2 .

[0108] Substituting the volume fraction and phase transition temperature data of seven groups of polystyrene / cyclohexane solution samples into a mathematical theoretical model established based on the universal scaling relation of polymer solution phase diagrams, the weight-average molecular weight M was obtained through fitting. w =8.90×10 4 The two-phase coexistence curve of g / mol polystyrene in cyclohexane, as shown Figure 3 As shown. Figure 3 The solid red stars represent measured data, the black curve represents the polystyrene / cyclohexane solution phase diagram derived from the theoretical model and experimental data, and the blue boxes are from experimental literature data (ARShultz, PJFlory. Journal of the American Chemical Society 74, 4760 (1952)). It can be seen that the polymer solution phase diagram data drawn by fusing the test data of this invention with the theoretical model is consistent with the weight-average molecular weight M in the literature.w =8.90×10 4 The measured data for the g / mol polystyrene / cyclohexane solution system are very close, indicating that the rapid polymer solution phase diagram testing method proposed in this invention has high accuracy and reliability.

[0109] Example 2

[0110] Polymethyl methacrylate standard, weight average molecular weight M w =4.58×10 4 g / mol, molecular weight distribution M w / M n =1.04; 3-Octanone was selected as the solvent.

[0111] First, different masses of polymethyl methacrylate (PMMA) were added to five square quartz bottles measuring 7.5 mm × 10 mm. Then, a certain amount of 3-octanone solution was added sequentially. After precise weighing, the volume fractions of PMMA / 3-octanone solution in the five groups were calculated to be 2.52 × 10⁻⁶. -2 V / V, 4.20×10 -2 V / V, 5.56×10 -2 V / V, 1.26×10 -1 V / V and 2.46×10 -1 V / V.

[0112] The polymethyl methacrylate macromolecular chains were fully swollen and dissolved in 3-octanone solvent by heating in a 60℃ oil bath to form a stable homogeneous solution.

[0113] After the sample has completely dissolved, turn on the temperature control component 10 to stabilize the temperature of the constant temperature heater 4 at around 40°C.

[0114] Take a completely dissolved polymer solution sample from the oil bath, wipe the bottle clean, and place the quartz bottle into the sample tank 9. Then adjust the height of the thermostatic heater 4 so that the laser is focused at the center height of the solution in the thermostatic heater 4.

[0115] After standing for 20 minutes, the temperature control component 10, controlled by computer 11, begins to cool down at a constant rate of 0.1℃ / min.

[0116] The scattered light signal detector 8 and the temperature control component 10's measured temperature recording module are simultaneously activated. As the temperature drops to a certain range, the scattered signal gradually increases in strength, starting from nothing. Once the scattered light signal appears and reaches its maximum value, the scattered light signal detector 8 and the temperature control component 10's measured temperature recording module are deactivated, and the recorded data is saved.

[0117] Plot the temperature-dependent scattered light signal intensity variation curve of the sample to obtain the phase transition temperature parameter, and simultaneously record the composition parameters of the sample.

[0118] Repeat the above experimental procedure for acquiring phase transition points using polymethyl methacrylate / 3-octanone solution samples with different compositions until all five volume fractions of the polymethyl methacrylate / 3-octanone solution samples have been measured. The measurement results are as follows: Figure 4 .

[0119] The volume fractions and phase transition temperatures of five groups of polymethyl methacrylate / 3-octanone solution samples were substituted into a mathematical theoretical model based on the universal scaling relation of polymer solution phase diagrams to obtain the weight-average molecular weight M. w =4.58×10 4 The two-phase coexistence curve of g / mol polymethyl methacrylate in 3-octanone, as shown Figure 5 As shown. Figure 5 The solid red stars represent measured data, the black curve represents the polymethyl methacrylate / 3-octanone solution phase diagram derived from the theoretical model and experimental data, and the blue boxes are from experimental data in the literature (KQXia, XQAn, WGShen. The Journal of Chemical Physics 105, 6018 (1996)). It can be seen that the polymer solution phase diagram data drawn by fusing the test data of this invention with the theoretical model is consistent with the weight-average molecular weight M in the literature. w =4.86×10 4 The measured data for the g / mol polymethyl methacrylate / 3-octanone solution system are very close, indicating that the rapid phase diagram testing method for polymer solutions proposed in this invention has high accuracy and reliability, as well as good universality in the field of polymer solutions.

[0120] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0121] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A rapid testing method for polymer solution phase diagrams that integrates test data and theoretical models, comprising the following steps: (1) Prepare multiple polymer solutions with different volume fractions, wherein at least two polymer solutions have a volume fraction higher than the critical volume fraction of the polymer, and at least two polymer solutions have a volume fraction lower than the critical volume fraction of the polymer; (2) Obtain the phase transition temperature T of each polymer solution; (3) Plot multiple numerical points with the phase transition temperature T and volume fraction φ of the polymer solution as the horizontal and vertical axes, and fit them using Formula 1 and Formula 2 to obtain the phase diagram of the polymer solution. The fitting method includes: for numerical points where the volume fraction of the polymer solution is lower than the critical volume fraction, Formula 1 is used for fitting; for numerical points where the volume fraction of the polymer solution is higher than the critical volume fraction, Formula 2 is used for fitting. Formula 1 Formula 2 In Formulas 1 and 2, α1, α2, β, and Δ are fixed parameters independent of the properties of the polymer system and the polymer chain length, N represents the degree of polymerization of the polymer chain, and T... C and φ c Φ0, Φ1, and Φ2 represent the critical temperature and critical volume fraction of the polymer solution, respectively; T represents the phase transition temperature of the polymer solution; φ represents the volume fraction of the polymer solution; and Φ0, Φ1, and Φ2 are unknown parameters that are not chain length dependent.

2. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 1, wherein, α1 = -0.22, α2 = 0.014, β = 0.326, Δ = 0.501; Φ0, Φ1 and Φ2 were obtained by fitting.

3. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 1, wherein, The number of the plurality of polymer solutions is not less than 5, preferably 5 to 6.

4. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 1, wherein, The phase transition temperature is measured by a static small-angle laser light scattering instrument, which includes the following components arranged in sequence: a laser source, a laser beam expander, a first lens, a temperature-controlled sample cell, and a small-angle confocal diode detection system. The small-angle confocal diode detection system includes a second lens with a first collimation system and a scattered light signal detector with a second collimation system.

5. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 4, wherein, The laser source is a helium-neon laser red light source with a wavelength of 632.8 nm and / or a green light source with a wavelength of 532 nm, used to provide an incident signal for the system.

6. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 4, wherein, The temperature-controllable sample cell includes: a sample container, a constant temperature heater, and a temperature control component; The sample container is used to hold the solution sample to be tested; the sample container is preferably an optical-grade quartz sealed bottle or a quartz capillary tube; The constant temperature heater serves as a solid medium for sample temperature control and provides a laser detection pathway; The temperature control component is used for precise temperature control of the thermostatic heater.

7. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 6, wherein, The constant temperature heater is placed perpendicular to the light path, and has a through light-transmitting hole in the direction parallel to the light path. The non-through hole in the vertical direction is set as a sample slot for placing the sample container. The size of the sample slot is such that the sample container fits tightly against the inner wall of the sample slot. The thermostatic heater has several interconnected flow channels inside. The inlet and outlet of the flow channels are located on both sides of the thermostatic heater. The heat medium from the temperature control component enters the flow channel from the lower inlet and circulates back to the temperature control component from the upper outlet on the other side.

8. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 7, wherein, The constant temperature heater is a multi-channel constant temperature heater; The multi-channel thermostatic heater is fixed on a precision parallel moving stage controlled by a computer and driven by a stepper motor. The position of the multi-channel thermostatic heater is controlled by the stepper motor. The position of the channel thermostatic heater allows the laser to be focused onto the center of the sample solution to be tested through the first lens. Through the repeated back-and-forth movement of the multi-channel thermostatic heater in the horizontal direction, the laser scans the sample container in each channel in sequence, realizing the automated acquisition of high-throughput signals. Preferably, the multi-channel thermostatic heater has 3 to 30 channels for accommodating sample containers, and more preferably 5 to 8 channels.

9. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 6, wherein, The constant temperature heater is made of a high thermal conductivity material, preferably stainless steel, copper or aluminum, and more preferably brass; The temperature-controllable sample cell is also equipped with thermocouples, heat-resistant pipelines and heat-insulating sleeves, and the constant temperature heater is covered with fireproof and heat-insulating foam cotton. When in use, the temperature sensing port of the thermocouple is immersed in a sealed container of a control group containing only the pure solvent of the test system, for real-time monitoring of the internal temperature of the sample cell.

10. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 6, wherein, The temperature control component includes a heating and cooling oil bath-constant temperature circulator and a heat medium; the heating range of the heating and cooling oil bath-constant temperature circulator is -50 to 300℃, and the temperature control accuracy is ±0.01℃.

11. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to claim 4, wherein, The second lens is positioned on the other side of the temperature-controlled sample cell at an angle of 3 to 10° to the direction of incident light, with the horizontal distance between the center of the lens and the center of the sample cell fixed at twice the focal length; the scattered light signal detector is positioned behind the second lens at twice the focal length.

12. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 4, wherein, The small-angle confocal diode detection system also includes a signal and data processing module. By recording the composition and temperature corresponding to the signal abrupt change at the phase transition point, the system calculates and processes the data using software to obtain the phase diagram of the polymer solution system.

13. The rapid testing method for polymer solution phase diagrams based on fusion test data and theoretical models according to claim 4, wherein, The centers of the heights of all components on the laser optical path are located at the same horizontal level.

14. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to claim 1, wherein, The sample preparation step (1) also includes keeping the prepared polymer solution in a homogeneous state.

15. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to claim 14, wherein, Using a quartz bottle as the sample container, the method for preparing the polymer solution includes the following steps: Step (1): Calculate the mass of polymer sample and organic solvent required for the target volume fraction of the test system based on the volume of the quartz bottle. Step (2): Based on the calculation results, accurately weigh the polymer sample and organic solvent, put them into a quartz bottle and seal it; Step (3) involves heating in an oil bath and waiting for the sample to dissolve into a homogeneous system.

16. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to claim 14, wherein, Using a quartz capillary tube as the sample container, the method for preparing the polymer solution includes the following steps: Step (1): Accurately weigh the polymer sample and organic solvent, mix them, heat and dissolve them to prepare a high-concentration polymer solution mother liquor; Step (2): Connect the inlet and outlet of the microfluidic chip using a pump tube with a suitable inner diameter, and connect the other end of the pump tube to the microsyringe and the quartz capillary port respectively. Step (3): Set the flow rate of different injection ports of the microsyringe according to the experimental requirements; Step (4): The polymer solution mother liquor, organic solvent and carrier solvent are injected into each microchannel inlet respectively. By controlling the flow rate and injection time, the polymer droplets that finally flow into the quartz capillary form the target concentration gradient. Step (5) involves sealing the quartz capillary containing several polymer droplets to be tested and placing it in a suitable temperature environment to keep each droplet in a stable homogeneous state.

17. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to any one of claims 4-13, wherein, The method for obtaining the phase transition temperature includes the following steps: (1) Place one or more sample containers containing polymer solutions in the sample bath of a temperature-controlled sample cell; (2) Start the device. The laser beam is focused to the center of the sample container by the laser beam expander and the first lens. After being scattered by the sample, the incident laser is focused again by the second lens through the first collimation system. Finally, it enters the scattered light signal detector through the second collimation system for data acquisition and processing. (3) Control the temperature during the test process, collect the scattered light signal of each sample at each temperature, and obtain the phase transition temperature parameters of each sample.

18. The rapid testing method for polymer solution phase diagrams based on the fusion of test data and theoretical models according to claim 17, wherein, The method for obtaining the phase transition temperature includes the following steps: Step (1): Preheat the temperature-controlled sample cell in advance so that the polymer solution can still maintain a stable homogeneous state after the sample container is placed in the sample cell. Step (2): Place the sample container into the sample cell and adjust the sample cell height so that the laser is focused at the center height of the polymer solution in the sample cell. Step (3): After standing for a period of time, once the temperature of the sample solution is consistent with the temperature in the tank measured by the thermocouple, start the programmed heating / cooling at a constant rate. Step (4): Detect the scattered light signal and record the measured temperature of the sample cell. When the temperature of the polymer solution system reaches a certain temperature range, the scattered light signal will increase from zero to strong. When the scattered light signal reaches its maximum value, the experiment ends. Step (5): Plot the temperature-dependent scattered light signal intensity change curve, and take the measured temperature corresponding to the moment when the scattered light signal intensity changes abruptly as the phase transition temperature of the polymer solution sample with this composition.

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