WO2023184998A1 - Method for determining fitted ternary phase diagram of microemulsion by means of fluorescence method - Google Patents

Abstract

A method for determining a fitted ternary phase diagram of a microemulsion by means of a fluorescence method. A ternary phase diagram of a microemulsion is fitted by preparing an up-conversion microemulsion, measuring up-conversion intensity and phosphorescence intensity, and drawing broken lines of a ternary phase diagram. In the method, a luminescence agent and a photosensitizer are used as detection agents for a microemulsion, and fluorescence signals of the microemulsion are detected by utilizing differences in the photophysical properties of the microemulsion, such that the components of the microemulsion are indirectly reflected, and a ternary phase diagram of the microemulsion is drawn; and the method has high determination sensitivity, high selectivity, a low reagent amount and a fast analysis speed, and is simple and convenient to apply.

Description

Fluorescence method for measuring microemulsions and fitting ternary phase diagram Technical field

The invention belongs to the technical field of phase change materials, and specifically relates to a fluorescence method for measuring microemulsion and fitting a ternary phase diagram.

Background technique

The concept of microemulsion was proposed by British chemist JH Schulman in 1959. Microemulsion is generally colorless, transparent (or translucent) composed of surfactants, co-surfactants, oil and water in appropriate proportions. ), low viscosity thermodynamic system. Due to its stable thermodynamic system with ultra-low interfacial tension (10 ^-6 -10 ^-7 N·m) and high solubilization capacity (the solubilization amount can reach 60%-70%), Shinoda and Friberg believe that microemulsion It is a swollen micelle. When the concentration of the surfactant aqueous solution is greater than the critical micelle concentration value, micelles will be formed. At this time, a certain amount of oil (can also be added together with a co-surfactant) will be added, and the oil will be Solubilization, as the amount of oil entering the micelles increases, the micelles swell the microemulsion, so the microemulsion is called micellar emulsion. Since solubilization occurs spontaneously, microemulsification also occurs automatically. The formation mechanism of microemulsion mainly includes double film theory, geometric arrangement model, and R ratio theory.

According to Winsor's classification of microemulsions, he named four types of phase equilibrium:

Type 1: A surfactant with good water solubility forms an O/W (oil-in-water) microemulsion. The surfactant-rich water phase and the oil phase coexist. The surfactant in the oil phase is in the form of a monomer with a lower concentration. exist;

Type 2: Surfactants mainly exist in the oil phase to form W/O (water-in-oil) microemulsions. A surfactant-rich oil phase coexists with a surfactant-poor aqueous phase;

Type 3: It is a three-phase system, in which the surfactant-rich middle phase coexists with the water and oil phases containing less surfactant;

Type 4: Single-phase (isotropic) micellar solution, formed when sufficient amphiphilic molecules are added.

Microemulsion itself has multiple functions such as wetting, foaming, solubilizing, emulsifying, and washing. Different types of microemulsions have different application fields. For example, in tertiary oil recovery, the microemulsion method is often used, that is, according to the appropriate formula, surfactants and some polymer compounds are added to the injected water to displace oil. This uses the surfactant aqueous solution in the oil well to form a bi-continuous microemulsion with the crude oil, which greatly reduces the tension between the two phases, lowers the viscosity of the crude oil, increases fluidity, and achieves the purpose of deepening mining. For another example, water-in-oil microemulsions can protect aqueous drugs, sustain release and improve the biological activity of drugs; oil-in-water microemulsions can increase the biological activity of drugs and the solubility of lipophilic drugs and enable sustained release.

Therefore, corresponding types of microemulsions are needed to meet different needs, but the type of microemulsion cannot be distinguished with the naked eye. Therefore, efficient and accurate microemulsion detection methods are essential in the development of microemulsions.

The most effective tool for studying the number, composition and boundaries of phase regions that coexist in equilibrium is the phase diagram. The phase behavior of the three components under isothermal and pressure conditions in the laboratory can be represented by a plane triangle and becomes a ternary phase diagram. Microemulsions can be studied using the ternary phase diagram method. The phase diagram is simple to draw. The microemulsion system can be determined based on the phase diagram, which intuitively reflects the changes in the microemulsion system.

In the existing technology, there are many methods for characterizing the structure of microemulsions. The dye method, phase dilution method, conductivity method, viscosity method, etc. are all simple and effective testing methods. With the continuous development of science and technology and the continuous improvement of experimental technology, more and more precision instruments such as light scattering instruments, Ft-IR, and NMR are used in the structural characterization of microemulsions. Among them, the nuclear magnetic method is relatively complex and difficult to popularize, and the phase diagram measured by light scattering has limitations.

Contents of the invention

The present invention aims to provide a method for measuring microemulsions by fluorescence method to fit a ternary phase diagram. A luminescent agent is introduced as a detection agent of the microemulsion, and the difference in photophysical properties of the microemulsion is used to detect its fluorescence signal, thereby indirectly It reflects the components of microemulsion and draws the three-phase diagram of microemulsion. It has high measurement sensitivity, high selectivity, less reagent consumption, fast analysis speed and easy application.

According to the technical solution of the present invention, the method for determining the microemulsion to fit the ternary phase diagram using the fluorescence method includes the following steps:

S1: Prepare a microemulsion. The microemulsion contains three components, namely surfactant, oil phase and water. A luminescent agent and a photosensitizer are dissolved in the oil phase, as follows:

a. Provide a mixture of the first component and the second component with different mass ratios in the microemulsion;

b. Add third components of different masses to the mixed solution to obtain multiple sets of microemulsions;

S2: Measure the upconversion intensity and phosphorescence intensity of the microemulsion respectively;

S3: Using the mass fraction of the third component in the microemulsion as the abscissa and the ratio of the upconversion intensity to the phosphorescence intensity as the ordinate, draw a three-phase diagram polyline for the same mixed solution;

S4: Taking the first component, the second component and the third component with a mass fraction of 100% as the vertices of the ternary phase diagram, and using the mass fraction as the coordinate, mark the break points of the three-phase diagram polyline of different mixed liquids. and connected together to obtain the ternary phase diagram of the microemulsion.

It should be noted that the microemulsion prepared above contains a luminescent agent and a photosensitizer, which can be called an up-conversion microemulsion. Since the mass proportion of the luminescent agent and photosensitizer is very small, it does not affect the drawing and rendering of the three-phase diagram polyline. Fitting of the ternary phase diagram of microemulsions.

The fluorescence method of the present invention is based on the difference in luminescent intensity of luminescent agents in different types of microemulsions. Photon upconversion luminescence refers to the property of certain materials that can convert low-energy light, usually in the infrared wavelength range, directly into higher-energy visible light or ultraviolet light. On this basis, the sample absorbs energy under irradiation, so that two atoms or molecules in the triplet state interact (usually upon collision) to produce one atom or molecule in the excited singlet state and another atom in the singlet ground state. or molecules. This will be accompanied by the appearance of delayed fluorescence. This process is called triplet-triplet annihilation upconversion (TTA-UC).

Further, the first component is surfactant, the second component is oil phase, and the third component is water.

Further, the surfactant includes a main surfactant and a co-surfactant, and the mass fraction of the co-surfactant does not exceed 10%.

In one embodiment of the present invention, the main surfactant is Tween-20, the co-surfactant is isobutanol, and the mass proportion of isobutanol in the surfactant is 2%.

Further, the step a also includes the operation of introducing a protective atmosphere to remove air from the mixed solution; the step b is performed under a protective atmosphere.

Further, the protective atmosphere is nitrogen, helium or argon.

Further, the oil in the oil phase is toluene, the luminescent agent is 9,10-diphenylanthracene (DPA) or perylene, and the photosensitizer is platinum octaethyl porphyrin (PtOEP) or racemic -Tetraphenyltetraphenylplatinum(II).

Specifically, when the luminescent agent is DPA, the photosensitizer is PtOEP; when the luminescent agent is perylene, the photosensitizer is racemic-tetraphenyltetraphenylplatinum(II).

Further, the concentration ratio of the luminescent agent and the photosensitizer in the oil phase is 30-100:1.

Further, the concentration of the luminescent agent in the oil phase is 1.5x10 ^-3 -5x10 ^-3 mol/L, and the concentration of the photosensitizer is 5x10 ^-5 mol/L.

Further, in the step S4, the up-conversion spectrum of the microemulsion is measured, the up-conversion peak area is used as the up-conversion intensity, and the integrated area of the phosphorescent peak is used as the phosphorescence intensity.

The second aspect of the present invention provides the application of fluorescence method in determining the fitting of ternary phase diagram of microemulsion.

The technical solution of the present invention has the following advantages compared with the prior art: the present invention introduces a luminescent agent and a photosensitizer as a detection agent of microemulsion, and uses the difference in photophysical properties of the microemulsion to detect its fluorescence signal, thereby indirectly reflecting Microemulsion components, draw the microemulsion three-phase diagram, have high measurement sensitivity, high selectivity, less reagent consumption, fast analysis speed, and easy application.

Description of drawings

Figure 1 shows the quenching spectra of DPA/PdOEP in W/O type (a), B.C. type (b) and O/W type (c) microemulsions.

Figure 2 shows the Stern-Volmer equation of DPA/PtOEP in three different structures of microemulsions.

Figure 3 shows the relationship between UC/PL and water content when the oil-to-surface ratio is 1:3.

Figure 4 shows the relationship between UC/PL and water content when the oil-to-surface ratio is 1:4.

Figure 5 shows the relationship between UC/PL and water content when the oil-to-surface ratio is 1:6.

Figure 6 shows the relationship between UC/PL and water content when the oil-to-surface ratio is 1:9.

Figure 7 is a ternary phase diagram fitted to microemulsion measured by fluorescence method.

Figure 8(a) is the relationship between conductivity and water content in oil surface microemulsion systems with different mass ratios; Figure 8(b) is the relationship between dy/dx and water content in oil surface microemulsions systems with different mass ratios. relationship diagram between.

Figure 9 is a ternary phase diagram fitted to microemulsion measured by conductivity method.

Figure 10 is a comparison diagram of the ternary phase diagram fitted to the microemulsion measured by the fluorescence method and the conductivity method.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples, so that those skilled in the art can better understand and implement the present invention, but the examples are not intended to limit the present invention.

The reagents and instruments used in the following examples are as follows:

Reagent or instrument name	level	manufacturer
Twain-20(T-20)	Analytically pure	Sinopharm Chemical Reagent Co., Ltd.
Toluene	Analytically pure	Sinopharm Chemical Reagent Co., Ltd.
Isobutanol	Analytically pure	Sinopharm Chemical Reagent Co., Ltd.
9,10-Diphenylanthracene (DPA)	Analytically pure	Bailingwei Technology Co., Ltd.
Platinum octaethylporphyrin (PtOEP)	Analytically pure	Bailingwei Technology Co., Ltd.
Steady-state/transient fluorescence spectrometer	FLS920	Edinburgh Instruments UK
UV-visible absorption spectrometer	UV-2600	Shimadzu Corporation
conductivity meter	DDS-307	Shanghai Leici Company
fiber optic spectrometer	PG-2000	Shanghai Fuxiang Optical Co., Ltd.
Electric constant temperature blast drying oven	DHG-9146A	Shanghai Xingmao Instrument Co., Ltd.

In addition, the UV-visible absorption spectrum was measured with a UV-2000 UV-visible spectrophotometer; the fluorescence spectrum was measured with an Edinburgh FLS-920 fluorescence spectrophotometer; transient lifetime: the fluorescence lifetime of the luminescent agent is measured at room temperature by The phosphorescence lifetime is measured with a nanosecond lamp (NKT), while the phosphorescence lifetime is measured with a microsecond xenon lamp in a nitrogen atmosphere.

Example 1 Feasibility Verification of Microemulsion Determination by Fluorescence Method

Taking the luminescent agent as DPA and the photosensitizer as PtOEP as an example, it is expressed according to the Stern-volmer equation F0/F=kq·τ0[DPA]+1, where F0 and F respectively represent the phosphorescence of the photosensitizer with or without the luminescent agent DPA. Integrated spectral intensity, τ0 is the phosphorescence lifetime of the photosensitizer itself, kq represents the two-component quenching constant, which can also be considered as the efficiency of energy transfer between the luminescent agent and the photosensitizer (ΦTTT). According to the above, the effect of DPA on PtOEP was measured in three microemulsions with different structures: oil-in-water type (O/W, 1a), bicontinuous phase type (BC, 1b) and water-in-oil type (W/O, 1c). The quenching process is shown in Figures 1 and 2. Among them, the concentration of DPA at the peak on the right side of Figure 1a is 0, 5 μM, 10 μM, 50 μM, 250 μM and 100 μM from top to bottom; the concentration of DPA at the peak on the right side of Figure 1b is 0, 5 μM, 10 μM, 50μM, 100μM and 250μM; the concentration of DPA at the peak on the left side of Figure 1c is 250μM, 100μM, 50μM, 26.7μM, 10μM, 5μM, 1.67μM and 0 from top to bottom, and the concentration of DPA at the peak on the right side from top to bottom The order is 1.67μM, 5μM, 0, 10μM, 26.7μM, 50μM, 100μM and 250μM; the slope of the straight line in Figure 2 is the K _sv value.

As shown in Figure 2, the K _SV of W/O type microemulsion, BC type microemulsion, and O/W type microemulsion are 1.529mM ^-1 , 0.357mM ^-1 and 0.055mM ^-1 respectively. According to the energy transfer efficiency k _TTET =K _sv /τ0, the k _TTET of W/O type microemulsion, BC type microemulsion, and O/W type microemulsion are calculated to be 1.729M ^-1 ·s ^-1 and 0.236M respectively. ^-1 ·s ^-1 , 0.033M ^-1 ·s ^-1 , in different types of microemulsion media, the collision process of the two components is quenched differently, and Ksv(O/W) is much smaller than Ksv(W/O ), and k _TTET (O/W) is much smaller than k _TTET (W/O). Moreover, as shown in Figure 2, no up-conversion phenomenon occurs in the O/W microemulsion. Combining the photophysical parameters of the luminescent agent DPA molecules and the photosensitizer PtOEP molecules in different types of microemulsions (as shown in Tables 1 and 2), these all indicate that the molecules exist in different states in microemulsions with different structures. Due to the realization TTA up-conversion luminescence requires a collision process between molecules. Therefore, in the W/O microemulsion, the two molecules of the luminescent agent and the photosensitizer collide, while in the O/W microemulsion, the luminescent agent and the photosensitizer collide. The two molecular formulas of the agent are independent of each other, and there is no energy transfer process. Therefore, luminescent agents and photosensitizers can be introduced as detection agents of microemulsions to detect their fluorescence signals, thereby indirectly reflecting the components of microemulsions.

Table 1 Photophysical parameters of DPA in microemulsions with different structures

Table 2 Photophysical parameters of PtOEP in microemulsions with different structures

Example 2 Fluorescence method for measuring microemulsion and fitting ternary phase diagram

1. Configure an upconversion toluene solution (oil phase) containing PtOEP and DPA, in which the concentration of PtOEP is 5x10 ^-5 mol/L and the concentration of DPA is 2.5x10 ^-3 mol/L (the concentration ratio of DPA and PtOEP is 50 : 1), mix evenly, and then vent nitrogen for 30 minutes.

2. According to the oil phase and surfactant (including 98wt% of the main surfactant is Tween-20 and 2wt% of the co-surfactant is isobutanol) Tween-20 mass ratio (oil to surface ratio) is 1: 3. Divide 1:4, 1:6 and 1:9 into four groups and mix them separately, and continue to pass nitrogen gas to remove oxygen for 30 minutes to obtain four groups of mixed liquids.

3. Divide each mixed solution into multiple parts, add water of different qualities to each part, and stir at 40r/min to form a transparent microemulsion (upconversion microemulsion). Taking the oil to surface ratio of 1:3 as an example, the mass ratios of oil phase, surfactant and water in multiple microemulsions are 1:3:1, 1:3:2, 1:3:3 and so on to 1: 3:9 (or similar mass ratio), the other oil meter ratios are the same, see Table 3-6 for details.

4. Measure the upconversion spectrum of the microemulsion obtained in step 3, use the area of the above conversion peak as the upconversion intensity (UC), and use the integrated area of the phosphorescence peak as the phosphorescence intensity (PL) to obtain Table 3-6.

Table 3 Up-conversion data of microemulsions under different water ratios when the oil-to-surface ratio is 1:3

Oil to water ratio 1:3	UC/(a.u.)	PL/(a.u.)	UC/PL	Moisture content/(%)
1:3:1	2.67x10 6	373014	7.16	20
1:3:2	1.14x10 6	363637	3.13	33.3
1:3:3	435024	1.58x10 6	0.27	42.8
1:3:3.5	109885	1.51x10 6	0.073	46.7
1:3:4	31646	1.24x10 6	0.026	50

1:3:4.5	22515	1.55x10 6	0.014	52.9
1:3:5	12495	1.30x10 6	0.009	55.6
1:3:6	7183	1.44x10 6	0.005	60
1:3:7	642	1.40x10 6	≈0	63.6
1:3:8	809	1.48x10 6	≈0	66.7
1:3:9	941	1.52x10 6	≈0	69.2

Table 4 Up-conversion data of microemulsions under different water ratios when the oil-to-surface ratio is 1:4

Oil to water ratio 1:4	UC/(a.u.)	PL/(a.u.)	UC/PL	Moisture content/(%)
1:4:2	2.41x10 6	516396	4.7	28.6
1:4:3	1.58x10 6	541809	2.92	37.5
1:4:4	852093	1.28x10 6	0.67	44.4
1:4:4.5	156094	897375	0.17	47.4
1:4:5	128895	1.03x10 6	0.12	50
1:4:6	87474	1.30x10 6	0.067	54.5
1:4:7	23983	1.55x10 6	0.014	58.3
1:6:8	354	993265	≈0	61.5
1:6:9	511	1.36x10 6	≈0	64.3
1:6:10	325	1.15x10 6	≈0	66.7
1:6:11	470	1.27x10 6	≈0	68.7

Table 5 Up-conversion data of microemulsions under different water ratios when the oil-to-surface ratio is 1:6

Oil to water ratio 1:6	UC/(a.u.)	PL/(a.u.)	UC/PL	Moisture content/(%)
1:6:3	1.08x10 6	1.66x10 7	0.6837	30
1:6:4	813053	2.00x10 6	0.4057	36.4
1:6:5	371561	2.02x10 6	0.1836	41.7

1:6:7	62062	724238	0.087	50
1:6:8.5	36701	507192	0.0723	54.8
1:6:10	24314	395178	0.0615	58.8
1:6:11.5	25885	492924	0.0525	62.1
1:6:12	54222	1.10x10 6	0.049	63.1
1:6:13	53083	1.14x10 6	0.047	65
1:6:14	59589	1.22x10 6	0.048	66.7
1:6:15	56968	1.14x10 6	0.049	68.2

Table 6 Up-conversion data of microemulsions under different water ratios when the oil-to-surface ratio is 1:9

Oil to water ratio 1:9	UC/(a.u.)	PL/(a.u.)	UC/PL	Moisture content/(%)
1:9:2	798691	1.56x10 7	0.51	16.6
1:9:3	540686	1.44x10 6	0.38	23.1
1:9:4	326385	1.25x10 6	0.26	28.6
1:9:5	180272	1.01x10 6	0.18	16.6
1:9:7	119922	943648	0.12	23.1
1:9:9	96971	1.22x10 6	0.08	28.6
1:9:11	26775	1.42x10 6	0.018	16.6
1:9:12	750	1.60x10 6	≈0	55
1:9:13	823	1.52x10 6	≈0	56.5
1:9:14	714	1.46x10 6	≈0	58.3
1:9:15	910	1.59x10 6	≈0	60

5. Since the concentration of luminescent agent and photosensitizer will change as the water content changes, the single UC and PL values will be affected by the concentration. The ratio of the two can offset the concentration effect. Therefore, according to the data in Table 3-6, with water content as the abscissa and UC/PL as the ordinate, the relationship between UC/PL and water content (three-phase diagram broken line) at different oil-to-surface ratios is obtained, as shown in Figure 3 -6 shown. According to Example 1, it can be seen that the breaking points in Figures 3-6 are the dividing points of different types of microemulsions.

6. Taking the oil phase, surfactant and water with a mass fraction of 1.0 (100%) as the vertices of the ternary phase diagram respectively, and using the mass fraction as the coordinate, mark the break points in Figure 3-6 and connect them together. The ternary phase diagram of the microemulsion was obtained, as shown in Figure 7.

Example 3 Conductivity method to measure microemulsion and fit ternary phase diagram

Because the electrical conductivity of the dispersed phase (droplets) and the electrical conductivity of the continuous phase in the microemulsion interact to determine the electrical conductivity of the entire microemulsion system. Conductivity increases with increasing water content. When the water content is small, the increase in water content has less effect on the conductivity. But when the water content exceeds the permeability threshold, the conductivity is proportional to the water content, which represents the beginning of the phase transition process. This is because when the water content exceeds the permeability threshold, the water droplets in the W/O microemulsion attract each other, causing viscosity. collision. Under the action of collision and aggregation, the volume of water droplets continues to increase, forming small channels. These channels can allow electrons to pass smoothly and increase the conductivity of the system. As the water content further increases, its conductivity begins to deviate from a straight line, which is mainly caused by the interconnection between narrow water channels. At this time, the entire system is in a state where water and oil coexist continuously, which is the bicontinuous phase (B.C.). Finally, due to excessive dilution, the conductivity will decrease with the water content, which indicates the formation of O/W microemulsion.

Specific steps are as follows:

1. According to the method of steps 2 and 3 in Example 2, use toluene as the oil phase to prepare a microemulsion.

2. Determine the mass ratio of oil and surfactant (same as Example 2), mix the binary components evenly, keep it in a water tank at a constant temperature of 25°C, and then gradually add water dropwise, adding 5% of the total mass each time, and measure Conductivity and record the data, as shown in Table 7-11.

Table 7 Conductivity data of microemulsions under different water ratios when the oil to surface ratio is 1:3

Table 8 Conductivity data of microemulsions under different water ratios when the oil to surface ratio is 1:4

Table 9 Conductivity data of microemulsions under different water ratios when the oil-to-surface ratio is 1:6

Table 10 Conductivity data of microemulsions under different water ratios when oil to surface ratio is 1:9

Table 11 Conductivity data of microemulsions under different water ratios when oil to surface ratio is 1:20

3. Study the structural properties of the microemulsion through conductivity testing and analyze the relationship between conductivity and water content. According to the penetration conductance model, the three structures of the microemulsion can be judged by the extreme point w ₁ and the maximum value w ₂ (W/O, BC and O/W). As shown in Figure 8(a), the conductivity curve is S-shaped and is fitted according to equation (1):

Z＝(XX _C )/W

y＝y ₀ +Ae ^{(-e(-z)-z)+1)} (1)

Among them, X is the water content, y is the electrical conductivity, and the others are fitting parameters, as shown in Table 12.

Table 12 Fitting parameter table of oil surface microemulsion systems with different mass ratios according to equation (1)

S/O	y 0	xc	w	A	R
1:3	12.37	60.98	20.09	193.24	0.985
1:4	15.55	61.93	19.42	200.10	0.970
1:6	9.47	63.62	26.47	256.35	0.993
1:9	8.98	52.64	22.36	218.73	0.995
1:20	1.03	50.44	21.89	208.32	0.996

When x=x _c , the y function reaches the maximum value, which is the distinguishing point between O/W microemulsion and BC type microemulsion. Secondly, the data is differentially processed, as shown in Figure 8(b), and the other inflection point obtained is the differentiation point between W/O type microemulsion and BC type microemulsion.

4. According to the calculation results of the conductivity method, the water content limit points between oil in water and the bicontinuous phase are obtained, as well as the water content limit points between water in oil and the bicontinuous phase. Then T- is calculated based on the oil to surface ratio. The proportions of each component of the 20/toluene/water microemulsion are shown in Tables 13 and 14. Finally, in the phase diagram (shown in Figure 9), the microemulsion area can be clearly divided into three corresponding structures. The regions are respectively oil-in-water (O/W) region, bicontinuous phase (B.C.) region, and water-in-oil (W/O) region.

Table 13 Boundary points between oil-in-water and bicontinuous phases at different oil-to-surface ratios

S/O	O%	S%	W%
1:3	9.75	29.26	60.98
1:4	7.61	30.45	61.93
1:6	5.19	31.18	63.62
1:9	4.73	42.62	52.64
1:20	2.36	47.20	50.44

Table 14 Boundary points between water-in-oil and bicontinuous phases at different oil-to-surface ratios

S/O	O%	S%	W%
1:3	13.75	41.25	45.00
1:4	10.72	42.88	46.40
1:6	7.98	47.82	44.20
1:9	6.70	60.30	33.00
1:20	3.33	66.67	30.00

Example 4

Comparing the ternary phase diagrams obtained in Examples 2 and 3, as shown in Figure 10, it can be seen that both the conductivity method and the fluorescence method can clearly distinguish the water-in-oil, bicontinuous and oil-in-water regions of the microemulsion, and both The results are basically consistent, further proving that fluorescence method can be used as another effective method to distinguish different types of microemulsions.

Obviously, the above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other changes or modifications may be made based on the above description. An exhaustive list of all implementations is neither necessary nor possible. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims (10)

1. A method for fitting a ternary phase diagram of a microemulsion using a fluorescence method, which is characterized in that it includes the following steps:

   S1: Prepare a microemulsion. The microemulsion contains three components, namely surfactant, oil phase and water. A luminescent agent and a photosensitizer are dissolved in the oil phase, as follows:

   a. Provide a mixture of the first component and the second component with different mass ratios in the microemulsion;

   b. Add third components of different masses to the mixed solution to obtain multiple sets of microemulsions;

   S2: Measure the upconversion intensity and phosphorescence intensity of the microemulsion respectively;

   S3: Using the mass fraction of the third component in the microemulsion as the abscissa and the ratio of the upconversion intensity to the phosphorescence intensity as the ordinate, draw a three-phase diagram polyline for the same mixed solution;

   S4: Taking the first component, the second component and the third component with a mass fraction of 100% as the vertices of the ternary phase diagram, and using the mass fraction as the coordinate, mark the break points of the three-phase diagram polyline of different mixed liquids. and connected together to obtain the ternary phase diagram of the microemulsion.
2. The method for fitting a ternary phase diagram of a microemulsion by fluorescence method according to claim 1, wherein the first component is a surfactant, the second component is an oil phase, and the third component is a surfactant. The component is water.
3. The method for measuring microemulsion fitting ternary phase diagram by fluorescence method according to claim 1, characterized in that the surfactant includes a main surfactant and a co-surfactant, and the mass fraction of the co-surfactant No more than 10%.
4. The method for fitting a ternary phase diagram of a microemulsion by fluorescence method according to claim 1, wherein the step a further includes the operation of introducing a protective atmosphere to remove the air in the mixed solution; the step b is in Carry out under protective atmosphere.
5. The method for measuring microemulsion fitting ternary phase diagram by fluorescence method according to claim 4, characterized in that the protective atmosphere is nitrogen, helium or argon.
6. The method for fitting a ternary phase diagram of a microemulsion by fluorescence method according to claim 1, wherein the oil in the oil phase is toluene, and the luminescent agent is 9,10-diphenylanthracene or perylene. , the photosensitizer is octaethylporphyrin platinum or racemic-tetraphenyltetraphenylplatinum(II).
7. The method for fitting a ternary phase diagram of a microemulsion by fluorescence method according to claim 1 or 6, characterized in that the concentration ratio of the luminescent agent and the photosensitizer in the oil phase is 30-100:1.
8. The method for measuring microemulsion fitting ternary phase diagram by fluorescence method according to claim 7, characterized in that the concentration of the luminescent agent in the oil phase is 1.5x10 ^-3 -5x10 ^-3 mol/L, and the concentration of the photosensitizer is The concentration is 5x10 ^-5 mol/L.
9. The method for measuring microemulsion fitting ternary phase diagram by fluorescence method according to claim 1, characterized in that, in the step S4, the up-conversion spectrum of the micro-emulsion is measured, and the area of the above-conversion peak is used as the up-conversion intensity. , taking the integrated area of the phosphorescence peak as the phosphorescence intensity.
10. Application of fluorescence method in determining microemulsion and fitting ternary phase diagram.

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