An oxygen-sensitive membrane, its preparation and use

Abstract

The application discloses an oxygen-sensitive film and a preparation method and application thereof, and comprises the following steps: S1: fluorine-containing silane is dissolved in an organic solvent, hydrochloric acid and water are added to completely hydrolyze the fluorine-containing silane, the solution is placed at 50-80 DEG C for 1-5h, a capping agent is added, and the mixture is uniformly stirred and baked at high temperature to obtain material I; S2: a fluorescent indicator is dissolved in an organic solvent, and nano inorganic oxide is added to the solution, stirred, and layered after standing; centrifugation, drying and grinding are carried out to obtain material II; the fluorescent indicator is a fullerene material; S3: material I and material II are added to an organic solvent in a mass ratio of 50:1-100:1, and the mixture is uniformly stirred; and S4: the uniformly stirred solution in S3 is dropped on a substrate, dried after spin coating to obtain an oxygen-sensitive film. The oxygen-sensitive film has high sensitivity, good light stability and high-temperature stability, can be used for preparing an oxygen sensor, and has a wide application range.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, in particular to an oxygen sensitive membrane and a preparation method and application thereof. Background Art

[0002] Oxygen sensors are designed to measure the oxygen concentration in the air or in a closed environment and can be used to measure oxygen consumption. Currently, the main methods for determining oxygen are electrochemical and fluorescence methods. The fluorescence method mainly uses the quenching effect of oxygen on the fluorescence of certain fluorescent substances, and determines the oxygen concentration based on the fluorescence intensity or quenching time. Compared with electrochemical oxygen sensors, the fluorescence method does not consume oxygen. Oxygen only needs to contact the oxygen-sensitive membrane containing fluorescent substances to determine the dissolved oxygen content in the environment through changes in fluorescence intensity or fluorescence lifetime. In addition, the fluorescence method has high sensitivity and low detection limit. Therefore, measuring the dissolved oxygen content using the fluorescence method has become a research focus in the field of oxygen sensing. However, the existing oxygen-sensitive membranes still have the following problems: (1) The existing oxygen-sensitive membranes are prone to signal attenuation after long-term light exposure, thereby affecting the accuracy of oxygen concentration measurement; (2) Long-term high temperature of 50°C causes signal attenuation, resulting in the oxygen sensor based on the fluorescence principle being unable to meet the needs of practical applications. Among them, the fluorescent indicator in the oxygen-sensitive membrane is easily decomposed by light and heat, and the loss of the indicator is also one of the main factors leading to the instability of the oxygen sensor. In addition, when solving the stability problem of the oxygen-sensitive membrane, the sensitivity of the oxygen sensor is easily affected. Therefore, it is necessary to produce an oxygen-sensitive membrane with better stability while ensuring higher sensitivity. Summary of the Invention

[0003] The purpose of the present invention is to provide an oxygen sensitive membrane with good stability and a preparation method and application thereof.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for preparing an oxygen sensitive membrane comprises the following steps:

[0006] S1: dissolving the fluorinated silane in an organic solvent, adding hydrochloric acid and water to completely hydrolyze the fluorinated silane, and standing at 50-80°C for 1-5 hours. After removing the solution, adding a capping agent, mixing and stirring uniformly, and then baking the solution at high temperature to obtain material I;

[0007] S2: dissolving a fluorescent indicator in an organic solvent, adding a nano-inorganic oxide to the solution, stirring, standing to separate layers, centrifuging, drying, and grinding to obtain material II; the fluorescent indicator is a fullerene material; and the mass ratio of the fluorescent indicator to the nano-inorganic oxide is 1:(5-25);

[0008] S3: Add material I and material II to the organic solvent at a mass ratio of 50:1 to 100:1, and stir to mix evenly;

[0009] S4: The evenly mixed solution in S3 is dropped onto a substrate (PET, transparent glass sheet, etc.), spin-coated and dried to obtain an oxygen-sensitive film.

[0010] Preferably, the concentration of the fluorescent indicator in S2 is 5-15 mg / ml, and the added amount of the nano-inorganic oxide is 0.05-0.2 g / ml.

[0011] Preferably, the molar ratio of the fluorine-containing silane to the end-capping agent is 15:1 to 25:1.

[0012] Preferably, the mass ratio of the fluorescent indicator to the nano-inorganic oxide is 1:(12.5±2.5); the nano-inorganic oxide is one or more of silicon oxide, aluminum oxide, and titanium oxide.

[0013] Preferably, the organic solvent in S1 is ethanol; and the organic solvents in S2 and S3 are one or both of toluene and dichlorotoluene.

[0014] Preferably, the fluorine-containing silane in S1 is one or more of trimethoxy(pentafluorophenyl)silane, triethoxy(pentafluorophenyl)silane, trimethyl(pentafluoroethyl)silane, and (3,3,3-trifluoropropyl)trimethoxysilane; and the end-capping agent is dimethyldimethoxysilane.

[0015] Preferably, the fullerene material in S2 is one or more of C60, C70, C82, and C84; and the stirring time of S2 is 12±2h.

[0016] Preferably, the concentration of the hydrochloric acid in S1 is 0.05-0.5 mol / l, and the mixture is allowed to stand at 65±10°C for 3±1 h; the high-temperature baking is baking at 200±50°C for 5±3 h; and the drying conditions in S2 and S4 are baking at 70±20°C for 12-36 h.

[0017] The oxygen sensitive membrane prepared by the above method is used to prepare an oxygen sensor, the oxygen sensitive membrane is assembled into a sensor, the sensor output signal is tested, and calibration is performed based on the sensor output signal.

[0018] When selecting fluorescent indicators, fullerene materials with better photostability, such as C60, C70, C82, and C84, are selected. C60, C70, or a mixture of the two are preferred. Fullerene materials have a stable structure and high strength, and can resist the effects of light intensity, temperature, and pressure.

[0019] The polymer matrix adopts a polymer containing a CF bond, such as a fluorophenyl group, a trifluoromethyl group, such as (optionally trimethoxy (pentafluorophenyl) silane, triethoxy (pentafluorophenyl) silane, trimethyl (pentafluoroethyl) silane, (3,3,3-trifluoropropyl) trimethoxy silane, etc., preferably a silane containing a fluorophenyl group, mainly utilizing the high electronegativity of the CF bond to reduce the electron cloud density, making the polymer structure more stable, and being able to reduce the photodegradation process, thereby reducing the stability of the sensor performance affected by the photodegradation of the matrix material.

[0020] The fluorescent indicator and matrix material (CF bond) selected in the present invention are hydrophobic and have good high-humidity resistance, thereby reducing the loss of the indicator.

[0021] The present invention is mainly based on the principle of the quenching effect of oxygen molecules on fluorescent substances. When a fluorescent substance is irradiated with incident light of a specific wavelength, the fluorescent substance emits fluorescence. Due to the presence of molecular oxygen, the fluorescence intensity and fluorescence lifetime of the fluorescent substance change. Moreover, molecular oxygen can completely reversibly change the fluorescence intensity and lifetime. By measuring the changes in fluorescence intensity or fluorescence lifetime under different oxygen concentrations, the oxygen concentration can be calculated. For details, see Figure 6 .

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention adopts the modification method of nano-inorganic oxide adsorption, and adsorbs the indicator inside the oxide, which can improve the compatibility with the fluorosilicone matrix material, improve the stability of the indicator and the matrix material, and make the oxygen sensitive film have good light stability and high temperature stability; on the other hand, the nanoparticles encapsulate the fluorescent indicator, retaining the properties of the indicator itself, thereby improving the life of the sensor.

[0024] (2) The sensor made of the oxygen sensitive membrane of the present invention not only has a good linear relationship, but also has a larger quenching constant, and the sensitivity of the sensor is higher.

[0025] (3) The oxygen sensor made of the oxygen sensitive membrane of the present invention can measure 0-21% oxygen, 0-25% or more than 40% oxygen-enriched air, and oxygen in high-temperature environments, and has a wider range of use environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a Stern-Volmer plot of different embodiments.

[0027] Figure 2 This is a diagram showing the effect of different illumination times on the sensor output signal in Example 1.

[0028] Figure 3 This is a diagram showing the effect of sustained high temperature on the oxygen concentration output by the sensor in Example 1.

[0029] Figure 4 This is a diagram showing the effect of different illumination times on the sensor (oxygen concentration 0%).

[0030] Figure 5 This is a graph showing the effect of continued high temperature on the sensor (oxygen concentration 99.0%).

[0031] Figure 6 This is a diagram showing the working principle of the oxygen sensitive membrane of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0033] Example 1

[0034] A method for preparing an oxygen sensitive membrane comprises the following steps:

[0035] Take 25 ml of trimethoxy(pentafluorophenyl)silane and dissolve it in 25 ml of ethanol, add 6 ml of 0.1 mol / l hydrochloric acid, add water to completely hydrolyze the fluorinated silane, place the solution at 65 ° C and let it stand for 3 hours, then take it out and add the capping agent dimethyldimethoxysilane (the molar ratio of the fluorinated silane to the capping agent is 18:1), mix and stir evenly, and then place the solution at 200 ° C and bake for 5 hours to obtain material I.

[0036] Weigh 50 mg of fullerene C60 fluorescent indicator, add 10 ml of toluene to prepare a 5 mg / ml solution, take 4 ml of the solution, add 0.5 g of fumed silica (Evonik), stir and let stand for 12 h, centrifuge, bake and grind to obtain material II loaded with oxygen-sensitive indicator.

[0037] Take 0.5g of material I and 5mg of material II and add them to 2.5ml of toluene solution, stir and mix them evenly at room temperature to obtain material III, then add the material III solution dropwise onto a polyester sheet and bake it at 70℃ for 1 day to obtain an oxygen sensitive membrane material.

[0038] Sensor production: Place the oxygen-sensitive membrane material on a support frame, then place it on the PCBA, secure it, install the outer chamber and bottom cover, and then affix a layer of waterproof and breathable film to the surface of the chamber. The entire device is placed at 70°C for aging for 1 day to obtain the finished sensor.

[0039] Example 2

[0040] Dissolve 25 ml of trimethoxy(pentafluorophenyl)silane in 25 ml of ethanol, add 6 ml of 0.1 mol / l hydrochloric acid, add water to completely hydrolyze the fluorinated silane, let it stand at 65°C for 3 h, take it out and add the capping agent dimethyldimethoxysilane (the molar ratio of the fluorinated silane to the capping agent is 18:1), mix and stir evenly, and then bake the solution at 200°C for 5 h to obtain material I.

[0041] 0.5 mg of fullerene C60 and 0.5 g of material I were added to 2.5 ml of toluene solution and ultrasonically stirred at 40°C for 30 min to obtain a uniform solution. The uniform solution was then dropped onto a polyester sheet and baked at 70°C for 1 day to obtain an oxygen sensitive membrane material.

[0042] According to the preparation steps of the sensor in the above embodiment 1, a response sensor is prepared, and then the sensor output signal is tested.

[0043] Example 3

[0044] The present invention is different from Example 1 in that:

[0045] The mass ratio of the fluorescent indicator to silica was 1:12.5 (50 mg of fullerene C60 fluorescent indicator was weighed, 5 ml of toluene was added to prepare a 10 mg / mL solution, 4 ml of the solution was taken, and 0.5 g of fumed silica was added). Other conditions were the same as in Example 1.

[0046] Example 4

[0047] The present invention is different from Example 1 in that:

[0048] The ratio of material I to material II is 40:1 (0.5 g of material I and 12.5 mg of material II). Other contents are the same as those in Example 1. The oxygen sensitive film obtained in Example 4 is in a cracked but non-film-forming state.

[0049] Example 5

[0050] The difference between the present invention and Example 1 is that the fluorescent indicator is C70.

[0051] Comparative Example 1

[0052] Styrene PS (MW280000) was dissolved in toluene to prepare a 30% toluene solution. Fullerene C60 was added to the toluene solution at a concentration of 5 mg / ml. The mixture was dropped onto a polyester sheet and baked at 70°C for 1 day to obtain an oxygen sensitive membrane material.

[0053] Stability testing

[0054] The stability of an oxygen sensor is generally measured by measuring the fluorescence signal of the oxygen-sensitive membrane over a period of time, or by measuring the relative standard deviation of the fluorescence signal under nitrogen-saturated or oxygen-saturated conditions. This invention uses a method that monitors the fluorescence output voltage signal. The experimental results are as follows:

[0055] Table 1

[0056] Example 1 Example 2 Example 3 Comparative Example 1 ％O2 I0 / I I0 / I I0 / I I0 / I 0 1 1 1 1 20 2.231 1.997 3.731 1.223 30 3.612 3.126 5.812 1.826 60 4.745 4.054 8.345 2.173 80 6.186 5.126 10.286 2.652 100 7.260 6.452 12.260 3.015

[0057] From Table 1 and Figure 1 It can be seen that the sensors prepared by the present invention (Example 1, Example 2, Example 3) have good linearity in the range of 0-100%. The sensor can be used to measure the oxygen concentration in the full range of 0-100%. Example 4 cracks and does not form a film. Among them, Example 3 has a larger quenching constant than Example 1, and the sensor sensitivity is higher.

[0058] Table 2 Effect of continuous illumination on performance in Example 1

[0059]

[0060] From Table 2 and Figure 2 It can be seen that in the range of 0-100%, under continuous illumination, the output voltage value of the illumination intensity of Example 1 shows a slight attenuation, indicating that the fluorescent indicator has good light stability.

[0061] Table 3 Effect of continuous high temperature of 60°C on product performance in Example 1

[0062]

[0063] From Table 3 and Figure 3 It can be seen that in the range of 0-100%, the high temperature is continued, and there is a certain deviation between Example 1 and the actual oxygen concentration. In particular, after 30 days of continuous high temperature, the deviation between the output oxygen concentration of the product and the output oxygen concentration in the range of 0-60% oxygen concentration is less than 1%, indicating that the high temperature stability of the fluorescent indicator is good.

[0064] Table 4 Effects of different illumination times on sensor output signals (under monitoring conditions of pure nitrogen concentration)

[0065]

[0066] From Table 4 and Figure 4 It can be seen that under pure nitrogen conditions (0% oxygen concentration) and different illumination times, the deviations of Example 1 and Example 3 are smaller than those of Example 2, indicating that adding inorganic oxides is beneficial to improving product stability; the signal value of Comparative Example 1 is greatly reduced compared to the initial signal value, indicating that Comparative Example 1 is not resistant to light and the indicator is unstable under light.

[0067] Table 5 Effect of continuous high temperature on sensor output signal (monitoring 99.0% oxygen concentration)

[0068]

[0069] From Table 5 and Figure 5 It can be seen that at an oxygen concentration of 99.0% and different high temperature times, the deviations of Examples 1 and 3 are smaller than those of Example 2, indicating that adding inorganic oxides is beneficial to improving product stability; the comparative example 1 is significantly lower than the initial signal value, indicating that the comparative example is not resistant to high temperatures and the indicator is unstable under high temperature conditions.

[0070] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing an oxygen sensitive membrane, comprising the following steps: S1: dissolving trimethoxy(pentafluorophenyl)silane in an organic solvent, adding hydrochloric acid and water to completely hydrolyze the fluorinated silane, and standing at 50-80°C for 1-5 hours. Then, adding dimethyldimethoxysilane as a capping agent, mixing and stirring uniformly, and then baking the solution at a high temperature to obtain material I; the molar ratio of trimethoxy(pentafluorophenyl)silane to the capping agent is 15:1 to 25:1; the organic solvent is ethanol; S2: dissolving a fluorescent indicator in an organic solvent, adding a nano-inorganic oxide to the solution, stirring thoroughly, standing to separate layers, centrifuging, drying, and grinding to obtain material II; the fluorescent indicator is fullerene C60; the mass ratio of the fluorescent indicator to the nano-inorganic oxide is 1:(5-25); the concentration of the fluorescent indicator is 5-15 mg / ml, and the amount of the nano-inorganic oxide added is 0.05-0.2 g / ml; the mass ratio of the fluorescent indicator to the nano-inorganic oxide is 1:(12.5±2.5); the nano-inorganic oxide is silicon dioxide; S3: Add material I and material II to the organic solvent at a mass ratio of 50:1 to 100:1, and stir to mix evenly; The organic solvent in S2 and S3 is one or both of toluene and dichlorotoluene; S4: The evenly mixed solution in S3 is dropped onto the substrate, spin-coated and then dried to obtain an oxygen sensitive film.

2. The preparation method according to claim 1, wherein the stirring time in S2 is 12±2 h.

3. The preparation method according to claim 2, wherein the concentration of the hydrochloric acid in S1 is 0.05-0.5 mol / l, and the mixture is allowed to stand at 65±10°C for 3±1 h; the high-temperature baking is baking at 200±50°C for 5±3 h; and the drying conditions in S2 and S4 are baking at 70±20°C for 12-36 h.

4. An oxygen sensitive membrane, characterized in that: The product is produced and formed by the preparation method according to any one of claims 1 to 3.

5. An oxygen sensor, characterized in that: It is prepared using the oxygen sensitive membrane described in claim 4.

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