Flexible self-supporting humidity sensitive film as well as preparation method and application thereof

Abstract

The invention discloses a flexible self-supporting humidity sensitive film as well as a preparation method and application thereof, and develops a flexible self-supporting humidity sensitive material integrating humidity sensitivity and flexibility characteristics in order to solve the problems of low sensitivity, low resolution, remarkable wet hysteresis effect, poor linearity and the like of a traditional humidity sensor. The use of a flexible substrate is abandoned, so that the comprehensive performance improvement problem of the flexible humidity sensor in the aspects of flexibility, high sensitivity, high resolution, low humidity hysteresis effect and the like is solved.

Description

Technical Field

[0001] The present invention belongs to the field of polymer technology, and particularly relates to a flexible self-supporting humidity-sensitive film, a preparation method thereof, and an application thereof. Background Art

[0002] Relative humidity (RH) is an essential key parameter to ensure the normal progress of life activities and the efficient operation of equipment. Therefore, to meet the special requirements of different fields, it is necessary to strictly maintain and monitor the RH level. In recent years, humidity sensors have been intensively studied due to their measurement accuracy, especially in monitoring air humidity. In addition to monitoring air humidity, humidity sensors can also be used to detect skin humidity and human respiration in special scenarios.

[0003] Generally, humidity sensors display humidity values by converting the content of water molecules absorbed from the environment into measurable physical signals. Humidity-sensitive materials are the core components of sensors, and these materials usually contain hydrophilic functional groups such as hydroxyl, amino, and carboxyl groups. Although most reported humidity sensors are sensitive in a wide humidity range, their measurement accuracy is not ideal. This need is particularly prominent in some scenarios that require high-precision monitoring of a specific humidity range. For example, high-humidity environments can accelerate the spread of bacteria and viruses, while fuel storage and power transmission are more suitable for low-humidity conditions. In addition, due to their inherent limitations, traditional rigid humidity sensors have difficulty meeting the diverse needs of modern monitoring systems. Especially when monitoring the high-humidity environment of complex curved objects, the application value of flexible humidity sensors becomes more prominent.

[0004] Currently, flexible humidity sensors are mainly composed of flexible substrates and humidity-sensitive materials. Unfortunately, the existing limitations of composite material technology make it difficult to solve the compatibility problem between flexible substrates and humidity-sensitive materials, thereby affecting the improvement of key performance indicators such as sensitivity, resolution, hysteresis effect, and linearity of flexible humidity sensors. Therefore, developing a flexible humidity-sensitive material that integrates humidity sensitivity and flexible characteristics, and abandoning the use of flexible substrates to solve the comprehensive performance improvement problems of flexible humidity sensors in terms of flexibility, high sensitivity, high resolution, and low hysteresis effect, has great academic significance. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a flexible self-supporting humidity-sensitive film.

[0008] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing a flexible self-supporting humidity-sensitive film, characterized by comprising:

[0009] Mix polyethylenimine and a neutralizing agent and dissolve them in an aqueous solution to obtain a polyethylenimine solution;

[0010] Dropwise add the modifier acryloyl chloride into the polyethylenimine solution, stir evenly, and then let it stand at room temperature, and extract to obtain a polyethylenimine APEI precursor solution;

[0011] Perform radiation or radical polymerization on the APEI precursor solution to obtain the flexible self-supporting humidity-sensitive film.

[0012] As a preferred embodiment of the preparation method of the present invention, wherein: when mixing polyethylenimine and a neutralizing agent and dissolving them in an aqueous solution, the volume-mass ratio of polyethylenimine, the neutralizing agent and water is 1 g: 8-10 ml: 20 ml.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the neutralizing agent includes one or more of triethylamine, sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: when dropping acryloyl chloride into the polyethylenimine solution, the temperature during dropping is -20 to 100 °C.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the volume-mass ratio of acryloyl chloride to the polyethylenimine solution is 6 ml: 1-3 g.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: after stirring evenly and letting it stand at room temperature, the standing time is 8-16 h.

[0017] As a preferred embodiment of the preparation method of the present invention, wherein: for the extraction, the extractant is ethyl acetate.

[0018] As a preferred embodiment of the preparation method of the present invention, wherein: the temperature of the radical polymerization is -20 °C to 100 °C.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a flexible self-supporting humidity-sensitive film.

[0020] As a preferred embodiment of the flexible self-supporting humidity-sensitive film of the present invention, wherein: the flexible self-supporting humidity-sensitive film comprises a hyperbranched structure and a nitrogen-rich group.

[0021] As a preferred embodiment of the flexible self-supporting humidity-sensitive film of the present invention, wherein: the hyperbranched structure is a polyethyleneimine structure, including linear polyethyleneimine, branched polyethyleneimine, and ethylenediamine-capped polyethyleneimine.

[0022] Advantages of the present invention:

[0023] The present invention has developed a humidity-sensitive material with nitrogen-rich hyperbranched polyethyleneimine as the core, obtained a polymer-based flexible humidity-sensitive material with both excellent humidity-sensitive performance and excellent flexibility, and directly used this material to construct a polymer-based flexible humidity sensor, thereby effectively avoiding the adverse effects that may be brought by the application of flexible substrates. Description of the drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings. Among them:

[0025] Figure 1 It is a process diagram for the preparation of the PAPEI flexible self-supporting humidity-sensitive film.

[0026] Figure 2 It is an FTIR diagram of the APEI precursor and the PAPEI humidity-sensitive film.

[0027] Figure 3 It is a temperature response performance diagram of the PAPEI flexible self-supporting device.

[0028] Figure 4 It is a stability performance diagram of the PAPEI flexible self-supporting device.

[0029] Figure 5 It is a hysteresis performance diagram of the PAPEI flexible self-supporting device. Detailed implementation manners

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0031] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0032] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0033] The raw materials used in the present invention: polyethyleneimine, acryloyl chloride, triethylamine, and ethyl acetate were all purchased from Shanghai Aladdin Chemical Reagent Co., Ltd.

[0034] The instruments used in the embodiments of the present invention: LCR digital bridge (VICTOR4092A, Suzhou Victory Precision Manufacturing Technology Co., Ltd.), constant temperature and humidity chamber (TEMI880, Suzhou Jiangkai Machinery Equipment Co., Ltd.).

[0035] Example 1

[0036] This example provides a preparation method for a flexible self-supporting humidity-sensitive film (PAPEI) material, as Figure 1 shown, including the following steps:

[0037] (1) First, disperse 2.5 g of polyethyleneimine and 20 ml of triethylamine in 50 ml of water, and then drop 12 ml of acryloyl chloride into the above mixture in an ice bath.

[0038] (2) React at room temperature for 12 h, and extract with ethyl acetate to obtain a precursor solution of vinyl-containing polyethyleneimine (APEI).

[0039] (3) Place the APEI precursor solution in a mold and obtain a flexible self-supporting humidity-sensitive film (PAPEI) material by means of radiation polymerization. The obtained self-supporting sensitive film can be directly used for humidity-sensitive testing.

[0040] Figure 2 are the FTIR spectra of the APEI precursor and the PAPEI adsorbent. In the APEI spectrum, the peaks corresponding to 931 and 983 cm -1 are for C═C, indicating that vinyl groups are attached to the polyethyleneimine molecular chain to obtain a vinyl polyethyleneimine (APEI) precursor. At the same time, in the PAPEI spectrum, no C═C peak is observed, indicating that the APEI precursor polymerizes to obtain a PAPEI flexible humidity-sensitive film.

[0041] Example 2

[0042] This example is for testing the temperature response performance of the PAPEI flexible humidity-sensitive film prepared in Example 1, and specifically includes the following steps:

[0043] Place the PAPEI flexible self-supporting humidity-sensitive film of Example 1 in a thermostatic and humidistatic chamber to test its temperature response performance. The temperature is kept constant at 40 °C, and the humidity is 70-97%, as Figure 3 shown. In the humidity range of 70-97%, the flexible sensitive film has good responsiveness, and the linearity is as high as 0.9998.

[0044] Example 3

[0045] This example is for testing the stability performance of the PAPEI flexible humidity-sensitive film prepared in Example 1, and specifically includes the following steps:

[0046] Place the PAPEI flexible self-supporting humidity-sensitive film of Example 1 in a thermostatic and humidistatic chamber to test its stability performance. The temperature is kept constant at 40 °C, and the humidity is 80%, 90%, 95%, as Figure 4 shown. Within 60 min, the PAPEI flexible self-supporting film can maintain a stable resistance, indicating that it has good stability performance.

[0047] Example 4

[0048] This example is for testing the hysteresis performance of the PAPEI flexible humidity-sensitive film prepared in Example 1, and specifically includes the following steps:

[0049] Place the PAPEI flexible self-supporting humidity-sensitive film of Example 1 in a thermostatic and humidistatic chamber to test its hysteresis performance. The temperature is kept constant at 40 °C, and the humidity is 80%, 85%, 90%, 95%, as Figure 5 shown. It can be seen from the figure that there is almost no humidity hysteresis performance, indicating that the PAPEI flexible self-supporting film has good anti-hysteresis ability.

[0050] Example 5

[0051] The difference between this example and Example 1 is that 20 g of triethylamine is used to replace 20 ml of triethylamine in step (1), and the remaining steps are the same as those in Example 1. The results show that in the humidity range of 70-97% for the prepared PAPEI flexible humidity-sensitive film, the flexible self-supporting sensitive film has good responsiveness, and the linearity is as high as 0.99.

[0052] Example 6

[0053] The difference between this example and Example 1 is that: 12 ml of acryloyl chloride in step (1) is replaced with 8 ml of acryloyl chloride, and the remaining steps are the same as those in Example 1. The results show that in the humidity range of 70-97%, the flexible self-supporting sensitive film of the prepared PAPEI flexible humidity sensor has good responsiveness and a linearity as high as 0.97.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that: 12 ml of acryloyl chloride in step (1) is replaced with 2 ml of acryloyl chloride, and the remaining steps are the same as those in Example 1. As a result, in the humidity range of 70-97%, the flexible self-supporting sensitive film of the PAPEI flexible humidity sensor has poor responsiveness and a linearity lower than 0.8.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that: gradually dropping 12 ml of acryloyl chloride in step (1) is replaced with adding 12 ml of acryloyl chloride at one time, and the remaining steps are the same as those in Example 1. The results show that the yield of the APEI precursor is low, and the humidity response ability of the obtained PAPEI flexible humidity sensor is poor. In the humidity range of 70-97%, the linearity is lower than 0.7.

[0058] Example 7

[0059] The difference between this example and Example 1 is that: reacting at room temperature in step (2) is replaced with reacting at 0 °C, and the remaining steps are the same as those in Example 1. The results show that the humidity response ability of the obtained PAPEI flexible humidity sensor is good. In the humidity range of 70-97%, the linearity is higher than 0.95.

[0060] Example 8

[0061] The difference between this example and Example 1 is that: reacting for 12 h at room temperature in step (2) is replaced with reacting for 24 h at room temperature, and the remaining steps are the same as those in Example 1. As a result, the humidity response ability of the obtained PAPEI flexible humidity sensor is good. In the humidity range of 70-97%, the linearity is higher than 0.92.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that: ethyl acetate in step (2) is replaced with N,N-dimethylformamide, and the remaining steps are the same as those in Example 1. The results show that the APEI precursor cannot be extracted from the solution, that is, the PAPEI flexible film cannot be prepared.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 1 lies in that ethyl acetate in step (2) is replaced with dimethyl sulfoxide, and the remaining steps are the same as those in Example 1. The results show that the APEI precursor cannot be extracted from the solution, that is, the PAPEI flexible film cannot be prepared.

[0066] The modified polyethyleneimine prepared by the present invention has a hyperbranched structure and nitrogen-rich groups, which are both beneficial to capturing water molecules in the environment and beneficial to constructing a flexible film, thereby obtaining a flexible self-supporting humidity sensor device with high humidity response. The obtained self-supporting sensitive film can be directly used for testing. The self-supporting device has a significant response to humidity and also has good flexibility.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A preparation method of a flexible self-supporting humidity-sensitive film, characterized in that: including Mix polyethyleneimine and a neutralizing agent and dissolve them in an aqueous solution to obtain a polyethyleneimine solution; Dropwise add a modifier, acryloyl chloride, into the polyethyleneimine solution. After stirring evenly, let it stand at room temperature, and then extract to obtain a polyethyleneimine APEI precursor solution; Perform radiation or radical polymerization on the APEI precursor solution to obtain the flexible self-supporting humidity-sensitive film.

2. The preparation method according to claim 1, characterized in that: When mixing and dissolving polyethyleneimine and the neutralizing agent in the aqueous solution, the volume-mass ratio of polyethyleneimine, the neutralizing agent, and water is 1 g: 8-10 ml: 20 ml.

3. The preparation method according to claim 1, characterized in that: The neutralizing agent includes one or more of triethylamine, sodium hydroxide, sodium carbonate, and sodium bicarbonate.

4. The preparation method according to claim 3, wherein: When dropwise adding acryloyl chloride into the polyethyleneimine solution, the temperature during the dropping is -20 to 100 °C.

5. The preparation method according to claim 1, characterized in that: The volume-mass ratio of acryloyl chloride to the polyethyleneimine solution is 6 ml: 1-3 g.

6. The preparation method according to claim 1, characterized in that: After stirring evenly, let it stand at room temperature, and the standing time is 8-16 h.

7. The preparation method according to claim 1, characterized in that: For the extraction, the extractant is ethyl acetate.

8. The preparation method according to claim 1, characterized in that: The temperature of the radical polymerization is -20 °C to 100 °C.

9. The flexible self-supporting humidity-sensitive film prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The flexible self-supporting humidity-sensitive film contains a hyperbranched structure and nitrogen-rich groups.

10. The flexible self-supporting humidity-sensitive film according to claim 9, characterized in that: The hyperbranched structure is a polyethyleneimine structure, including linear polyethyleneimine, branched polyethyleneimine, and ethylenediamine-capped polyethyleneimine.

Images