A PC / PAM ion-conducting hydrogel, its preparation method and application

Abstract

This invention belongs to the field of flexible sensing materials technology, and discloses an HPC / PAM ion-conductive hydrogel, its preparation method, and its application. The method includes: mixing acrylamide monomer with a hydroxypropyl cellulose solution, adding a crosslinking agent and an initiator, and stirring to obtain an HPC / AM solution; subjecting the HPC / AM solution to a free radical polymerization reaction, and after standing, obtaining an HPC / PAM hydrogel; immersing the HPC / PAM hydrogel in a FeCl3 solution, and then aging it to obtain the HPC / PAM ion-conductive hydrogel. The HPC / PAM ion-conductive hydrogel prepared by this invention has good mechanical and electrical properties; the mechanical and temperature / humidity sensors prepared using the HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensing materials technology, and specifically relates to an HPC / PAM ion-conducting hydrogel, its preparation method, and its application. Background Technology

[0002] Flexible sensors are sensors made of flexible sensing materials. They can perfectly solve the defects of traditional rigid sensing materials (such as semiconductor materials, ceramic materials, etc.), making the sensors more adaptable to different shapes and surfaces, with better wearability and comfort, and can be used for information acquisition under curved or dynamic conditions.

[0003] However, existing flexible sensing materials often suffer from problems such as insufficient flexibility, poor biocompatibility, limited functionality, or delamination between electronic fillers and the substrate in practical applications. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides an HPC / PAM ion-conductive hydrogel, its preparation method, and its application, in order to solve the technical problems that existing flexible sensing materials often suffer from inadequate flexibility, poor biocompatibility, limited functionality, or delamination between electronic fillers and the substrate in practical applications.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing HPC / PAM ion-conducting hydrogels, comprising:

[0007] Acrylamide monomer was mixed with hydroxypropyl cellulose solution, and crosslinking agent and initiator were added. The mixture was stirred to obtain HPC / AM solution.

[0008] The HPC / AM solution was subjected to free radical polymerization, and after standing, HPC / PAM hydrogel was obtained.

[0009] The HPC / PAM hydrogel was placed in FeCl3 solution, soaked, and then aged to obtain HPC / PAM ion-conducting hydrogel.

[0010] Furthermore, the preparation process of the hydroxypropyl cellulose solution is as follows:

[0011] Hydroxypropyl cellulose was added to preheated deionized water and stirred to disperse it. Then, it was transferred to room temperature and stirred to obtain a hydroxypropyl cellulose solution.

[0012] Furthermore, the crosslinking agent is methylenebisacrylamide, and the initiator is ammonium persulfate.

[0013] Furthermore, the HPC / AM solution is subjected to a free radical polymerization reaction, and after standing, the HPC / PAM hydrogel is obtained, as detailed below:

[0014] The HPC / AM solution was placed in a mold and subjected to free radical polymerization at 60-70°C for 10-20 hours, followed by standing at room temperature for 12-24 hours.

[0015] Furthermore, the soaking time is 12-36 hours.

[0016] Furthermore, during the aging process, the aging temperature is 20-30℃, the relative humidity is 65-75%, and the aging time is 12-48 hours.

[0017] The present invention also provides an HPC / PAM ion-conducting hydrogel, which is prepared by the method described above.

[0018] Furthermore, the HPC / PAM ion-conductive hydrogel has a tensile strength of 100-200 kPa and an electrical conductivity of 300-500 Sm. -1 The adhesion is 5-30 kPa.

[0019] The present invention also provides an application of HPC / PAM ion-conducting hydrogel, characterized in that the HPC / PAM ion-conducting hydrogel is used as a flexible sensing material to prepare a flexible sensor.

[0020] Furthermore, the stress-strain sensing current change rate of the flexible sensor is 80%-110%, the humidity sensing current change rate is 10%-20%, and the temperature response range is 10-60℃.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention provides an HPC / PAM ion-conductive hydrogel, its preparation method, and its applications. HPC, with its excellent water solubility and biocompatibility, is selected as the temperature and humidity sensing material for sensors. PAM serves as a transparent, flexible hydrogel. FeCl3 is added to the HPC / PAM system to provide ion conductivity. The hydrogel prepared from PAM exhibits good water absorption, stability, and transparency. HPC material possesses excellent water retention. The polyhydroxyl groups on its surface enhance the humidity sensing performance of the hydrogel. A low critical dissolution temperature enables temperature sensing performance even at high temperatures with reduced material transparency. The good ion conductivity provided by FeCl3 facilitates the output of the sensing signal. During the preparation process, HPC is uniformly distributed within the hydrogel in a network structure, resulting in better humidity sensing sensitivity compared to other hydrogels. Furthermore, HPC can exist in the hydrogel matrix as an aqueous solution, enhancing humidity sensitivity without affecting other material properties such as mechanical properties and transparency. The HPC / PAM ion-conductive hydrogel prepared by this invention possesses excellent mechanical and electrical properties. The mechanical and temperature / humidity sensors prepared using the HPC / PAM ion-conductive hydrogel exhibit good mechanical properties and high temperature and humidity response sensitivity. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a 2000x magnified SEM image of the HPC / PAM ion-conducting hydrogel prepared in Example 5.

[0025] Figure 2 This is a 10,000x magnified SEM image of the HPC / PAM ion-conducting hydrogel prepared in Example 5. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0027] This invention provides a method for preparing HPC / PAM ion-conducting hydrogels, comprising the following steps:

[0028] Step 1: Add HPC to deionized water preheated to 60℃ and mechanically stir for 15-60 min, then transfer to room temperature and stir for 6-24 h to obtain an HPC solution with a mass fraction of 0.5%-10%.

[0029] Step 2: Add 4-10g of acrylamide monomer (AM) to 10-40g of the HEC solution, and then add 0.0025-0.05g of methylenebisacrylamide (MBA) and 0.01-0.2g of ammonium persulfate (APS) sequentially. Stir at room temperature for 1-3 hours to obtain an HPC / AM solution; wherein, methylenebisacrylamide is used as a crosslinking agent and ammonium persulfate is used as an initiator.

[0030] Step 3: Place 10-40g of the HPC / AM solution in a polytetrafluoroethylene mold with a diameter of 8-15cm, and perform free radical polymerization at 60-70℃ for 10-20h. Then, let it stand at room temperature for 12-24h to obtain HPC / PAM hydrogel.

[0031] Step 4: Add 25-100g of ferric chloride hexahydrate to 100-1000ml of deionized water and stir at room temperature for 2-6 hours to obtain FeCl3 solution.

[0032] Step 5: Cut the HPC / PAM hydrogel into rectangles 2-5cm long and 1-4cm wide, place them in a 100mL beaker, add 20-40mL of the FeCl3 solution, soak for 12-36h, and then age for 12-48h at 20-30℃ and 65-75%RH to prepare HPC / PAM ion-conductive hydrogel.

[0033] Preparation principle:

[0034] The preparation method of the HPC / PAM ion-conductive hydrogel described in this invention uses HPC as the temperature and humidity sensitive material for the sensor, PAM as the transparent and flexible hydrogel, and FeCl3 is added to the HPC / PAM system to provide ion conductivity. The excellent water retention properties of FeCl3 and HPC / PAM are combined to provide stable ion conductivity for the HPC / PAM hydrogel. Specifically, the hydrogel prepared from PAM has good water absorption, stability, and transparency, while HPC material has excellent water retention. The polyhydroxyl groups on its surface enhance the humidity sensing performance of the hydrogel, and the low critical dissolution temperature enables temperature sensing performance with reduced material transparency at high temperatures. The good ion conductivity provided by FeCl3 enables the output of the sensing signal. During the preparation process, HPC is uniformly distributed in a network within the hydrogel, resulting in better humidity sensing sensitivity compared to other hydrogels. Furthermore, HPC can exist in the hydrogel matrix as an aqueous solution, enhancing humidity sensitivity without affecting other material properties such as mechanical properties and transparency.

[0035] The HPC / PAM ion-conducting hydrogel prepared by this invention possesses excellent mechanical and electrical properties; wherein, the tensile strength of the HPC / PAM ion-conducting hydrogel is 100-200 kPa, and the electrical conductivity is 300-500 Sm. -1 The adhesion is 5-30KPa; the mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity; among them, the stress-strain sensing current change rate is as high as 80%~110%, the humidity sensing current change rate is as high as 10%-20%, and the temperature response range is 10-60℃.

[0036] Example 1

[0037] This embodiment 1 provides a method for preparing HPC / PAM ion-conducting hydrogels, including the following steps:

[0038] Step 1: Add HPC to deionized water preheated to 60°C and mechanically stir for 15 min, then transfer to room temperature and stir for 6 h to obtain a 0.5% HPC solution.

[0039] Step 2: Add 4g of acrylamide monomer (AM) to 10g of the HEC solution, and then add 0.0025g of methylenebisacrylamide (MBA) and 0.01g of ammonium persulfate (APS) in sequence. Stir at room temperature for 1h to obtain HPC / AM solution.

[0040] Step 3: Place 10g of the HPC / AM solution in a polytetrafluoroethylene mold with a diameter of 8cm, and perform free radical polymerization at 60°C for 10h. Then, let it stand at room temperature for 12h to obtain HPC / PAM hydrogel.

[0041] Step 4: Add 25g of ferric chloride hexahydrate to 100ml of deionized water and stir at room temperature for 2 hours to obtain FeCl3 solution.

[0042] Step 5: Cut the HPC / PAM hydrogel into rectangles 2cm long and 1cm wide, place them in a 100mL beaker, add 20mL of the FeCl3 solution, soak for 12h, and then age them at 30℃ and 70%RH for 12h to prepare HPC / PAM ion-conductive hydrogel.

[0043] The HPC / PAM ion-conducting hydrogel prepared in Example 1 has a tensile strength of 100 kPa and an electrical conductivity of 450 Sm. -1 The adhesion is 5 kPa. The mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity. Among them, the stress-strain sensing current change rate is as high as 88%, the humidity sensing current change rate is as high as 15%, and the temperature response range is 10-60℃.

[0044] Example 2

[0045] This embodiment 2 provides a method for preparing HPC / PAM ion-conducting hydrogels, including the following steps:

[0046] Step 1: Add HPC to deionized water preheated to 60°C and mechanically stir for 60 min, then transfer to room temperature and stir for 24 h to obtain a 10% HPC solution.

[0047] Step 2: Add 10g of acrylamide monomer (AM) to 40g of the HEC solution, and then add 0.05g of methylenebisacrylamide (MBA) and 0.2g of ammonium persulfate (APS) in sequence. Stir at room temperature for 3h to obtain HPC / AM solution.

[0048] Step 3: Place 40g of the HPC / AM solution in a polytetrafluoroethylene mold with a diameter of 15cm, and perform free radical polymerization at 70°C for 20h. Then, let it stand at room temperature for 24h to obtain HPC / PAM hydrogel.

[0049] Step 4: Add 100g of ferric chloride hexahydrate to 1000ml of deionized water and stir at room temperature for 6 hours to obtain FeCl3 solution.

[0050] Step 5: Cut the HPC / PAM hydrogel into rectangles 5cm long and 4cm wide, place them in a 100mL beaker, add 40mL of the FeCl3 solution, soak for 36h, and then age for 12h at 20℃ and 75%RH to prepare HPC / PAM ion-conductive hydrogel.

[0051] The HPC / PAM ion-conducting hydrogel prepared in Example 2 has a tensile strength of 180 kPa and an electrical conductivity of 370 Sm. -1 The adhesion is 30 kPa. The mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity. Among them, the stress-strain sensing current change rate is as high as 82%, the humidity sensing current change rate is as high as 18%, and the temperature response range is 10-60℃.

[0052] Example 3

[0053] This embodiment 3 provides a method for preparing HPC / PAM ion-conducting hydrogels, including the following steps:

[0054] Step 1: Add HPC to deionized water preheated to 60°C and mechanically stir for 40 min, then transfer to room temperature and stir for 12 h to obtain a 2% HPC solution.

[0055] Step 2: Add 6g of acrylamide monomer (AM) to 20g of the HEC solution, and then add 0.01g of methylenebisacrylamide (MBA) and 0.05g of ammonium persulfate (APS) in sequence. Stir at room temperature for 2h to obtain HPC / AM solution.

[0056] Step 3: Place 20g of the HPC / AM solution in a polytetrafluoroethylene mold with a diameter of 10cm, and perform free radical polymerization at 60°C for 14h. Then, let it stand at room temperature for 12h to obtain HPC / PAM hydrogel.

[0057] Step 4: Add 50g of ferric chloride hexahydrate to 1000ml of deionized water and stir at room temperature for 4 hours to obtain FeCl3 solution.

[0058] Step 5: Cut the HPC / PAM hydrogel into rectangles 4cm long and 2cm wide, place them in a 100mL beaker, add 30mL of the FeCl3 solution, soak for 24h, and then age at 25℃ and 70%RH for 24h to prepare HPC / PAM ion-conductive hydrogel.

[0059] The HPC / PAM ion-conducting hydrogel prepared in Example 3 has a tensile strength of 140 kPa and an electrical conductivity of 400 Sm. -1The adhesion is 24 kPa. The mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity. Among them, the stress-strain sensing current change rate is as high as 97%, the humidity sensing current change rate is as high as 16%, and the temperature response range is 10-60℃.

[0060] Example 4

[0061] This embodiment 4 provides a method for preparing HPC / PAM ion-conducting hydrogels, including the following steps:

[0062] Step 1: Add HPC to deionized water preheated to 60°C and mechanically stir for 40 min, then transfer to room temperature and stir for 20 h to obtain a 5% HPC solution.

[0063] Step 2: Add 8g of acrylamide monomer (AM) to 30g of the HEC solution, and then add 0.0055g of methylenebisacrylamide (MBA) and 0.05g of ammonium persulfate (APS) in sequence. Stir at room temperature for 2h to obtain HPC / AM solution.

[0064] Step 3: Place 30g of the HPC / AM solution in a 12cm diameter polytetrafluoroethylene mold and perform free radical polymerization at 65°C for 18h. Then, allow it to stand at room temperature for 12h to obtain HPC / PAM hydrogel.

[0065] Step 4: Add 70g of ferric chloride hexahydrate to 500ml of deionized water and stir at room temperature for 5 hours to obtain FeCl3 solution.

[0066] Step 5: Cut the HPC / PAM hydrogel into rectangles 4cm long and 3cm wide, place them in a 100mL beaker, add 35mL of the FeCl3 solution, soak for 30h, and then age for 24h at 20℃ and 70%RH to prepare HPC / PAM ion-conductive hydrogel.

[0067] The HPC / PAM ion-conducting hydrogel prepared in Example 4 has a tensile strength of 120 kPa and an electrical conductivity of 500 Sm. -1 The adhesion is 19 kPa. The mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity. Among them, the stress-strain sensing current change rate is as high as 80%, the humidity sensing current change rate is as high as 10%, and the temperature response range is 10-60℃.

[0068] Example 5

[0069] This embodiment 5 provides a method for preparing HPC / PAM ion-conducting hydrogels, including the following steps:

[0070] Step 1: Add HPC to deionized water preheated to 60°C and mechanically stir for 30 min, then transfer to room temperature and stir for 18 h to obtain a 1% HPC solution.

[0071] Step 2: Add 6g of acrylamide monomer (AM) to 20g of the HEC solution, and then add 0.02g of methylenebisacrylamide (MBA) and 0.08g of ammonium persulfate (APS) in sequence. Stir at room temperature for 1.5h to obtain HPC / AM solution.

[0072] Step 3: Place 20g of the HPC / AM solution in a polytetrafluoroethylene mold with a diameter of 9cm, and perform free radical polymerization at 60°C for 20h. Then, let it stand at room temperature for 20h to obtain HPC / PAM hydrogel.

[0073] Step 4: Add 30g of ferric chloride hexahydrate to 500ml of deionized water and stir at room temperature for 3 hours to obtain FeCl3 solution.

[0074] Step 5: Cut the HPC / PAM hydrogel into rectangles 3cm long and 2cm wide, place them in a 100mL beaker, add 28mL of the FeCl3 solution, soak for 32h, and then age for 20h at 25℃ and 70%RH to prepare HPC / PAM ion-conductive hydrogel.

[0075] The HPC / PAM ion-conducting hydrogel prepared in Example 4 has a tensile strength of 170 kPa and an electrical conductivity of 320 Sm. -1 The adhesion is 12 kPa. The mechanical and temperature and humidity sensors prepared by HPC / PAM ion-conductive hydrogel have good mechanical properties and high temperature and humidity response sensitivity. Among them, the stress-strain sensing current change rate is as high as 110%, the humidity sensing current change rate is as high as 20%, and the temperature response range is 10-60℃.

[0076] As attached Figure 1-2 As shown, attached Figure 1 SEM images of the HPC / PAM ion-conducting hydrogel prepared in Example 5 are provided, along with... Figure 2 The attached image shows a SEM image of the HPC / PAM ion-conducting hydrogel prepared in Example 5; from the attached image... Figure 1-2 As can be seen, HPC is uniformly distributed inside the composite hydrogel and forms a network structure, and the addition of HPC has no effect on the structure of PAM.

[0077] This invention relates to an HPC / PAM ion-conductive hydrogel, its preparation method, and its applications. HPC is uniformly distributed within the hydrogel in a network structure, resulting in better humidity sensing sensitivity compared to other hydrogels. Furthermore, HPC can exist in the hydrogel matrix as an aqueous solution, enhancing humidity sensitivity without affecting other material properties such as mechanical properties and transparency. The addition of FeCl3 to the HPC / PAM system, combined with the excellent water retention of both components, provides stable ion conductivity for the HPC / PAM hydrogel. By using PAM as the matrix, HPC as the temperature and humidity sensitive component, and FeCl3 as the conductive component, a flexible sensor material with stress-strain sensing and temperature and humidity sensing capabilities is prepared.

[0078] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for preparing an HPC / PAM ion-conducting hydrogel, characterized in that, include: Acrylamide monomer was mixed with hydroxypropyl cellulose solution, and crosslinking agent and initiator were added. The mixture was stirred to obtain HPC / AM solution. The HPC / AM solution was subjected to free radical polymerization, and after standing, HPC / PAM hydrogel was obtained. The HPC / PAM hydrogel was placed in FeCl3 solution, soaked, and aged to obtain HPC / PAM ion-conducting hydrogel. The preparation process of hydroxypropyl cellulose solution is as follows: Hydroxypropyl cellulose was added to preheated deionized water and stirred to disperse it. Then it was transferred to room temperature and stirred to obtain a hydroxypropyl cellulose solution. During the aging process, the aging temperature is 20-30℃, the relative humidity is 65-75%, and the aging time is 12-48h.

2. The method for preparing an HPC / PAM ion-conducting hydrogel according to claim 1, characterized in that, The crosslinking agent used is methylenebisacrylamide, and the initiator used is ammonium persulfate.

3. The method for preparing an HPC / PAM ion-conducting hydrogel according to claim 1, characterized in that, The process of subjecting the HPC / AM solution to free radical polymerization and allowing it to stand to obtain the HPC / PAM hydrogel is as follows: The HPC / AM solution was placed in a mold and subjected to free radical polymerization at 60-70°C for 10-20 hours, followed by standing at room temperature for 12-24 hours.

4. The method for preparing an HPC / PAM ion-conducting hydrogel according to claim 1, characterized in that, Soaking time is 12-36 hours.

5. An HPC / PAM ion-conducting hydrogel, characterized in that, The HPC / PAM ion-conducting hydrogel was prepared using the preparation method of HPC / PAM ion-conducting hydrogel as described in any one of claims 1-4.

6. The HPC / PAM ion-conducting hydrogel according to claim 5, characterized in that, The HPC / PAM ion-conductive hydrogel has a tensile strength of 100-200 kPa and an electrical conductivity of 300-500 Sm. -1 The adhesion is 5-30 kPa.

7. The application of the HPC / PAM ion-conducting hydrogel as described in claim 5 or 6, characterized in that, The HPC / PAM ion-conductive hydrogel was used as a flexible sensing material to prepare a flexible sensor.

8. The application of the HPC / PAM ion-conducting hydrogel as described in claim 7, characterized in that, The flexible sensor has a stress-strain sensing current change rate of 80%-110%, a humidity sensing current change rate of 10%-20%, and a temperature response range of 10-60℃.

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