Modified kappa-carrageenan as well as preparation method and application thereof

Abstract

The invention discloses modified kappa-carrageenan as well as a preparation method and application thereof, and belongs to the field of development and application of high polymer materials. The prepared modified carrageenan has quaternary ammonium groups with positive charges and sulfate radicals with negative charges at the same time, the sol-gel transition temperature of the carrageenan is remarkably reduced by regulating and controlling the acting force between molecular chains, flexible machinability is achieved, and meanwhile the mechanical strength of the carrageenan is enhanced. According to the modification strategy, efficient fixation of salt ions is achieved, and the material is endowed with excellent atmospheric water trapping capacity and stable moisture power generation performance. On the basis, an intelligent self-powered sensor is constructed, and real-time monitoring of the breathing state can be achieved. Based on the unique salt ion cross-linking characteristic of the kappa-carrageenan, the sol-gel transition temperature of the kappa-carrageenan is optimized, the machinability of the kappa-carrageenan is enhanced, the application of the kappa-carrageenan in the fields of moisture-related water drawing, power generation and sensing is expanded, and the kappa-carrageenan has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of development and application of polymer materials, and particularly relates to κ the modified preparation and application of kappa-carrageenan. Background Art

[0002] The sustainable development in the field of energy and environment and the innovation of intelligent wearable sensing technology have put forward an urgent demand for high-performance materials, and the role of material design in improving its performance and functional integration is crucial. Natural carrageenan, as a green matrix material, has received extensive attention due to its good biocompatibility, biodegradability, non-toxicity and diverse functional characteristics. Among them, κ a remarkable property of kappa-carrageenan is its thermoreversibility: it dissolves to form a homogeneous solution when heated, and forms a gel with a three-dimensional network structure when cooled to room temperature or lower. Therefore, its processing and application usually require strict control of temperature conditions. Dissolution requires heating to a relatively high temperature (usually ~70 °C), and during the cooling process, the gel formation rate is relatively fast, which may not be conducive to the preparation of complex geometric structures or high-precision materials. In particular, some functional components (such as proteins, enzymes or thermosensitive drugs) may be inactivated or degraded at high temperatures, which further limits κ the application of kappa-carrageenan in some biomedical fields. Therefore, regulating κ the sol-gel transition temperature of kappa-carrageenan is very important, which can ensure its dissolution and maintenance of liquid state at lower temperatures, reduce the dependence on high-temperature conditions, reduce energy consumption while shortening the processing time, achieve flexible processability, and thus expand its application in the fields of food, medicine and biomedicine.

[0003] In recent years, applications related to moisture, such as water absorption, power generation and sensing, have attracted more and more attention. Among them, combining hygroscopic salts with polymer matrices is a common method for designing hygroscopic materials. It is worth noting that due to the lack of interaction between salts and macromolecular chains, the salts embedded in the gel are easily leaked into the environment, resulting in the deterioration of the performance and corrosion of related devices. Therefore, how to stably lock salts in the gel and avoid salt leakage is still a challenge. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified κ kappa-carrageenan, and provide a preparation method and specific application of the modified κ kappa-carrageenan to make up for the deficiencies of the prior art.

[0005] In order to achieve the above purpose, the specific technical solutions provided by the present invention are as follows: The present invention regulates the κ sol-gel transition behavior of kappa-carrageenan, and uses molecular design for κ-Carrageenan is chemically modified to introduce positively charged groups, which changes the intermolecular forces and significantly reduces κ -The dissolution temperature of carrageenan, thus giving it flexible processability.

[0006] A modified κ - Carrageenan, modified κ -Carrageenan is made from κ -Carrageenan is modified by introducing positively charged groups.

[0007] The modification κ -Carrageenan (QKC) modification method is: κ -Carrageenan is heated and dissolved to prepare a carrageenan aqueous solution, and then sodium hydroxide is added. After stirring, a modifier capable of carrying out quaternary ammonium salt group is added, and the stirring and mixing reaction is continued. After the reaction is terminated, the product is dialyzed to remove unreacted substances and impurities, and the dialyzed sample is freeze-dried to obtain quaternary ammonium group-modified carrageenan (QKC).

[0008] Furthermore, the modification method is specifically as follows: dissolving carrageenan in deionized water, heating at 70°C, dispersing uniformly, and preparing a 0.1-10 wt% (preferably 3 wt%) solution; then adding sodium hydroxide to obtain a concentration of 0.5-5M, preferably 2 M), stirring for 30 min, adding epoxypropyl trialkylammonium chloride, and continuing to stir the reaction. Subsequently, the reaction mixture is diluted with water to terminate the reaction. The product is then transferred to a dialysis bag with a molecular weight cutoff of 3500-14000 and dialyzed in deionized water for 3-7 days to remove unreacted substances and impurities. Finally, the dialyzed sample is freeze-dried to obtain QKC. The sol-gel transition temperature of the QKC solution can be determined by observing the changes in the QKC solution in different temperature environments and combining it with DSC testing.

[0009] Furthermore, the modifier for introducing a quaternary ammonium salt group includes but is not limited to glycidyl trialkyl ammonium chloride, glycidyl dimethyl ammonium chloride, glycidyl trialkyl ammonium chloride, glycidyl triethylamine, glycidyl trimethyl ammonium bromide, glycidyl trimethyl ammonium sulfate, N, N, N-trimethyl-2, 3-epoxypropylamine hydrochloride and benzyl epoxy quaternary ammonium salt.

[0010] The modification κ - Application of carrageenan in the preparation of hydrogel or aerogel; the hydrogel or aerogel can be used for atmospheric water collection.

[0011] Preparation method of the QKC hydrogel or aerogel: Prepare a QKC sample solution, then perform low-temperature mold forming, then soak it in a hygroscopic salt solution, then rinse it with a large amount of deionized water, and then soak it in water to remove free salt ions; after removing the surface water, the QKC hydrogel can be obtained; further perform freeze-drying treatment on it to prepare the QKC aerogel.

[0012] Further, dissolve the QKC sample in deionized water, stir and disperse it evenly to obtain a solution with a concentration of 1−10 wt%. Then take the sample and transfer it to a polytetrafluoroethylene mold. After low-temperature forming, add a 0.1−10 M hygroscopic salt solution to soak it to promote the helix-helix aggregation of polymer molecular chains.

[0013] Further, the hygroscopic salts include: lithium chloride, lithium bromide, lithium sulfate, calcium chloride, calcium bromide, calcium sulfate, calcium nitrate.

[0014] The modified κ -carrageenan in the application of preparing self-powered devices.

[0015] Based on the modified κ -carrageenan self-powered device, using the modified κ -carrageenan as the matrix material, introducing hygroscopic salts, and effectively locking the hygroscopic salts through zwitterionic groups. The modified κ -carrageenan in the application of moisture power generation and intelligent sensing monitoring.

[0016] A preparation method of a QKC moisture power generation (QLMEG) device is as follows: The QKC hydrogel is used as the power generation material. The top electrode and the bottom electrode in the device are respectively selected as Ag and Cu. The power generation material is sandwiched between the Ag / Cu electrodes to obtain a QKC moisture power generation (QLMEG) device, which can obtain electrical energy by absorbing moisture and can utilize this characteristic to realize self-powered health monitoring.

[0017] Further, the top electrode and the bottom electrode are respectively selected as Ag and Cu, and these two electrodes can also be replaced with Pt, Au, Al, Ti.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows: The modified carrageenan prepared by the present invention simultaneously has quaternary ammonium groups with positive charges and sulfate groups with negative charges. By regulating the intermolecular forces, the sol-gel transition temperature of carrageenan is significantly reduced, achieving flexible processability while enhancing its mechanical strength. This modification strategy realizes the efficient fixation of salt ions, endowing the material with excellent atmospheric water capture ability (2.1 g g⁻¹) and stable moisture power generation performance (open circuit voltage up to 0.9 V). Based on this, an intelligent self-powered sensor is constructed, which can realize real-time monitoring of the breathing state.

[0019] Based on κ - the unique salt ion cross-linking characteristics of carrageenan, the κ - sol-gel transition temperature of carrageenan is optimized, its processability is enhanced, and its applications in moisture-related water extraction, power generation, and sensing fields are expanded, showing broad application prospects. Brief Description of the Drawings

[0020] Figure 1 It is the infrared spectrum of the QKC sample of the present invention and the KC sample in Comparative Example 1.

[0021] Figure 2 It is the XPS spectrum of the QKC sample of the present invention and the KC sample in Comparative Example 1.

[0022] Figure 3 It is the high-resolution XPS spectrum of N element of the QKC sample of the present invention.

[0023] Figure 4 It is the nuclear magnetic resonance hydrogen spectrum of the QKC sample of the present invention and the KC sample in Comparative Example 1.

[0024] Figure 5 It is the gel behavior change diagram of the 5 wt% QKC sample of the present invention and the 5 wt% KC sample in Comparative Example 1 at different temperatures.

[0025] Figure 6 It is the DSC spectrum of the QKC sample of the present invention and the KC sample in Comparative Example 1.

[0026] Figure 7 It is the compressive stress-strain curve of the QKC sample of the present invention and the KC sample in Comparative Example 1.

[0027] Figure 8 It is the comparison diagram of the moisture absorption performance of the QKC / LiCl aerogel of the present invention and the KC / LiCl aerogel in Comparative Example 1.

[0028] Figure 9 It is the moisture power generation performance of the QLMEG device of the present invention in different humidity environments.

[0029] Figure 10It is a data graph of the QLMEG device of the present invention for monitoring the breathing of different human states. Specific Embodiments

[0030] The present invention will be further explained and illustrated below through examples in conjunction with the accompanying drawings. Examples

[0031] 1. A preparation method of quaternary ammonium group modified carrageenan (QKC) is as follows: Take 3 g of carrageenan and dissolve it in 100 ml of deionized water, heat it at 70 °C, disperse it evenly, and prepare a 3 wt% solution. Then add 8 g of sodium hydroxide to obtain a concentration of 2 M, stir for 30 min, then add glycidyl trialkyl ammonium chloride, and continue to stir and react for 5 h. Subsequently, dilute the reaction mixture 3 times with water to terminate the reaction. Then transfer the product to a dialysis bag with a molecular weight cut-off of 3500 and dialyze it in deionized water for 5 days to remove unreacted substances and impurities. Finally, freeze-dry the dialyzed sample to obtain quaternary ammonium group modified carrageenan (QKC). The sol-gel transition temperature can be determined by observing the changes of the QKC solution in different temperature environments and combining DSC tests.

[0032] 2. Preparation method of QKC / LiCl hydrogel or QKC / LiCl aerogel: Dissolve 1 g of QKC sample in 20 ml of deionized water, stir and disperse it evenly to obtain a solution with a concentration of 5 wt%. Then take 1 ml of the sample and transfer it to a polytetrafluoroethylene mold. After low-temperature molding, add 1 ml of 4 M LiCl solution to soak it to promote the helix-helix aggregation of polymer molecular chains. Subsequently, rinse it with a large amount of deionized water and then soak it in water for 1 h to remove free LiCl. After removing the surface water, QKC / LiCl hydrogel can be obtained. Further perform freeze-drying treatment on it to prepare QKC / LiCl aerogel, which can be used for outdoor atmospheric water collection.

[0033] 3. Preparation method of QKC / LiCl moisture-powered electricity generation (QLMEG) device: Using the QKC / LiCl hydrogel as the power generation material, the top electrode and the bottom electrode in the device are respectively selected as Ag and Cu, and the power generation material is sandwiched between the Ag / Cu electrodes to obtain a QKC / LiCl moisture-powered electricity generation (QLMEG) device, which can obtain electric energy by absorbing moisture and can utilize this characteristic to realize self-powered health monitoring.

[0034] Comparative Example 1: The difference between this embodiment and Example 1 is that carrageenan (KC) is not chemically modified by the method 1, and KC is directly used for the operations of method 2 and method 3.

[0035] Performance testing and result analysis: Infrared tests were conducted on the QKC prepared in Example 1 and the KC sample in Comparative Example 1. As Figure 1 shown, a new peak appeared in the spectrum of QKC at 1475 cm −1 , attributed to the deformation vibration of the quaternary ammonium group. In addition, elemental analysis tests were conducted on the QKC prepared in Example 1. As Figure 2 and 3 shown, N element exists in QKC, and there are two peaks at 339.7 and 402.5 eV, corresponding to N−H and −N + (CH 3 ) 3 bonds. Further, a nuclear magnetic resonance hydrogen spectrum was performed on the QKC prepared in Example 1. As Figure 4 shown, a new peak attributed to −N + (CH 3 ) 3 was clearly observed at 3.13 ppm. These test results all indicate the presence of quaternary ammonium groups in QKC, and the chemical modification has successfully introduced positively charged quaternary ammonium groups.

[0036] The sol-gel transition behavior of the QKC prepared in Example 1 and the KC sample in Comparative Example 1 was tested. As Figure 5 shown, at 60 °C, both QKC and KC presented a sol state. When the temperature was below 50 °C, the KC sample no longer flowed and became a gel, while the QKC sample remained a flowing sol. Continuing to lower the temperature to 10 °C, QKC became a gel. Further DSC tests were conducted. As Figure 6 shown, an exothermic peak caused by the sol-gel transition could be clearly observed. Among them, the exothermic peak position of 5 wt% KC appeared at 44.5 °C, while the gelation temperature of the QKC sample decreased significantly to 8.5 °C. These results further indicate that the introduction of quaternary ammonium groups can significantly change the original gel behavior of KC and achieve the regulation of the gel-sol transition temperature.

[0037] Compression tests were conducted on the QKC prepared in Example 1 and the KC sample in Comparative Example 1. As Figure 7 shown, small cracks began to appear in the KC sample at 10% strain and it was completely broken after 40%. On the contrary, the QKC aerogel showed better compressive strength, and the compressive strength reached 796 kPa at 60% strain. The results show the high brittleness of KC, while the QKC aerogel has been well improved, showing better uniformity and flexibility.

[0038] The moisture absorption performance of the QKC / LiCl prepared in Example 1 and the KC / LiCl sample in Comparative Example 1 was tested. As Figure 8As shown, at 90% relative humidity, the maximum water vapor absorption of QKC / LiCl aerogel is 2.10 g g −1 , significantly higher than that of unmodified KC / LiCl aerogel, indicating the good moisture absorption performance of the QKC / LiCl aerogel prepared by the present invention.

[0039] The moisture power generation performance of the QLMEG device prepared in Example 1 was tested. As Figure 9 shown, in a low humidity environment of 30%, QLMEG can provide an open circuit voltage of 0.43 V. When absorbing moisture from high humidity air (90% RH), QLMEG can generate an open circuit voltage of up to 0.92 V. The results show that the QLMEG device prepared by the present invention has good moisture power generation performance and can generate electricity in a wide humidity range.

[0040] The application of the QLMEG device prepared in Example 1 in human respiration monitoring was tested. As Figure 10 shown, at different breathing frequencies, QLMEG can display the breathing signal in real time. During rapid breathing, QLMEG shows a rapid voltage response, while the voltage response during slow breathing is relatively slow. The results show that the QLMEG device prepared by the present invention can judge different breathing states through the response speed of the electrical signal and record the breathing frequency during movement and rest in real time.

[0041] Finally, although this specification is described according to the embodiments, not each embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A modification κ - Carrageenan, characterized in that The modification κ -Carrageenan is made from κ -Carrageenan is obtained by introducing positively charged groups into it and modifying it with quaternary ammonium groups.

2. The modification according to claim 1 κ - A method for modifying carrageenan, characterized in that: Will κ -Carrageenan is heated and dissolved, and prepared κ -carrageenan aqueous solution, then add sodium hydroxide, stir, then add a modifier capable of quaternary ammonium group modification, continue to stir and mix, after terminating the reaction, dialyze the product, and freeze-dry the dialyzed sample to obtain quaternary ammonium group modified κ -Carrageenan (QKC).

3. The modification method according to claim 2, characterized in that: The modifier for introducing quaternary ammonium salt groups includes one or more mixtures of glycidyl trialkyl ammonium chloride, glycidyl dimethyl ammonium chloride, glycidyl trialkyl ammonium chloride, glycidyl triethylamine, glycidyl trimethyl ammonium bromide, glycidyl trimethyl ammonium sulfate, N, N, N-trimethyl-2, 3-epoxypropylamine hydrochloride and benzyl epoxy quaternary ammonium salt.

4. The modification according to claim 1 κ - Application of carrageenan in the preparation of hydrogel or aerogel; the hydrogel or aerogel can be used for atmospheric water collection.

5. The use according to claim 4, characterized in that Preparation method of QKC hydrogel or aerogel: prepare QKC sample solution, then perform low-temperature mold forming, then add hygroscopic salt solution for immersion, then rinse with a large amount of deionized water, and then soak with water to remove free salt ions; after removing the surface water, QKC hydrogel is obtained; further freeze-drying the QKC hydrogel to obtain QKC aerogel.

6. The use according to claim 5, characterized in that The QKC sample was dissolved in deionized water and stirred to obtain a solution with a concentration of 1-10wt%. The sample was then transferred to a polytetrafluoroethylene mold and, after low-temperature molding, a 0.1-10M hygroscopic salt solution was added to promote the helix-helix aggregation of the polymer molecular chains.

7. The use according to claim 6, characterized in that The hygroscopic salts include: lithium chloride, lithium bromide, lithium sulfate, calcium chloride, calcium bromide, calcium sulfate, and calcium nitrate.

8. The modification according to claim 1 κ -Application of carrageenan in the preparation of self-powered devices.

9. The use according to claim 8, characterized in that Based on the modification κ -Carrageenan self-powered device, using the modified κ -Carrageenan is used as the matrix material, and hygroscopic salt is introduced. The hygroscopic salt is effectively locked through zwitterionic groups, so that it can be applied in moisture power generation and intelligent sensor monitoring.

10. The use according to claim 9, characterized in that A method for preparing a QKC moisture power generation device is as follows: the QKC hydrogel is used as a power generation material, and the power generation material is sandwiched between a top electrode and a bottom electrode to obtain a QKC moisture power generation device, which obtains electrical energy by absorbing moisture, and uses this characteristic to achieve self-powered health monitoring.

Images