Preparation method and application of Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

Abstract

The present invention discloses a preparation method and application of Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range. The present invention adds 18-crown ether-6 with good solubility to glycerol or a glycerol-based mixture to solubilize potassium salt, and selects Kappa-carrageenan as a gel matrix, and dissolves the above components by heating, and a stable Kappa-carrageenan flexible conductive organic gel can be obtained after cooling. The organic gel prepared by the present invention still maintains good flexibility after being refrigerated for 24 hours under an environment of 80°C, and can be stably present for a long time in a high temperature environment of up to 80°C, while having better mechanical and conductive properties. The preparation method of the present invention is simple, efficient, and low-cost, and can have a relatively broad application prospect in extremely harsh environments and flexible electronic devices.

Description

Technical Field

[0001] The invention relates to the technical field of organic gels, and in particular to a preparation method and application of Kappa-carrageenan flexible conductive organic gel applicable to an ultra-wide temperature range. Background Art

[0002] In recent years, with the continuous development of multifunctional hydrogels, hydrogels have been widely used in many fields. Due to their good flexibility and conductivity, hydrogels have been widely used as flexible conductive materials and flexible wearable devices in signal detection, battery and capacitor development. However, the operating temperature range of hydrogels is usually narrow. For example, they will freeze and lose flexibility at temperatures of -10°C and below, and at temperatures of 50°C and above, the water evaporates quickly and has poor dimensional stability. Therefore, traditional conductive hydrogels face huge challenges in practical applications.

[0003] In view of the above technical problems, the use of organic solvents with higher boiling points and lower freezing points to prepare conductive gels is a new alternative. Organic solvents usually do not have the ability to conduct electricity and require the additional introduction of inorganic salt electrolytes. According to the colligative properties of dilute solutions, the dissolution of inorganic salt electrolytes will further reduce the freezing point and boiling point of organic solvents. The solubility of inorganic salt electrolytes in organic solvents is usually low, so improving the solubility of inorganic salt electrolytes in organic solvents is the key technical problem to be solved first. On the other hand, the formation of oil gels also requires polymer compounds that can spontaneously form gels in organic solvents. Natural polysaccharides such as agar, agarose, iota-carrageenan and Kappa carrageenan can form cross-linked gel networks in aqueous solutions through hydrogen bonding, but there are few reports on the technology of forming oil gels in pure organic solvents.

[0004] Carrageenan, also known as carrageenan, is a polysaccharide extracted from the cell walls of red algae marine plants such as Gelidium agar and Staghorn. Its skeleton structure is formed by alternating 1,3-β-D galactose and 1,4-α-D galactose. The types of κ-, ι-, and λ-carrageenan can be distinguished according to the number of sulfate groups on galactose. The hydrogel formed by κ-carrageenan is a hard gel, while the gel formed by ι-carrageenan is a soft gel. Unlike κ-carrageenan, ι-carrageenan tends to produce a more elastic gel. However, both hydrogels will lose water seriously if left at room temperature for a long time. As the water evaporates, the gel will become very hard. In the case of low temperature, it will freeze, resulting in the loss of its softness and biocompatibility. For example, the hydrogel prepared by Kappa-carrageenan is easy to freeze at -20°C and lose its elasticity.

[0005] Glycerol is a polyol with good antifreeze properties and a high boiling point, but there has been no report on glycerol-based Kappa-carrageenan conductive organogels.

[0006] Chinese invention patent CN114835943A discloses a novel method for preparing organic gel, which achieves antifreeze, conductive and stretchable properties through specific chemical reactions and material combinations. The stability and mechanical properties of the gel are improved by utilizing the hydrogen bonding between nanocellulose and lipoic acid in the glycerol system. The conductivity of the gel is improved by introducing nanogold, and the cross-linking of the gel is achieved by introducing ferric chloride. Although the patent points out that the gel has good antifreeze properties, its stability and durability in extreme environments (such as extremely high or extremely low temperatures) have not yet been clarified.

[0007] Chinese invention patent CN116063700A discloses a highly antifreeze self-conductive hydrogel with an inorganic-organic double cross-linked network structure and a preparation method thereof. In the presence of an alcohol solvent, the method mixes an iron salt solution with an aqueous solution of ammonium molybdate, and stirs them thoroughly until they become viscous and form a gel. The alcohol solvent in the system is ethylene glycol and / or propylene glycol. The invention belongs to a binary organic hydrogel system, and the gel shows good water retention and antifreeze properties in the temperature range of -20°C to 60°C. However, its low temperature resistance range is narrow, and its mechanical properties are not clear, and its application field is narrow.

[0008] Chinese invention patent CN114516936A discloses an antifreeze conductive gel composed of bacterial cellulose, acrylates, carbon nanotubes, ionic liquids, glycerol and deionized water; the ionic liquid is an imidazole ionic liquid. The antifreeze conductive gel here has good stability and mechanical properties, can be used for operation at low temperatures, and has good conductivity under low temperature conditions. However, its preparation process includes multiple steps such as carbon nanotube modification, polymerization cross-linking reaction and glycerol solvent replacement, which increases the complexity and control difficulty of the preparation process, and the gel can only resist freezing at a minimum of -40°C. Due to the use of ionic liquids and carbon nanotube materials, the cost is high and the economic benefit is low. Some strong oxidizing and corrosive chemical reagents used in the preparation process, such as concentrated sulfuric acid and concentrated nitric acid, are also dangerous.

[0009] Chinese invention patent CN117659274A discloses a method for preparing gel by polymerization reaction of acrylamide, QBV reagent (refer to Chinese invention patent CN112110947A), N, N'methylenebisacrylamide, 2-hydroxy-2-methylpropiophenone, ethylene glycol and triethylamine under nitrogen atmosphere protection and ultraviolet light for 8 hours. The obtained gel has the characteristics of heat resistance and high strength. Compared with hydrogel, it has higher environmental stability and wider application range. However, the organogel does not show obvious antifreeze performance, but only shows antifreeze effect at -20°C, and the preparation process of the gel is cumbersome and time-consuming.

[0010] Chinese invention patent CN109796621A discloses an antifreeze high-strength supramolecular organic hydrogel and its preparation method; a binary solvent water-glycerol system with antifreeze properties is combined with a high-strength supramolecular hydrogel; a gelatin pre-hydrogel is soaked in a water-glycerol mixed solution of sodium citrate, and part of the water molecules in the gelatin pre-gel is replaced by glycerol to form an organic hydrogel, and the gelatin molecular chains produce hydrophobic associations, and the Cit 3- NH 3+ Supramolecular interactions such as ion coordination are generated, and the mechanical properties of the gel are enhanced, resulting in an antifreeze high-strength supramolecular organic hydrogel. The resulting organic hydrogel can maintain good flexibility at -80°C and has good performance in extreme low-temperature environments, but the patent requires an additional solvent replacement step, and the final water content in the gel is as high as 30wt% or more. Since the boiling point of water is only 100°C, it is easy to evaporate and dehydrate at higher ambient temperatures. Finally, the patent does not involve research on dimensional stability in high-temperature environments, which limits its application at higher temperatures.

[0011] Therefore, it is of great significance to develop a simple preparation method, and the prepared gel can be both antifreeze and conductive. Summary of the invention

[0012] In order to overcome the above-mentioned defects and deficiencies in the prior art, the present invention provides a preparation method and application of Kappa-carrageenan flexible conductive organic gel suitable for an ultra-wide temperature range. Compared with hydrogel, the Kappa-carrageenan flexible conductive organic gel of the present invention will not dehydrate and deform below an ambient temperature of 80°C. Due to the addition of potassium salt, the interior of the organic gel is a double network system cross-linked by hydrogen bonds and potassium ions, and the structure is stable and not easy to decompose. And by introducing the crown ether system, the ion content can be increased, and the two systems of carrageenan-potassium ion and crown ether-potassium ion can be constructed at the same time, so that potassium ions can dynamically compete in the two systems, thereby improving the conductive properties of the organic gel.

[0013] The first object of the present invention is to provide a composition for preparing Kappa-carrageenan flexible conductive organic gel.

[0014] The second object of the present invention is to provide a blended system prepared from the above composition.

[0015] The third object of the present invention is to provide a method for preparing Kappa-carrageenan flexible conductive organic gel.

[0016] The fourth object of the present invention is to provide a Kappa-carrageenan flexible conductive organic gel prepared by the above-mentioned preparation method.

[0017] The fifth object of the present invention is to provide the application of the above-mentioned Kappa-carrageenan flexible conductive organic gel in flexible electronic devices.

[0018] Therefore, the present invention claims the following:

[0019] A composition for preparing a Kappa-carrageenan flexible conductive organic gel, the composition comprising Kappa-carrageenan, potassium salt and an alcohol organic solvent;

[0020] The volume fraction of glycerol in the alcohol organic solvent is not less than 85%;

[0021] The dosage ratio of the potassium salt, Kappa-carrageenan and alcohol organic solvent is 0.02-0.06 g: 0.1 g: 10 mL.

[0022] Preferably, the composition further comprises a crown ether.

[0023] Preferably, the molar ratio of the potassium salt to the crown ether is 2-8 mol:1 mol.

[0024] More preferably, the molar ratio of the potassium salt to the crown ether is 2 mol:1 mol.

[0025] By adding 18-crown ether-6 as a solubilizer for potassium ions and utilizing the selective complexation characteristics of crown ether holes for ions, when the crown ether is added to the system and complexed with ions, more ions can be brought into the organic reagent, thereby increasing the concentration of metal ions in the organic reagent.

[0026] More preferably, the molar ratio of the potassium salt to 18-crown ether-6 is 4 mol:1 mol, and the usage ratio of the potassium salt, Kappa-carrageenan and alcohol organic solvent is 0.02 g:0.1 g:10 mL;

[0027] The molar ratio of the potassium salt to 18-crown ether-6 is 2 mol:1 mol, and the usage ratio of the potassium salt, Kappa-carrageenan and alcohol organic solvent is 0.04-0.06 g:0.1 g:10 mL.

[0028] Preferably, the inorganic metal salt is a soluble potassium salt other than potassium sulfate, potassium persulfate, potassium tert-butoxide and potassium hydroxide.

[0029] More preferably, the potassium salt is any one of potassium bromide, potassium chloride, potassium iodide, potassium nitrate, potassium citrate, potassium carbonate, potassium phosphate, potassium ferrocyanide trihydrate, potassium dichromate, anhydrous dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium polyacrylate, potassium antimony tartrate, potassium sodium tartrate tetrahydrate, potassium sorbate, potassium ferrocyanide or potassium ferrate.

[0030] Preferably, the alcohol organic solvent is a mixture of any one of polyethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, dipropylene glycol or 1,2,4-butanetriol with a number average molecular weight not exceeding 600 and glycerol, wherein the volume fraction of glycerol is 85% to 100% by volume.

[0031] Preferably, the crown ether is 18-crown-6.

[0032] The blended system prepared from any of the above compositions: after the composition is fully mixed, it is heated at 94-98° C. to fully dissolve.

[0033] Preferably, the sufficient mixing is stirring at 24-26° C. for 8-12 min.

[0034] More preferably, the sufficient mixing is stirring at 24-26° C. for 10 min.

[0035] Preferably, the heating is carried out by stirring and heating in an oil bath at 95-97° C., so that the solution is free of particles.

[0036] More preferably, the heating time is 28 to 32 minutes.

[0037] More preferably, the heating time is 30 minutes.

[0038] A method for preparing a Kappa-carrageenan flexible conductive organic gel is provided. The Kappa-carrageenan flexible conductive organic gel is obtained by cooling the above-mentioned blending system.

[0039] Preferably, the mixture is cooled at 24-26° C., and then demolded to obtain the Kappa-carrageenan flexible conductive organic gel.

[0040] The Kappa-carrageenan flexible conductive organic gel prepared by the above preparation method.

[0041] The application of the above-mentioned Kappa-carrageenan flexible conductive organic gel in flexible electronic devices.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention discloses a preparation method and application of a Kappa-carrageenan flexible conductive organic gel suitable for an ultra-wide temperature range. In the present invention, 18-crown ether-6 with good solubility is added to glycerol or a glycerol-based mixture to solubilize potassium salt, and Kappa-carrageenan is selected as a gel matrix. The above components are dissolved by heating, and a stable Kappa-carrageenan flexible conductive organic gel can be obtained after cooling. After the Kappa-carrageenan flexible conductive organic gel prepared by the present invention is refrigerated for 24 hours at -30°C and -80°C, the gel does not freeze, the softness is still excellent, and the transparency is very high. At the same time, it also has better conductive and mechanical properties, wherein the conductivity can reach 3.3mS / m, and when stretched at -30°C, the gel tensile strength can reach an average of 64-141kPa, the elongation at break can reach an average of 93-165%, and the work of fracture can reach an average of 4098-12827KJ / m 3 , Young's modulus reaches between 75 and 209 kPa. In addition, after adding crown ether, the melting temperature of the gel increases, which enhances the environmental tolerance of the organogel.

[0044] Therefore, the Kappa-carrageenan flexible conductive organic gel of the present invention has the characteristics of high temperature resistance and ultra-low temperature resistance, which is conducive to the application of the gel in more severe environments.

[0045] Compared with Chinese invention patent CN114835943A, Chinese invention patent CN116063700A, Chinese invention patent CN117659274A and Chinese invention patent CN109796621A, the Kappa-carrageenan flexible conductive organic gel prepared by the present invention has the advantages of a wide temperature application range (-80°C to 85°C), a simple operation process and a wide application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 1 after being stored at -30°C and -80°C for 24 hours.

[0047] Figure 2 This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 2 after being stored at -30°C and -80°C for 24 hours.

[0048] Figure 3 This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 3 after being stored at -30°C and -80°C for 24 hours.

[0049] Figure 4This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 4 after being stored at -30°C and -80°C for 24 hours.

[0050] Figure 5 This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 5 after being stored at -30°C and -80°C for 24 hours.

[0051] Figure 6 This is a test chart of the softness of the Kappa-carrageenan flexible conductive organogel prepared in Example 6 after being stored at -30°C and -80°C for 24 hours.

[0052] Figure 7 This is a test chart of the softness of the carrageenan hydrogel prepared in Comparative Example 2 after being stored at -30°C and -80°C for 24 hours.

[0053] Figure 8 This is a test chart of the softness performance of the Kappa-carrageenan organogel prepared in Comparative Example 4 after being stored at -30°C and -80°C for 24 hours.

[0054] Fig. 9 This is a test chart of the softness performance of the Kappa-carrageenan organogel prepared in Comparative Example 5 after being stored at -30°C and -80°C for 24 hours.

[0055] Fig.10 This is a test chart of the softness performance of the Kappa-carrageenan organogel prepared in Comparative Example 6 after being stored at -30°C and -80°C for 24 hours. DETAILED DESCRIPTION

[0056] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0057] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0058] The use of glycerol is for illustrative purposes only, and other mixed alcohol organic solvents may also be used. The mixed alcohol organic solvent that can replace glycerol is a mixture of any one of polyethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, dipropylene glycol or 1,2,4-butanetriol having a number average molecular weight not exceeding 600 and glycerol, wherein the volume fraction of glycerol is 85% to 100% by volume.

[0059] For the convenience of weighing, the masses of 18-crown-6, 15-crown-5 and other chelating agents were calculated according to the molar ratio, and 4 significant figures were retained after the decimal point.

[0060] Example 1 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0061] S1. Add 0.1 g (precisely weighed to 0.001 g) of Kappa-carrageenan powder and 0.02 g of potassium chloride powder to 10 mL of glycerol and stir at room temperature for 10 min to obtain KC-Gly-P 0.2 Prepare solution;

[0062] S2. KC-Gly-P 0.2 The preliminary solution was placed in an oil bath at 95-97°C and stirred and heated until the solution was free of particles, thereby obtaining KC-Gly-P 0.2 Hot solution;

[0063] S3. KC-Gly-P 0.2 The hot solution is taken out from the oil bath, quickly poured into a mold, cooled at room temperature, and the Kappa-carrageenan flexible conductive organic gel is obtained after demolding.

[0064] Example 2 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0065] The difference between this embodiment and embodiment 1 is that a macrocyclic polyether (18-crown ether-6) is added in step S1, and the molar ratio of 18-crown ether-6 to potassium chloride is 1:2, that is:

[0066] S1. Add 0.0355 g 18-crown ether-6, 0.02 g potassium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir at room temperature for 10 min to obtain KC-Gly-18C 1 / 2 -P 0.2 Prepare solution;

[0067] Step S2 and step S3 are the same as those in Embodiment 1.

[0068] Example 3 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0069] The difference between this embodiment and embodiment 1 is that a macrocyclic polyether (18-crown ether-6) is added in step S1, and the molar ratio of 18-crown ether-6 to potassium chloride is 1:4, that is:

[0070] S1. Add 0.0177 g 18-crown ether-6, 0.02 g potassium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir to dissolve at room temperature for 10 min to obtain KC-Gly-18C1 / 4 -P 0.2 Prepare solution;

[0071] Step S2 and step S3 are the same as those in Embodiment 1.

[0072] Example 4 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0073] The difference between this embodiment and embodiment 1 is that a macrocyclic polyether (18-crown ether-6) is added in step S1, and the molar ratio of 18-crown ether-6 to potassium chloride is 1:8, that is:

[0074] S1. Add 0.0089 g 18-crown ether-6, 0.02 g potassium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir to dissolve at room temperature for 10 min to obtain KC-Gly-18C 1 / 8 -P 0.2 Prepare solution;

[0075] Step S2 and step S3 are the same as those in Embodiment 1.

[0076] Example 5 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0077] The difference between this embodiment and embodiment 1 is that the concentration of potassium chloride in step S1 is 0.4 wv%, and a macrocyclic polyether (18-crown ether-6) is added, and the molar ratio of 18-crown ether-6 to potassium chloride is 1:2, that is:

[0078] S1. Add 0.0710 g 18-crown ether-6, 0.04 g potassium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder into 10 mL glycerol and stir to dissolve at room temperature for 10 min to obtain KC-Gly-18C 1 / 2 -P 0.4 Prepare solution;

[0079] Step S2 and step S3 are the same as those in Embodiment 1.

[0080] Example 6 A Kappa-carrageenan flexible conductive organic gel suitable for ultra-wide temperature range

[0081] The difference between this embodiment and embodiment 1 is that the concentration of potassium chloride in step S1 is 0.6 wv%, and a macrocyclic polyether (18-crown ether-6) is added, and the molar ratio of 18-crown ether-6 to potassium chloride is 1:2, that is:

[0082] S1. Add 0.1064 g 18-crown ether-6, 0.06 g potassium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir to dissolve at room temperature for 10 min to obtain KC-Gly-18C 1 / 2 -P 0.6 Prepare solution;

[0083] Step S2 and step S3 are the same as those in Embodiment 1.

[0084] Example 7 Antifreeze Performance Test

[0085] 1. Experimental Methods

[0086] The Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 was placed in a -30°C and -80°C freezing layer of a refrigerator for 24 hours. After 24 hours, the softness of the Kappa-carrageenan flexible conductive organic gel was measured. If the Kappa-carrageenan flexible conductive organic gel could be bent without breaking, it was considered to have an antifreeze effect at this temperature.

[0087] 2. Experimental Results

[0088] The softness test results of the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 after refrigeration at -30°C and -80°C for 24 hours are as follows: Figures 1 to 6 As shown. Figures 1 to 6 It can be seen that the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 still has good softness after being placed at -30°C and -80°C for 24 hours, and always maintains a transparent state at low temperatures, indicating that the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 has good antifreeze properties.

[0089] Compared with traditional Kappa-carrageenan hydrogel, it can be found that Kappa-carrageenan flexible conductive organic gel has excellent antifreeze properties. This is because the organic solvent propylene glycol is an excellent antifreeze solvent, and there are many hydroxyl groups inside propylene glycol, which can form abundant hydrogen bonds with Kappa-carrageenan.

[0090] Example 8 Mechanical Properties

[0091] 1. Experimental Methods

[0092] The Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 was transferred to a -30°C refrigerator for 24 hours, and then the two ends of the Kappa-carrageenan flexible conductive organic gel were wrapped with cut paper pieces. The samples were tensile tested using a high and low temperature electronic universal testing machine of Shenzhen Sansi Zongheng Technology Co., Ltd. The stretching speed was 100mm / min, and the end of the fracture was judged to be when the difference between the rear and front forces was greater than 0.5N. The temperature in the high and low temperature constant temperature box was set to -30°C, and each sample was kept at a constant temperature for 15 minutes before testing and then stretched. Each Kappa-carrageenan flexible conductive organic gel was repeated for 3 samples, and then the tensile strength, work at break, elongation at break, and Young's modulus of the Kappa-carrageenan flexible conductive organic gel were obtained.

[0093] 2. Experimental Results

[0094] Since there is a strong hydrogen bond between glycerol and Kappa-carrageenan, it is helpful for the formation of gel. At the same time, due to the low freezing point of glycerol, the Kappa-carrageenan flexible conductive organic gel has antifreeze properties. And because of the unique double helix structure of Kappa-carrageenan flexible conductive organic gel, the gel has a certain softness and tensile properties. Therefore, in order to evaluate the mechanical properties of the organic gel in a sub-zero temperature environment, the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 was placed at -30°C to measure the mechanical properties of the gel, mainly in the tensile mode, to explore the changes in the internal hydrogen bond strength of the gel under the refrigerated environment.

[0095] The mechanical data of the Kappa-carrageenan flexible conductive organogels prepared in Examples 1 to 6 are shown in Table 1. It is worth noting that the organogels do not freeze or turn white at low temperatures, and the organogels can still maintain good flexibility at -30°C and -80°C, and can withstand large deformations including twisting or bending.

[0096] The results show that the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 is stretched at -30°C, and the gel tensile strength can reach an average of 64 to 141 kPa, the elongation at break can reach an average of 93 to 165%, and the work of fracture can reach an average of 4098 to 12827 kJ / m 3 , Young's modulus reaches between 75 and 209 kPa.

[0097] Table 1 Mechanical properties of Kappa-carrageenan flexible conductive organogels prepared in Examples 1 to 6

[0098]

[0099]

[0100] Example 9 Conductive Properties

[0101] 1. Experimental Methods

[0102] The conductivity of the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 was tested by a digital universal instrument. Three samples of each Kappa-carrageenan flexible conductive organic gel (size 30 mm × 10 mm × 2 mm) were repeated, and the Kappa-carrageenan flexible conductive organic gel was fixed and clamped at both ends of the electrode clamp, and the voltage was set to 5 V. Then the resistance value (Ω) of the Kappa-carrageenan flexible conductive organic gel at room temperature was obtained, and the conductivity (σ) of the sample was calculated as follows:

[0103] σ=d / (R×A);

[0104] d: distance between adjacent electrodes (0.02 m), R: resistance of Kappa-carrageenan flexible conductive organogel sample (Ω), A: cross-sectional area of ​​Kappa-carrageenan flexible conductive organogel (0.00002 m 2 ).

[0105] 2. Experimental Results

[0106] The results are shown in Table 2. The conductivity of the Kappa-carrageenan flexible conductive organic gel was tested at room temperature. It can be seen from Table 2 that under room temperature, the addition of 18-crown ether-6 can increase the electrolyte loading of the Kappa-carrageenan flexible conductive organic gel and significantly improve the conductivity. According to the results of the Kappa-carrageenan flexible conductive organic gel in Examples 2, 5 and 6, when the molar ratio of 18-crown ether-6 to potassium chloride is 1:2, as the content of potassium ions increases, the conductivity of the Kappa-carrageenan flexible conductive organic gel also increases. And at the same concentration of inorganic salts, the addition of crown ethers has no significant enhancement effect on conductivity.

[0107] Table 2 Conductive properties of Kappa-carrageenan flexible conductive organogels prepared in Examples 1 to 6

[0108]

[0109] Example 10 Characteristic Temperature Determination

[0110] 1. Experimental Methods

[0111] The melting temperature and solidification temperature of the sample were determined by using a high-precision thermostatic bath. Accurately weigh the Kappa-carrageenan flexible conductive organic gel prepared in Examples 1 to 6 in a beaker, dissolve it in an oil bath at 95°C, and put it into a glass test tube after the organic gel is completely dissolved. Then cool the high-precision thermostatic bath to 20°C, and immerse the above glass test tube in a high-precision low-temperature thermostatic bath and keep it at a constant temperature for 20 minutes. Put glass beads with a diameter of about 4 mm into the glass test tube containing the organic gel, and heat it at a rate of 1°C / min. When the organic gel in the glass test tube melts again, the rigid ball begins to fall. The temperature when the rigid ball falls to the bottom of the glass test tube is defined as the melting temperature of the organic gel. To avoid experimental errors, all experimental data measurements were repeated three times and the average value was taken.

[0112] 2. Experimental Results

[0113] The results are shown in Table 3. As shown in Table 3, the addition of crown ether can significantly increase the melting temperature of the Kappa-carrageenan flexible conductive organogel, and the Kappa-carrageenan flexible conductive organogel prepared in Examples 1 to 6 has a significant increase compared to the organogel without adding potassium ions (melting temperature: 75.76±0.17°C), indicating that the presence of crown ether and potassium ions does strengthen the intermolecular forces in the organogel, thereby increasing the melting temperature of the organogel.

[0114] Table 3 Characteristic temperature of Kappa-carrageenan flexible conductive organogels prepared in Examples 1 to 6

[0115]

[0116] Example 11 Kappa-carrageenan flexible conductive organic gel

[0117] According to Table 4, 18-crown-6, potassium salt powder and Kappa-carrageenan powder (KC) were weighed and added to 10 mL of alcohol organic solvent, the molar ratio of 18-crown-6 to potassium salt was 1:2, and stirred at room temperature for 10 minutes to make the solution dispersed evenly, and then placed in an oil bath at 95-97°C for stirring and heating for 30 minutes to make the solution particle-free, and a hot solution was prepared. The hot solution was taken out of the oil bath pot, cooled to room temperature, and the inversion method was used to determine whether the gel was formed (inverted for 10 minutes, the gel had no flow phenomenon), and the results are shown in Table 4.

[0118] The Kappa-carrageenan organogel prepared in this embodiment was subjected to antifreeze performance test, mechanical performance test, electrical conductivity test and characteristic temperature measurement according to the methods of Examples 7 to 10. The results show that the Kappa-carrageenan flexible conductive organogel prepared in this embodiment is not much different from that prepared in Examples 1 to 6 in terms of antifreeze performance, mechanical properties and electrical conductivity, and is not much different from that prepared in Example 2 in terms of characteristic temperature.

[0119] Table 4 Kappa-carrageenan flexible conductive organic gel

[0120]

[0121] Comparative Example 1

[0122] According to Table 5, the chelating agent, potassium chloride powder and Kappa-carrageenan powder (KC) were weighed and added to 10 mL of glycerol, and stirred at room temperature for 10 minutes to make the solution dispersed evenly, and then placed in an oil bath at 95-97°C for stirring and heating for 30 minutes to make the solution free of particles, thereby preparing a hot solution. The hot solution was taken out of the oil bath pot, placed at room temperature to cool to room temperature, and the inversion method was used to determine whether a gel was formed (inverted for 10 minutes, the gel had no flow phenomenon), and the visual method was used to determine whether there was a precipitate, and whether the chelating agent, Kappa-carrageenan powder, and potassium chloride powder had dissolved. The results are shown in Table 5.

[0123] Table 5 Effect of chelating agent on the formation of potassium salt-containing organic gel

[0124]

[0125] Comparative Example 2

[0126] Take 0.1g Kappa-carrageenan powder (precisely weighed to 0.001g) and 0.02g potassium chloride, add 10.00mL deionized water, stir at room temperature for 10min to obtain a preliminary solution. Place the preliminary solution in a water bath at 95-97°C and stir and heat for 30min, so that the solution is transparent without particles, and a hot solution is prepared. Take the hot solution out of the water bath, quickly pour it into the mold, cool it at room temperature, and remove the mold to obtain the carrageenan hydrogel.

[0127] The hydrogel was placed in -30℃ and -80℃ environments for antifreeze performance testing. The results showed that the prepared carrageenan hydrogel would freeze and could not bend or perform large-scale behaviors ( Figure 7 ).

[0128] Comparative Example 3

[0129] According to Table 6, the chelating agent, sodium chloride powder and Kappa-carrageenan powder (KC) were weighed and added to 10 mL of glycerol, and stirred at room temperature for 10 minutes to make the solution uniformly dispersed, and then placed in an oil bath at 95-97°C for stirring and heating for 30 minutes to make the solution non-granular, and a hot solution was prepared. The hot solution was taken out of the oil bath pot, placed at room temperature and cooled to room temperature, and the inversion method was used to determine whether a gel was formed (inverted for 10 minutes, the gel had no flow phenomenon), and the visual method was used to determine whether there was a precipitate, and whether the chelating agent, Kappa-carrageenan powder, and sodium chloride powder had dissolved. The results are shown in Table 6.

[0130] Table 6 Effect of chelating agent on the formation of sodium salt-containing organic gel

[0131]

[0132] Comparative Example 4

[0133] The difference between this comparative example and Example 1 is that potassium chloride is replaced by sodium chloride in step S1, that is:

[0134] S1. Add 0.1 g (precisely weighed to 0.001 g) of Kappa-carrageenan powder and 0.03 g of sodium chloride powder to 10 mL of glycerol and stir at room temperature for 10 min to obtain KC-Gly-S 0.3 Prepare solution;

[0135] S2. KC-Gly-S 0.3 The preliminary solution was placed in an oil bath at 95-97°C and stirred and heated until the solution was free of particles, thereby obtaining KC-Gly-S 0.3 Hot solution;

[0136] S3. KC-Gly-S 0.3 The hot solution is taken out from the oil bath, quickly poured into a mold, cooled at room temperature, and Kappa-carrageenan organogel is obtained after demolding.

[0137] Comparative Example 5

[0138] The difference between this comparative example and comparative example 4 is that a macrocyclic polyether (15-crown ether-5) is added in step S1, and the molar ratio of 15-crown ether-5 to sodium chloride is 1:8, that is:

[0139] S1. Add 0.0141 g 15-crown ether-5, 0.03 g sodium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir at room temperature for 10 min to obtain KC-Gly-15C 1 / 8 -S 0.3 Prepare solution;

[0140] Step S2 and step S3 are the same as those in Comparative Example 4.

[0141] Comparative Example 6

[0142] The difference between this comparative example and comparative example 4 is that the concentration of sodium chloride in step S1 is 0.6 wv%, a macrocyclic polyether (15-crown ether-5) is added, and the molar ratio of 15-crown ether-5 to sodium chloride is 1:8, that is:

[0143] S1. Add 0.0283 g 15-crown ether-5, 0.06 g sodium chloride powder, and 0.1 g (precisely weighed to 0.001 g) Kappa-carrageenan powder to 10 mL glycerol and stir at room temperature for 10 min to obtain KC-Gly-15C 1 / 8 -S 0.6 Prepare solution;

[0144] Step S2 and step S3 are the same as those in Comparative Example 4.

[0145] Comparative Example 7

[0146] The difference between this comparative example and Example 1 is that potassium chloride is replaced by anhydrous lithium chloride, that is:

[0147] S1. Add 0.1 g (precisely weighed to 0.001 g) of Kappa-carrageenan powder and 0.03 g of anhydrous lithium chloride powder to 10 mL of glycerol and stir at room temperature for 10 min to obtain KC-Gly-L 0.3 Prepare solution;

[0148] S2. KC-Gly-L 0.3 The preliminary solution was placed in an oil bath at 95-97°C and stirred and heated until the solution was free of particles, thereby obtaining KC-Gly-L 0.3 Hot solution;

[0149] S3. KC-Gly-L 0.3 The hot solution is taken out from the oil bath, quickly poured into a mold, cooled at room temperature, and Kappa-carrageenan organogel is obtained after demolding.

[0150] Comparative Example 8

[0151] The difference between this comparative example and comparative example 7 is that the concentration of anhydrous lithium chloride is 0.6wv%, that is:

[0152] S1. Add 0.06g of anhydrous lithium chloride powder and 0.1g (precisely weighed to 0.001g) of Kappa-carrageenan powder to 10mL of glycerol and stir and dissolve at room temperature for 10min to obtain KC-Gly-L 0.6 Prepare solution;

[0153] Step S2 and step S3 are the same as those in Comparative Example 7.

[0154] Comparative Example 9

[0155] The difference between this comparative example and comparative example 7 is that the concentration of anhydrous lithium chloride is 1.1 wv%, that is:

[0156] S1. Add 0.11g of anhydrous lithium chloride powder and 0.1g (precisely weighed to 0.001g) of Kappa-carrageenan powder to 10mL of glycerol and stir at room temperature for 10min to obtain KC-Gly-L 1.1 Prepare solution;

[0157] Step S2 and step S3 are the same as those in Comparative Example 7.

[0158] Performance Testing

[0159] The antifreeze performance of the Kappa-carrageenan organogels prepared in Comparative Examples 4 to 6 was tested according to the method of Example 7. The results are as follows: Figures 8 to 10 The results show that the Kappa-carrageenan organogels prepared in Comparative Examples 4 to 6 still have good softness after being placed at -30°C and -80°C for 24 hours, and always maintain a transparent state at low temperatures, indicating that the Kappa-carrageenan organogels prepared in Comparative Examples 4 to 6 have good antifreeze properties.

[0160] The mechanical properties, electrical conductivity and characteristic temperature of the Kappa-carrageenan organogels prepared in Comparative Examples 4 to 9 were measured according to the methods of Examples 8 to 10, respectively. The mechanical properties and electrical conductivity of the Kappa-carrageenan organogels prepared in Comparative Examples 4 to 9 were inferior to those of the Kappa-carrageenan flexible conductive organogels prepared in Examples 1 to 6. The characteristic temperature results are shown in Table 7.

[0161] Table 3 shows that in the preparation of Kappa-carrageenan flexible conductive organogel, 18-crown ether-6 can combine well with potassium ions to form organogel and can increase the content of potassium ions in the organogel. For EDTA, potassium sodium tartrate tetrahydrate and sodium tetraborate decahydrate, when the molar ratio of chelating agent to potassium salt is 1:1, organogel can be formed, but the loading amount of electrolyte in the organogel cannot be increased, which may be caused by the incomplete combination of chelating agent and potassium ions.

[0162] Table 6 and Comparative Examples 4 to 6 show that among many chelating agents, only 15-crown ether-5 can combine with sodium ions to form an organogel; when the chelating agent is potassium sodium tartrate tetrahydrate, the organogel can be formed probably because the presence of potassium ions promotes the cross-linking of the carrageenan organogel. When the sodium ions increase, the salting-out effect of the sodium salt occurs, and the formation of the organogel is inhibited.

[0163] However, it can be seen from Table 7 that the addition of sodium ions or lithium ions will reduce the characteristic temperature of the organogel. Even after the addition of 15-crown ether-5 to the sodium salt organogel, the melting temperature of the organogel is still lower than that of KC-Gly-S 0.3 In Comparative Examples 4 to 9, the melting temperature of the organogels showed a downward trend after the electrolyte was replaced with sodium chloride or anhydrous lithium chloride. This may be because sodium salts and lithium salts in the organogels are similar to those in the hydrogel system, and are weakly bound to carrageenan, and reduce the intermolecular forces of the organogels. This also shows that for Kappa-carrageenan organogels, only potassium ions can be used to obtain Kappa-carrageenan organogels with higher melting temperatures.

[0164] Table 7 Characteristic temperatures of Kappa-carrageenan organogels prepared in Comparative Examples 4 to 9

[0165]

[0166]

[0167] Comparative Example 10

[0168] According to Table 8, rubidium salt powder and Kappa-carrageenan powder (KC) were weighed and added to 10 mL of glycerol, and stirred at room temperature for 10 minutes to make the solution evenly dispersed, and then placed in an oil bath at 95-97°C for stirring and heating for 30 minutes to make the solution free of particles, thereby preparing a hot solution. The hot solution was taken out of the oil bath pot, cooled to room temperature, and the inversion method was used to determine whether a gel was formed (inverted for 10 minutes, the gel had no flow phenomenon), and the results are shown in Table 8.

[0169] The results in Table 8 show that rubidium salts cannot form organogels when mixed with Kappa-carrageenan and glycerol at low content. The results also show that not all alkaline metal salts can be used as electrolyte media for organogels; in the glycerol system, Kappa-carrageenan is still a marine polysaccharide that is sensitive to potassium ions.

[0170] Table 8 Effect of rubidium salt on the formation of organic gel

[0171] name Rubidium salt type Rubidium salt / g KC / g Glycerol / mL Phenomenon KC-Gly-RbCl Rb 0.02 0.1 10 No gel <![CDATA[KC-Gly-RbNO3]]> <![CDATA[RbNO3]]> 0.02 0.1 10 No gel

[0172] Comparative Example 11

[0173] According to Table 9, the chelating agent, lithium nitrate powder and Kappa-carrageenan powder (KC) were weighed and added to 10 mL of glycerol, and stirred at room temperature for 10 minutes to make the solution uniformly dispersed, and then placed in an oil bath at 95-97°C for stirring and heating for 30 minutes to make the solution non-granular, and a hot solution was prepared. The hot solution was taken out of the oil bath pot, cooled to room temperature, and the inversion method was used to determine whether the gel was formed (inverted for 10 minutes, the gel had no flow phenomenon), and the visual method was used to determine whether there was a precipitate, and whether the chelating agent, Kappa-carrageenan powder, and lithium nitrate powder had dissolved. The results are shown in Table 9.

[0174] The results in Table 9 show that it is still difficult for lithium ions to form an organogel with high transparency (i.e., the chelate can be completely dissolved) after adding most chelating agents; that is, most chelating agents cannot combine with lithium salts to form an organogel. When the chelating agent is potassium sodium tartrate tetrahydrate, the organogel can be formed probably because the presence of potassium ions promotes the cross-linking of the carrageenan organogel.

[0175] Table 9 Effect of chelating agent on the formation of lithium salt-containing organic gel

[0176]

[0177] 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A composition for preparing a Kappa-carrageenan flexible conductive organic gel, characterized in that: The composition contains Kappa-carrageenan, potassium salt, crown ether and alcohol organic solvent; The volume fraction of glycerol in the alcohol organic solvent is not less than 85%; The potassium salt, Kappa-carrageenan and alcohol organic solvent are used in a ratio of 0.02-0.06 g: 0.1 g: 10 mL; The molar ratio of the potassium salt to the crown ether is 2-8 mol:1 mol; The crown ether is 18-crown-6; The potassium salt is any one of potassium bromide, potassium chloride, potassium iodide, potassium nitrate, potassium citrate, potassium carbonate, potassium phosphate, potassium ferrocyanide trihydrate, potassium dichromate, anhydrous dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium polyacrylate, potassium antimony tartrate, potassium sodium tartrate tetrahydrate, potassium sorbate, potassium ferrocyanide or potassium ferrate; The alcohol organic solvent is a mixture of any one of polyethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, dipropylene glycol or 1,2,4-butanetriol with a number average molecular weight not exceeding 600 and glycerol, wherein the volume fraction of glycerol is 85% to 100% by volume.

2. The blending system prepared from the composition according to claim 1, characterized in that: After the composition is thoroughly mixed, heat at 94-98°C to fully dissolve.

3. A method for preparing a Kappa-carrageenan flexible conductive organic gel, characterized in that: The Kappa-carrageenan flexible conductive organic gel is obtained by cooling the blended system described in claim 2.

4. The Kappa-carrageenan flexible conductive organic gel prepared by the preparation method according to claim 3.

5. Use of the Kappa-carrageenan flexible conductive organic gel according to claim 4 in flexible electronic devices.

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