A new type of low-temperature-resistant and super-long-stretchable organic ion gel

Abstract

The application discloses a novel low-temperature-resistant and super-long-stretchable organic ionic gel. The organic ionic gel is obtained by polymerization of a prepolymer solution; the composition of the prepolymer solution is as follows: 1) ethylene glycol, ionic liquid, acrylic acid, photoinitiator and crosslinking agent; 2) ethylene glycol, ionic liquid, acrylic acid, gelatin, photoinitiator and crosslinking agent. The organic ionic gel has excellent low-temperature resistance, and the strain reaches at least 346% (the highest value of a test device) at-50 DEG C, and is not obviously hardened compared with at room temperature. The organic ionic gel has super-long stretchability, and the strain can reach 6441% at room temperature by adjusting the content of the crosslinking agent and the gelatin. The organic ionic gel has stable effect, is not easy to volatilize, and can keep a flexible gel state for a long time in air. The preparation method and process of the organic ionic gel are simple, and the raw materials are cheap and easy to obtain.

Description

TECHNICAL FIELD

[0001] The present application relates to a novel low-temperature-resistant and super-long stretchable organic ionic gel. BACKGROUND

[0002] Flexible conductive materials have good flexibility, excellent mechanical properties, and high electrical conductivity, and have important applications in sensing technology, electronic skin, human-computer interaction, and intelligent wearable devices. Gel materials represented by hydrogels have excellent deformability, stretchability, and self-healing properties, and have broad application prospects in practical applications. However, most hydrogels are volatile, not resistant to low temperatures, and have insufficient stretchability, making them difficult to be applied to daily, long-term, and stable sensing responses at low temperatures, thereby greatly limiting their practical applications.

[0003] In recent years, the preparation of new gels as low-temperature-resistant and non-volatile flexible conductive materials has gradually attracted widespread attention in the academic community. Currently, there are two main methods to improve the performance of gels: hydrogel modification and ionic liquid gel. However, these two materials have the following problems: the hydrogel modification method usually dopes inorganic ions in the hydrogel, and reduces the melting point of the hydrogel through the colligative properties of the solution and the hydrophilic modification of the gel. However, due to the small influence, it cannot meet the needs of practical applications; ionic liquid gels have good thermal stability, low melting point, and high boiling point, and can have the advantages of low temperature resistance and non-volatility. However, due to the poor solubility of ionic liquids for monomer molecules, it is difficult to be compatible with traditional high polymer gel systems, so the application system is strictly limited.

[0004] "Skin-like mechanoresponsive self-healing ionic elastomer from supramolecular zwitterionic network" reports a hydrogel ionic skin prepared from polyacrylic acid (PAA) and betaine, which can realize elastic stretching and strain electrical response at low temperature. However, the stretchability of this material is not outstanding, and it is easy to harden at low temperature, resulting in small tensile strain.

[0005] In view of the above deficiencies of the prior art, there is an urgent need for a flexible conductive material with good frost resistance, wide application temperature, and super-long stretchability. SUMMARY

[0006] The present application aims to provide a novel low-temperature-resistant and super-long stretchable organic ionic gel, which has the advantages of simple preparation method, low-temperature resistance, super-long stretchability, and stable effect, and provides a basis for sensing applications based on flexible conductive materials.

[0007] The organic ionic gel provided by the application is low-temperature resistant and can be stretched for a long time, and is obtained by polymerization of a prepolymer solution;

[0008] The composition of the prepolymer solution is as follows 1) or 2):

[0009] 1) ethylene glycol, ionic liquid, acrylic acid, photoinitiator and crosslinking agent;

[0010] 2) ethylene glycol, ionic liquid, acrylic acid, gelatin, photoinitiator and crosslinking agent.

[0011] Preferably, the ionic liquid is 1-hexyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium hexafluorophosphate, etc.

[0012] Preferably, the photoinitiator is photoinitiator 2959, photoinitiator 1173, photoinitiator 184, etc.

[0013] Preferably, the crosslinking agent is N,N-methylene bisacrylamide, 2,2'-diallyl bisphenol A, p-divinylbenzene, etc.

[0014] The preparation method of the organic ionic gel provided by the application comprises the following steps:

[0015] S1, mixing the ethylene glycol, the ionic liquid, the acrylic acid, the gelatin, the photoinitiator and the crosslinking agent, and obtaining a prepolymer solution by heating;

[0016] S2, dropping the prepolymer solution into a mold, and performing polymerization under ultraviolet light.

[0017] In the above preparation method, the mass ratio of the ethylene glycol, the ionic liquid and the acrylic acid is as follows:

[0018] The mass ratio of the ethylene glycol and the ionic liquid can be 1-4:1, preferably 2:1;

[0019] The mass ratio of the ethylene glycol and the acrylic acid can be 1-5:1, preferably 5:3.

[0020] In the above preparation method, the mass of the gelatin is 0-30% of the total mass of the ethylene glycol and the ionic liquid, and specifically can be a range value composed of any two values of 5%, 10%, 20% and 30%.

[0021] In the above preparation method, the mass of the crosslinking agent is 0.1-0.4% of the mass of the acrylic acid, and specifically can be a range value composed of any two values of 0.1%, 0.2%, 0.3% and 0.4%.

[0022] The mass of the photoinitiator is 0.5-2% of the mass of the acrylic acid, preferably 0.5%, 1% or 2%, more preferably 1%.

[0023] In the preparation method, in step S1, the heating temperature is 60-70 DEG C, and the time is 1-3 hours.

[0024] In the preparation method, in step S2, the polymerization time is 0.5-1h.

[0025] In the preparation method, in step S2, the wavelength of the ultraviolet light can be 365nm.

[0026] The organic ion gel provided by the application can be used as a flexible conductive material, and can be applied to the fields of sensing technology, electronic skin, human-computer interaction and intelligent wearable devices.

[0027] The application has the following beneficial effects:

[0028] 1. The organic ion gel has excellent low-temperature resistance, and the strain at-50 DEG C is at least 346% (the maximum value of the test equipment), and there is no obvious hardening compared with room temperature.

[0029] 2. The organic ion gel has super-long tensile properties, and by adjusting the content of the crosslinking agent and the gelatin, the strain at room temperature can reach 6441%.

[0030] 3. The organic ion gel has stable effect and is not easy to volatilize, and can maintain a flexible gel state for a long time in the air.

[0031] 4. The preparation method and process of the organic ion gel are simple, and the raw materials are cheap and easy to obtain. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a preparation process schematic diagram of the organic ion gel.

[0033] Figure 2 It is a stress-strain curve of the organic ion gel prepared in Example 2 of the application at-50 DEG C, 25 DEG C and 50 DEG C.

[0034] Figure 3 It is a stress-strain curve of the organic ion gel prepared in Examples 1-4 of the application at room temperature.

[0035] Figure 4 It is a stress-strain curve of the organic ion gel prepared in Examples 1, 5-8 of the application at room temperature.

[0036] Figure 5Stress-strain curves of the organic ionogel materials prepared in Examples 2, 15-16 at room temperature.

[0037] Figure 6 Mass change of the organic ionogel prepared in Example 2 placed in air for different time (compared with a hydrogel of the same composition). DETAILED DESCRIPTION

[0038] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0039] The materials, reagents, etc. used in the following examples can be obtained commercially unless otherwise specified.

[0040] A schematic diagram of the method for preparing the organic ionogel provided by the present application is shown in Figure 1 .

[0041] Example 1,

[0042] (1) The raw materials used in this example are composed of the following components, in mass:

[0043]

[0044] (2) The preparation steps are as follows:

[0045] At room temperature, ethylene glycol (EG) and 1-hexyl-3-methylimidazolium chloride ([HMIm]Cl) are mixed as the "complex solvent" of the organic ionogel, and acrylic acid (AA) monomer, gelatin (GA), photoinitiator (I-2959), and crosslinking agent N,N-methylenebisacrylamide (MBA) are added. A pre-polymer solution of the organic ionogel is obtained by heating at 65°C for 2 hours with a magnetic stirring heating instrument, and the pre-polymer solution is dropped on a mold, and ultraviolet light is polymerized for 30 minutes to obtain the organic ionogel.

[0046] Example 2,

[0047] (1) The composition of the raw materials is basically the same as in Example 1, except that the amount of MBA is adjusted to 0.12 parts.

[0048] (2) The preparation method is the same as in Example 1.

[0049] Example 3,

[0050] (1) The composition of the raw materials is basically the same as in Example 1, except that the amount of MBA is adjusted to 0.18 parts.

[0051] (2) The preparation method is the same as in Example 1.

[0052] Example 4,

[0053] (1) The composition of the raw materials was substantially the same as in Example 1, except that the amount of MBA was adjusted to 0.24 parts.

[0054] (2) The preparation method was the same as in Example 1.

[0055] Example 5,

[0056] (1) The composition of the raw materials was substantially the same as in Example 2, except that no GA was added.

[0057] (2) The preparation method was the same as in Example 2.

[0058] Example 6,

[0059] (1) The composition of the raw materials was substantially the same as in Example 2, except that the amount of GA was adjusted to 7.5 parts.

[0060] (2) The preparation method was the same as in Example 2.

[0061] Example 7,

[0062] (1) The composition of the raw materials was substantially the same as in Example 2, except that the amount of GA was adjusted to 15 parts.

[0063] (2) The preparation method was the same as in Example 2.

[0064] Example 8,

[0065] (1) The composition of the raw materials was substantially the same as in Example 2, except that the amount of GA was adjusted to 45 parts.

[0066] (2) The preparation method was the same as in Example 2.

[0067] Example 9,

[0068] (1) The composition of the raw materials was substantially the same as in Example 2, except that [HMIm]Cl was adjusted to 1-butyl-3-methylimidazolium chloride.

[0069] (2) The preparation method was the same as in Example 2.

[0070] Example 10,

[0071] (1) The composition of the raw materials was substantially the same as in Example 2, except that [HMIm]Cl was adjusted to 1-hexyl-3-methylimidazolium hexafluorophosphate.

[0072] (2) The preparation method was the same as in Example 2.

[0073] Example 11,

[0074] (1) The composition of the raw materials was essentially the same as in Example 2, except that I-2959 was adjusted to be photoinitiator 1173.

[0075] (2) The preparation method was the same as in Example 2.

[0076] Example 12,

[0077] (1) The composition of the raw materials was essentially the same as in Example 2, except that I-2959 was adjusted to be photoinitiator 184.

[0078] (2) The preparation method was the same as in Example 2.

[0079] Example 13,

[0080] (1) The composition of the raw materials was essentially the same as in Example 2, except that MBA was adjusted to be 2,2'-diallyl bisphenol A.

[0081] (2) The preparation method was the same as in Example 2.

[0082] Example 14,

[0083] (1) The composition of the raw materials was essentially the same as in Example 2, except that MBA was adjusted to be p-divinyl benzene.

[0084] (2) The preparation method was the same as in Example 2.

[0085] Example 15,

[0086] (1) The composition of the raw materials was essentially the same as in Example 2, except that the amount of I-2959 was adjusted to be 0.3 parts.

[0087] (2) The preparation method was the same as in Example 2.

[0088] Example 16,

[0089] (1) The composition of the raw materials was essentially the same as in Example 2, except that the amount of I-2959 was adjusted to be 1.2 parts.

[0090] (2) The preparation method was the same as in Example 2.

[0091] The following analytical methods were used for all examples, unless otherwise specified.

[0092] Tensile properties: Organic ionogel materials measuring 30 mm × 10 mm × 2 mm were stretched at room temperature using Instron LEGEND 2367 at a stretching rate of 50 mm / min until fracture. Each material was tested three times, and the average tensile strain was recorded as shown in Table 1. Except for Examples 3 and 4, all tensile strains were above 2000%, demonstrating excellent tensile properties; among all examples, Example 2 exhibited the best tensile properties.

[0093] The stress-strain curves of the organic ionogel materials prepared in Examples 1-4 at room temperature are shown below. Figure 3 As shown, the stress-strain curves of the organic ionogel materials prepared in Examples 2 and 5-8 at room temperature are as follows. Figure 4 As shown, the stress-strain curves of the organic ionogel materials prepared in Examples 2 and 15-16 at room temperature are as follows. Figure 5 As shown. By Figure 3 It can be seen that as the MBA content gradually increases, the tensile properties of the organic ionic gel first increase and then decrease, achieving the best effect in the proportions of Example 2; Figure 4 It can be seen that as the GA content gradually increases, the tensile properties of the organic ionic gel first increase and then decrease, achieving the best effect in the proportions of Example 2; Figure 5 It can be seen that as the content of I-2959 increases, according to the free radical polymerization theory, the molecular weight of polyacrylic acid will gradually decrease, and the tensile properties of the organic ionic gel will first increase and then decrease, achieving the best effect in the proportion of Example 2.

[0094] Figure 2 The stress-strain curves of the organic ionogel material prepared in Example 2 are shown at -50℃, 25℃, and 50℃. The tensile strain of this organic ionogel material at both -50℃ and 50℃ is greater than 300%, demonstrating its high and low temperature resistance and good mechanical properties over a wide temperature range. The modulus of this organic ionogel material does not change significantly at -50℃ and 50℃, indicating that no gel phase transition occurs within the temperature range of -50℃ to 50℃, and it possesses stable mechanical properties.

[0095] Figure 6 The mass change of the organic ionic gel material prepared in Example 2 when placed in air for different times (compared with a hydrogel of the same composition, where the hydrogel of the same composition refers to replacing the ionic liquid and ethylene glycol in Example 2 with water of equal total mass, while other components are the same). Figure 6It can be proved that the solvent (ionic liquid, ethylene glycol) of the ionic gel hardly volatilizes in a long time, so that the gel remains elastic and tough, and the effect is stable; compared with the same composition of the water gel, the water in the water gel volatilizes a lot, causing serious performance loss.

[0096] Table 1 Tensile strain of organic ionic gels prepared in examples 1-8, 15-16 at room temperature

[0097] Example Tensile strain 1 2966％ 2 6441％ 3 979％ 4 627％ 5 2324％ 6 2380％ 7 2404％ 8 2142％ 15 3885％ 16 5704％

Claims

1. A low-temperature resistant, ultra-long stretchable organic ionic gel, obtained by prepolymer solution polymerization; The prepolymer solution is composed of: ethylene glycol, ionic liquid, acrylic acid, gelatin, photoinitiator and crosslinking agent; The ionic liquid is 1-hexyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, or 1-hexyl-3-methylimidazolium hexafluorophosphate; The photoinitiator is photoinitiator 2959, photoinitiator 1173, or photoinitiator 184; The crosslinking agent is N,N-methylenebisacrylamide, 2,2'-diallylbisphenol A, or p-divinylbenzene; The mass ratio of ethylene glycol to the ionic liquid is 1~4:1; The mass ratio of ethylene glycol to acrylic acid is 1~5:1; The mass of the gelatin is 0-30% of the total mass of the ethylene glycol and the ionic liquid. The mass of the crosslinking agent is 0.1~0.4% of the mass of the acrylic acid; The photoinitiator has a mass of 0.5% to 2% of the mass of acrylic acid.

2. The method for preparing the organic ionic gel according to claim 1, comprising the following steps: S1. The ethylene glycol, the ionic liquid, the acrylic acid, the gelatin, the photoinitiator, and the crosslinking agent are mixed and heated to obtain a prepolymer solution; S2. The prepolymer solution is dropped onto a mold and polymerized under ultraviolet light to obtain the final product.

3. The preparation method according to claim 2, characterized in that: In step S1, the heating temperature is 60°C. o C~70 o C, the time is 1 to 3 hours.

4. The preparation method according to claim 2 or 3, characterized in that: In step S2, the polymerization time is 0.5~1h.

5. The application of the organic ionogel of claim 1 as a flexible conductive material.

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