JP2011236320A - Ion liquid-retaining material, method for producing the same, and ionically electroconductive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ionically electroconductive material having a high stability by introducing a tertiary boron to glucose-based polysaccharides and then mixing with ionic liquid.SOLUTION: The composition is provided by having a composition having a substrate material obtained by reacting a borane compound consisting of hydroborane or an alkoxy borane toward the glucose-based polysaccharides having the glucose as a constituting unit, i. e., with substantially all of the free OH that the glucose-based polysaccharide has, and the ionic liquid. For example, as shown by chemical reaction formula, the ionically electroconductive material is the composition of: a compound 22 obtained by reacting mesityl borane 15 with an amylose derivative 21; and the ionic liquid.

Description

  The present invention relates to an ionic liquid holding material, a manufacturing method thereof, and an ion conductive material.

  An ionic liquid is a general term for salts that become liquid around room temperature. Generally, salts are known to be solid at room temperature, as represented by NaCl, and have a high melting temperature of several hundred degrees Celsius or higher. However, it has been found that by designing an ionic structure that weakens the interaction between ions and is difficult to crystallize, the melting point can be remarkably lowered and a salt that becomes liquid at room temperature (ie, an ionic liquid) can be created.

  Since the ionic liquid which is stable to water and air and has a melting point of room temperature or lower has been reported (Non-patent Document 1), research and application development have been actively promoted. Since ionic liquids have properties such as flame retardancy and volatility, they are less likely to scatter in the environment and can be recycled, attracting attention as environmentally friendly green solvents.

  Furthermore, at present, research and development for using ionic liquids as electrolytes for solar cells, fuel cells, capacitors, lithium secondary batteries, etc. are actively carried out, and as promising materials in the fields of chemistry, electricity, automobiles, etc. Expected. Moreover, it can also apply to a touch panel, an antistatic agent, an electrochromic element, etc. using the electroconductivity.

In recent years, lithium ion secondary batteries have been used as power sources for portable electronic devices such as mobile phones and laptop computers, and are also being considered for use in hybrid vehicles and electric vehicles. On the other hand, many issues have been piled up to improve safety so that battery recalls are frequently reported, and improvements in both safety and functionality of electrolytes for lithium ion secondary batteries are desired. . One solution is the use of flame retardant ionic liquids and the introduction of boron. By adding a boron compound that is a Lewis acid to the electrolyte, it is expected that a single ion conductor having both high ionic conductivity and lithium ion transport number can be obtained by promoting salt dissociation while trapping anions. The present inventors thought that it was possible. Examples of introducing boron into an ionic liquid include (1) an imidazolium-based ionic liquid having an anion receptor (Non-patent Document 2), and (2) a zwitterionic ionic liquid containing a highly dissociable borate (Non-patent Document 3). Etc. The compound presented in Non-Patent Document 2 exhibits a lithium ion transport number of 0.67 at room temperature, and the compound presented in Non-Patent Document 3 exhibits an ionic conductivity of 3.00 × 10 ⁻⁵ S / cm at 50 ° C. The lithium ion transport number was 0.69 at room temperature.

J. S. Wilkes and M. J. Zaworotko, Chem. Commun. 1992, 965. N. Matsumi, M. Miyake, and H. Ohno, Chem. Commun. 2004, 2852. A. Narita, W. Shibayama, K. Sakamoto, T. Mizuno, N. Matsumi and H. Ohno, Chem. Commun. 2006, 1926. R. D. Swatloski, S. K. Spear, J. D. Holbrey, and R. D. Rogers, J. Am. Chem. Soc. 2002, 124, 4974. T. Hirata, K. E. Werner, J. Appl.Polym. Sci. 1987, 33, 1533. N. Matsumi. Y. Nakamura, K. Aoi, T. Watanabe, T. Mizumo and H. Ohno, Polym. J. 2009, 41, 437. H. Zhang, J. Wu, J. Zhang, and J. He, Macromolecules 2005, 38, 8272.

  In recent years, the synthesis of materials using plant-derived biosources has been encouraged for environmental considerations. On the other hand, many plant-derived polymers generally have problems such as thermal stability. Thus, the high crystallinity and low solubility make chemical modification difficult.

  Roger et al. Reported that 1-butyl-3-methylimidazolium chloride, which is an ionic liquid, can be dissolved by heating cellulose to about 100 ° C. (Non-patent Document 4). It has also been reported that thermal stability is imparted by surface treatment of cellulose with boric acid (Non-patent Document 5).

From these facts, it can be expected that a polymer electrolyte having excellent thermal stability and ion conduction characteristics can be obtained by introducing boron into cellulose dissolved in an ionic liquid. In recent years, the present inventors have synthesized an ionic gel having a highly dissociable pentafluorophenyl borate salt by condensing cellulose and boric acid in an ionic liquid, and have a high ionic conductivity exceeding 10 ⁻⁴ Scm ^−1. (Non-patent document 6).

By the way, when boric acid is introduced into the glucose-based polysaccharide, quaternary boron (B ⁻ ) is formed. However, considering application to ion-conductive materials, if tertiary boron could be introduced, it would be more advantageous for selective ion transport, and a new material with tertiary boron instead of quaternary boron was studied. .

  In the present invention, in view of the above problems, an ionic liquid holding material capable of obtaining a highly stable ionic conductive material by introducing tertiary boron into a glucose-based polysaccharide and mixing with the ionic liquid. Providing is a problem to be solved. Furthermore, another object to be solved is to provide an ion conductive material formed using the ionic liquid holding material.

  The feature of the ionic liquid holding material of the present invention according to claim 1 that solves the above-described problem is that the glucose-based polysaccharide having glucose as a constituent unit is substantially free of free OH groups of the glucose-based polysaccharide. In particular, it is a composition having a base material obtained by reacting a borane compound composed of hydroborane or alkoxyborane.

  The ionic liquid holding material of the present invention according to claim 2 which solves the above-mentioned problem is characterized in that, in claim 1, the glucose polysaccharide is amylose, cellulose, amylopectin, glycogen, dextrin, cyclodextrin, dextran, pullulan. And one or more compounds selected from the group consisting of curdlan.

  The feature of the ionic liquid holding material of the present invention according to claim 3 that solves the above-mentioned problem is that, in claim 2, the glucose polysaccharide is amylose, and the glucose that the amylose has before the borane compound is reacted. The purpose is to introduce a protective group into the 6-position OH group in the structure.

  The feature of the ionic liquid holding material of the present invention according to claim 4 that solves the above-mentioned problem is that, in claim 2, the glucose polysaccharide is cellulose, and the cellulose is dissolved in cellulose before the borane compound is reacted. It is dissolved in the agent.

  The feature of the ionic liquid holding material of the present invention according to claim 5 that solves the above-mentioned problem is that, in any one of claims 1 to 4, the borane compound is mesityl borane or mesityl dimethoxy borane. .

  A feature of the ionic conductive material according to a sixth aspect of the present invention that solves the above-described problem resides in having the ionic liquid holding material according to any one of the first to fifth aspects and the ionic liquid.

  The feature of the ion conductive material of the present invention according to claim 7 which solves the above-mentioned problem is that, in claim 6, it further has a lithium salt.

The characteristics of the manufacturing method of the ionic liquid holding material of the present invention according to claim 8 that solves the above-mentioned problem include a dissolving step of dissolving a glucose-based polysaccharide having glucose as a structural unit in a dissolving agent to form a polysaccharide solution; ,
And a reaction step of reacting substantially all of the free OH groups of the glucose-based polysaccharide with a borane compound composed of hydroborane or alkoxyborane.

  The feature of the method for producing an ionic liquid holding material of the present invention according to claim 9 that solves the above-mentioned problem is that, in claim 8, the glucose polysaccharide is amylose, and the amylose is reacted before reacting the borane compound. The present invention has a protective group introduction step of introducing a protective group into the OH group at the 6-position in the glucose structure possessed by.

  A feature of the method for producing an ionic liquid holding material of the present invention according to claim 10 that solves the above-mentioned problem is that, in claim 9, the borane compound is mesitylborane or mesityldimethoxyborane.

  ADVANTAGE OF THE INVENTION According to this invention, the ionic liquid holding | maintenance material which has a novel compound which introduce | transduced tertiary boron with respect to glucose type polysaccharide, and an ion conductive material using the same can be provided. By introducing tertiary boron into the glucose-based polysaccharide, an ion conductive material having high ionic conductivity and high thermal stability can be provided.

It is a graph which shows the cellulose concentration dependence of ionic conductivity in an Example. The VFT plot was performed about the graph shown in FIG. It is a graph which shows the lithium salt density | concentration dependence of ion conductivity in an Example. The VFT plot was performed about the graph shown in FIG. It is a graph which shows the boron addition amount dependence of ion conductivity in an Example. The VFT plot was performed about the graph shown in FIG. It is a graph which shows the ionic conductivity at the time of using the compound 7 as an ionic liquid in an Example. It is a graph which shows the ionic conductivity at the time of using the compound 22, an ionic liquid, and lithium salt in an Example. It is a graph which shows the thermal stability at the time of using the compound 22, an ionic liquid, and lithium salt in an Example.

  The ionic liquid holding material and ionic conductive material of the present invention will be described in detail below based on the embodiments. The ion conductive material of this embodiment can be used as an electrolyte for solar cells, fuel cells, capacitors, lithium secondary batteries and the like. Furthermore, it can apply to a touch panel, an antistatic agent, an electrochromic element, etc. using the electroconductivity.

(Ionic liquid holding material and manufacturing method thereof)
The ionic liquid holding material of the present embodiment can stably hold the ionic liquid by mixing with the ionic liquid. The ionic liquid holding material of this embodiment can provide an ion conductive material having excellent thermal stability by containing boron. In the ionic liquid holding material of the present embodiment, a borane compound composed of hydroborane or alkoxyborane is added to substantially all of the free OH groups of the glucose polysaccharide with respect to the glucose polysaccharide having glucose as a structural unit. It is a composition which has a base material obtained by making it react. When the borane compound is bonded to a free OH group having a glucose-based polysaccharide, the free OH group is substantially not contained.

  It is sufficient for the glucose-based polysaccharide to have a free OH group that is a functional group with which the borane compound reacts. For example, the glucose-based polysaccharide includes one or more compounds selected from the group consisting of amylose, cellulose, amylopectin, glycogen, dextrin, cyclodextrin, dextran, pullulan, and curdlan. Particularly preferred are amylose and cellulose. Furthermore, as long as the glucose-based polysaccharide has a free OH group, a part of the OH group may be modified. For example, in the case where the substituent itself such as hydroxyethyl cellulose, hydroxypropyl cellulose, etc. has an OH group, or in cyanoethyl cellulose, carboxymethyl cellulose, ethyl cellulose, propyl cellulose, methyl cellulose, etc., the introduction amount of the substituent is set so as to leave a free OH group The thing which was done is mentioned.

  The degree of polymerization of monosaccharides (the number of glucose residues) in glucose-based polysaccharides is not particularly limited, and the physical performance required for ionic liquid holding materials and ionic conductive materials to be finally produced, and the production thereof You can choose from the ease of doing. For example, it can be expected that the mechanical strength increases as the degree of polymerization increases. On the contrary, if the degree of polymerization is reduced, it can be expected that the viscosity when applied to an ion conductive material is reduced. Furthermore, if the degree of polymerization is reduced, it can be expected that the handling of the ionic liquid holding material is facilitated.

  It is desirable that the glucose-based polysaccharide is dissolved by some kind of solubilizer when the borane compound is reacted. The reaction can be advanced by bringing the borane compound into contact with the glucose-based polysaccharide dissolved in a solubilizer.

  The solubilizer is appropriately selected according to the type of glucose polysaccharide. When amylose is used as the glucose-based polysaccharide, various ionic liquids including imidazolium halide ionic liquids (including imidazolium formate ionic liquids, imidazolium phosphate ionic liquids), dimethyl sulfoxide (DMSO) ), Pyridine and the like can be exemplified as the solubilizer. Moreover, the solubility of amylose can also be improved by adding lithium salt (LiCl, LiBr, etc.) with respect to these solubilizers. Since the lithium salt has a high ionization tendency and has a high dissociation property and easily generates anions, the hydrogen bonds can be effectively broken by the action of the generated anions, and the solubility in a dissolving agent is improved.

  When cellulose is used as the glucose-based polysaccharide, an ionic liquid such as an imidazolium halide ionic liquid, an imidazolium formate ionic liquid, an imidazolium phosphate ionic liquid, or the like, DMSO, N, What added lithium salt (LiCl, LiBr, etc.) with respect to solvents, such as N-dimethylformamide, can be employ | adopted as a solubilizer. Moreover, the solubility of a cellulose can also be improved by adding lithium salt also with respect to the above-mentioned ionic liquid. As for glucose-based polysaccharides other than amylose and cellulose, those described above can be appropriately employed as a solubilizer.

  Among glucose residues possessed by glucose-based polysaccharides, those having a free OH group at the 6-position of glucose (amylose, cellulose, etc.) utilize the difference in reactivity between the 6-position OH group and other OH groups. Thus, the free OH group at the 6-position can be selectively protected from the reaction of the borane compound. By protecting the OH group at the 6-position, there is only a maximum of two free OH groups per glucose residue. For example, when a protective group is introduced into the 6-position free OH group with respect to amylose, the free OH group remains in the state adjacent to the 2-position and 3-position, and a bifunctional compound is adopted as the borane compound. , The probability of completion with adjacent OH groups is increased rather than the borane compound progressing across molecules, and a linear polymer that can be dissolved in a solvent is obtained as an ionic liquid holding material or ionic conductive material It becomes possible to do so.

  In addition to the reaction capable of distinguishing the OH group at the 6-position from other OH groups, the glucose polysaccharide possesses by introducing a protective group in an amount smaller than the number of free OH groups possessed by the glucose polysaccharide. The amount of free OH groups can be controlled. By controlling the amount of free OH groups, it is possible to control the degree of crosslinking of the ionic liquid holding material or ion conductive material produced and the amount of boron introduced.

As a method for protecting the OH group, a general protecting group for the OH group can be employed. For example, those in which a trityl group is introduced by reacting with triphenylchloromethane, carboxylic acid ester protection using various carboxylic acids or acyl halides (such as cellulose acetate in which acetic acid as a carboxylic acid is introduced into cellulose), nitric acid / those nitrification OH groups by utilizing the mixed acid of sulfuric acid (such as those with nitrocellulose perform nitrification to cellulose), introducing -O-SO 3 _Na in place of the OH group by reaction with SO 3 _/ base which _was, after dissolving cellulose in (concentrated sodium hydroxide which was introduced -O-CS-SNa instead OH groups by reaction with CS 2 / NaOH, etc. is reacted with carbon disulfide. viscose during rayon production intermediate), guiding the -OSO ₂ R instead of an OH group by reaction with _R-SO 2 Cl / base (R is an alkyl group) of Which was, that the cyanoethyl ether groups _(-OCH 2 _CH 2 CN) in place of the OH group by reaction with acrylonitrile in place of the OH groups by silyl protection with a silane coupling agent such as TMSCl or TBSCl, - Examples thereof include those in which an OSiMe ₃ group or an -OSiMe ₂ (t-Bu) group is introduced.

  The borane compound is selected from hydroborane and alkoxyborane. Hydroborane is a compound having a B—H bond, and a trifunctional (having three B—H bonds) hydroborane, bifunctional hydroborane, monofunctional hydroborane, and the like can be employed. By changing the functional group bonded to the boron atom, the functional group can be introduced into the produced ionic liquid holding material or ion conductive material. Since the trifunctional borane compound and the bifunctional borane compound can react with a plurality of OH groups, the reacting OH groups can be changed by controlling the reaction conditions. For example, by reacting with OH groups present in different molecules, the different molecules can be cross-linked. Intermolecular cross-linking does not proceed by reacting a bifunctional borane compound between adjacent OH groups (for example, between the 2-position and 3-position of the same glucose residue). In particular, when a trifunctional borane compound (borane) is used, a gel-like substance in which different molecules are cross-linked is obtained in most cases.

  Examples of the trifunctional hydroborane include borane and diborane. Borane can form a complex with a Lewis base as shown below to enhance stability. Borane / tetrahydrofuran complex, borane / pyridine complex, borane / tert-butylamine complex, borane / dimethylsulfide complex, borane / ammonia complex, borane / trimethylamine complex, borane / triethylamine complex, borane / dimethylamine complex, borane / diethylamine complex, borane・ Diisopropylamine complex, borane / ethyldiisopropylamine complex, borane / piperidine complex, borane / morpholine complex, borane / 4-methylmorpholine complex, borane / 4-ethylmorpholine complex, borane / diethylaniline complex, borane / oxathian complex, borane -Triphenylphosline complex, borane-tributylphosline complex, borane-lutidine complex, etc. Bifunctional hydroboranes include pyrrolylborane, mesitylborane, tripyrborane, texylborane, isopinocampheylborane, and various complexes thereof. Examples of monofunctional hydroboranes include 9-borabicyclononane, diciamylborane, dicyclohexylborane, dimesitylborane, catecholborane, diisopinocampheylborane, and various complexes thereof. Examples of the alkoxyborane include mesityldimethoxyborane, trimethoxyborane, triethoxyborane, tripropoxyborane, triisopropoxyborane, tributoxyborane, and tritert-butoxyborane. The hydroborane is preferably a borane complex, mesitylborane, or mesityldimethoxyborane.

(Ion conductive material and manufacturing method thereof)
The ion conductive material of this embodiment has the ionic liquid holding material and the ionic liquid described above. The ionic liquid is not particularly limited, but N (CF ₃ SO ₂ ) ⁻ , BF ₄ ⁻ , PF based on pyridinium cation, imidazolium cation, ammonium cation, pyrrolidinium cation, piperidinium cation, phosphonium cation ^{_{6 -, B (CN) 4}} -, [(C 2 F 5) 3 PF 3] -, [(CN) 2 N] -, CF 3 SO 3 -, CF 3 CO 2 -, N (FSO 2) 2 ^In particular, it is desirable to use imidazolium TFSA, imidazolium PF ₆ and imidazolium BF ₄ for reasons of ion conductivity and thermal stability.

  When the ionic liquid is used as a cellulose solubilizer in the production of the ionic liquid holding material, an imidazolium halide ionic liquid, an imidazolium formate ionic liquid, or an imidazolium phosphate ionic liquid is employed. be able to.

It is desirable that the ion conductive material of this embodiment further has a lithium salt. The lithium salt is not particularly limited. Examples include LiCl, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiSbF ₆ , LiSCN, LiClO ₄ , and LiAlCl ₄ . Among these, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ From the viewpoint of electrical characteristics, it is preferable to use one or more salts selected from the group consisting of (SO ₂ ) (C ₄ F ₉ SO ₂ ), and further LiN (CF ₃ SO ₂ ) ₂ (hereinafter referred to as “LiTFSA”). Is preferably used). Note that lithium salts include those that are ionic liquids.

  When lithium salt is mixed or dissolved with an ion conductive material, the ion conductivity is improved. For example, when manufacturing an ionic liquid holding material, a lithium salt can be contained by making a lithium salt coexist. Furthermore, the base material and the lithium salt can be dissolved or dispersed in a solvent that does not cause an undesirable reaction with respect to both the ionic liquid holding material and the lithium salt, and then mixed. After mixing is completed, the lithium ion conductive material in which the lithium salt is dispersed can be obtained by removing the solvent. Since general lithium salts are easily affected by moisture, the solvent is removed in a dry atmosphere. Here, as a solvent desirable when producing a lithium ion conductive material, a solvent that does not react with a lithium salt can be selected from among the solvents capable of dissolving the glucose-based polysaccharide described above.

  The ionic liquid holding material, the ion conductive material, and the production method thereof according to the present invention will be described in detail based on examples.

(Preparation of reagents)
The organic solvent used in the experiment was a commercially available special grade or general product as it was or after drying and distillation as necessary. DMSO was dried under calcium hydride and then distilled under reduced pressure. Pyridine was dried with calcium hydride and then distilled at normal pressure. Diethyl ether was pre-dried with calcium chloride, dried with sodium, and distilled at normal pressure. The sources of various reagents used in the synthesis are as follows. Derived from amylose potato (SIGMA), triphenylchloromethane (ALDRICH), N-methylimidazole (Tokyo Chemical Industry Co., Ltd.), allyl chloride (Tokyo Chemical Industry Co., Ltd.), activated carbon, crushed, 0.2-1mm (Kanto Chemical Co., Inc.) Company), mesityl bromide (Tokyo Chemical Industry Co., Ltd.), magnesium shaving (Kishida Chemical), trimethoxyborane (Wako Pure Chemical Industries, Ltd.), triisopropylborane (ALDRICH), borane-THF complex in THF (Kanto Chemical Co., Ltd.) ), Lithium aluminum hydride (Kanto Chemical Co., Ltd.), cellulose microcrystalline powder (ALDRICH), lithium chloride (anhydrous) (Kishida Chemical), 1-ethyl-3-methylimidazolium TFSA (Kanto Chemical Co., Ltd.).

(Synthesis of ionic liquid (1-butyl-3-methylimidazolium chloride) (hereinafter referred to as [BMIm] [Cl]) (compound 5))
1-Butyl-3-methylimidazolium chloride was synthesized according to the literature (Non-patent Document 7). N-methylimidazole (compound 3) 31.0 g (0.38 mol) and n-butyl chloride (compound 4) 60 mL (0.58 mol) were added to a 200 mL eggplant flask equipped with a condenser, and the mixture was heated to reflux for 5 hours. Excess n-butyl chloride was distilled off under reduced pressure, followed by reprecipitation with diethyl ether. After leaving for 30 minutes and removing the supernatant, it was heated and vacuum dried for 1.5 hours. Further, after dissolving in methanol and passing through activated carbon, methanol was distilled off under reduced pressure. It was heated and vacuum dried for about 1 hour to obtain 22.5 g (1.27 mol) of a colorless transparent and high viscosity target compound (Compound 5). (Yield 34%)
¹ H-NMR (CD ₃ OD): δ (ppm) 1.02 (3H, -CH ₂ CH ₂ CH ₃ ), 1.40 (2H, -CH ₂ CH ₂ CH ₃ ), 1.90 (2H, -CH ₂ CH ₂ CH _2- ), 3.96 (3H, -NCH ₃ ), 4.26 (2H, -NCH ₂ CH _2- ), 7.61, 7.68 (2H, -NCHCHN-), 9.02 (1H, -NCHN)

(Synthesis of ionic liquid (1-allyl-3-methylimidazolium chloride) (hereinafter referred to as [AMIm] [Cl]) (compound 7))
1-allyl-3-methylimidazolium chloride was synthesized according to the literature (Non-patent Document 7). To a 100 mL eggplant flask equipped with a condenser, 10.8 g (0.24 mol) of N-methylimidazole (compound 3) was added 40.8 mL (0.54 mol) of allyl chloride (compound 6), and the mixture was heated to reflux at 80 ° C. for 6 hours. Excess allyl chloride was distilled off under reduced pressure, followed by reprecipitation with diethyl ether. After leaving for 30 minutes and removing the supernatant, it was vacuum dried for 1.5 hours. Furthermore, after dissolving in methanol and passing through activated carbon, methanol was distilled off under reduced pressure. Then, it was heated and vacuum-dried for about 1 day to obtain 30.7 g (compound 7) (0.20 mol) of a colorless and transparent target product having a slightly high viscosity. (Yield 81%)
¹ H-NMR (CDCl ₃ ): δ (ppm) 4.05 (3H, -NCH ₃ ), 4.97 (2H, -NCH ₂ CH ₃ ), 5.39-5.47 (2H, -CH = CH ₂ ), 5.57-5.65 ( 1H, -CH ₂ CH = CH ₂ ), 7.59, 7.74 (2H, -NCH = CHN), 9.92 (1H, -NCHN)

(Synthesis of mesityl dimethoxyborane (compound 12))
A stirrer chip and 3.107 g (0.128 mol) of magnesium (compound 9) were added to a 200 mL three-necked flask equipped with a condenser, a dropping funnel, and a three-way cock. After heating with a heat gun and vacuum drying to activate magnesium, the atmosphere was replaced with nitrogen. To a dropping funnel, a solution of 17.0 g (0.117 mol) of mesityl bromide (Compound 8) in THF (80 mL) was added dropwise at room temperature with vigorous stirring. After completion of the dropwise addition, the mixture was refluxed at 85 ° C. for 3 hours to return to room temperature to obtain Compound 10. Separately, a stirrer chip was placed in a two-necked flask equipped with a three-way cock and a dropping funnel and purged with nitrogen. 26 mL of trimethoxyborane (compound 11) was added to the flask and dissolved in 80 mL of diethyl ether. All of the THF solution of Compound 10 was added to the dropping funnel and added dropwise at -15 ° C. After completion of dropping, stirring was continued at -15 ° C for 3 hours. After returning to room temperature and stirring for one day, the reaction solution was filtered under a nitrogen atmosphere to remove a white precipitate, and the precipitate was washed twice with 20 mL of hexane. The mixed filtrate was concentrated by an evaporator and then distilled under reduced pressure to obtain the desired product (Compound 12). (Yield 42%)
¹ H-NMR (DMSO): δ (ppm) 2.19-2.23 (9H, -CH ₃ ), 3.49 (6H, -OCH ₃ ), 6.80 (2H, C ₆ H ₂ )
11B NMR (DMSO): δ (ppm) 30.6

(Synthesis of mesitylborane (compound 15))
Under a nitrogen atmosphere, 40 mL of diethyl ether and 20 mL of hexane were added to 1.988 g of mesityldimethoxyborane (compound 12) and dissolved (solution A). On the other hand, 20 mL of diethyl ether was dissolved in 0.410 g of lithium aluminum hydride (compound 13) powder in a nitrogen atmosphere, and the mixture was cooled to 0 ° C. and held with ice (solution B). Liquid B was added dropwise to liquid A and stirred at room temperature for 3 hours for reaction. After completion of the reaction, the reaction solution was filtered under a nitrogen atmosphere, and the precipitate was washed with 20 mL of diethyl ether and 10 mL of hexane. To the filtrate was added dropwise 1.20 mL of triethylsilyl chloride (Compound 14), and the mixture was stirred for 3 hours and then left to stand to produce a white precipitate. The supernatant was dried to obtain the desired product (compound 15) as a white solid. (Yield 56%)

(Synthesis of ion gel)
Put a stirrer tip and ionic liquid ([BMIm] [Cl] (compound 5) or [AMIm] [Cl] (compound 7)) 2.3 g in a test tube with a three-way cock and put an appropriate amount of cellulose (compound 16) was added and dissolved by heating to 110-120 ° C. while vacuum drying. After returning to room temperature, a THF solution of dichloromethane and lithium chloride (compound 18) was added, and after stirring, borane (compound 17) or mesityl borane (compound 15) was added and reacted (room temperature, 1 hour). After the reaction, the target gel-like substance was obtained by heating and vacuum drying the solution for 1 day. During the reaction, the generation of gas considered to be hydrogen was confirmed. By adding dichloromethane, the uniformity of the reaction solution was improved and the reaction proceeded efficiently. The obtained gel-like substance comprises the ionic liquid holding material of the present invention (compound obtained by reacting cellulose with borane 17 or mesityl borane 15) and the ionic liquid (compound 5 or 7) held in the ionic liquid holding material. It is one of the ion conductive materials. Table 1 shows the amount of each compound added particularly when borane is reacted.

(Synthesis of 6-O-trityl amylose (Compound 21) by selective protection of the 6-position hydroxyl group of amylose (Compound 19))
Under a nitrogen atmosphere, 0.65 g (4.0 unit mmol) of 19 was placed in a 100 mL two-necked flask equipped with a condenser and a three-way cock, and DMSO 15 mL and pyridine 15 mL were added and dissolved (solution A). On the other hand, in a nitrogen atmosphere, 2.78 g (10.0 mol) of trityl chloride (Compound 20) was placed in a 50 mL eggplant flask equipped with a three-way cock, and 5 mL of pyridine was added and dissolved (solution B). Liquid B was added dropwise to liquid A. After completion of the dropwise addition, the reaction was carried out at an appropriate time and temperature. After completion of the reaction, pyridine was distilled off under reduced pressure, and then the reaction solution was added to an excessive amount of methanol to reprecipitate the produced polymer. The product (Compound 21) was collected by filtration, washed several times with a small amount of methanol, and then dried in a vacuum for 6 hours. The structure was determined by ¹³ C-NMR. (Yield 94%)
¹³ C-NMR (DMSO): δ (ppm) 62.0-66.0 (C-6), 69.0-76.0 (C-2, C-3), 80.0 (C-5), 86.5 (C-4), 101 ( C-1), 126-132 (-OC (C ₆ H ₅ ) ₃ ), 145 (-OC (C ₆ H ₅ ) ₃ ).

(Boronation of amylose protected at position 6 by condensation reaction of 6-O-trityl amylose (compound 21) and mesityl borane (compound 15))
In a 50 mL eggplant flask equipped with a three-way cock, 0.24 g (0.60 unit mmol) of a stirrer chip and Compound 21 was added, and 0.5 mL of THF was added and dissolved. 0.60 mL (0.60 mmol) of a 1.0 M solution of compound 15 was added dropwise at room temperature with a microsyringe and stirred. After the reaction, the obtained solid (compound 22) was heated and vacuum-dried for 1 day. The structure was confirmed by ¹¹ B-NMR and ¹ H-NMR. In addition, it was found that the obtained compound 22 was soluble in a solvent, had a low degree of crosslinking, and had a substantially linear structure.
¹ H-NMR (DMSO): δ (ppm) 2.19 (9H -CH3), 4.18-5.73 (sugar protons), 6.73 (2H, C ₆ H ₂ ), 6.40-7.75 (-OC (C ₆ H ₅ ) ₃ ).
¹¹ B-NMR (DMSO): δ (ppm) 28.4

(Evaluation test)
<Ion conductivity measurement by AC impedance method>
When determining the conductivity of an ionic conductor, it should be noted that since electrode polarization and electrochemical reaction occur at the electrode and interface, the conductivity that is the characteristics of the sample bulk must be separated unless the characteristics of the sample bulk and interface are separated by an appropriate method. It is a point that cannot be obtained.

One method for solving this problem is a method using the following AC method. The AC method is a method of measuring by changing the frequency under a constant AC voltage. This is because the AC response measured by changing the frequency is analyzed by an equivalent circuit, so that not only the intrinsic properties such as the conductivity and dielectric constant of the ionic conductor, but also the non-uniformity inside the ionic conductor, It is a method that can obtain a lot of information such as information on the current / ion conductor interface. The AC impedance measurement was performed using a Solartron 1260.
-Effect of cellulose concentration on ion conductivity The ion conductivity characteristics of the ion conductive materials of Test Examples 1 and 2 were evaluated by the AC impedance method. In the measurement by the AC impedance method, the temperature dependence of the ion conduction characteristics was evaluated by changing the temperature. The ion conductive material of Test Example 1 contains 5% by mass of cellulose based on the mass of the ionic liquid. The ion conductive material of Test Example 2 contains 7% by mass of cellulose based on the mass of the ionic liquid. The results are shown in FIG. The amount of borane increased and decreased in proportion to the amount of cellulose. The amount of lithium salt increased or decreased in proportion to the amount of borane (the same applies hereinafter).

  As is clear from FIG. 1, the ion conductive material of Test Example 1 containing 5% by mass of cellulose is more excellent in ion conduction characteristics than the ion conductive material of Test Example 2 containing 7% by mass of cellulose. I understood.

  With respect to this result, the ion conduction behavior was analyzed by a Vogel-Fulcher-Tamman plot (hereinafter referred to as “VFT plot”). The VFT plot is a method of performing analysis using the following equation (1), and is a method capable of estimating the mechanism of ion conduction in the measured ion conductive material.

In the formula (1), A and B are parameters corresponding to the number of carrier ions in the system and the activation energy of ion transport, respectively. T ₀ is an ideal glass transition temperature. By using this equation, it is possible to eliminate the influence of deviation from the ideal solution and obtain a linear fitting. When the result shown in FIG. 1 was applied to the formula (1), a good linear relationship shown in FIG. 2 was obtained. From this result, A, B, and T ₀ in equation (1) were calculated. The ion conductive material of Test Example 1 (5% by mass cellulose) has A of 133 Scm ⁻¹ K ^1/2 , B of 1526K, and T ₀ of 170K, and the ion conductive material of Test Example 2 (7% by mass cellulose) A was 166 Scm ⁻¹ K ^1/2 , B was 1666 K, and T ₀ was 170 K.

From this result, although the ion conductive material (7 mass%) of Test Example 2 exceeds the ion conductive material (5 mass%) of Test Example 1 in the number of carrier ions (A), the ion transport activity is higher. The chemical energy (B) is high. This suggests that the viscosity of the system increases as the cellulose concentration increases, and that the matrix environment is difficult for carrier ions to move.
・ Effect of the presence or absence of lithium salt on ionic conductivity To examine how the addition of lithium salt to ionic gel affects ionic conductivity, Test Example 1 (with lithium salt) and Test Example 3 ( The ionic conductivity was measured for lithium salt). The measurement results are shown in FIG. 3, and the VFT plot is shown in FIG.

As shown in FIG. 4, the VFT plot of the ion conductive material of each test example showed good linearity. Obtained by analysis using VFT equation. From this result, A, B, and T ₀ in equation (1) were calculated. The ion conductive material (without lithium salt) of Test Example 3 had A of 1535 Scm ⁻¹ K ^1/2 , B of 2091 K, and T ₀ of 150 K. The reason why the ion conductive material of Test Example 1 has higher ionic conductivity than the ion conductive material of Test Example 3 is that the addition of lithium salt causes excessive charges to aggregate and decrease carrier ions. This is thought to be due to a decrease in the ion transport activation energy that exceeded that effect.
・ Effects of boron addition amount (number of cross-linking points) on ionic conductivity In order to investigate how the boron content of ionic gel affects ionic conductivity, the amount of boron to glucose unit etc. AC impedance measurement was performed on two of the ion conductive material of Test Example 1 made into a molar amount and the ion conductive material of Test Example 4 made into 1/3 equivalent. The measurement results are shown in FIG. 5, and the VFT plot is shown in FIG. From this result, A, B, and T ₀ in equation (1) were calculated. In the ion conductive material of Test Example 4, A was 119 Scm ⁻¹ K ^1/2 , B was 1463 K, and T ₀ was 150 K.

As is apparent from FIGS. 5 and 6, it was found that the ionic conductivity decreases as the amount of boron increases. When the amount of boron decreased, the effect of promoting salt dissociation due to the decrease in Lewis acid was lost, and the decrease in carrier ions was observed. However, it is considered that the activation energy of ion transport decreases due to the decrease in viscosity due to the decrease in crosslinking points, and as a result, the ionic conductivity is improved. Therefore, the addition of boron does not cause cross-linking (ionic liquid holding material having a linear molecular structure, etc., such as those in which the 6-position OH group is protected in amylose as a glucose-based polysaccharide described later) If the amount of boron added is increased, the viscosity does not increase, and the ionic conductivity accompanying the increase of carrier ions is considered to be improved.
-Evaluation of ion conduction characteristics when the ionic liquid is compound 7 (1-allyl-3-methylimidazolium chloride) The ion conductive material of Test Example 5 was measured. FIG. 7 shows the measurement results. The ion conductive material of Test Example 5 exhibits an ionic conductivity of 6.83 × 10 ⁻⁴ Scm ⁻¹ at 51 ° C., and the ion of Test Example 1 using Compound 5 (1-butyl-3-methylimidazolium chloride) as a solvent. The value was higher than that of the conductive material. There was a possibility that the allyl group of the ionic liquid and borane had reacted, but when extraction was performed using methanol as a solvent, a transparent gel was obtained. This suggested that the gel produced was formed by intermolecular cross-linking.
・ Ionic conductivity of compound 22 Measurement of ionic conductivity in compound 22 (1-ethyl-3-methylimidazolium TFSA) and LiTFSA mixed matrix (mass ratio 1: 1: 1, ion conductive material) The results are shown in FIG. This mixed matrix exhibited an ionic conductivity of 1.05 × 10 ⁻⁴ Scm ⁻¹ at 51 ° C.
<Evaluation of thermal stability>
-Thermostability of Compound 22 Thermogravimetric analysis (TGA) was performed on Compound 22. For TGA measurement, a TGA-6200 thermogravimetric analyzer manufactured by Seiko Instruments Inc. was used. The results are shown in FIG. It was found that the mixed matrix has a higher thermal stability over a range of about 290 ° C. to 450 ° C. as compared with the TGA measurement result of amylose alone. In addition, it is considered that the mass reduction of the mixed matrix in the vicinity of 200 ° C. was caused by the decomposition of boron. The 5 mass% decomposition temperature (T _5% ) of Compound 22 is 242 ° C., the 50 mass% decomposition temperature (T _50% ) is 430 ° C., and although T _5% is slightly lower than that of amylose alone, It was found that T _50% was significantly increased.

Claims (10)

  A substrate obtained by reacting a borane compound composed of hydroborane or alkoxyborane with substantially all of the free OH groups of the glucose-based polysaccharide with respect to the glucose-based polysaccharide having glucose as a structural unit. An ionic liquid holding material, which is a composition having   2. The glucose-based polysaccharide is one or more compounds selected from the group consisting of amylose, cellulose, amylopectin, glycogen, dextrin, cyclodextrin, dextran, pullulan, and curdlan. Ionic liquid holding material.   The ionic liquid holding material according to claim 2, wherein the glucose polysaccharide is amylose, and a protective group is introduced into the 6-position OH group in the glucose structure of the amylose before the borane compound is reacted.   The ionic liquid holding material according to claim 2, wherein the glucose-based polysaccharide is cellulose, and the cellulose is dissolved in a cellulose solubilizer before the borane compound is reacted.   The ionic liquid holding material according to any one of claims 1 to 4, wherein the borane compound is mesityl borane or mesityl dimethoxy borane.   An ionic conductive material comprising the ionic liquid holding material according to claim 1 and an ionic liquid.   Furthermore, the ion conductive material of Claim 6 which has lithium salt. A dissolution step of dissolving a glucose-based polysaccharide having glucose as a constituent unit in a solubilizer to form a polysaccharide solution;
A reaction step of reacting substantially all of the free OH groups of the glucose-based polysaccharide with a borane compound comprising hydroborane or alkoxyborane with respect to the polysaccharide solution. A method for producing a liquid holding material.   9. The ionic liquid according to claim 8, wherein the glucose-based polysaccharide is amylose, and has a protective group introduction step of introducing a protective group into an OH group at the 6-position in the glucose structure of the amylose before the borane compound is reacted. A method for manufacturing a holding material.   The method for producing an ionic liquid holding material according to claim 8 or 9, wherein the borane compound is mesityl borane or mesityl dimethoxy borane.

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