Polyether copolymer, crosslinkable polyether copolymer composition and electrolyte

Abstract

Provided is a material which exhibits excellent ion conductivity and excellent processability and which can provide an electrolyte that exhibits excellent water-resistant shape retention properties after processing. A polyether copolymer having polyether segment blocks having cationic groups and hydrophobic polyether segment blocks. The polyether segments having cationic groups preferably have oxirane monomer units represented by general formula (1). The polyether copolymer may have oxirane monomer units having crosslinkable groups. An electrolyte is obtained by crosslinking a composition containing the polyether copolymer and a crosslinking agent. (In general formula (1), A+ denotes a group having an onium cation structure having a cationic nitrogen atom, and X denotes an anion). ##STR00001##

Claims

1. A polyether copolymer comprising: a polyether segment block containing a cationic group and a hydrophobic polyether segment block, the hydrophobic polyether segment block comprising, as a repeat unit, a nonionic oxirane monomer unit, wherein the proportion of the nonionic oxirane monomer unit in the hydrophobic polyether segment block is 80 mol % to 100 mol %, wherein the proportion of the nonionic oxirane monomer unit to total oxirane monomer units constituting the polyether copolymer is 20 mol % to 90 mol %, wherein the hydrophobic polyether segment block has hydrophobicity as a whole, and wherein the ratio of the weight-average molecular weight to the number-average molecular weight of the polyether copolymer is 1.0 to 2.0.

2. The polyether copolymer according to claim 1, wherein the polyether segment block containing a cationic group has an oxirane monomer unit represented by General Formula (1) ##STR00004## wherein A.sup.+ is a cationic group which has an onium cation structure containing a nitrogen atom, and X.sup. is an anion.

3. The polyether copolymer according to claim 1, further having an oxirane monomer unit bearing a crosslinkable group.

4. The polyether copolymer according to claim 3, wherein the oxirane monomer unit bearing a crosslinkable group is contained in the hydrophobic polyether segment block.

5. The polyether copolymer according to claim 3, wherein the oxirane monomer unit bearing a crosslinkable group is at least one selected from the group consisting of an allyl glycidyl ether monomer unit, a glycidyl acrylate monomer unit and a glycidyl methacrylate monomer unit.

6. A crosslinkable polyether copolymer composition comprising the polyether copolymer according to claim 3, and a crosslinking agent for the crosslinkable group contained in an oxirane monomer unit in the polyether copolymer.

7. An electrolyte produced by crosslinking the crosslinkable polyether copolymer composition according to claim 6.

8. A composite comprising the polyether copolymer according to claim 1 and a porous support.

9. The composite according to claim 8 which is an electrolyte film.

10. The polyether copolymer according to claim 1, wherein the polyether segment block containing a cationic group comprises a cationic group-bearing repeating unit and wherein the proportion of the cationic group-bearing repeating unit in the polyether segment block containing a cationic group is 30 mol % to 100 mol %.

Description

EXAMPLES

(1) Hereinafter, the invention will be described more specifically by providing examples and comparative examples. In addition, part(s) and % in examples are based on weight, unless otherwise specified.

(2) Measurements of various properties were carried out in accordance with the following methods.

(3) [Number-Average Molecular Weight (Mn) and Molecular Weight Distribution (Mw/Mn)]

(4) Number-average molecular weight and molecular weight distribution were measured in terms of polystyrene by gel permeation chromatography (GPC) using dimethylformamide as a solvent. HLC-8320 (produced by Tosoh Corporation) was used as a measuring device; two columns of TSK gel -M (produced by Tosoh Corporation) arrayed in series were used; and a differential refractometer RI-8320 (produced by Tosoh Corporation) was used as a detector.

(5) [Compositional Ratio (Molar Ratio) of Monomer Units of Polymers]

(6) The compositional ratio of monomer units is determined by .sup.1H-NMR and elemental analysis.

(7) [Waterproof Shape-Retaining Properties]

(8) Samples are kept still in water at 60 C., and it is judged whether or not the samples are dissolved in water after passage of 24 hours. In a case where a sample is not dissolved in water thereby losing its shape but retains its shape even though swelled, the sample is considered to have superior waterproof shape-retaining properties. A sample is considered that it is not dissolved, if any weight loss is not observed in the sample when it is taken out from water after 24 hours has passed and the water is distilled away from the sample.

(9) [Volume Resistivity]

(10) A coin-type cell is prepared of a sample, and a volume resistivity thereof is measured under a test atmosphere at 25 C. by jointly using an impedance analyzer Type 1260 and a potentiostat Type 1287 (both manufactured by Solartron) as measuring devices. The measurement voltage amplitude is 100 mV, the measurement frequency range is 1 MHz to 0.1 Hz, and an SUS304 electrode is used as a main electrode. When a sample has a lower volume resistivity, it has superior ion conductivity.

Production Example 1

(11) (Production of a Polyether Copolymer of Epichlorohydrin and Propylene Oxide)

(12) 0.080 g of tetra-n-butylammonium bromide and 30 mL of toluene were added to a glass reactor equipped with a stirrer, and the mixture was cooled to 0 C. Further, a solution obtained by dissolving 0.0356 g of triethylaluminum in 1 mL of n-hexane was added to the mixture, and the mixture was reacted for 15 minutes.

(13) 2.5 g of epichlorohydrin was added to the thus-obtained mixture, and the temperature was raised to 20 C. to carry out a polymerization reaction. After the polymerization reaction was initiated, the viscosity of the solution gradually increased. The solution was reacted for 30 minutes, and then, a portion of the solution was sampled, and the molecular weight of the polymer in the solution was measured. The polymer was found to have a number-average molecular weight (Mn) of 10,200; a weight-average molecular weight (Mw) of 11,100; and a molecular weight distribution (Mw/Mn) of 1.09.

(14) A solution obtained by dissolving 0.021 g of triethylaluminum in 1 mL of n-hexane was further added to the reaction solution, and the solution was reacted for 15 minutes. Then, 5.0 g of propylene oxide was added to the solution, and a second-stage polymerization reaction was carried out. After the polymerization reaction had started, the viscosity of the solution gradually increased further. After the solution was reacted for 30 minutes, a small amount of water was poured to the polymerization reaction solution to terminate the reaction. Then, the solution was dried under reduced pressure at 50 C. for 12 hours.

(15) The yield of the resultant polymer (referred to as copolymer (OR1)) was 7.5 g. Furthermore, the number-average molecular weight (Mn) of the resultant polymer was 30,800, and the molecular weight distribution (Mw/Mn) thereof was 1.19. In addition, the monomer unit compositional ratio (molar ratio) of the resultant polymer was such that epichlorohydrin monomer units: propylene oxide monomer units=24:76, and confirmed synthesis of poly(epichlorohydrin-block-propylene oxide).

Example 1

(16) (Quaternarization of Epichlorohydrin Units in Copolymer (OR1) with n-Butyldimethylamine)

(17) 5.0 g of the copolymer (OR1) obtained in Production Example 1, 10.9 g of n-butyldimethylamine and 10.0 g of acetonitrile were added to an argon-replaced glass reactor equipped with a stirrer, and the mixture was heated to 80 C. After reacted at 80 C. for 96 hours, the mixture was cooled to room temperature to terminate the reaction. The resultant reaction product was dried at 50 C. under reduced pressure for 120 hours to give 10.2 g of an orange solid.

(18) The solid was subjected to .sup.1H-NMR measurement and elemental analysis to be identified as poly(3-(chloro-n-butyldimethylammonium)-1,2-epoxypropane-block-propylene oxide) (referred to as copolymer (A1)) where a chloro group in all epichlorohydrin monomer units in the copolymer (OR1) had been replaced by an n-butyldimethylammonium chloride group while a bromo group of a bromomethyl group at all polymerization-initiative terminals had been replaced by an n-butyldimethylammonium bromide group. In the polyether copolymer, a counter anion for a chloro-n-butyldimethylammonium group is a chloride ion.

(19) The composition of repeating units of the polyether copolymer (A1) is shown in Table 1.

Example 2

(20) (Anion Exchange of Copolymer (A1) with Potassium Hydroxide)

(21) 2.5 g of the polyether copolymer (A1) obtained in Example 1, 2.0 g of potassium hydroxide, 20 mL of ion-exchanged water and 20 mL of ethanol were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then, dried at 50 C. under reduced pressure for 1 hour to give a pale purple, oil-like substance. The obtained oil-like substance was dissolved in a mixture solvent of acetone/THF, and, after crystalline undissolved matter was separated, was dried at 50 C. under reduced pressure for 1 hour to give a pale purple, oil-like substance. The obtained oil-like substance was again dissolved in a mixture solvent of acetone/THF, and, after crystalline undissolved matter was separated, was dried at 50 C. under reduced pressure for 12 hours to give 2.2 g of a pale purple, oil-like substance. The obtained oil-like substance was subjected to Fourier transform infrared spectrometric measurement and elemental analysis to be identified as poly(3-(hydroxyl-n-butyldimethylammonium)-1,2-epoxypropane-block-propylene oxide) having a hydroxide ion as a counter anion, where all chloride ions of n-butyldimethylammonium chloride groups in repeating units, and all bromide ions of n-butyldimethylammonium bromide groups at polymerization-initiative terminals in the polyether copolymer (A1) as thestarting material, had been replaced by a hydroxide ion. This copolymer is referred to as copolymer (A2).

(22) The composition of repeating units of polyether copolymer (A2) is shown in Table 1.

Example 3

(23) (Anion Exchange of Copolymer (A1) with Lithium bis(trifluoromethanesulgonyl)imide)

(24) 2.5 g of polyether copolymer (A1) obtained in Example 1, 4.1 g of lithium bis(trifluoromethanesulfonyl)imide). 20 mL of ion-exchanged water and 20 mL of ethanol were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then, was dried at 50 C. under reduced pressure for 12 hours. The resultant solid-liquid mixture was washed with water to remove inorganic salts, and then subjected to extraction of the liquid phase with toluene. The resultant toluene solution was dried at 50 C. under reduced pressure for 12 hours to give 3.6 g of a very pale purple viscous liquid substance. The obtained viscous liquid substance was subjected to .sup.1H-NMR spectrum measurement and elemental analysis to be identified as poly(3-(bis(trifluoromethanesulfonyl)imide)n-butyldimethylammonium)-1,2-epoxypropane-block-propylene oxide) having a bis(trifluoromethanesulfonyl)imide anion as a counter anion where all chloride ions of n-butyldimethylammonium chloride groups in repeating units, and all bromide ions of n-butyldimethylammonium bromide groups at polymerization-initiative terminals of the polyether copolymer (A1) as the starting material had been replaced by a bis(trifluoromethanesulfonyl)imide anion. This copolymer is referred to as copolymer (A3).

(25) The composition of repeating units of polyether copolymer (A3) is shown in Table 1.

Production Example 2

(26) (Production of a Polyether Copolymer of Epichlorohydrin and Propylene Oxide/Glycidyl Methacrylate)

(27) 0.080 g of tetra-n-butylammonium bromide and 30 mL of toluene were added to a glass reactor equipped with a stirrer, and the mixture was cooled to 0 C. Further, a solution obtained by dissolving 0.0356 g of triethylaluminum in 1 mL of n-hexane was added to the mixture, and the mixture was reacted for 15 minutes. 2.5 g of epichlorohydrin was added to the thus-obtained mixture, and the temperature was raised to 20 C. to carry out a polymerization reaction. After the polymerization reaction was initiated, the viscosity of the solution gradually increased. After the solution was reacted for 30 minutes, a portion of the solution was sampled, and the molecular weight of the polymer in the solution was measured. The polymer was found to have a number-average molecular weight (Mn) of 10,200; a weight-average molecular weight (Mw) of 11,100; and a molecular weight distribution (Mw/Mn) of 1.09. A solution obtained by dissolving 0.021 g of triethylaluminum in 1 mL of n-hexane was further added to the reaction solution, and the solution was reacted for 15 minutes. Then, 2.0 g of propylene oxide and 0.5 g of glycidyl methacrylate were added to the mixture, and a second-stage polymerization reaction was carried out. After the polymerization reaction had started, the viscosity of the solution gradually increased further. After the solution was reacted for 30 minutes, a small amount of water was poured to the polymerization reaction solution to terminate the reaction. Then, the solution was dried under reduced pressure at 50 C. for 12 hours. The yield of the resultant polymer was 5.0 g. The resultant polymer was found to have a number-average molecular weight (Mn) of 21,300 and a molecular weight distribution (Mw/Mn) of 1.25. In addition, the monomer unit compositional ratio (molar ratio) obtained by .sup.1H-NMR of the polymer was such that epichlorohydrin monomer units: propylene oxide monomer units:glycidyl methacrylate monomer units=42:53:5 (mole: mole: mole), and confirmed synthesis of poly(epichlorohydrin-block-(propylene oxide-ran-glycidyl methacrylate)). This copolymer is referred to as copolymer (OR2).

Example 4

(28) (Quaternarization of Epichlorohydrin Units in Copolymer (OR2) with n-butyldimethylamine)

(29) 5.0 g of the copolymer (OR2) obtained in Production Example 2, 10.9 g of n-butyldimethylamine and 10.0 g of acetonitrile were added to an argon-replaced glass reactor equipped with a stirrer, and the mixture was heated to 80 C. After reacted at 80 C. for 96 hours, the mixture was cooled to room temperature to terminate the reaction. The resultant reaction product was dried at 50 C. under reduced pressure for 120 hours to give 7.7 g of an orange solid. The solid was subjected to .sup.1H-NMR measurement and the elemental analysis to be identified as poly(3-(chloro-n-butyldimethylammonium)-1,2-epoxypropane-block-(propylene oxide-ran-glycidyl methacrylate), where a chloro group in all epichlorohydrin monomer units in the copolymer (OR2) as the starting material had been replaced by an n-butyldimethylammonium chloride group while a bromo group of bromomethyl groups at all polymerization-initiative terminals had been replaced by an n-butyldimethylammonium bromide group. This copolymer is referred to as copolymer (B1).

(30) The composition of repeating units of the polyether copolymer (B1) is shown in Table 2.

Example 5

(31) (Anion Exchange of Polyether Copolymer (B1) with Potassium Hydroxide)

(32) 2.5 g of polyether copolymer (B1) obtained in Example 4, 2.0 g of potassium hydroxide, 20 mL of ion-exchanged water and 20 mL of ethanol were added to a glass reactor equipped with a stirrer. The resultant mixture was reacted at room temperature for 30 minutes, and then, dried at 50 C. under reduced pressure for 1 hour to give a pale purple, oil-like substance. The obtained oil-like substance was dissolved in a mixture solvent of acetone/THF, and, after crystalline undissolved matter was separated, was dried at 50 C. under reduced pressure for 1 hour to give a pale purple, oil-like substance. The obtained oil-like substance was again dissolved in a mixture solvent of acetone/THF, and, after crystalline undissolved matter was separated, was dried at 50 C. under reduced pressure for 12 hours to give 2.1 g of a pale purple, oil-like substance. The obtained oil-like substance was subjected to Fourier transform infrared spectrometric measurement and elemental analysis to be identified as poly(3-(hydroxyl-n-butyldimethylammonium)-1,2-epoxypropane-block-(propylene oxide-ran-glycidyl methacrylate)) having a hydroxide ion as a counter anion, where all chloride ions of n-butyldimethylammonium chloride groups in repeating units, and all bromide ions of n-butyldimethylammonium bromide groups at polymerization-initiative terminals in the polyether copolymer (B1) as the starting material, had been replaced by a hydroxide ion. This copolymer is referred to as copolymer (B2).

(33) The composition of repeating units of polyether copolymer (B2) is shown in Table 2.

Example 6

(34) (Anion Exchange of Copolymer (B1) with Lithium bis(trifluoromethanesulfonyl)imide)

(35) 2.5 g of polyether copolymer (B1) obtained in Example 4, 4.1 g of lithium bis(trifluoromethanesulfonyl)imide, 20 mL of ion-exchanged water and 20 mL of ethanol were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then, was dried at 50 C. under reduced pressure for 12 hours. The resultant solid-liquid mixture was washed with water to remove inorganic salts, and then subjected to extraction of the liquid phase with toluene. The resultant toluene solution was dried at 50 C. under reduced pressure for 12 hours to give 3.87 g of a very pale purple viscous liquid substance. The obtained viscous liquid substance was subjected to .sup.1H-NMR spectrum measurement and elemental analysis to be identified as poly(3-((bis(trifluoromethanesulfonyl)imide)n-butyldimethylammonium)-1,2-epoxypropane-block-(propylene oxide-ran-glycidyl methacrylate)) having a bis(trifluoromethanesulfonly)imide anion as a counter anion, where all chloride ions of n-butyldimethylammonium chloride groups in repeating units, and all bromide ions of n-butyldimethylammonium bromide groups at polymerization-initiative terminals of the polyether copolymer (B1) as the starting material had been replaced by a bis(trifluoromethanesulfonyl)imide anion. This copolymer is referred to as copolymer (B3).

(36) The composition of repeating units of polyether copolymer (B3) is shown in Table 2.

Example 7

(37) 100 parts of polyether copolymer (A1) obtained in Example 1 and 1,000 parts of dimethylformamide were stirred in an automatic mortar under an atmosphere of an atmospheric temperature of 25 C. and a humidity of 60% for 10 minutes. The resultant solution was homogeneous, pale purple oil-like matter. A polypropylene porous film having a thickness of 25 m (Celgard 2400 manufactured by Polypore K.K.) was impregnated with the solution, and the film was vacuum-dried in an oven at 100 C. for 24 hours to distill away the solvent, dimethylformamide to give a composite (A1). The composite (A1) was subjected to the test for waterproof shape-retaining properties to give no ingredients dissolved in water at room temperature and retained the shape of the film. Furthermore, the composite (A1) was incorporated into a coin-type cell under an atmosphere of an atmospheric temperature of 25 C. and a humidity of 60%, and was molded. Volume resistivity of the composite (A1) was measured to be 10.sup.3.50 (/cm). The constitution, the waterproof shape-retaining properties and the volume resistivity of the composite (A1) are shown in Table 1.

Example 8

(38) Preparation of a solution, preparation of a composite (A2), the test for the waterproof shape-retaining properties, and the measurement of volume resistivity were carried out in the same manner as in Example 7 except that the polyether copolymer (A2) obtained in Example 2 was used instead of the polyether copolymer (A1) obtained in Example 1. The constitution, the waterproof shape-retaining properties and the volume resistivity of the composite (A2) are shown in Table 1.

Example 9

(39) Preparation of a solution, preparation of a composite (A3), the test for the waterproof shape-retaining properties, and the measurement of volume resistivity were carried out in the same manner as in Example 7 except that the polyether copolymer (A3) obtained in Example 3 was used instead of the polyether copolymer (A1) obtained in Example 1. The constitution, the waterproof shape-retaining properties and the volume resistivity of the composite (A3) are shown in Table 1.

Example 10

(40) 100 parts of polyether copolymers (B1) obtained in Example 4, and 3 parts of dicumyl peroxide as a crosslinking agent (PERCUMYL D-40 manufactured by NOF CORPORATION) were stirred in an automatic mortar for 10 minutes under an atmosphere of an atmospheric temperature of 25 C. and a humidity of 60%. The resultant crosslinkable polyether copolymer composition was homogeneous, pale purple oil-like matter. The composition was processed into a thin cylindrical product having a diameter of 12 mm and a thickness of 200 m and was kept in an oven at 40 C. for 1 hour and then, in an oven at 160 C. for 20 minutes to effect a crosslinking reaction. Consequently, the product turned into a rubber-like crosslinked product. This crosslinked product (B1) was subjected to the test for the waterproof shape-retaining properties to retain the shape of the product in water. Furthermore, the crosslinked product was incorporated into a coin-type cell under an atmosphere of an atmospheric temperature of 25 C. and a humidity of 60%, and was molded. Volume resistivity was measured to be 10.sup.3.10 (/cm). The constitution of the crosslinkable polyether copolymer composition, results of the test for the waterproof shape-retaining properties, and the volume resistivity are shown in Table 2. The obtained crosslinked product had sufficient functions as an electrolyte.

Example 11

(41) Preparation of a composition, a crosslinking reaction and preparation of a crosslinked product (B2) were carried out in the same manner as in Example 10 except that the polyether copolymer (B2) obtained in Example 5 was used instead of the polyether copolymer (B1) obtained in Example 4. The constitution of the crosslinkable polyether copolymer composition, results of the test for the waterproof shape-retaining properties, and the volume resistivity are shown in Table 2. The resultant crosslinked product had sufficient functions as an electrolyte.

Example 12

(42) Preparation of a composition, a crosslinking reaction and preparation of a crosslinked product (B3) were carried out in the same manner as in Example 10 except that the polyether copolymer (B3) obtained in Example 6 was used instead of the polyether copolymer (B1) obtained in Example 4. The constitution of the crosslinkable polyether copolymer composition used therein, results of the test for the waterproof shape-retaining properties, and the volume resistivity are shown in Table 2. The resultant crosslinked product had sufficient functions as an electrolyte.

Reference Production Example 1

(43) (Production of an Epichlorohydrin Polymer)

(44) 0.080 g of tetra-n-butylammonium bromide and 30 mL of toluene were added to a glass reactor equipped with a stirrer, and the resultant mixture was cooled to 0 C. Further, a solution obtained by dissolving 0.0356 g of triethylaluminum in 1 mL of n-hexane was added to the mixture, and the mixture was reacted for 15 minutes. 2.5 g of epichlorohydrin was added to the thus-obtained mixture, and the temperature was raised to 20 C. to carry out a polymerization reaction. After the polymerization reaction was started, the viscosity of the solution gradually increased. The solution was reacted for 30 minutes, and then, a small amount of water was poured to the polymerization reaction solution to terminate the reaction. Then, the reaction solution was dried at 50 C. under reduced pressure for 12 hours. The resultant polymer has a number-average molecular weight (Mn) of 10,200, a weight-average molecular weight (Mw) of 11,100, and a molecular weight distribution (Mw/Mn) of 1.09. Synthesis of poly(epichlorohydrin) was confirmed by .sup.1H-NMR. This copolymer is referred to as copolymer (ORC).

Comparative Example 1

(45) (Quaternarization of Epichlorohydrin Monomer Units in Polymer (ORC) with n-butyldimethylamine)

(46) 5.0 g of poly(epichlorohydrin) (polymer (ORC)) obtained in Reference Production Example 1, 10.9 g of n-butyldimethylamine and 10.0 g of acetonitrile were added to an argon-replaced glass reactor equipped with a stirrer, and the mixture was heated to 80 C. After reacted at 80 C. for 96 hours, the mixture was cooled to room temperature to terminate the reaction. The resultant reaction product was dried at 50 C. under reduced pressure for 120 hours to give 10.4 g of an orange solid. The solid was subjected to .sup.1H-NMR measurement and elemental analysis to be identified as poly(3-(chloro-n-butyldimethylammonium)-1,2-epoxypropane), where a chloro group in all epichlorohydrin monomer units in polymer (ORC) as the starting material had been replaced by an n-butyldimethylammonium chloride group while a bromo group of a bromomethyl group at all polymerization-initiative terminals had been replaced by an n-butyldimethylammonium bromide group. This polymer is referred to as polymer (C1).

Comparative Example 2

(47) Preparation of a solution, preparation of a composite (C1), the test for the waterproof shape-retaining properties and the measurement of volume resistivity of composite (C1) were carried out in the same manner as in Example 7 except that the polymer (C1) obtained in Comparative Example 1 was used instead of the polyether copolymer (A1). The composition of repeating units of the polymer (C1), the constitution of the composite (C1), results of the test for the waterproof shape-retaining properties and the volume resistivity of the composite (C1) are all shown in Table 1. In addition, when the composite (C1) was kept in water for the test for the waterproof shape-retaining properties, the entire body of the composite was dissolved therein, and thus, the composite (C1) has very poor waterproof shape-retaining properties. No polymer (C1) remained in the sample piece after the test for the waterproof shape-retaining properties, and the volume resistivity was 10.sup.16 (/cm) or more, and thus, the composite (C1) was found to be an insulator.

Reference Production Example 2

(48) (Production of a Propylene Oxide Polymer)

(49) 0.080 g of tetra-n-butylammonium bromide and 30 mL of toluene were added to a glass reactor equipped with a stirrer, and the resultant mixture was cooled to 0 C. Further, a solution obtained by dissolving 0.0356 g of triethylaluminum in 1 mL of n-hexane was added to the mixture, and the mixture was reacted for 15 minutes.

(50) 5.0 g of propylene oxide was added to the thus-obtained mixture, and the temperature was raised to 20 C. to carry out a polymerization reaction. After the polymerization reaction was started, the viscosity of the solution gradually increased. The solution was reacted for 30 minutes, and then, a small amount of water was poured to the polymerization reaction solution to terminate the reaction. Then, the reaction solution was dried at 50 C. under reduced pressure for 12 hours.

(51) The yield of the resultant polymer (C2) was 5.0 g. The resultant polymer (C2) was found to have a number-average molecular weight (Mn) of 20,700, a weight-average molecular weight (Mw) of 23,300 and a molecular weight distribution (Mw/Mn) of 1.13.

(52) Synthesis of poly(propylene oxide) was confirmed by .sup.1H-NMR.

Comparative Example 3

(53) Preparation of a solution, preparation of a composite (C2), the test for the waterproof shape-retaining properties and the measurement of volume resistivity of the composite (C2) were carried out in the same manner as in Example 7 except that the polymer (C2) obtained in Reference Production Example 2 was used instead of the polyether copolymer (A1). The composition of repeating units of polymer (C2), the constitution of the composite, results of the test for the waterproof shape-retaining properties, and the volume resistivity are all shown in Table 2. Though the composite (C2) retained its shape in the test for the waterproof shape-retaining properties, the volume resistivity measurement showed a volume resistivity of 10.sup.10 (/cm) or more, and thus, the composite (C2) was an insulator.

(54) As seen from results shown in Tables 1 and 2, the polyether copolymers of the invention provide electrolytes which have higher waterproof shape-retaining properties and also superior ion conductivity (Examples 7 to 12). Furthermore, the polyether copolymers of the invention have processability superior enough to be impregnated into a porous film before they are crosslinked (Examples 7 to 9) or to be crosslinked with a crosslinking agent (Examples 10 to 12). On the other hand, a polyether copolymer which had a polyether segment containing a cationic group but which did not have any hydrophobic polyether segment was inferior in the waterproof shape-retaining properties (Comparative Example 2). Furthermore, the polyether copolymer which had a hydrophobic polyether segment but had not any polyether segment containing a cationic group was inferior in ion conductivity (Comparative Example 3).

(55) TABLE-US-00001 TABLE 1 Comparative Example 1 Example 2 Example 3 Example 1 Block Copolymer (A1) (A2) (A3) (C1) Monomer unit composition (mol %) Segment containing a cationic 24 24 24 100 group Repeating units of general 24 24 24 100 formula (1) Cationic group in repeating units BDM(*1) BDM(*1) BDM(*1) BDM(*1) of general formula (1) Counter anion species in Cl.sup. OH.sup. TFMS(*2) Cl.sup. repeating units of general formula (1) Hydrophobic polyether segment 76 76 76 Propylene oxide units 76 76 76 Glycidyl methacrylate units Comparative Example 7 Example 8 Example 9 Example 2 Composite Composite (A1) Composite (A2) Composite (A3) Composite (C1) Block copolymer (A1) (A2) (A3) (C1) Crosslinking agent None None None Porous film Present Present Present Present Waterproof shape-retaining properties Superior Superior Superior Inferior Dissolution or No No dissolution No dissolution No dissolution Entire body dissolved Shape-retained or No Shape retained Shape retained Shape retained Volume resistivity values (/cm) 10.sup.3.5 10.sup.3.4 10.sup.4.0 10.sup.16 (*1)n-butyldimethylammonium group (*2)bis(trifluoromethylsulfonyl) imide anion

(56) TABLE-US-00002 TABLE 2 Example 4 Example 5 Example 6 Block Copolymer (B1) (B2) (B3) Monomer unit composition (mol %) Segment containing a cationic 42 42 42 group Repeating units of general 42 42 42 formula (1) Cationic group in repeating units BDM(*1) BDM(*1) BDM(*1) of general formula (1) Counter anion species in Cl.sup. OH.sup. TFMS(*2) repeating units of general formula (1) Hydrophobic polyether segment 58 58 58 Propylene oxide units 53 53 53 Glycidyl methacrylate units 5 5 5 Comparative Example 10 Example 11 Example 12 Example 3 Composite/Crosslinked product Crosslinked Crosslinked Crosslinked Composite (C2) product (B1) product (B2) product (B3) Block copolymers (B1) (B2) (B3) (C2) Crosslinking agent Peroxide Peroxide Peroxide Porous film None None None Present Waterproof shape-retaining properties Superior Superior Superior Superior Dissolution or No No dissolution No dissolution No dissolution No dissolution Shape-retained or No Shape retained Shape retained Shape retained Shape retained Volume resistivity values (/cm) 10.sup.3.1 10.sup.3.2 10.sup.3.5 10.sup.16 (*1)n-butyldimethylammonium group (*2)bis(trifluoromethylsulfonyl)imide anion