(EP897941-A1)      A polyether copolymer comprises: (A) 1-98 mol.% repeating units derived from a monomer of formula (I); (B) 95-1 mol.% repeating units derived from a monomer of formula (II); and (C) 0.005-15 mol.% repeating units derived from a monomer having one epoxy group and additionally at least one reactive functional group, with number-average molecular weight 50,000-2,000,000, glass transition temperature (Tg) of the copolymer by DSC of -60C, and heat of melting 70 J/g. (where, R1 = 1-12C alkyl, 2-8C alkenyl, 3-8C cycloalkyl, 6-14C aryl, 7-12C aralkyl or tetrahydropyranyl). Also claimed are: (i) a crosslinked body formed by crosslinking using the reactivity of the reactive functional group(s) of the copolymer; and (ii) a solid polyelectrolyte containing a crosslinked body and electrolyte salt compound.    USE -   The crosslinked polyether copolymer may be used to prepare solid polyelectrolytes for application in batteries (claimed), condensers and display elements, such as electrochromic display e.g. of electronic machinery.    ADVANTAGE -   Crosslinked solid electrolytes produced with the composition has excellent ion conductivity, processability, mechanical strength, flexibility, heat resistance, suitable for ultra-miniaturisation and thinning-down.    (JP9539740-X)      A polyether copolymer comprises: (A) 1-98 mol.% repeating units derived from a monomer of formula (I); (B) 95-1 mol.% repeating units derived from a monomer of formula (II); and (C) 0.005-15 mol.% repeating units derived from a monomer having one epoxy group and additionally at least one reactive functional group, with number-average molecular weight 50,000-2,000,000, glass transition temperature (Tg) of the copolymer by DSC of -60C, and heat of melting 70 J/g. (where, R1 = 1-12C alkyl, 2-8C alkenyl, 3-8C cycloalkyl, 6-14C aryl, 7-12C aralkyl or tetrahydropyranyl). Also claimed are: (i) a crosslinked body formed by crosslinking using the reactivity of the reactive functional group(s) of the copolymer; and (ii) a solid polyelectrolyte containing a crosslinked body and electrolyte salt compound.    USE -   The crosslinked polyether copolymer may be used to prepare solid polyelectrolytes for application in batteries (claimed), condensers and display elements, such as electrochromic display e.g. of electronic machinery.    ADVANTAGE -   Crosslinked solid electrolytes produced with the composition has excellent ion conductivity, processability, mechanical strength, flexibility, heat resistance, suitable for ultra-miniaturisation and thinning-down.    (CN1215416-A)      A polyether copolymer comprises: (A) 1-98 mol.% repeating units derived from a monomer of formula (I); (B) 95-1 mol.% repeating units derived from a monomer of formula (II); and (C) 0.005-15 mol.% repeating units derived from a monomer having one epoxy group and additionally at least one reactive functional group, with number-average molecular weight 50,000-2,000,000, glass transition temperature (Tg) of the copolymer by DSC of -60C, and heat of melting 70 J/g. (where, R1 = 1-12C alkyl, 2-8C alkenyl, 3-8C cycloalkyl, 6-14C aryl, 7-12C aralkyl or tetrahydropyranyl). Also claimed are: (i) a crosslinked body formed by crosslinking using the reactivity of the reactive functional group(s) of the copolymer; and (ii) a solid polyelectrolyte containing a crosslinked body and electrolyte salt compound.    USE -   The crosslinked polyether copolymer may be used to prepare solid polyelectrolytes for application in batteries (claimed), condensers and display elements, such as electrochromic display e.g. of electronic machinery.    ADVANTAGE -   Crosslinked solid electrolytes produced with the composition has excellent ion conductivity, processability, mechanical strength, flexibility, heat resistance, suitable for ultra-miniaturisation and thinning-down.    (US6239204-B1)      A polyether copolymer comprises: (A) 1-98 mol.% repeating units derived from a monomer of formula (I); (B) 95-1 mol.% repeating units derived from a monomer of formula (II); and (C) 0.005-15 mol.% repeating units derived from a monomer having one epoxy group and additionally at least one reactive functional group, with number-average molecular weight 50,000-2,000,000, glass transition temperature (Tg) of the copolymer by DSC of -60C, and heat of melting 70 J/g. (where, R1 = 1-12C alkyl, 2-8C alkenyl, 3-8C cycloalkyl, 6-14C aryl, 7-12C aralkyl or tetrahydropyranyl). Also claimed are: (i) a crosslinked body formed by crosslinking using the reactivity of the reactive functional group(s) of the copolymer; and (ii) a solid polyelectrolyte containing a crosslinked body and electrolyte salt compound.    USE -   The crosslinked polyether copolymer may be used to prepare solid polyelectrolytes for application in batteries (claimed), condensers and display elements, such as electrochromic display e.g. of electronic machinery.    ADVANTAGE -   Crosslinked solid electrolytes produced with the composition has excellent ion conductivity, processability, mechanical strength, flexibility, heat resistance, suitable for ultra-miniaturisation and thinning-down.