TECHNOLOGY FOCUS - POLYMERS - Preferred Process: The isocyano group containing component is toluene diisocyanate, methylene diphenylene diisocyanate and/or isophorone diisocyanate. The hydroxyl group containing component is polyethylene glycol, polypropylene glycol, and/or polytetramethylene glycol. Step (a) is carried out at 60-100degreesC. The functionality ratio of isocyano to hydroxyl groups is 1.0-2.0. The second solvent is acetone and an ionic group, preferably a carboxyl or sulfonic group is provided to the prepolymer by addition of an ionic group containing compound, preferably dimethanol propionic acid in step (a) to enhance the hydrophilicity of the matrix material or the ionic group is provided to the hydroxyl or isocyano containing component prior to polymerisation. Step (b) includes the substeps of (b1) dropwise addition of water to the matrix material formed in step (a) to form the dispersion solution; and (b2) removing the second solvent in the dispersion solution. Step (c) is carried out by blowing the dispersion solution in air or by heating in an oven. Step (d) is carried out by immersing the matrix into a dried organic electrolyte solution containing a salt electrolyte and a third solvent to swell the matrix. The electrolyte salt is a lithium salt of LiCF3SO3, LiClO4, LiPF6, LiBF4, LiAsF6 and/or LiN(CF3SO2). The third solvent is propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, diethyl ether, gamma-butyrolactone, 2-methyl-tetrahydrofuran, 1,2-dimethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone and/or dioxolane. EXAMPLE - A 1M solution of LiPF6/propylene carbonate/diethyl carbonate was added to a polyurethane thin film (prepared by addition of acetone and diaminosulfonate to a prepolymer of polyethylene glycol (87.5), isophorone diisocyanate (32 g) and dimethanol propionic acid (1.2 g), followed by dropwise addition of pure water, recovery of acetone under reduced pressure and drying of the waterborne dispersion to form a thin film). The resulting thin film had a conductivity of around 10-3 S/cm and good mechanical toughness.