Polymer electrolyte membrane, method for producing the same, and proton conductivity evaluation method for polymer electrolyte membrane

A method for producing a polymer electrolyte membrane containing a polymer electrolyte comprising a polymer compound having an ionic segment having an ionic functional group and a nonionic segment having substantially no ionic functional group;

• said method comprising the steps of:
• applying a solution containing the polymer electrolyte to a substrate having a surface comprising a metal or a metal oxide;
• and
• evaporating the solvent from the solution, wherein
• in the evaporation step, the time from the start of solvent evaporation until completion thereof is 60 minutes or less.

A proton conductivity evaluation method for a polymer electrolyte membrane containing a polymer compound comprising an ionic segment having an ionic functional group and a nonionic segment having substantially no ionic functional group,

• said method comprising:
• a first step of performing sputtering in use of C60 ions from the surface toward the interior, and by performing X-ray photoelectron spectroscopy on the surface at sputtering elapsed time t for each time point, obtaining the intensity A of a specific signal selected from signals originating in the ionic segment and the intensity B of a specific signal selected from signals originating in the nonionic segment for each time point t;
• and
• a second step of determining a change in value represented by A/(A+B) plotted against t is whether substantially monotonically decreasing or not.