SULFONATED POLYIMIDE COPOLYMER HAVING PROPERTIES SUITABLE FOR ELECTROLYTE MEMBRANE FOR DMFC BY CONTROLLING CONTENT OF SULFONATE GROUP BONDED TO MAIN CHAIN OF POLYIMIDE, ELECTROLYTE MEMBRANE FOR DMFC AND PREPARATION METHOD THEREOF

摘要

PURPOSE: Provided are a sulfonated polyimide copolymer, an electrolyte membrane for a direct methanol fuel cell (DMFC) containing the copolymer which has high hydrogen ion conductivity, a low methanol permeability and an excellent stability and its preparation method. CONSTITUTION: The sulfonated polyimide copolymer is represented by the formula 1, wherein 0<x<=0.65, 0.35<=y<1, and x+y is 1; and n is 100-1,000. The method comprises the steps of polycondensing a sulfonated monomer and a non-sulfonated monomer to obtain a poly(amic acid) and preparing a membrane having a thickness of 50-80 micrometers from the poly(amic acid); and preparing a sulfonated polyimide membrane by the thermal imidation of the obtained poly(amic acid) membrane. Preferably the sulfonated monomer is 2,2'-benzidinedisulfonic acid and the non-sulfonated monomer is 3,3',4,4'-benzophenonetetracarboxyl dianhydride and 4,4'-oxydianiline.