as 2,2-bishydroxymethylpropionic acid; conduction channel is formed on peripheral wall of cylindrical structure; fuel cell electrolytesUS8124294 *Mar 30, 2007Feb 28, 2012Samsung Sdi Co., Ltd.Polymer electrolyte membrane comprising inorganic nanoparticle bonded with proton-conducting group and solid acid, fuel cell including the same, and method of preparing the polymer electrolyte membraneUS829872