PREPARATION OF MACROPOROUS CARBONS FROM PHASE-INVERSION MEMBRANES

Preparation of porous carbons from phase-inversion membranes was inves tigated as a control method of pore structure in carbon materials. The structure in carbon films was estimated by means of electron microsco py, mercury porosimetry, and gas-adsorption methods. When phase-invers ion membranes of Kapton-type polyimide were carbonized, they maintaine d the film form and gave macroporous carbon films having high porosity . However, micro- and mesopore structures in the carbon films were not influenced by phase inversion in the polymer stage, and, thus, the ma croporous carbons had a molecular sieve property similar to that of ca rbons prepared from nonporous polyimide films. A macroporous structure in cellulose membranes was similarly maintained through the carboniza tion step, but some of these were fractured or deformed owing to the l arge shrinkage. Polymer membranes have a capability as porous carbon p recursors if they satisfy two requirements: solid-state carbonization and relatively high carbon yield. A composite membrane of a macroporou s carbon with a dense carbon having an impervious ability was readily produced by shaping at the precursor stage. (C) 1995 John Wiley and So ns, Inc.