GAS-TRANSPORT PROPERTIES OF SUBSTITUTED PEEKS

Tert-butyl and di-tert-butyl were added as pendant groups to the ether -ether phenyl ring of poly( ether ether ketone), PEEK. tert-butyl PEEK , TBPEEK, was amorphous and di-tert-butyl PEEK, DBPEEK, was semicrysta lline. However, a 2 : I random copolymer of TBPEEK and DBPEEK, TBDBPEE K, was amorphous. Gas transport of N-2, O-2, CH4, and CO2 through amor phous films of PEEK, TBPEEK, TBDBPEEK, and tetramethylbiphenyl PEEK we re determined at 35 degrees C and at pressures to about 15 atm. The re sults support previous observations that tert-butyl and tetramethylbip henyl groups are very effective in disrupting chain packing in the pol ymer. For the present polymers, these substitutions led to a 5-18-fold increase in permeability, and, in some cases, at no loss in permselec tivity. (C) 1997 John Wiley & Sons, Inc.