Field et al. modified cross- linked PDMS membranes by sequential introduction of two different side arm functional groups, −(CH2)3OC2H5 and −(CH2)3NMe2. Membranes containing 20% ethyl ether (in AEE membranes) and 10% dimethylamino (in AMI mem- branes) groups produced a high cresol flux (30% higher than that achievable using either AEE or AMI modified membranes) and a high separation factor (α = 50.4).