After pre-conditioning, the papers were
immediately placed inside a closed reaction chamber containing a
vial with liquid DMDCS (10, 50 and 1000 ml) in 40 ml of anhydrous
toluene. Reactions between DMDCS vapor and the papers were
carried out at 80 8C for 30, 60 and 240 min, respectively. The papers
were then isolated, washed and dried in the manner as described
above for the solution-immersion method