Synthesis of polysiloxane-based quaternized imidazolium salts with a hydroxy group at the end of alkyl groups

A series of polysiloxane derivatives having quaternized imidazolium moieties with hydroxyalkyl groups ([HPImnOH]Xs) (where n is the number of methylene group and X is counter anion) were prepared by quaternization of poly(3-chloropropylmethylsiloxane) (P1) using 1-(ω-hydroxyalkyl)imidazole derivatives (ImnOHs) and anion-exchange reaction using lithium bis(trifluoromethanesulfonyl)imide. Polysiloxane-based quaternized imidazolium salts having hydroxyalkyl groups with chloride anion ([HPImnOH]Cls) were obtained with high quaternization ratio of approximately 100 mol%. The glass transition temperatures (Tgs) of [HPImnOH]Xs were reduced by introducing a hydroxy group at the end of alkyl groups; however, no significant reduction in Tgs was observed by anion exchange from chloride anion to bis(trifluoromethanesulfonyl)imide one (Tf2N−).