A compound having the formula: Each R1 is C1-C3 alkyl group or fluoridated C1-C3 alkyl group. The value n is a positive integer. Each R2 is alkylene group or polyethylene glycol group. Y1 is hydrogen, quaternary ammonium containing group, or phenol-containing group. Y2 is quaternary ammonium-containing group or phenol-containing group. The quaternary ammonium-containing group is non-aromatic and contains no more than one quaternary ammonium.