Three series of oxyalkylene copolymers containing chloromethyl and methylthiomethyl side groups were synthesized by reacting the starting chloromethyl polymers with sodium methanethiolate. The methylthiomethyl groups were oxidized to sulfone groups using m-CPBA to produce oxyalkylene copolymers containing chloromethyl and methylsulfonylmethyl side groups. T-g versus composition for methylthiomethyl-substituted copolymers followed those calculated from the Fox equation, while 2 of the 3 series of methylsulfonylmethyl-substituted copolymers showed positive deviations from the Fox equation. T(g)s of the copolymers calculated using the Johnston equation showed very good agreement with experimental values in all cases.