Described is a tri-block prepolymer having a chemical structure of [A]-[B]-[C], comprising at least one monovalent reactive group, wherein segment [A] and [C] independently comprise polymeric segments based on a first hydrophilic monomer comprising functionality selected from the group consisting of hydroxyalkyl, alkylamine, and mixtures thereof and optionally a second hydrophilic monomer, and [B] comprises a polymeric segment of at least one silicone-containing macromer and optionally a third hydrophilic monomer comprising functionality selected from the group consisting of hydroxyalkyl, alkylamine, and mixtures thereof and optionally a silicone-containing monomer. These prepolymers may be used alone or in combination with other components in reactive monomer mixtures for making silicone hydrogels and ophthalmic devices made therefrom, including contact lenses.