Provided are compositions comprising a block copolymer of the following formula: [A]-B-[Q], wherein [A] is a polymer that has an affinity for a substrate； B is a linking group comprising an optionally-substituted, polyvalent linking group having a molecular weight of no more than 1000 g/mole； and [Q] comprises a semi-crosslinked, ungelled polymer derived from copolymerization of an ethylenically unsaturated monomer with a poly-functional ethylenically unsaturated monomer. Such block copolymers are cross-linked via the [Q] segment, but not macroscopically gelled. The [Q] segment is hydrophilic and has a degree of polymerization in the range of about 10 to about 10,000. The [A] segment is located on at least one terminal end of said block copolymer, comprises between about 1 and about 200 repeating units. The block copolymer is associated, via the linear substrate associative segment with a surface comprising at least one hydrophobic site, such as a silicone hydrogel. The polymers may be incorporated into a formulation from which the silicone hydrogel is made or may be contacted with the silicone hydrogel post-formation.
