A synthetic route to polymers comprised of at least two monomers each with a very different reactivity ratio by using a corresponding crosslink agent for each monomer. Novel crosslink agents are described that provide for the copolymerization of at least one hydrophilic monomer with at least one lens monomer typically used to prepare materials for ophthalmic lenses. The new crosslink agents have a relatively high selectivity for the hydrophilic monomer and limited reactivity with the crosslink agent used to polymerize the lens monomer.