Biomedical devices such as contact lenses formed from a polymerization product of a mixture comprising (a) a multi-armed macromonomer comprising multiple side chains attached to a nucleus, wherein each side chain comprises a thio carbonyl thio fragment of the same or different reversible addition fragmentation chain transfer (&ldquo；RAFT&rdquo；) agent； and (b) one or more biomedical device-forming monomers are disclosed.
