In some aspects, the present disclosure pertains to multi-arm polymers that comprise a core, a plurality of polymer segments having a first end that is covalently attached to the core and a second end comprising a moiety that comprises a reactive group, wherein the polymer segments comprise one or more free-radical-polymerizable monomers. In some aspects, systems are provided that comprise a first composition comprising such a multi-arm polymer and a second composition comprising a multifunctional compound that comprises functional groups that are reactive with the reactive groups of the multi-arm polymer. In some aspects, systems are provided that comprise crosslinked reaction products of such a multi-arm polymer and such a multifunctional compound.