Polymer hydrogels synthesized bychemical cross-linking of acrylateor acrylamide monomers can absorb more than 100 times their weightin water. However, such gels are usually fragile and rupture whenstretched to moderate strains (∼50%). Many strategies havebeen developed to create tougher gels, including double-networking,incorporation of nanoparticles as cross-linkers, etc., but these strategiestypically retard the water absorbency of the gel. Here, we presenta new approach that gives rise to superabsorbent hydrogels havingsuperior mechanical properties. The key to our approach is the self-cross-linkingability of N,N-dimethylacrylamide(DMAA). That is, we conduct a free-radical polymerization of DMAA(along with an ionic comonomer such as sodium acrylate) but withoutany multifunctional monomers. A hydrogel still forms due to interchaincovalent bonds between the growing linear polymer chains. Gels formedby this route can be stretched up to 1350% strain in the unswollenstate. The same gels are also superabsorbent and can imbibe up to3000 times their weight in water (which is believed to be a record).Even in the swollen state, these gels can be stretched up to strains∼400% before rupture, which substantially exceeds that of conventionalsuperabsorbent gels. The superior properties of DMAA-based gels areattributed to a more uniform distribution of cross-links within theirnetworks. [ABSTRACT FROM AUTHOR]