In conventional polymer materials, mechanical performance is traditionally engineered via material structure, using motifs such as polymer molecular weight, polymer branching, or block copolymer design1. Here, by means of a model system of 4-arm poly(ethylene glycol) hydrogels crosslinked with multiple, kinetically distinct dynamic metal–ligand coordinate complexes, we show that polymer materials with decoupled spatial structure and mechanical performance can be designed. By tuning the relative concentration of two types of metal–ligand crosslinks, we demonstrate control over the material’s mechanical hierarchy of energy-dissipating modes under dynamic mechanical loading, and therefore the ability to engineer a priori the viscoelastic properties of these materials by controlling the types of crosslinks rather than by modifying the polymer itself. This strategy to decouple material mechanics from structure is general and may inform the design of soft materials for use in complex mechanical environments. Three examples that demonstrate this are provided.
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S.C.G. was supported by the Anne M. Mayes Fellowship. S.C.G. and N.H.-A. were supported by the MRSEC programme of the National Science Foundation under award number DMR—0819762 and DMR-1419807. N.H.-A. was supported by the MIT Sea Grant via the Doherty Professorship in Ocean Utilization. D.G.B., J.C. and P.B.M. were supported by the National Institutes of Health under award number R37DE014193. D.M. and Z.G. were supported by the US Department of Energy, Division of Materials Sciences, under award number DE-FG02-04ER46162.
The authors declare no competing financial interests.
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Grindy, S., Learsch, R., Mozhdehi, D. et al. Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics. Nature Mater 14, 1210–1216 (2015). https://doi.org/10.1038/nmat4401
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