Control and optical mapping of mechanical transitions in polymer networks and DNA-based soft materials

Complex mechanical changes in response to an external trigger are pervasive in natural soft materials and often sought for applications. Be it the reversible stiffening of sea cucumber, the failure of a polymeric or colloidal gel under load, or the dissolution of a biosensing hydrogel upon target binding, mechanical transitions are typically enabled, and critically affected, by heterogeneous structures and reversible bonds. New possibilities to monitor evolving properties and to gain access to stress propagation with temporal and spatial resolution are being disclosed by mechanochromic molecules and molecular complexes, which transduce a mechanical stress into a light signal and act as built-in stress reporters. I will review recent strategies and identify future directions for the design of mechanically responsive soft networks and for their optical mapping, focusing particular attention on the emerging class of hydrogels based on DNA self-assembly.