Self-healing polymers can significantly extend the service life of materials and structures by autonomously repairing damage. Intrinsic healing holds great promise as a design strategy to mitigate the risks of damage by delaying or preventing catastrophic failure. However, experimentally resolving the microscopic mechanisms of intrinsic repair has proven highly challenging. This work demonstrates how optical micromechanical mapping enables the quantitative imaging of these molecular-scale dynamics with high spatiotemporal resolution. This approach allows disentangling delocalized viscoplastic relaxation and localized cohesion-restoring rebonding processes that occur simultaneously upon damage to a self-healing polymer. Moreover, frequency- and temperature-dependent imaging provides a way to pinpoint the repair modes in the relaxation spectrum of the quiescent material. These results give rise to a complete picture of autonomous repair that will guide the rational design of improved self-healing materials.

@en

On page 5 of 6 (Experimental Section, subsection Laser Speckle Imaging), the sentence “The LSI method is based on the multiple scattering of light, essentially the imaging equivalent of Ddffusive Wwve Ssectroscopy.[27]” was typeset incorrectly during production of the article, and is hereby corrected to (changes indicated in bold): “The LSI method is based on the multiple scattering of light, essentially the imaging equivalent of diffusive wave spectroscopy.[27]” Furthermore, the sentence “At frequencies below ∼0.1 Hz and above ≈100 Hz, localized repair dynamics vanish.” was typeset incorrectly during production of the article, and is hereby corrected to (changes indicated in bold): “At frequencies below ≈0.1 Hz and above ≈100 Hz, localized repair dynamics vanish.”.@en

The response of many soft materials to external fields is dominated by transient forces, which arise from memory of the configurations the system has undergone in the past. Using large-scale particle-based simulations we show that these transient forces lead to a rich non-equilibrium behavior in networks of soft polymeric particles or polymer-engrafted colloids. We compute the diagram of states for an experimental system of network-forming associative polymers and show viscoelastic instabilities such as shear banding, melt fracture and a shear-induced disorder-order transition.@en

Transient polymer networks are known to undergo a wide variety of viscoelastic flow instabilities. In this paper we investigate two of these flow failure modes: shear banding and melt fracture. Using particle-based simulations we reveal a transition from gradient banding to fracture in transient polymer networks with reversible associative nodes. We discuss the failure-mode transition on the basis of an energetic and a kinetic approach to fracturing in soft materials.@en