Schmitt trigger using a self-healing ionic liquid gated transistor

Electrical double layer transistors using ionic liquids as the gate and ZnO as the semiconductor exhibit stable operation in the presence of redox active additives. The characteristics of the device enable single components with the response of a Schmitt trigger

Surface-initiated self-healing of polymers in aqueous media

Polymeric materials that intrinsically heal at damage sites under wet or moist conditions are urgently needed for biomedical and environmental applications(1-6). Although hydrogels with self-mending properties have been engineered by means of mussel-inspired metal-chelating catechol-functionalized polymer networks(7-10), biological self-healing in wet conditions, as occurs in self-assembled holdfast proteins in mussels and other marine organisms(11,12), is generally thought to involve more than reversible metal chelates. Here we demonstrate self-mending in metal-free water of synthetic polyacrylate and polymethacrylate materials that are surface-functionalized with mussel-inspired catechols. Wet self-mending of scission in these polymers is initiated and accelerated by hydrogen bonding between interfacial catechol moieties, and consolidated by the recruitment of other non-covalent interactions contributed by subsurface moieties. The repaired and pristine samples show similar mechanical properties, suggesting that the triggering of complete self-healing is enabled underwater by the formation of extensive catechol-mediated interfacial hydrogen bonds.close303

Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics

In conventional polymer materials, mechanical performance is traditionally engineered via material structure, using motifs such as polymer molecular weight, polymer branching, or copolymer-block design(1). 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 may inform the design of soft materials for use in complex mechanical environments