Ethanol-Switchable Silane Crosslinking of Hydrogels

The successful application of hydrogel requires a general strategy to avoid on-site polymerization, one that preserves activity of the precursor over months to years of storage while allowing hydrogel curing to be triggered within seconds to minutes. Here, we propose an ethanol-switchable silane crosslinking strategy for versatile gels. The silane crosslinker is stabilized in the presence of ethanol during storage, achieving the polymer precursor solution with preserved reactivity for over 32 months. Upon ethanol evaporation, spontaneous and rapid crosslinking is triggered, resulting in mega-pascal-strong gels at ambient conditions. Our strategy is compatible with diverse types of hydrogels (anion, cation, and neutral) and coating techniques (spraying, casting, printing etc.). This ethanol-switchable silane crosslinking strategy provides a versatile platform for constructing functional gel materials with long-term precursor stability, on-demand curing, and tunable properties, architectures, and compositions.