Transparent, stretchable and anti-freezing hybrid double-network organohydrogels

Abstract

Stretchable ionic conductors with high transparency and excellent resilience are highly desired for flexible electronics, but traditional ionic conductive hydrogels are easy to dry and freeze. Herein, a newly hybrid crosslinking strategy is presented for preparing a stretchable and transparent hydrogel by using sodium alginate (SA) and acrylamide based on the unique physically and covalently hybrid crosslinking mechanism, which is transformed into organohydrogel by simple solvent replacement. Due to the combination of hybrid crosslinking double network and hydrogen bond interactions introduced by the glycerin-water binary solvent, the SA-poly (acrylamide)-organohydrogel (SPOH) demonstrates excellent anti-freezing (−20°C) property, stability (>2 days), transparency, stretchability (∼1600%) and high ionic conductivity (17.1 mS cm−1). Thus, a triboelectric nanogenerator made from SPOH (O-TENG) shows an instantaneous peak power density of 262 mW m−2 at a load resistance of 10 M∛ and efficiently harvests biomechanical energy to drive an electronic watch and light-emitting diode. Moreover, The O-TENG exhibits favorable long-term stability (2 weeks) and temperature tolerance (-20°C). In addition, the raw materials can be prepared into SPOH fibers by a simple tubular mold method, exhibiting high transparency, which can be used for laser transmission. The various abilities of the SPOH promise the application of energy harvesting and laser transmission for wearable electronics and biomedical field.