Soft elastomer coatings for ionogels

Ionogels are stretchable ionic conductors with unique advantages, such as non-volatility, thermal, chemical, and electrochemical stability. Nevertheless, the exchange of solvent between ionogels and the external environment hinders their applications. Ionogel has the problem of ionic liquid (IL) leakage, or the ionogel absorbs moisture from the atmosphere. Here we develop a strategy to coat thin elastomers on ionogels. Silanes are added into the precursor of ionogels and elastomers to form a strong interface adhesion between the two polymer networks. The elastomer coating can prevent ionogels from absorbing moisture or leaking ionic liquid, while does not change their transparency, stretchability, and conductivity. We establish a procedure to quantify the loss of ionic liquid from ionogels, with the calibrated relation of conductivity/volume ratio. We find that the elastomer coatings work well because of their low diffusivity to ionic liquid on the order of 10⁻¹⁶m²/s. The coating strategy would be universal to various ionogels and elastomers, thus we expect its application in soft robots and stretchable devices made of ionogels.