Could you explain the significance of your article to the non-specialist?

The usage in materials science of the very powerful « ionic liquids » is showing a very rapid expansion since around year 2000. These liquids, formed exclusively by cations and anions, are non-volatile, non-flammable, can be separated from many other liquids and thus recycled ; they are finding applications in fields as diverse as energy storage and transformation (e.g. electrolyte for lithium batteries), chemical and biochemical sensors (e.g. enzymes solubilisation and electrochromic devices), physical and biophysical actuators (e.g. dispersant for carbon nanotubes and cellulose). Nevertheless, their liquid state remains a major drawback for most applications since shaping is ever a critical point for industrial applications of novel materials. This major impediment is circumvented here by hosting these liquids in a solid-state sponge-like structure. From these sponge-like host network which can be shaped, liquids do not leak and are shown to present the same properties as genuine ionic liquids thus allowing their expected wide range of applications in material science.

What has motivated you to conduct this work?

The poor usage of ionic liquids as materials themselves a few years ago (around year 2003) led us to apply our knowledge in sol-gel chemistry and physical-chemistry of materials science to find a general procedure for opening the route to fill this gap. We have named at that time the monoliths obtained through sol-gel chemistry carried out in the ionic liquid "ionogels". The success of the first physical measurements (high values of ionic conductivities) prompted us to gain more in-depth insights of the behaviour of the confined ionic liquids, showing the real liquid state of the ionic liquids confined in solid state host networks.

Where do you see this work developing in the future?

As mentioned above this opens a wide range of applications, from simple electrolytic membranes (for lithium batteries, fuel cells, solar cells) to physical, chemical, biophysical and biochemical sensors and actuators ; this is based on the tremendous current increase of researches led on exploiting the versatile properties of ionic liquids, from simple electrolyte to polysaccharide solvent, CNT dispersants, task specific solvents for organic chemistry (e.g. enantioselectivity)

Are there any particular challenges facing future research in this area?

Mechanical strength of thin devices has to be increased and task specific host oxide networks with a variety of metals will be developed. Interfaces between ionogels and others components in multi-layers devices will have to be controlled (works are in progress in our group for these purposes).