Sunscreen, cosmetics, food products, packaging, clothing and disinfectants – just to name a few – all rely on our ability to make nanomaterials. Developing economically viable and value-added sustainable processes for manufacturing nanomaterials is an increasingly important task. In relation to that, Professor Anja-Verena Mudring and Postdoc Oliver Hammond from Stockholm University recently published a review paper on ionic liquids (ILs) and deep eutectic solvents (DES) in Chemical Communications – a paper that might help solve sustainability and efficiency issues within nanotechnology.

ILs, also known as liquid salts, are an uncommon class of solvent that are composed of discrete ions and usually have melting points below 100°C. Properties that can be realised by ionic liquids cannot necessarily be attained by conventional molecular solvents, including non-volatility, high thermal stability and wide liquid windows. Through the cation-anion combination they can be tailor-made. This gives the unbelievable power in the synthesis of nanomaterials as they can be the solvent, the nanoparticle stabiliser and the structure-directing agent all-in-one. ILs have the power to tune phase, size, morphology and nanostructure without using additional chemical additives. Simply said, ILs are becoming a revolutionary synthesis medium for inorganic nanomaterials, permitting more efficient, safer and environmentally benign preparation of high-quality products.

Deep eutectic solvents (DES) are eutectic mixtures of two or more compounds, where the melting point is particularly depressed, making the important liquid state accessible. They are regarded to be in the same category as ILs as solvents and offer a similarly broad combinatorial playground, which is also beginning to translate into applications.

Anja and Oliver’s review demonstrates and confirms that these liquids are great green alternatives for producing nanomaterials, as well as functioning as powerful green synthesis tools when combined with unconventional synthesis techniques such as microwave, ultrasound and sputtering. Most importantly, and what the researchers want to promote, is that when ILs and DES are approached holistically, new universal manufacturing techniques that provide solutions to the existing problems of nanomanufacturing are enabled. Furthermore, that will open new possibilities for controlling the growth and assembly of nanostructures. The review of examples in the article illustrates this power of ILs and DES in the improved manufacturing of nanomaterials.

In short, ILs and DES look to be some of the future’s green and efficient problem-solvers within nanotechnology.