Deep Eutectic Solvents: A Convenient Route Towards a More Sustainable Functionalization of Carbon Nanoforms

Abstract

The solvent use accounts for over 80% of waste produced in pharmaceuticals/fine chemicals batch chemical operations. The most obvious solution would be to reduce or preferably avoid the use of the solvent at all, however this option is seldom viable. In this context, deep eutectic solvents (DESs) could represent a suitable solution that offer a convenient route towards the design of more sustainable processes. Most functionalization techniques of carbon nanoforms (CNFs), such as carbon nanotubes (CNTs), usually require a large amount of solvents to ensure their dispersion. The environmental, safety, and health issues push towards the adoption of alternative and more benign media. DESs can actively contribute to this green transition by defining a novel class of "reactive solvents" capable of both efficiently dispersing CNFs and reducing the amount of solvent used. In this regard, the proper combination of hydrogen bond acceptor (HBA) and donor (HBD) species can produce novel DESs composed by reactive constituents (HBA or HBD) able to functionalize the selected CNFs in a more sustainable, atom-economical and highly time-saving way (Figure 1). We have focused our attention towards this promising research field and further studies are currently ongoing.