(629e) First Proof of Self-Assembly of Block Copolymers in a Deep Eutectic Solvent

It was in 2003 when a new class of innovative solvents was presented in literature.^[1] These so called deep eutectic solvents (DESs) are a combination of two or more solids, which undergo interactions via hydrogen bonding and presumably Van der Waals forces upon the formation of the liquid DES.^[2] DESs can be seen as the successors of ILs with many advantages over them. The main advantage is their easy preparation, which is simply mixing the two components at moderate temperatures to form the liquid DES. Furthermore, DESs are considered as sustainable solvents, an aspect that can be tuned by the selection of the components.

From the start, the search for news DESs mainly focused on using solid components with a high amount of hydrogen bonding groups, leading to hydrophilic DESs. In 2015 hydrophobic DESs were discovered, which were used for the removal of volatile fatty acids from water.^[3] These hydrophobic DESs were composed of decanoic acid and quaternary ammonium salts. Recently, more applications regarding hydrophobic DESs were presented in the literature. These include the removal of biomolecules from an aquatic environment, the removal of metal ions from pure water and the capture of CO₂.^[4,5]

An area that is not explored yet in the literature is the self-assembly of block copolymers in DESs, while this can be of interest for many applications such as drug delivery, nanomaterial synthesis and separation processes, where the sustainable character and cheap production costs of DESs can offer a major advantage over ILs and conventional solvents. The first step towards studying self-assembly of polymers in DESs was measuring the solubilities of hydrophobic and hydrophilic polymers in DESs. Results that gave an insight towards which block copolymers would self-assemble in the DESs. Subsequently, a block copolymer was designed, which was self assembled in the DESs for the first time.

References

[1] A. P. Abbott, G. Capper, D. L. Davies, R. K. Rasheed, and V. Tambyrajah, Chemical Communications, 2003, 70–71.

[2] M. Francisco, A. van den Bruinhorst, and M. C. Kroon, Angew. Chem. Int. Ed., 2013, 52, 3074–85.

[3] D. J. G. P. van Osch, L. F. Zubeir, A. van den Bruinhorst, M. A. A. Rocha, and M. C. Kroon, Green Chemistry, 2015, 17, 4518–4521.

[4] B. D. Ribeiro, C. Florindo, L. C. Iff, M. A. Coelho, and I. M. Marrucho, ACS Sustainable Chemistry & Engineering, 2015, 3, 2469–2477.

[5] D. J. G. P. van Osch, D. Parmentier, C. H. J. T. Dietz, A. van den Bruinhorst, R. Tuinier, and M. C. Kroon, Chemical Communications, 2016, 52, 11987–11990.