Meta‐separation: Improvement of Properties by Molecular Design of Metamaterials for Organophosphorous Flame Retardants

Abstract

The separation of liquid mixture has been studied for a long time. Separation proceeds based on the difference in physical properties including pore size and electrostatic interaction. Therefore, there are many difficulties in separation of materials having similar size and/or polarities in physical properties. Recently, meta-separation which is novel separation strategy employing a metamaterial was reported. It utilizes the structural properties of metamaterials rather than electrostatic characteristics to separate water-organic mixtures. Although it proposes a new method for separation of aqueous liquid mixtures, it has a low phase transition temperature and melting point. A newly designed and synthesized 12,12',12'',12'''-(pyrene-4,5,9,10-tetrayltetrakis(oxy))tetrakis(dodecan-1-ol)(P-TOH) can significantly increase the thermal stability by replacing the end of the building block with a hydroxyl group. This dramatically improves the stability of the metamaterial in the xy plane through hydrogen bonding interaction, thereby increasing the phase transition temperature by 23.49°C. Furthermore, organophosphorous flame retardants (OPFRs), critical hazardous organic compounds, are entirely eliminated from the water mixture by molecular metamaterial with PTOH.