Synthesis and characterization of metamaterial self-assembled by pyrene and hydroxyl moieties and its application to the separation of organophosphorus flame retardants in aqueous system

Abstract

As the use of Organophosphorus flame retardants (OPFRs) increases, they have been detected in many environmental media and aquatic organisms, including indoor and outdoor air, surface water, groundwater and drinking water. Under this circumstance, it is in urgent to develop efficient and safe removal methods for OPFRs that applied to many consumer products and widely dissolved in water.

As adsorption chosen as a competitive method with its simple operation and low cost, porous metal-organic-frameworks (MOFs) have developed. However, their coordination bonds resulted in unsatisfactory stability in water. Therefore, new framework development for effective adsorption is still in progress.

This novel organic material is designed to enable intermolecular self-assembly through secondary forces such as van der Waals interaction and π-π interaction. If the molecules form the structure that has periodicity and regularity, it would have unique properties that found in metamaterials. Therefore, 3D organic metamaterial with large internal pores are essentially formed, which has potential to be applied as separators and sensors. However, it is still difficult to apply because the structure is easily broken by a relatively weak secondary force.

This thesis specifically addressed to the development of 3D molecular metamaterial, named HYSORB, with high thermal stability by introducing primary alcohols. Hydrogen bonds which classified as a strong secondary force, achieved higher melting point of 130℃. As the stability improves, the molecule, through its secondary force, creates the regular and periodic pores in a unique way of intermolecular self-assembly, and the capillary force by regular pores can quickly eliminate OPFRs. The new 3D porous structure can only take OPFRs, not water, so that it can easily remove OPFRs in a minute without any other process.