Glucose/fructose-based boric acid-bridged in situ generated macrocyclic polymers and their behaviors in capturing dyes

Abstract

To better study the mechanism of hierarchical porous polymers towards target substrates at a molecular level, we fabricated glucose/fructose-based crosslinked porous polymers with boric acid as the covalent bridge to in situ generate flexible macrocyclic skeletons including BA–G and BA–F. The thus obtained BA–G/BA–F polymers were fully characterized by SEM, FT-IR, XRD, TGA, DTG, BET, zeta potential and XPS, indicating the formation of porous structures with a good specific surface area. We also demonstrate the successful application of those polymers to efficient adsorption of diverse cationic dyes. The adsorption properties of BA–G/BA–F polymeric materials were studied by analyzing the adsorption effect towards a single category of dyes. Interestingly, as revealed by the adsorption kinetic studies and adsorption isotherm, chemical adsorption played a dominant role in molecular recognition of BA–G/BA–F towards cationic dyes, exhibiting a maximum adsorption capacity of 756.91 mg g⁻¹ (q_max of BA–G) towards MG. Thermal kinetic studies also show related trends in parameters, indicating in situ generated porous structures spontaneously adsorbing dyes driven by electrostatic and hydrogen bonding interactions. Furthermore, the mimicking behavior of macrocyclic skeletons by in situ fabrication was then proved by the analysis of elemental composition via EDS, molecular weight of materials via MALDI test, as well as proposed in situ generated macrocyclic structures towards target substrates via DFT calculations.