Block-copolymer-armed star polyampholyte with pH- and temperature-tunable supramolecular nanostructures for enhanced dye adsorption

Abstract

The present investigation involves the synthesis of a series of block-copolymer-armed polyampholyte star polymers with sensitivity to changes in pH and temperature. The polymers are prepared using poly(2-hydroxyethyl methacrylate) core, while the arms are composed of a block copolymers consisting of acrylic acid and 2-(dimethylamino)ethyl methacrylate. The synthesis process involves a three-stage polymerization procedure utilizing reversible addition fragmentation chain transfer. The synthesized structures undergo characterization, and their self-assembly behavior is examined in relation to the adsorption of methylene blue, methyl orange, and the concurrent adsorption of both dyes. The development of spherical electrostatic complexes with varying diameters are seen as a consequence of pH variation. The present study investigates the impact of various parameters, including time, block location in the arms, pH, molecular weight, self-assembly effects, dye concentration, and temperature, on the process of adsorption. The study elucidates the adsorption phenomenon by examining its kinetics, thermodynamics, and adsorption isotherms. The findings of the study reveal that the greatest percentages of methylene blue adsorption are seen under alkaline pH conditions, whereas the most adsorption of methyl orange occurres under acidic pH conditions. The adsorption process by star-block polymers may be characterized as a spontaneous and endothermic mechanism, including heterojunction and multilayer adsorption. The polymers show promise for water purification applications due to their ability to simultaneously adsorb two dyes and their sensitivity to temperature and pH.