Magnetite/Polymer Brush Nanocomposites with Switchable Uptake Behavior Toward Methylene Blue

Abstract

The grafting from approach was used to prepare pH-responsive polyacid brushes using poly(itaconic acid) (PIA) and poly(acrylic acid) (PAA) at the amine functional groups of chitosan. Hybrid materials consisting of polymer brushes and magnetite nanoparticles (MNPs) were also prepared. The products were structurally characterized and displayed reversible pH-responsive behavior and controlled adsorption/desorption of methylene blue (MB). Switchable binding of MB involves cooperative effects due to conformational changes of brushes and swelling phenomena in solution which arise from response to changes in pH. Above the pKa, magnetic nanocomposites (MNCs) are deprotonated and display enhanced electrostatic interactions with high MB removal efficiency (>99%). Below the pKa, MNCs undergo self-assembly and release the cationic dye. The switchable binding of MB and the structure of the polymer brush between collapsed and extended forms relate to changes in osmotic pressure due to reversible ionization of acid groups at variable pH. Reversible adsorption-desorption with variable binding affinity and regeneration ability was demonstrated after five cycles.

Surface-Modified Chitosan: An Adsorption Study of a “Tweezer-Like” Biopolymer with Fluorescein

“…The IR spectrum of pristine chitosan is characterized by a broad band at 3000-3500 cm −1 which is due to the strong intermolecular hydrogen bonds of -OH and -NH 2 (amide II) groups. Bands near 2900 cm −1 relate to C-H stretching, 1652 cm −1 to amide I (C=O), 1593 cm −1 to amide II (N-H) bending, 1380 cm −1 to -CH and -CHOH and 1140 cm −1 to C-O-C in agreement with another report [52]. The spectra of CS-Ac-An shows similar features, where the intensity of 3000-3500 cm −1 band decreased due to grafting of -NH 2 groups and disruption of the intermolecular hydrogen bonds.…”

“…R L = 0 and 1 indicated irreversible and linear interactions, respectively. The separation factor was calculated for different initial concentrations [52].…”

Synthesis of silver-anchored polyaniline–chitosan magnetic nanocomposite: a smart system for catalysis

“…1C, the new peaks at 595 cm À1 and 449 cm À1 support the presence of magnetite and are related to vibrational Fe-O bond. 51,53 The shiing of the magnetite peaks from that of parent magnetite peak indicates the interaction of magnetite with PANI and CS particles. Track D shows the nger print of track C with small shi of NH and OH peaks position from 1636 cm À1 and 3435 cm À1 (Fig.…”

Environmental implications and applications of engineered nanoscale magnetite and its hybrid nanocomposites: A review of recent literature

“…A C18-functionalized core-shell magnetic mesoporous silica composite (Fe3O4/mSiO2-C18) has excellent adsorption ability toward MB dye due to the large surface area and the abundant hydrophobic C18 groups [237]. Reversible pH-responsive behavior and controlled adsorption/desorption of MB have been demonstrated on hybrid materials consisting of polyacid brushes using poly(itaconic acid) (PIA) and poly(acrylic acid) (PAA) at the amine functional groups of chitosan and MNPs [238].…”