Poly(acrylic acid-co-methyl methacrylate)-Modified Poly(ether sulfone) Porous Monolith Fabricated Using a Freezing-Induced Phase Separation Method

Traditional poly(ether sulfone) (PES) membranes and spheres exhibit asymmetrical and non-interconnected porous structures, which results in relatively low mass transfer efficiency and thus limits their applications in separation and adsorption to some extent. In this work, PES-based monolithic materials are fabricated by a simple method termed freezing-induced phase separation (FIPS). The as-prepared monoliths show a uniform and interconnected porous structure, high porosity (73.11–83.32%), and good mechanical properties (Young’s modulus higher than 3.70 MPa). A hydrophilic copolymer (poly(2-aminoethyl methacrylate)─PAMA) of acrylic acid (AA) and methyl methacrylate (MMA) is introduced into the monolith, which improved the hydrophilicity and endowed the modified PES-based monolith with a negatively charged surface. The pseudo-ternary PES/PAMA, EtOH, and N,N-dimethylformamide (DMF) systems are studied. The monoliths show a denser and more uniform porous structure when a relatively high PES concentration and PAMA amount are used. The adsorption capacity of monoliths for methylene blue (MB) increases with increasing PAMA content, from 10.26 to 64.38 mg/g. Meanwhile, the adsorption capacity can be further improved by hot water post-treatment, from 64.38 to 108.33 mg/g. Batch adsorption tests indicate that the adsorption behavior of the MB monoliths fit the pseudo-second-order kinetic and Langmuir isotherm models. The dynamic adsorption results indicate that the monoliths could remove MB rapidly and effectively. In addition, the modified PES-based monolith selectively adsorb the cationic dyes in a mixed dye solution and has good recyclability.