Polysulfone–chitosan hybrids via imine chemistry: a versatile strategy for functional bioactive materials

Abstract

The paper aimed to develop a new approach to improve the hydrophilicity and bioactivity of polysulfone-based materials through covalent bonding with chitosan via imine or amine linkages. To achieve this, different synthetic strategies were employed, including the chloromethylation and etherification of polysulfone to introduce formyl functionalities along the polymer backbone. These formyl groups subsequently participated in condensation reactions with the amino groups of the chitosan chains, either on the surface or within the bulk. Additionally, reductive amination was applied to convert imine bonds into more stable amine linkages. A comprehensive characterization by ATR-FTIR, WXRD, UV-Vis, TGA, and SEM analyses confirmed the successful formation of the targeted hybrid materials, with a semicrystalline structure favoured by deep polymer blending through covalent bonding, high thermal stability and a porous morphology. Water uptake, contact angle and permeability assessments, conducted using dynamic vapor sorption and cup test methods, revealed significantly enhanced hydrophilicity, with water absorption levels reaching up to 45% and moderate wettability, with a water contact angle in the 60–90° range, swelling capacities of up to 2 g g⁻¹, and enzymatic degradation in lysozyme solutions reaching 45% mass loss over 21 days, depending on the chitosan content. Moreover, antioxidant activity evaluated via DPPH assays demonstrated a free radical scavenging capacity of approximately 20%, while antibacterial tests indicated the ability to inhibit bacterial growth by more than 30%, placing these materials in the bacteriostatic range. Overall, these findings support the modification of polysulfone with chitosan via imine bonds as an effective strategy for the design of advanced biomaterials and filtration technologies.