Preparation of magnetic Fe3O4-decorated stereocomplex polylactide microspheres for efficient photocatalytic degradation.

Stereocomplex polylactide composite microspheres decorated with ferroferric oxide nanoparticles (SC-PLA@Fe3O4) with excellent photocatalysis and magnetic recyclability were successfully prepared via a facile strategy combining phase separation and Fe3O4 surface modification. First, poly(ethylene oxide) (PEO) was used as the phase-separation agent and porogen to trigger phase separation of the PEO/SC-PLA blend and produce SC-PLA microspheres with porous surfaces. Subsequently, SC-PLA@Fe3O4 composite microspheres were fabricated by immobilizing Fe3O4 nanoparticles onto porous SC-PLA microspheres via polydopamine adhesion. The results revealed that the as-prepared SC-PLA microspheres consisted exclusively of SC crystallites, and their porous surface was highly favorable for the immobilization of Fe3O4 nanoparticles. With increasing Fe3O4 dosage, the Fe3O4 loading within SC-PLA@Fe3O4 composite microspheres rose gradually, alongside an increase in diameter from 2.49 to 2.98 μm. SC-PLA@Fe3O4 composite microspheres exhibited superior photocatalytic activity toward methylene blue (MB) degradation, with a maximum MB removal efficiency of 87.65%. Kinetic results indicated that MB degradation conformed well to the pseudo-second-order model via synergistic surface adsorption and photocatalytic oxidation. Moreover, SC-PLA@Fe3O4 composite microspheres possessed rapid magnetic responsiveness and outstanding cyclic reusability, retaining a degradation efficiency exceeding 83% after five cycles. This work offers significant guidance for the fabrication and application of functional SC-PLA microspheres.