Fast fabrication of Janus particles via photo-initiated seeded swelling polymerization and their application in removal of copper(II) ion

Asymmetric particles (Janus particles) with discrete surface regions owning different chemical compositions or physical shapes have attracted increasing attention in the last two decades. Exploring novel strategies for synthesis of Janus particles is a great challenge due to somewhat complicated process and taking long time. In this work, several micron-scale Janus particles were rapidly prepared by photo-initiated seeded swelling polymerization for the first time, using glycyl methacrylate (GMA) as monomer and pentaerythritol tetraacrylate (PET4A) as crosslinker. After swelling of the seeds, the polymerization could be completed with ultraviolet light of 365 nm for 15 min. The effects of seed amount, molar ratio of monomer to crosslinker, volume ratio and type of porogenic agent and illumination time on Janus particle morphology were systematically investigated, and the resulting Janus particles with semi-raspberry-like morphology could be adjusted. Additionally, Janus particles were modified with a layer of polymer brush by surface-initiated atom transfer radical polymerization. The as-synthesized Janus@poly(GMA)-EDA was utilized for the adsorption of Cu(II) ion, and the adsorption capacity reached 349.6 mg g⁻¹, indicating that Janus@poly(GMA)-EDA exhibited great application potential for heavy metal removal.