Magnetothermally responsive composite submicron particles for recyclable catalytic applications

To improve the recycling efficiency of magnetic recycling system, magnetothermally responsive composite submicron particles (CFMNs@PEG CSPs) were designed and prepared for recyclable catalytic applications, in which poly(ethylene glycol) gel was used as the shell and clusters of cobalt ferrite magnetic nanoparticles as the core. A novel strategy for recycling both loadings and carriers was proposed based on loadings immobilized CFMNs@PEG CSPs via magnetic separation at first and then magnetothermally responsive release. The morphology and core–shell structure were observed by transmission electron microscope . The physicochemical characteristics were investigated by Fourier transform infrared, 1 H NMR, Magnetic property measurement system, thermogravimetric analysis and X-ray photoelectron spectroscopy. The size of CFMNs@PEG CSPs was 285.1 ± 7.6 nm (the core was 160.0 ± 13.2 nm and PEG gel shell was 62.6 nm). The shell thickness of CFMNs@PEG CSPs shrunk from 62.6 nm to 35.5 nm when the temperature changed from 25 °C to 50 °C, and more than 95% of the loadings were released in 30 min by magnetothermally responsive release. Combing magnetic separation and magnetothermally responsive release, CFMNs@PEG CSPs were recycled over 42 times for horseradish peroxidase catalysis (horseradish peroxidase was re-immobilized for six times and reused seven times for each re-immobilization) and 25 times for gold nanoparticles catalysis (reactivated gold nanoparticles were re-immobilized for five times and reused five times for each re-immobilization) without significant catalytic activity loss, indicating their extensive potential in recyclable catalytic applications and other applications.