Magnetothermally responsive composite submicron particles for recyclable catalytic applications

To improve the recycling efficiency of magnetic recycling system, magnetothermally responsive composite submicron particles ([email protected] 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 [email protected] 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, 1H NMR, Magnetic property measurement system, thermogravimetric analysis and X-ray photoelectron spectroscopy. The size of [email protected] 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 [email protected] 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, [email protected] 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.