Responsive Single-Chain/Colloid Composite Janus Nanoparticle

A facile approach is reported toward a thermoresponsive single-chain/colloid composite Janus nanoparticle by the termination of the corresponding anionic living single polymer chain onto the chlorine-capped Fe3O4 nanoparticle. Poly(2-(2-methoxyethoxy) ethyl methacrylate) (PMEO(2)MA) is selected as an example of a thermoresponsive polymer, which can be easily synthesized by anionic living polymerization. The Janus nanoparticle serves as a highly effective thermoresponsive solid surfactant, which can be manipulated with a magnet. The Janus/hydrophobic reversible transition can be triggered by near-infrared (NIR) irradiation to occur at a lower surrounding temperature owing to the photothermal effect of Fe3O4 nanoparticle. Integration of thermal response from PMEO(2)MA and paramagnetic and photothermal effects from Fe3O4 within the Janus nanoparticle, a powerful tool is provided to easily control the stability and microstructure of the emulsions.