One-step synthesis of amine-functionalized thermo-responsive magnetite nanoparticles and single-crystal hollow structures

A high-temperature solution phase hydrolysis has been developed for the synthesis of amine-functionalized Fe3O4 nanostructures. The concentrations of the reagents and the reaction time have great influence on the morphologies of the products. Increasing the amounts of poly (propylene glycol) bis (2-aminopropyl ether) transformed the product morphology from hollow nanostructures to magnetite nanoparticles. Single-crystal solid spherical aggregates, hollow spheres, loose nanoclusters and polyhedral-like magnetite particles can be selectively synthesized by varying the synthesis parameters, including the reaction time or the weight ratio of iron precursors to polyetheramine. The morphological transformation could be attributed to the cooperation of oriented aggregation and Ostwald ripening mechanisms. By using poly (propylene glycol) bis (2-aminopropyl ether) as the capping agent, the amine-functionalized nanoparticles show high water dispersibility and thermo-responsive. In addition, the Pickering emulsion stabilized by amine-functionalized nanoparticles was fabricated. One of the most promising applications of the as-prepared single-crystal hollow structures is as support materials for biological testing, catalysis and targeted drug delivery.