Direct Continuous Synthesis of Oleic Acid-Modified Fe₃O₄ Nanoparticles in a Microflow System

Abstract

In this work, a direct continuous synthesis route of oleic acid (OA)-modified Fe3O4 nanoparticles was proposed and achieved by combining flow co-precipitation of Fe3O4 nanoparticles in a membrane dispersion microcontactor with the in-line introduction of OA. A systematic characterization confirms the effective and controllable covalent binding between OA and the nanoparticles during an extremely short period in a microflow system. Through comprehensively investigating the effects of different factors, the proper time to introduce a modifier was explored, and the mechanism of sequential nanoparticle generation and modification was revealed. A quantitative regulation relationship for the modification process was established as guidance to achieve an accurate and flexible modification degree. Compared with the traditional multistep and hour-level duration in the batch process, this highly controlled continuous synthesis method within seconds opens a horizon for the broad applications of OA-modified Fe3O4 nanoparticles in the future.