Janus is the name of an ancient Roman god who has two faces looking in two opposite directions. Different from the concept of colloidal molecules, Janus particle research emphasizes the different chemical make-up on each side of a single particle. The morphology control and large-scale synthesis of Janus nanoparticles are formidable challenges but promises to have broad implications in a wide range of industrial applications, drug delivery, and separation. A lot of effort has been invested in synthesizing Janus particles with desired surface chemistry and morphology.<sup> </sup>However, many processes for synthesizing Janus nanoparticles require unique chemistry and reaction conditions, and some methods require an extra cleaning and separation step.<br/>To address these challenges, we focused on continuous emulsion polymerization in this study. In order to simplify the emulsion polymerization system, styrene and tert-butyl acrylate were used as a model monomer couple. The ratio of monomers can tune to correlate with the final morphology. Different types of emulsifiers such as sodium dodecyl sulfate, polyvinylpyrrolidone, and poly(vinyl alcohol), Tween 20, and didecyldimethylammonium bromide were tested. Then, prepared Janus particles were used for surface modification. The size, size distribution, and charge of spherical nanoparticles were measured using dynamic light scattering (DLS) and zeta potential measurement. The morphology of nanoparticles was checked using scanning electron microscopy (SEM). Prepared surfaces were characterized using SEM, ellipsometry, atomic force microscopy (AFM), and water contact angle measurements.<br/>This study provided the groundwork and deepened our fundamental understanding of emulsion polymerization and led to the next generation of colloidal materials through innovative manufacturing processes to reduce production time and improve throughput. The results can be readily translatable to industrial applications, paving the way towards the energy-efficient manufacture of polymeric Janus nanoparticles with well-defined geometry and chemistry.

Facile synthesis of polymeric Janus nanoparticles via emulsion polymerization

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.