Effect of Solvent Polarity on Fabrication of Dual Janus Particles with Asymmetric Morphology and Chemical Identity via Photo-initiated Seeded Swelling Polymerization

Particles with asymmetric morphology or surface chemical identity (Janus) are of great interest in the field of materials due to their special composition and structure. However, it is still a challenge to prepare particles with dual asymmetry via simple and convenient synthesis strategies. Herein, micron-sized dual-asymmetry Janus particles were prepared via photo-induced seeded swelling polymerization within 30 min. By controlling the polarity of the organic solvent (porogenic reagent), Janus particles with various morphologies were fabricated. The particles with convex surfaces, such as dumbbell-shaped, snowman-shaped, and golf-shaped morphologies, were obtained in the polar porogenic system, while the concave surface particles, such as bowl-shaped and ball-in-bowl, were acquired in the non-polar porogenic system. Mushroom-shaped and pinecone-shaped particles were generated in the binary porogenic system. Particularly, snowman-shaped, bowl-shaped, and pinecone-shaped particles were characterized by confocal laser scanning microscopy, exhibiting asymmetric chemical identity. They could be easily modified into amphiphilic solid surfactants for emulsifying oil–water incompatible mixtures with a definite interfacial orientation. This strategy provides a possibility for the simple and rapid preparation of dual Janus particles with asymmetric morphology and chemical identity, which are expected to be produced on a large scale.