Precisely Tailoring Bubble Morphology in Microchannel by Nanoparticles Self-assembly

Precisely tailoring bubble morphology is always a long-standing great challenge. In this work, a facile and scalable method to generate nonspherical bubbles with long-term stability is proposed. Taking advantage of the electrostatic interaction between silica nanoparticles (SNPs) and cationic surfactants, the SNPs are decorated with surfactants and endowed with interfacial activity. Due to the rearrangement of surfactants, the decorated SNPs transform to a kind of Janus particles at the gas-liquid interface. By precisely manipulating the surface activity, packing density, and jamming of Janus SNPs at the bubble surface, four different shapes such as oblaten-like, bullet-like, tadpole-like, and worm-like bubble were obtained continuously in the microchannel. Herein, our method to generate bubbles with a prescribed shape poses opportunities for gas microreactor, cavity material, gas storage, and provide a platform to study the applicable scope of the Young-Laplace equation.