The flow behaviors of nanoparticle-stabilized bubbles in microchannel: Influence of surface hardening

This work aims at understanding the influence of nanoparticle (NP) adsorption on the bubble behaviors in three-dimensional pore throat structures and straight microchannel. Results show that the assembly of NPs at gas-liquid interface plays a pivotal role in determining bubble behaviors. The adsorption of NPs at bubble surface results in an increase of surface elastic modulus to 112.4 mN/m. The flow field surrounding bubble was measured by microparticle image velocimetry and demonstrates first the influences of NPs adsorption on the velocity gradient close to bubble surface. The surface of nanoparticle-dodecyltrimethyl ammonium bromide (NP-DTAB) complexes stabilized bubble tends to harden and behaves as solid wall in tangential directions. The degree of surface hardening increases with the improvement of NP amphipathy, which leads to an augment of the shear force acting on bubble surface. Consequently, NP-DTAB complexes stabilized bubbles possess high flow resistance and are easier to break.