Density and porosity analyses of porous hybrid microparticles containing gas in closed pores using centrifugal liquid sedimentation-dynamic light scattering combined analytical method

Porous hybrid microparticles are characterized by their densities and porosities. Consequently, the evaluation for density and porosity of porous hybrid microparticles in liquids is crucial for predicting the transport of particles in the atmosphere, human body, and industrial processes. However, direct measurement of the density and porosity of porous hybrid microparticles in liquids remains a challenge. In this study, we investigated the centrifugal sedimentation of polystyrene-silica hybrid microparticles with and without gas-containing closed pores. A centrifugal liquid sedimentation-dynamic light scattering combined analytical method was employed to determine the apparent densities of hybrid microparticles with and without gas-containing closed pores. The porosity of the hybrid microparticles with gas-containing closed pores was elucidated based on the inner buoyancy, which is a centrifugal force generated by the presence of low-density gas inside numerous closed pores. Further, the inner gas buoyancy was analyzed to estimate the particle porosity in liquids. The results obtained in this study confirmed the feasibility of utilizing the proposed method to determine the apparent density and porosity of porous hybrid microparticles in liquids.