10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Hybrid Fractality and Formation Mechanism of Aerosol Gels
YULI W. HEINSON, William Heinson, Pai Liu, Rajan K. Chakrabarty, Washington University in Saint Louis
Abstract Number: 982 Working Group: Aerosol Physics
Abstract Aerosol gels are volume spanning, semi-rigid networks of solid nanoparticles possessing ultralow density and high surface area. The current consensus is that aerosol gels have a hybrid morphology with a mass (D) and surface (Ds) fractal dimension ~ 2.5 at super-micron length scale and ~ 1.8 at submicron length scale. In this study, we show that this consensus is partially complete and is not universal. Using our light scattering apparatus, we studied the structure factor of carbon aerosol gels produced using a buoyancy-opposed flame (BoF) aerosol reactor which facilitates continuous aerogelation on a millisecond time-frame. Our light scattering apparatus measured the scattered intensity by the gel particles in the scattering angle range of 1˚ ~ 168˚. We were able to probe the hybrid morphology by plotting the scattering intensity versus q, where q=4π/λ sin(θ/2) with λ the wavelength and θ the scattering angle. Our light scattering results indicate that aerosol gel particles produced from our BoF reactor process a D ≈ 2.5 and a Ds ≈ 2. This surprising, yet previously undescribed morphology was further investigated for a convincing explanation using numerical simulation of diffusion limited cluster-cluster aggregates under varying monomer volume fraction conditions. This talk will present in detail our experimental findings and modeling interpretations.