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Determination of the Water-polymer Interaction Parameter and Hygroscopicity of Particles
Chun-Ning Mao, AKUA ASA-AWUKU, University of Maryland
Abstract Number: 163
Working Group: Aerosols, Clouds and Climate
Abstract
Hygroscopicity determines the ability of a particle to swell or contract in the presence of water vapor. The hygroscopicity for organic nano-particles is a known function of the solute molar volume. This is particularly true for low-molecular weight (< 200 g mol -1 ) organic compounds used for drug delivery. In this work, four commonly used biodegradable hydrophilic compounds, mannitol, lactose, gelatin and polyethylene glycol are measured with a fast and unique hygroscopicity-cloud condensation nuclei activation technique. Flory-Huggins Köhler theory is used to estimate the single parameter hygroscopicity. Results show that for the high molecular weight compounds, a water-polymer interaction parameter must also be considered and the water-polymer interaction parameter for nanoparticles can be determined in the supersaturated regime. The water affinity becomes essential for nanoparticle hygroscopicity, and the organic molar volume contribution starts to decrease as the molecular weight increases. In summary, the water affinity of the interaction parameter can be measured for nano-particles and plays an important role in the water uptake of biodegradable organic nano-particles.