Hygroscopicity and the water-polymer interaction parameter of nano-sized biodegradable hydrophilic substances

Abstract

Hygroscopicity is one of the most important physicochemical properties for nanoparticle science and engineering. Hygroscopicity determines the ability of a particle to swell or contract in the presence of water vapor. The hygroscopicity for organic aerosol 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 to nanoparticle hygroscopicity, and the organic molar volume contribution starts to decrease as the molecular weight increases. Furthermore, we provide a new size-dependent parameterization for hygroscopicity of polymers. In summary, the water affinity of the interaction parameter can be measured for nano-particles and plays an important role of the water uptake of organic nano-particles.

Copyright © 2021 American Association for Aerosol Research

EDITOR:

• Nicole Riemer

Disclosure statement

The authors declare that they have no conflict of interest.

Data availability statement

Data will be available from the authors upon request.

Additional information

Funding

This work was supported by the U.S National Science Foundation NSF: AGS-1723290 and NSF: CHEM-1708337.