AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
The Effect of Molecular Weight on the Phase Separation of Polymer-Polymer Aerosol Particles
EMILY-JEAN OTT, Miriam Freedman, The Pennsylvania State University
Abstract Number: 458 Working Group: Aerosol Chemistry
Abstract The creation of core shell polymer aerosol particles often occurs by following typical nanoparticle synthesis methods and then aerosolizing the solution that contains the nanoparticles. We are able to create polymer aerosols directly from a solution, and the particles show predictable morphologies. We atomize solutions containing two water soluble polymers that are able to under to liquid-liquid phase separation, rapidly dry the particles, and then impact them on carbon grids. The particles are then studied using cryo-transmission electron microscopy. The images are analyzed for particle area equivalent diameters and morphology. The polymers used in this study are polyethylene glycol (PEG) and dextran. By imaging submicron particles composed of these polymers with particle diameters as small as approximately 30 nm, we are able to determine that the particles exhibit a size dependent morphology. The larger particles undergo phase separation and exist in a core shell morphology, while smaller particles do not and maintain a homogenous morphology. We show that the region of particle sizes where morphology transitions from phase separated to homogenous can be tuned by changing the molecular weight of the polymers. We kept the monomer ratio between the PEG and dextran polymers approximately the same as we changed the molecular weights. In the molecular weight range studied, systems composed of low molecular weight polymers maintained a homogenous morphology in particles at larger sizes than systems composed of polymers with higher molecular weights. We are able to model this trend by using a system of equations that combine classical nucleation theory and Flory-Huggins theory. These morphology tunable aerosol particles could have potential applications in the pharmaceutical and sensor industries.