(630f) Fine Tuning of Anisotropic Polymer Particle Morphologies through Vapor-Phase Condensed Droplet Polymerization

Anisotropic polymer nano-micro particles exhibit interesting physicochemical properties, compared to isotropic polymer particles, and can be assembled into complex structures. However, polymer synthesis strategies, such as emulsion polymerization, currently known for polymer nanoparticles, cannot reliably create non-spherical particles and may not be practical due to solvent restrictions, low efficiency, and time. Here, we show that reaction conditions significantly influence the aspect ratio of polymer domes during the vapor-phase condensed droplet polymerization (CDP) process. We find that higher filament temperatures lead to access to lower aspect ratio with larger diameter polymer domes, while lower filament temperatures result in higher aspect ratios with smaller diameter polymer domes. This is attributed to the different kinetics of more reactive methyl radical species at higher temperatures resulting from the β-scission reaction of less reactive tert-butoxy radical species, which are initiators of free radical polymerization. Notably, we reveal that reaction conditions play crucial roles in polymerization kinetics and molecular weight distribution. We also demonstrate that the size of polymer domes and the degree of polymerization can be manipulated by initiator pressure and reaction time during CDP, leading to a wide range of morphological and mechanical properties of polymer particles for various applications, including drug delivery and soft robotics.