Interplay of kinetics and interfacial interactions in breath figure templating - A phenomenological interpretation

Breath Figure BF templating is an attractive technique for the production of polymer films with controlled porosity: upon the exposure to a moist airflow, monodisperse water droplets condense on the surface of evaporating polymer solution into ordered arrays, acting as a template for the final film structure.This work has been focused on polylactic acid (PDLLA), a biocompatible biodegradable polymer, and aims to provide a phenomenological interpretation of BF process based on the role of kinetics and the influence of interfacial tension. The effects of physical and chemical properties of solvents have been evaluated; the contribution of kinetics has been assessed by modifying the rate of film hardening from seconds to minutes, via different experimental set-up. Our experimental observations indicated that the interplay of kinetics and interfacial tension defines the structure of BF films: interfacial forces govern the physical interactions among water, solvent and polymer, but the dynamics of the process and thus the final pore structure is regulated by kinetics.