Effects of CO₂ bubbles on layer-by-layer assembled hybrid thin film

In recent years, polyelectrolytes such as poly (diallyldimethylammonium chloride) and polystyrene sulfonate have been widely applied to hybrid thin films for industrial applications. In this paper, we report a method to modify the film by applying CO₂ bubbles during layer-by-layer (LbL) assembly. The differences in thickness, mass, and surface morphology between CO₂-treated hybrid LbL and pristine films were analyzed by quartz crystal microbalance, atomic force microscopy, scanning electron microscopy, and profilometry. The internal structure of the hybrid LbL films was investigated by analyzing the release of doxorubicin (DOX) incorporated in each film through photoluminescence. Upon CO₂ treatment, the thickness, mass, and surface roughness increased, while the amount of incorporated DOX decreased.