Surface Morphology, Crystallinity, and Hydrophilicity of Poly (ε‐caprolactone) Films Prepared Via Casting of Ethyl Lactate and Ethyl Acetate Solutions

Films of semicrystalline poly(ε-caprolactone) (PCL) are fabricated by casting drops of fully biocompatible ethyl lactate (EL) and ethyl acetate (EA) solutions onto a glass substrate. The main goals of this work are: i) to assess the interplay among the physico-chemical properties of the solution and its interaction with the casting substrate; and ii) determine how the solution/substrate interactions influence the formation of the films and their final surface morphology and hydrophilicity. The competition between the rates of solution drop spreading and solvent evaporation controls the polymer crystallization process and the final film properties. Compared with EA, EL provides better wetting properties and a slower evaporation rate, eventually resulting in thinner films. The film thickness increases with polymer concentration in the solution; this parameter also affects the crystalline structure and, ultimately, the film surface roughness. As a result, the film hydrophilicity is finely tunable by changing the solution composition, so as to control the crystal nucleation density.