Poly(caprolactone) thin film preparation, morphology, and surface texture

The properties and surface uniformity of poly(caprolactone) (PCL) thin films were measured. Thin films were prepared using a spin-coating technique. Film thickness and roughness were correlated with variation in solution concentration, spinning speed and spinning time. Differential scanning calorimetry (DSC) was used to investigate the crystallization and melting processes. The enthalpy of melting variation correlated with the film thickness, while melting temperature was independent of film thickness. In addition, surface roughness was found to be a function of PCL thickness. Film thickness and roughness showed a progressive decrease when spinning speed was increased, while spinning time provided no significant influence on film thickness. PCL thickness and roughness significantly increased when PCL solution concentration increased. Hot stage optical microscopy showed that larger spherulitic crystals were present in thin films, and the smaller crystals present in thicker films had a coarser texture consistent with increased surface roughness.