Structure–Property Relationships of Eco-friendly Spincoated Poly(ε-caprolactone) (PCL) Thin Films
J. Environ. Nanotechnol., Volume 15, No 3 (September 2026) pp. 18-24
Abstract
The increasing demand for sustainable polymer processing requires the replacement of conventional toxic solvents. However, limited information is available on how environmentally friendly solvents, particularly ethyl acetate (EA) as a sustainable alternative to chloroform (H), influence the structural, morphological, surface, and optical properties of spincoated poly(ε-caprolactone) (PCL) thin films. In this study, the effect of solvent selection on the properties of PCL thin films prepared by spin coating was investigated, highlighting the potential of EA as a more environmentally friendly alternative for PCL film fabrication. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle measurements, and UV–Vis spectroscopy. XRD analysis confirmed the preservation of the orthorhombic crystalline structure of PCL, with similar crystallite size values indicating that the choice of solvent had no significant effect on the crystallization process or the size of the crystalline domains. SEM analysis showed that both films have a characteristic spherulite morphology, with the PCL-EA film forming larger spherulites than the PCL-H film. At the same time, the PCLEA film exhibited a higher surface free energy and a more pronounced polar component, with a measured surface free energy of 54.70 mN/m compared with 41.62 mN/m for the PCL-H film, indicating better wettability and more favorable interfacial interactions. UV–Vis analysis showed higher optical band gap values for both direct and indirect electronic transitions in the PCL-EA film compared to the PCL-H film, with direct and indirect band gap values of 5.0 eV and 4.8 eV for PCL-EA, and 4.8 eV and 4.1 eV for PCL-H, respectively, which may indicate a reduced number of localized energy states and greater structural order, with both films retaining the optical properties characteristic of PCL as an electrically insulating polymer. The results confirm that ethyl acetate is a suitable, more sustainable alternative to chloroform for preparing PCL thin films, thereby improving surface and optical properties while preserving the structural characteristics of the biodegradable polymer. Such thin films have potential applications in sustainable polymer coatings, packaging materials, and other environmentally friendly technologies, contributing to the development of greener polymer fabrication approaches.
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Reference
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