Nanostructural organization of thin films prepared by sequential dip-coating deposition of poly(butylene succinate), poly(ε-caprolactone) and their copolyesters (PBS-ran-PCL)

M. I. Peñas, C. Ocando, E. Penott-Chang, M. Safari, T. A. Ezquerra, E. Rebollar, A. Nogales, R. Hernández and A. J. Müller

Polymer 226, 123812 (2021)
In this work, we prepare and characterize multiphasic thin films containing poly(ε-caprolactone), PCL, poly(butylene succinate), PBS, and a poly (butylene succinate-ran-ϵ-caprolactone) (PBS-ran-PCL) random copolyester. To that aim, thin films were prepared by sequential dipping of a silicon substrate into chloroform solutions of the respective polymers. The preparation method resulted in films with varying compositions of PCL and PBS components depending on the initial concentration of the dipping solutions and the number of dipping steps employed for the preparation of the samples. Atomic force microscopy (AFM), grazing incidence X-ray scattering at wide angle (GIWAXS) and scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR) were employed to characterize the films obtained. As chloroform can dissolve all components, the final composition of the film was always rich in the last deposited layer component. The thin films obtained were semicrystalline with a complex axialitic or dendritic morphology of the dominant component (that one deposited last) with traces of the other components, whose presence and location was revealed by s-SNOM/nano-FTIR.