Surface properties of poly (e- caprolactone) - poly (dimethylsiloxane) -poly (e- caprolactone) triblock copolymers

Abstract

Surface properties of polymers are of very much importance in many application fields such as adhesion, wettability, printing and biocompatibility. In this industrial areas polydimethylsiloxanes are materials of broad applicability because of their well-known surface modifying properties. In this work, the surfaces of two grades of triblock polycaprolactone-polydimethylsiloxane-polycaprolactone (PCL-PDMS-PCL) copolymers differing only in the molecular weights of PCL end-blocks and homopolymer polycaprolactone were characterized by contact angle measurements and Electron Spectroscopy for Chemical Analysis (ESCA) technique.Contact angle measurements give information about the surface energetics on the gross structure of the immediate outer boundary of a polymer. Measurements were made with different polar liquids, and with apolar liquid paraffin. Measurements according to the two-liquid method (a three phase system of two immiscible liquids and a solid surface) were also made. Surface energy parameters of the polymers were calculated using different approaches. Surface enrichment of the copolymers by PDMS segments was also shown quantitatively from the evaluation of binding energies of ESCA spectra.