Water erodible coatings based on a hydrolyzable PDMS/polyester network

Abstract

In this work, the objective is to design an elastomer network predominantly composed of poly(dimethylsiloxane) (PDMS) with small crosslinked hydrolyzable polyesters to finally provide a new eco-friendly antifouling system. This PDMS/polyester network is expected to maintain a low surface energy during water immersion while, at the same time, ensuring a continuous renewal of its surface through an erosion process. The PDMS/polyester networks were crosslinked via a condensation reaction of a bis-silanol PDMS oil and various bis(trialkoxysilane)-terminated polyester macrocrosslinkers. Chain ends of poly(ε-caprolactone), poly(ε-caprolactone)-b-PDMS-b-poly(ε-caprolactone) and poly(d,l-lactide-co-glycolide) were quantitatively functionalized using (3-isocyanatopropyl)trimethoxysilane as crosslinking reactant. These polyester macrocrosslinkers were highly inserted in the PDMS-based networks in quantities ranging from 12 to 40 wt.%. The microtopography of these PDMS/polyester coatings revealed relatively low roughness values for most of the coatings. Contact angle measurements highlighted an increase of hydrophilicity for PCL-based coatings contrary to the poly(d,l-lactide-co-glycolide)-based coating which demonstrated a surface hydrophobicity as well as a low surface free energy (γs ≤ 25 mJ/m²) even after 5 weeks of immersion in deionized water. The insertion of polyesters within a silicone matrix affected both the elastic modulus and the cristallinity of the network depending on the polyester nature. Finally, mass loss tests demonstrated that these PDMS/polyester coatings had the ability to erode themselves.