Catalyst-free crosslinked sustainable functional silicones by supramolecular interactions

Abstract

Supramolecular full silicone networks are built on the basis of siloxane polymers with low content of amino (6.4 or 9.8 mol%), and carboxyl (14.9 mo%) groups. Alternatively, the carboxyl groups involved are attached to a polyhedral silsesquioxane cage (i.e., octakis(2-carboxymethylene-thioethyl)silsesquioxane), POSS-COOH, which have also been found to play a filler role. Networks substantiated as free-standing films through the development of physical interactions between polar groups forming transverse bridges between chains were analyzed structurally by IR analysis, but also in a more original way by fluorimetric approach, and evaluated in terms of thermal, mechanical, electrical properties and their suitability as biointerfaces. It has been found that these properties are strongly dependent and can be adjusted by the content and the ratio between the two types of polar groups (-NH2 and -COOH), as well as by the substrate to which the carboxyl groups are attached (polysiloxane or POSS). Being elastomers crosslinked by supramolecular interactions, it was necessary to evaluate their reversibility, for which, temperature-dependent IR and dielectric spectroscopy studies were performed. The reflection of this reversibility in the self-healing capacity of the material in the film and solvoplasticity in solvents with different polarities and media that mimic biological fluids was highlighted supporting the sustainability of these materials obtained in the absence of any catalyst.