How solvent-free crosslinking conditions alter the chemistry and topology of hemiketal based polymer networks

Abstract

A solvent free reaction of PCL based polyester polyols with a crosslinking molecule based on a vicinal tricarbonyl results covalent adaptable polymer networks that differ in their thermal behavior, swelling, and solubility properties. Mild processing results polymer networks based on hemiketal/ketone equilibrium with properties typical for dissociative networks including dissolution in presence of water or elevated temperature and self-healing properties. Further thermal treatment of the polymer entails changes in swelling, and solubility properties. Constant glass transition temperatures of the differently treated polymers indicate a steady overall network density, but changes in the nature of the network structure. By varying the number of OH-groups, molar mass and stoichiometric ratio of the polyester polyol and the crosslinking molecule, respectively, material properties can be adjusted. This approach gives access to reversibly crosslinked polymers varying in their responsivness and overall mechanical properties.