A new class of vitrimers based on aliphatic poly(thiourethane) networks with shape memory and permanent shape reconfiguration

Abstract

Vitrimers are a new promising class of polymeric materials which are attracting increasing attention thanks to their thermosetting characteristics with their capability of being reprocessed and recyclable, which make them more environmentally friendly in reference to the conventional thermosets. In the present study, we report a new class of vitrimeric materials consisting in poly(thiourethane) networks. These materials can be easily prepared from readily available isocyanate and thiol monomers in the presence of dibutyltin dilaurate (DBTDL) as the catalyst. The reaction has a click nature and therefore leads to highly homogeneous networks. The materials studied behave as conventional thermosets until topological rearrangement started. Freezing topological temperatures (Tv) between 132 and 95 °C were determined depending on the amount of catalyst in the material. The vitrimers prepared showed good shape memory and welding abilities and a high optical transparency and therefore they have a great potentiality in advanced engineering applications. The occurrence of the trans-thiocarbamoylation reaction, responsible of the rearrangement, has been confirmed by using model compounds. The materials remained unaltered after reprocessing, which was proved by means of FTIR and thermomechanical studies.