Non-isocyanate polyurethane elastomers: from their synthesis using cyclic carbonates to 3D printed medical devices

Polyurethanes (PUs) are among the most widely produced polymers in the world and are used in many applications. Thanks to their remarkable mechanical performances combined with their proven in vivo biocompatibility, they are also currently employed in the medical sector. However, they are industrially produced from highly toxic isocyanate precursors, which causes serious environmental and health concerns. As regulations increasingly restrict the use of isocyanate compounds, exploring greener and safer alternatives to produce PUs has become imperative. The research of health-friendlier synthesis processes has therefore triggered the emergence of a new family of PUs called non-isocyanate polyurethanes (NIPUs). Among the latter, those produced from bifunctional cyclic carbonates and diamines take center stage, as these cyclic carbonates are easily accessible by a more ecofriendly synthesis, i.e., the quantitative catalytic coupling of CO2 to bifunctional epoxides or propargylic alcohols. They produce NIPUs called either poly(hydroxy-urethane)s (PHUs) or poly(hydroxy-oxazolidone)s (PHOxs), respectively. These NIPUs exhibit structures that differ from those of isocyanate- based PUs, as they bear additional hydroxyl groups (in addition to cyclic urethanes for PHOx) which impart specific properties. This thesis aims to explore the impact of these structural differences on the properties of NIPUs, while highlighting their potential to design biomaterials of choice in order to develop novel alternatives to meet the needs of the healthcare sector. Indeed, as few reports have emerged for the design of PHU, and even none for PHOx biomaterials, this thesis focuses on the development and the characterization of various NIPUs (both PHUs and PHOxs) for biomedical applications, especially in the cardiovascular field. Different systems are envisaged to mainly produce implantable elastomers, such as the thermal and photo-crosslinking of linear PHUs, some of which are functionalized with another CO2-sourced molecule, the development of PHOx networks for drug-eluting implants, of easily (re)processable thermoplastic PHOxs, or of PHOx-based covalent adaptable networks. In each of these systems, particular attention is paid to the printability of these materials to produce 3D printed implants which are customizable according to patients. In addition, their biocompatibility and hemocompatibility are assessed by means of a series of biological tests to ensure their non-toxicity in view of their future implantation, especially in contact with the cardiovascular system. We therefore position both PHUs and PHOxs as unprecedented safer and greener options for the design of future (customizable) medical devices.