Polythiourethanes: Synthesis, applications, and opportunities

Concern over the production, use, and disposal of polymeric materials have led to increased societal pressure to search for sustainable alternatives that are better aligned with circular economy models. In this regard, polythiourethanes are a relatively unknown polymer family with similar properties and potential applications to conventional polyurethanes, but with enhanced dynamic behavior. This dynamic behavior allows for improved recyclability and for reprocessing at milder conditions without diminishing physical or mechanical properties. In this review article, we report a comprehensive summary of the work covering polythiourethanes, which from our perspective constitute an interesting alternative to tackle environmental issues arising from plastic waste. The review first covers the main synthetic routes for the preparation of polythiourethanes with a particular focus on catalysis and non-isocyanate routes. Subsequently, the thermo-mechanical and optical properties of polythiourethane materials are discussed, highlighting the similarities and differences concerning polyurethanes. Following this, the opportunities arising from the enhanced dynamic character of the thiourethane bond are considered, emphasizing works covering the chemical recycling and/or reprocessing of polythiourethane thermosets. Finally, we discuss their use for advanced applications and current advanced manufacturing processes and highlight our perspective on the future challenges and opportunities offered by polythiourethane materials.