Carbenes as versatile tools in polymer chemistry

This thesis explores the various uses of carbenes and the roles they can fulfill in the materials transition by attacking different problems with different carbenes. In the era of sustainable chemistry and evolving regulations, academic and industrial research is largely driven by the imperative to replace hazardous chemicals and harsh reaction conditions with eco-friendlier intermediates and processes.
We present a new isocyanate-free method to produce polyureas by Ru-catalyzed carbene insertion into the N–H bonds of urea itself in combination with a series of bis-diazo compounds as carbene precursors. This shows the possibility of using diazo compounds in combination with transition metal catalysis to furnish novel routes towards isocyanate-free polyureas.
We present the development of carbene based crosslinkers that are shown to crosslink acrylic polymers through O–H insertion. The best crosslinker was shown to provide a hardness similar to the currently utilized melamine curing systems, and films with excellent water resistance. We show the development of a polyurethane based crosslinker that can be used to formulate a one-component polyurethane coating with material properties similar to isocyanate-based polyurethane coatings. This shows the usage of free carbenes as an alternative curing method for isocyanate-free polyurethanes.
Overall, the findings acquired in the research presented in this thesis provide valuable insight into the role carbenes can fulfill in various places in materials chemistry. Thereby, the obtained knowledge opens up new avenues for the development of new catalysts, new monomers and new crosslinkers based on carbenes.