4-isocyanato TEMPO is primarily used in the field of polymer chemistry and materials science. It serves as a functionalizing agent, enabling the introduction of stable nitroxide radicals into various polymers and surfaces. This modification is crucial for creating materials with enhanced properties such as improved durability, resistance to degradation, and specific functionalities like spin labeling for electron paramagnetic resonance (EPR) studies. Additionally, it is employed in the development of advanced coatings, adhesives, and composites, where its ability to form stable covalent bonds with substrates is highly valued. The chemical also finds applications in biomedical research, particularly in the design of smart materials and drug delivery systems, where its radical properties can be exploited for targeted interactions and controlled release mechanisms.