Azido-PEG9-azide is widely used in bioconjugation and click chemistry applications due to its dual azide functional groups. It serves as a versatile linker for connecting molecules, such as proteins, peptides, or small molecules, in a controlled and efficient manner. The PEG (polyethylene glycol) spacer provides flexibility and solubility, making it suitable for use in aqueous environments. This chemical is particularly valuable in drug delivery systems, where it can be used to create targeted conjugates or modify biomolecules to enhance their stability and bioavailability. Additionally, it plays a role in materials science for surface functionalization and the development of polymers with specific properties. Its compatibility with copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions makes it a key component in the synthesis of complex molecular architectures.