Azido-PEG11-t-butyl ester is a PROTAC linker within the PEG category, utilized in the synthesis of PROTAC molecules. As a click chemistry reagent, it features an Azide group that can engage in copper-catalyzed azide-alkyne cycloaddition reactions (CuAAC) with alkyne-containing molecules. Additionally, it participates in strain-promoted azide-alkyne cycloaddition (SPAAC) with molecules containing DBCO or BCN groups.