Applicated in medical research, drug-release, nanotechnology and new materials research, cell culture. In the study of ligand, polypeptide synthesis support, a graft polymer compounds, new materials, and polyethylene glycol-modified functional coatings and other aspects of the active compound. Monodisperse Azido-PEG10-acid (N3-PEG10-COOH) is a water soluble PEG compound containing an azide (N3) group with a terminal carboxylic acid (COOH). The azide (N3) group is reactive with alkyne, BCN, DBCO via Click Chemistry to yield a stable triazole linkage. The terminal carboxylic acid can react with primary amine groups in the presence of activators (e.g. EDC, or HATU) to form a stable amide bond.