4,8-dioxaundecane-1,11-diol (CAS No. 4161-32-4) is a small-molecule polyethylene glycol (PEG) compound with the molecular formula C₉H₂₀O₄. Its structure contains two hydroxyl groups (-OH) and three oxygen bridge bonds, forming a linear diol structure with 1,3-propanediol as the backbone. It is typically produced using 1,3-propanediol as the raw material, undergoing multi-step oxidation and etherification reactions to construct the oxygen bridge chain, followed by introduction of hydroxyl groups and purification to obtain a high-purity product (≥95%). Due to its good biocompatibility and hydrophilicity, this compound is widely used in drug delivery systems, such as modifying immunobiological proteins, designing sustained/controlled-release formulations, and developing targeted drug carriers. It can also serve as an intermediate in organic synthesis.