Used as a hydrophilic spacer or linker in pharmaceutical and biotechnological applications, enhancing solubility and reducing immunogenicity of conjugated drugs. Commonly employed in the synthesis of PEGylated therapeutics, drug delivery systems, and surface modifications of nanoparticles. Its long PEG chain (18 units) provides extended circulation time in vivo by minimizing rapid clearance. Also utilized in hydrogels and tissue engineering scaffolds due to its biocompatibility and water-absorbing properties.