HydroxylTerminated

Hydroxylterminated refers to molecules that have hydroxyl groups (-OH) at one or both ends of the molecule. These terminal alcohol groups make the compound reactive toward a range of condensation and coupling reactions, enabling chain extension, crosslinking, or further functionalization. Molecules with two hydroxyl groups are often called diols, while those with three or more are triols or polyols, depending on functionality.

Production and end-capping methods commonly involve terminating polymers with hydroxy-functional reagents or quenching living polymer chains with water or alcohols. This yields polymers and small molecules whose termini contain hydroxyl groups. Well-known examples include hydroxyl-terminated polyethers (such as PEG and PPG variants) and hydroxyl-terminated polybutadienes, the latter known for use as binders in energetic formulations. Hydroxyl-terminated materials are also synthesized by selective functionalization of preformed polymers or through step-growth polymerization that introduces -OH endpoints.

Properties of hydroxylterminated compounds are dominated by hydrogen bonding and polarity from the -OH groups. These features influence solubility, viscosity, and reactivity. The hydroxyl content is quantified as the hydroxyl number (or hydroxyl value), expressed in milligrams of KOH per gram of material. Reactivity with electrophiles, especially isocyanates, makes hydroxyl groups central to polyurethane chemistry, including foams, coatings, and elastomers.

Applications span polyurethanes, coatings, adhesives, sealants, and elastomeric materials. In specialty fields, hydroxyl-terminated polymers such as HTPB serve as binders or customized precursors.