Polyol

Polyol is a chemical term for an organic compound containing more than one hydroxyl (-OH) group. Polyols occur in many forms, including simple sugar alcohols, higher polyols used as intermediates in polymer synthesis, and polyether or polyester polyols used in polyurethane technology. Common sugar alcohols include sorbitol, xylitol, mannitol, and erythritol, produced by hydrogenating aldoses or ketoses and used as sweeteners and humectants. Glycerol (propane-1,2,3-triol) is a widely known triol that serves as a solvent and intermediate in various industries.

In polymer chemistry, polyols react with isocyanates to form polyurethane or related networks. The number of hydroxyl groups (functionality) and the molecular weight of the polyol influence the structure and properties of the final material. Major classes used for polyurethanes are polyether polyols (made from propylene oxide or ethylene oxide) and polyester polyols (made from polycarboxylic acids and glycols); specialty polyols include hydroxy-functional acrylics and silicone or fluorinated polyols. Key properties used to specify polyols include hydroxyl value, functionality, and viscosity, which affect processing and the stiffness, resilience, and foam characteristics of the product.

Production and sources: Sugar alcohols are derived from sugars or biomass, while glycerol is produced in biodiesel and soap manufacture. Polyols for polyurethane are typically synthesized from petroleum-derived feedstocks, though bio-based routes are increasingly explored.

Applications and safety: Sugar alcohols are widely used as low-calorie sweeteners and texturizers, while polymer polyols provide the essential polyol component for flexible and rigid foams, coatings, adhesives, sealants, and elastomers. Safety and regulation vary by use; sugar alcohols can cause gastrointestinal effects in large amounts, and handling of polyurethane polyols involves standard industrial precautions.