Polyol

A polyol is an alcohol containing multiple hydroxyl groups. In two different technological disciplines the term "polyol" has a special meaning: food science and polymer chemistry.

Food science

Sugar alcohols, a class of polyols, are commonly added to foods because of their lower caloric content than sugars; however, they are also, in general, less sweet, and are often combined with high-intensity sweeteners. They are also added to chewing gum because they are not broken down by bacteria in the mouth or metabolized to acids, and thus do not contribute to tooth decay.Maltitol, sorbitol, xylitol, erythritol, and isomalt are some of the more common types. Sugar alcohols may be formed under mild reducing conditions from their analogue sugars.

Polymer chemistry

In polymer chemistry, polyols are compounds with multiple hydroxyl functional groups available for organic reactions. A molecule with two hydroxyl groups is a diol, one with three is a triol, one with four is a tetrol and so on.

Monomeric polyols such as glycerin, pentaerythritol, ethylene glycol and sucrose often serve as the starting point for polymeric polyols. These materials are often referred to as the "initiators" and reacted with propylene oxide or ethylene oxide to produce polymeric polyols. However, they should not be confused with free radical "initiators" used to promote other polymerization reactions. The functional group used as the starting point for a polymeric polyol need not be a hydroxyl group; there are a number of important polyols which are built up from amines. A primary amino group (-NH₂) often functions as the starting point for two polymeric chains, especially in the case of polyether polyols.