What are the groups of polyols?

December 13, 2025 •

2 min read

In organic chemistry, a polyol is an organic compound containing multiple hydroxyl (−OH) groups. The primary classification of these compounds can differ depending on their use, most notably in food science versus polymer chemistry. Understanding the distinct properties of these groups is key to appreciating their widespread application.

Quick Summary

Polyols are categorized into distinct groups based on their chemical structure, molecular weight, and application, including sugar alcohols used in food and polymeric polyols like polyethers and polyesters for industrial manufacturing. These classifications determine their unique properties, from sweetness and digestion to mechanical strength and flexibility in finished products.

Key Points

Low Molecular Weight Polyols: Primarily used in food as sugar substitutes (sugar alcohols), offering reduced calories and dental health benefits.
Sugar Alcohol Examples: Includes sorbitol, erythritol, xylitol, and maltitol, each with specific properties.
Polymeric Polyols: High molecular weight compounds vital for industrial uses like polyurethanes, adhesives, and coatings.
Polyether vs. Polyester: Polyethers provide flexibility and water resistance; polyesters offer superior mechanical strength and chemical resistance.
Sustainable Polyols: Emerging from renewable sources like vegetable oils and recycled materials for eco-friendly manufacturing.
Application-Based Classification: The term "polyol" has different meanings in food science and polymer chemistry, leading to a classification based on their end use.

Low Molecular Weight Polyols (Sugar Alcohols)

In food and pharmaceuticals, low molecular weight polyols are commonly known as sugar alcohols. Produced by the hydrogenation of sugars and starches, they serve as sugar substitutes due to their lower caloric content, reduced impact on blood glucose, and non-cariogenic properties.

Sorbitol: Found naturally in fruits, used in sugar-free products and as a humectant.
Erythritol: Produced via glucose fermentation with near-zero calories and good digestive tolerance.
Xylitol: Derived from plant material, used in sugar-free gum and candy, and inhibits tooth decay.
Maltitol: Produced from maltose, used in sugar-free sweets as it mimics sucrose.

Polymeric Polyols

Polymeric polyols, with higher molecular weights, are crucial in the polymer industry, particularly for polyurethanes. They are classified based on their chemical backbone, mainly into polyether and polyester types.

Polyether Polyols

Formed from epoxides reacting with an initiator, these polyols are known for flexibility, low viscosity, and hydrolytic stability.

Flexible Polyether Polyols: Primarily from propylene oxide, used for flexible foams in furniture and automotive.
Rigid Polyether Polyols: Higher branching for rigid foams used in insulation.
CASE Applications: Specific types for coatings, adhesives, sealants, and elastomers.

Polyester Polyols

Resulting from dicarboxylic acids and glycols condensation, polyester polyols offer enhanced mechanical strength, adhesion, and resistance to solvents.

Aliphatic Polyesters: Often from adipic acid, used in TPU elastomers and adhesives.
Aromatic Polyesters: Contain aromatic rings for strength, heat, and flame resistance, used in rigid foams.
Caprolactone-based Polyesters: Provide improved hydrolysis resistance.

Comparison of Polymeric Polyol Groups

The table below summarizes key differences between polyether and polyester polyols, influencing their application.


Characteristic	Polyether Polyols	Polyester Polyols
Hydrolytic Stability	High	Lower
Chemical Resistance	Limited	Superior
Mechanical Strength	Lower resilience and toughness	Higher tensile strength and abrasion resistance
Flexibility	Higher flexibility and resilience	More rigid and dimensionally stable
Cost	Generally more cost-effective	Production can be more expensive
Main Applications	Flexible foams (mattresses, furniture)	Rigid foams (insulation panels), adhesives, coatings

Bio-Based and Recycled Polyols

Growing interest in sustainability has led to the development of polyols from renewable and recycled sources.

Bio-Based Polyols: Derived from biomass like vegetable oils or agricultural waste, they reduce reliance on petrochemicals.
Recycled Polyols: Obtained from depolymerizing post-consumer or industrial polyurethane waste, promoting a circular economy.

Conclusion

Polyols are categorized into low molecular weight sugar alcohols for food and high molecular weight polymeric polyols for industry. Sugar alcohols offer sweetening with health benefits, while polymeric polyols like polyethers and polyesters provide diverse properties for materials like polyurethanes. Innovations in bio-based and recycled polyols support sustainable practices. The choice of polyol group is application-dependent, from sweetening to structural uses. Additional information can be found on resources like the Calorie Control Council website.

Frequently Asked Questions

Polyether polyols offer greater flexibility and resistance to hydrolysis (water damage), making them ideal for soft foams like mattresses. Polyester polyols, conversely, provide superior mechanical strength and resistance to chemicals, so they are used in more durable products like rigid insulation and coatings.

No, while polyols (or sugar alcohols) are carbohydrates, they are not classified as sugars. Their chemical structure is different, leading to slower and incomplete absorption in the body, which is why they have fewer calories and a lesser impact on blood glucose levels.

In the food industry, low molecular weight polyols serve as bulk sweeteners, replacing sugar in products like chewing gum, candy, and ice cream. They also act as humectants to retain moisture, texturizers, and preservatives.

Bio-based polyols are derived from renewable sources like vegetable oils, agricultural waste, and biomass, rather than from petrochemicals. Examples include polyols from castor oil and soy, used to produce more sustainable polymers.

Consuming large quantities of polyols can cause digestive issues such as bloating, intestinal gas, and a laxative effect in some individuals. This is because they are poorly absorbed by the small intestine and are fermented by gut bacteria.

Common polymeric polyols include polyether polyols like polyethylene glycol (PEG) and polypropylene glycol (PPG), and polyester polyols synthesized from reactions involving dicarboxylic acids and glycols.

Polymeric polyols are key ingredients in the production of polyurethanes, which are used to make a wide variety of goods, including flexible and rigid foams for mattresses and insulation, coatings, adhesives, and elastomers.