Polyol

Source: Wikipedia, the free encyclopedia.

In

hydroxyl groups (−OH). The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols,[1] triols,[2] and tetrols,[3][4]
respectively.

Classification

Polyols may be classified according to their chemistry.

polyethylene oxide or polyethylene glycol (PEG), polypropylene glycol (PPG) and Polytetrahydrofuran or PTMEG. These have 2, 3 and 4 carbons respectively per oxygen atom in the repeat unit. Polycaprolactone polyols are also commercially available.[11] There is also an increasing trend to use biobased (and hence renewable) polyols.[12][13][14][15]

Uses

Polyether polyols have numerous uses.[16][17] As an example, polyurethane foam is a big user of polyether polyols.[18]

Polyester polyols can be used to produce rigid foam.[19][20] They are available in both aromatic and aliphatic versions.[21][22] They are also available in mixed aliphatic-aromatic versions often made from recycled raw materials, typically polyethylene terephthalate (PET).[23]

Acrylic polyols are generally used in higher performance applications where stability to ultraviolet light is required[24] and also lower VOC coatings.[25][26] Other uses include direct to metal coatings.[27] As they are used where good UV resistance is required, such as automotive coatings, the isocyanate component also tends to be UV resistant and hence isocyanate oligomers or prepolymers based on Isophorone diisocyanate are generally used.[28]

Caprolactone-based polyols produce polyurethanes with enhanced hydrolysis resistance.[29][30]

Polycarbonate polyols are more expensive than other polyols and are thus used in more demanding applications.[31][32] They have been used to make an isophorone diisocyanate based prepolymer which is then used in glass coatings.[33] They may be used in reactive hotmelt adhesives.[34]

All polyols may be used to produce polyurethane

elastomers.[39]

Low molecular weight polyols

alkyd resin derived from the polyol glycerol (red, a low molecular weight polyol) and phthalic anhydride
.

Low molecular weight polyols are widely used in

hydrogen bonding is introduced.[38]

Low molecular weight polyols

Pentaerythritol

Xylitol

Sugar alcohols

Sugar alcohols, a class of low molecular weight polyols, are commonly obtained by hydrogenation of sugars.[41]: 363  They have the formula (CHOH)nH2, where n = 4–6.[42]

Sugar alcohols are added to foods because of their lower caloric content than

metabolized to acids, and thus do not contribute to tooth decay. Maltitol, sorbitol, xylitol, erythritol, and isomalt
are common sugar alcohols.

Polymeric polyols

Polymeric polyols

Polyether polyol

(The oxygen atoms of the ether linkages

are shown in blue.)

Polyester polyol

(The oxygen and carbon atoms

of the

ester groups
are shown in blue.)

The term polyol is used for various chemistries of the molecular backbone. Polyols may be reacted with

The term polyol is also attributed to other molecules containing hydroxyl groups. For instance, polyvinyl alcohol is (CH2CHOH)n with n hydroxyl groups where n can be in the thousands. Cellulose is a polymer with many hydroxyl groups, but it is not referred to as a polyol.

Polyols from recycled or renewable sources

There are polyols based on renewable sources such as plant-based materials including castor oil and cottonseed oil.[45][46][47] Vegetable oils and biomass are also potential renewable polyol raw materials.[48] Seed oil can even be used to produce polyester polyols.[49]

Properties

Since the generic term polyol is only derived from chemical nomenclature and just indicates the presence of several hydroxyl groups, no common properties can be assigned to all polyols. However, polyols are usually viscous at room temperature due to hydrogen bonding.

See also

References

  1. ^ "Basic IUPAC Organic Nomenclature - Diols (or polyols)". University of Calgary. 2022.
  2. ^ "Definition of TRIOL". www.merriam-webster.com. Retrieved 2022-02-12.
  3. ^ "Tetrol Meaning". www.yourdictionary.com. Retrieved 2022-02-12.
  4. ^ PubChem. "Butane-1,2,3,4-tetrol". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-02-12.
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  6. ^ "Polyester Polyols - an overview". www.sciencedirect.com. Retrieved 2022-02-12.
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  8. ^ WO2011129940A1, Montgomery, Steven; Brown, Shawn & Sonnenschein, Mark et al., "Polycarbonate polyols and polyurethanes made therefrom", issued 2011-10-20 
  9. ^ Roesler, Richard (26 March 1986). "Acrylic polyols having low residual monomer content European Patent" (PDF). European Patent.
  10. ^ "Polyacrylate Polyols". Ebrary. Retrieved 2022-02-13.
  11. ^ "Polycaprolactone Polyols Market Report - Size and Share by 2026 | AMR". Allied Market Research. Retrieved 2022-02-12.
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  13. ^ Patel JV, Desai SD, Sinha, VK (March 2004). "Bio-acrylic polyols for two pack polyurethane coating". Journal of Scientific and Industrial Research. 63 (3): 259–264. Retrieved 2022-02-13.
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  20. ^ "Polyester polyols for rigid foam" (PDF). Stepan. February 2022.
  21. ^ "Aromatic Polyester Polyols". purinova.com. Retrieved 2022-02-12.
  22. ^ "Polyester Polyols" (PDF). Nord. May 2018.
  23. ^ Makuska, Ricardas (2008). "Glycolysis of industrial poly(ethylene terephthalate) waste directed to bis(hydroxyethylene) terephthalate and aromatic polyester polyols" (PDF). Chemija. 19 (2): 29–34.
  24. ^ US6762262B1, Wang, Wei & Harris, Stephen H., "Preparation of acrylic polyols", issued 2004-07-13 
  25. S2CID 241043906
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  26. ^ "New Acrylic Polyols for Low-VOC Coatings". www.pcimag.com. 2002-05-31. Retrieved 2022-02-13.
  27. ^ "Acrylic polyol with enhanced performance for 2K PUR direct-to-metal coatings". BASF. Retrieved 2022-02-13.
  28. ISSN 0300-9440
    .
  29. ^ Takaaki, Fujiwa (19 July 1990). "A polycaprolactone polyol and hydrolysis resistant polyurethane resins prepared therefrom patent 0 409 735 A1" (PDF). European Patent Office.
  30. ISSN 0300-9440
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  31. .
  32. ^ "Polycarbonate Diols for Ultimate Performance Polyurethanes". www.gantrade.com. Retrieved 2022-02-14.
  33. ^ Wilson, Michael G. (November 1991). "New coatings for glass". Journal of the Oil and Colour Chemists Association. 11: 412–415 – via Springer.
  34. ^ Cherian, Anna (2014-11-01). "Carbon Dioxide-Based Polycarbonate Polyols for Polyurethane Systems". www.adhesivesmag.com. Retrieved 2022-02-14.
  35. ISSN 1097-4628
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  43. , retrieved 2022-02-12
  44. ^ Boustead, I. (2005). "Polyurethane rigid foam" (PDF). Eco-Profiles of the European Plastics Industry. Brussels: PlasticsEurope. Archived from the original (PDF) on 2013-09-25.
  45. from the original on 2023-03-14. Retrieved 2023-03-09.
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External links

  • Media related to Polyols at Wikimedia Commons
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