Polyols

Polyols are sugar alcohols with variable chain length and stereochemistry. Polyols are monosaccharide and disaccharide molecules in which the aldehyde group is replaced by a hydroxyl. For example, D glucose and D glucitol (also called sorbitol) share very similar structures.

Typical polyols, which can be used as monomers in the process of polyester polyols, are showed in figure 1.

Fig. 1 Typical polyol monomers

Polymers Derived from Polyols

Polyester polyols are derivatives of polyacids and polyols which are mainly synthesized from petroleum. With the increasing demand of the bio-based economy, the polyester polyols derived from renewable resources are drawing increasing attention.

Fig. 2 Basic chemical structure of polyester polyol

Polyester polyols made from renewable resources, such as vegetable oils, sorbitol, diacids, and cellulose, can be used to reduce the high demand for petrochemical products and their harmful effects on the environment. They contribute to a large number of applications such as elastomers, sealants, and adhesives. They are generally environmentally degradable and, during prolonged contact with tissues, polyester polyols hydrolyze to the natural building chemical blocks.

Synthesis of Bio-based Polyester Polyols

Recently, different routes for the preparation of polyester polyols derived from biomass have been explored, including the step-growth polymerization of bio-based polyols and polyacids, the modification of lipids by means of transesterification reactions followed by further modification to create hydroxyl functionalities, and the ring opening polymerization (ROP) of bio-based cyclic esters, as shown in figure 3^[2].

Fig. 3 Different routes for the synthesis of bio-sourced polyester polyols including (A) the polycondensation of a diacid (succinic acid) and a diol (1,3-propanediol), (B) the transformation of lipids from vegetable oil (castor oil) into polyols, and (C) the ring opening polymerization of cyclic esters (lactide).

Up to now, the polycondensation reaction between a dicarboxylic acid and a polyol represents the most studied and the most frequently explored route for the synthesis of commercial polyester polyols. Thus, polyols and dicarboxylic acids from renewable resources have been investigated both in academia and in industry.

• Dicarboxylic acids

Dicarboxylic acids, as important platform chemicals, can be used as the monomers for polymerization of high molecular material. The yeast, Saccharomyces cerevisiae, is regarded as an ideal organism for bio-based production of dicarboxylic acids with high tolerance to acidic and hyperosmotic environments, robust growth using a broad range of substrates, great convenience for genetic manipulation, stable inheritance via sub-cultivation, and food compatibility. Global metabolic map of S. cerevisiae and strategies for dicarboxylates production is showed in figure 4.

Fig. 4 Global metabolic map of S. cerevisiae and strategies for dicarboxylates production

In recent years, the development of polyester polyols based on bio-derived C4-C36 dicarboxylic acids combined with bio-based diols, such as 1,3-propanediol (PDO), and 1,4-butanediol (BDO), have progressed rapidly, resulting in polyester polyols with up to 100% bio content.

Our Polyols

Alfa Chemistry provides a range of grease polyols which are based on renewable raw materials and are solvent-free for paints, adhesives, etc.

Alfa Chemistry is a professional supplier of biosynthetic polyols. For high quality products, professional technical service, use suggestion and latest industry news, please feel free to contact us.

References

1. Lang, K., Sánchez-Leija, R. J., Gross, R. A., & Linhardt, R. J. Review on the Impact of Polyols on the Properties of Bio-Based Polyesters. Polymers, 2020, 12(12), 2969.
2. Haritz Sardon, David Mecerreyes, Andere Basterretxea, et al. From Lab to Market: Current Strategies for the Production of Biobased Polyols. ACS Sustainable Chem. Eng. 2021, 9, 10664−10677.
3. Zhang, X., Zhao, Y., Liu, Y., Wang, J., & Deng, Y. Recent progress on bio-based production of dicarboxylic acids in yeast. Applied Microbiology and Biotechnology, 2020, 104(10), 4259–4272.

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