Third generation polyol

Figure 19.6 shows the structure of a third generation of a dendritic polyester polyol, based on dimethylolpropionic acid, initiated by pentaerythritol. 

In addition to third-generation ILs, a new class of ionic solvent systems, called DES, has been developed. DES are typically formed by mixing a quaternary ammonium salt, such as choline chloride, and an uncharged hydrogen-bond donor, such as urea, carboxylic acids (e.g., oxalic or amino acids), or polyols (e.g., glycerol) [11,131]. Although DES are not entirely composed of ionic species, their physicochemical properties are very close to those of common ILs [132]. 

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