Dendritic polyols

As sea biodegradation investigation of cross-linked dendritic polyols is under scrutiny at Natick, tests were conducted to compare abiotic (hydrolysis) degradation of pure H40 Boltom and H40 cross-linked with HDI... 

An oligo-polyol for polyurethanes, may have two, three, four, five, six, seven or a maximum of eight hydroxyl groups/mol. Polyols with a higher number of hydroxyl groups/mol are rarely used (for example dendritic polyols). Oligo-polyols with only one hydroxyl groups/mol are present in all the polyether polyols based on propylene oxide (see Chapters 4.1.1-4.1.4). 

By polyaddition of 3-ethyl-3-methylol-oxetane to the hydroxyl group of TMP a dendritic polyol is obtained, with a hyperbranched and much more symmetrical structure compared to glycidol. In principle, the structure is very similar to the structure presented in the Figure 20.2 with the difference that the repeating unit is different (Figure 19.5) ... 

Figure 19.5 Repeating unit in the dendritic polyols based on 3-ethyl-3-methylol...

Dendritic polyester polyols of 1st, 2nd, 3rd and 4th generation could be obtained by self-condensation of dimthylolpropionic acid initiated by pentaerythritol. The resulting dendritic polyols have 8, 16, 32 and 64 hydroxyl groups/mol, respectively. 

The hydrosilylation-allylation protocol is applicable to the syntheses of dendritic polyols . The hydroboration-oxidation of G0-G3 dendrimers prepared in accordance with the synthetic routes shown in Scheme 24 give the corresponding dendritic polyols, GO-OH-G3-OH, which are characterized by H NMR and MALDI-TOF analyses. Further modifications of the dendritic polyols with cholesteryl chloroformate yield unique dendrimers possessing 12, 36 and 108 cholesteryl units, providing the first examples of flexible dendrimers substituted with rigid mesogenic units that are expected to have unusual liquid crystalline properties . The second generation polyol dendrimer 264... 

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