Unexpected formation of a significant amount of polymer primary hydroxyl groups in synthesis of star-shaped polymer from linear alcoholate chains and diepoxides

- Formation of primary alcoholate groups in synthesis of star-polymers has been studied.
- Formation of primary alcoholate groups in the reaction of epoxide polymer groups with alcoholates was detected in NMR spectra.
- Main route of formation of primary alcoholate group is cyclization involving alcoholate and epoxy groups of macromolecule.
- Cyclization route of formation of primary alcoholate groups was supported by the quantum-mechanical calculations.

Following our previous paper on the course of the formation of star-polymers from oligo(oxyethylene)alcoholates as arms precursors and diglycidyl ethers as core building units [1], the nature of polymer alcoholate groups formed in this process has been studied. Primary alcoholate groups reacting with diepoxide or epoxide function in polymer give initially predominantly secondary alcoholate groups in the product. However, a small fraction of primary alcoholate groups of polymer is formed from the very beginning. When consumption of epoxide groups increases the contribution of polymer primary groups increases too, reaching eventually from 5 to 15% of total alcoholate groups, depending on reaction conditions. The increase of this proportion with the reaction progress is explained by intramolecular reaction of alcoholate groups with epoxide ones (cyclization) giving a large proportion of primary alcoholate groups. This explanation was supported by the quantum-mechanical calculations of the possible routes of cyclization.

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