Synthesis of poly(2-methyl-3-hydroxyoctanoate) via anionic polymerization of ?-methyl-ß-pentyl-ß-propiolactone

Synthesis of an ?,ß-alkyl branched polyester, i.e., poly(2-methyl-3-hydroxyoctanoate), has been accomplished via anionic polymerization of ?-methyl-ß-pentyl-ß-propiolactone mediated by supramolecular complexes of potassium methoxide or potassium hydroxide, respectively. The structure of resulting polymers has been established by electrospray ionization multistage mass spectrometry (ESI-MSn), FT-IR, NMR, and GPC analyses. Previously proposed addition-elimination mechanism of the polymerization of ß-lactones containing ?-hydrogen by alkoxide anion has been confirmed to operate also in the case of ß-lactone having alkyl substituents in both ? and ß positions