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Keywords:

  • ring-opening polymerization;
  • macrocycles;
  • MALDI;
  • polyoxetanes;
  • postpolymerization modification

Abstract

The synthesis of 3-allyloxymethyl-3-ethyloxetane (AllylEHO) and its polymerization with BF3 × Et2O is described in this study. Size exclusion chromatography (SEC) and membrane osmometry are used for the determination of molecular weights of the obtained products, ranging from Mn,SEC = 41,500-131,500 g/mol. 1H NMR spectroscopy, SEC, as well as MALDI-TOF MS reveal the formation of cyclic tetramer beside low, but detectable concentrations of larger cyclic oligomers as by-products during the polymerization process. These results help to understand mechanistically why attempts for a controlled homopolymerization of AllylEHO fail and why a controlled homopolymerization of oxetanes has not been described so far in the literature. Additionally, the high versatility of allyl-functional polyoxetane for postpolymerization modification is proven by thiol–ene reactions with 3-mercaptopropionic acid and N-acetyl-L-cysteine methyl ester. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013