Ring-opening polymerization of ε-caprolactone from cellulose acetate by reactive processing
2021
Imre, Balázs | Kiss, Elek Z. | Domján, Attila | Cui, Lu | Pukánszky, Béla
The internal plasticization of cellulose acetate (CA) was achieved by grafting with ε-caprolactone (CL) via reactive processing. The effect of varying concentrations of tin(II) bis(2-ethylhexanoate) [Sn(Oct)₂] and iron(III) acetylacetonate [Fe(Acac)₃] catalysts on the ring-opening polymerization (ROP) of CL were compared with each other. The analysis of processing parameters, weight loss measurements, FTIR, and ¹H NMR spectrometry all showed improving grafting efficiency with increasing concentrations of both catalysts. Processing conditions also significantly affect the characteristics of the final product. The resulting structure, i.e., relatively long (2200 g/mol) PCL chains grafted to a small number (1–3%) of CA hydroxyls, promotes thermoplasticity, thus enabling processing in the melt state, while also preserving the biodegradable character of cellulose acetate. The performances of the two catalysts were found to be very similar, which suggests that conventional Sn(Oct)₂ could be substituted with the less toxic Fe(Acac)₃ for the graft ROP of caprolactone.
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