Quasiliving Cationic Polymerization of Anethole: Accessing High-Performance Plastic from the Biomass-Derived Monomer

Abstract

Quasiliving cationic polymerization of the naturally occurring β-methylstyrene derivative, anethole, is reported for the first time. The effect of solvent polarity, initiator nature as well as Lewis acid, proton trap, and initiator concentrations on the cationic polymerization of anethole in the presence of SnCl4 as a coinitiator was studied in detail. It was shown that SnCl4-coinitiated cationic polymerization of anethole proceeds in a quasiliving fashion in the presence of different initiators (cumyl chloride, p-methoxystyrene-HCl, and dicumyl chloride) using 2,6-lutidine as a proton trap and toluene as a solvent at -50 and -60 °C affording poly(anethole)s with the number-average molecular weight up to 24,000 g mol-1 and relatively low polydispersity (D = 1.25-1.51). The quasiliving nature of polymerization was confirmed by the linearity of first-order kinetic plot, linear increase of Mn with increasing conversion, as well as by monomer addition experiment. The analysis of size exclusion chromatography traces of the synthesized polymers revealed the presence of a high-molecular-weight fraction (from 9 to 20% depending on solvent polarity and temperature), which is generated due to competitive chain transfer to the monomer via its alkylation by growing macrocations and occurring simultaneously with propagation. The synthesized poly(anethole)s are characterized by a high value of glass transition temperature (Tg up to 255 °C), high thermal stability (Td5 = 386 °C), and high Young's modulus (3.1 ± 0.5 GPa) comparable with values for such commercially available plastics as polystyrene and poly(methyl methacrylate). In addition, the obtained polymer shows increased resistance to bacterial (Escherichia coli) growth on the polymer surface in comparison with polystyrene.