Cationic homopolymerization of trans-anethole in the presence of solvate ionic liquid comprising LiN(SO2CF3)2 and Lewis bases

Cationic homopolymerization of a biomass-derived monomer, trans-4-methoxy-β-methylstyrene (trans-anethole: Ane), was achieved with a combination of bis(trifluoromethylsulfonyl)imide and solvate ionic liquid comprising lithium bis(trifluoromethylsulfonyl)imide and a Lewis base, such as ethyl acetate and diisopropyl ether (iPr2O). The number-average molecular weight (Mn) of the obtained poly(Ane) reached 15.6 × 103 by adding iPr2O in toluene at –10 °C. The solubility of poly(Ane) varied drastically with a change of solvent: the polymers obtained in CH2Cl2 were not completely soluble in common organic solvents such as toluene, chloroform, and tetrahydrofuran, except for 1,1,2,2,-tetrachloroethane (C2H2Cl4) at 140 °C, whereas the polymers obtained in toluene were soluble in these solvents. The 1H NMR spectrum measured in C2D2Cl4 at 140 °C revealed that the stereostructure of poly(Ane) depended significantly on the solvent and the temperature: a polymer with a more regulated stereostructure was obtained from polymerization in CH2Cl2 at –40 °C than those obtained by polymerization in toluene at –10 °C.

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