CATIONIC POLYMERIZATION OF TETRAHYDROFURAN INITIATED BY TRIMETHYLSILYL TRIFLUOROMETHANESULFONATE

The initiation of the cationic ring-opening polymerization of tetrahydrofuran by trimethylsilyl trifluoromethanesulfonate has been investigated by 1H NMR and 19F NMR. These studies indicate that the formation of the 1-(trimethylsilyl)tetrahydrofuranium cation is reversible due to a fast exchange process. Equilibrium constants K = 1.5 L/mol in CD2CI2 at 25 °C for this reaction have been calculated from the NMR data. A series of MNDO calculations for various tetrahydrofuranium cations indicate that charge is mostly located on the silyl moiety. Grafting of poly(tetrahydrofuran) side chains from poly-(phenylmethylsilylene) containing a few trifluoromethanesulfonate groups has been studied. Grafting has been confirmed by a strong change of molecular weight of a copolymer before and after photochemical degradation of a polysilane backbone. © 1990, American Chemical Society. All rights reserved.