Triethyloxonium hexafluoroantimonate initiation

Addition of trimethylamine to the triethyloxonium hexafluoroantimonate-initiated living PDXL yields telechelics with one trimethyl ammonium end group and one ethoxy end group. An activated monomer mechanism similar to that described for oxiranes has been proposed to account for the formation of hydroxy-terminated PDXL. ... 

Another pathway yields a thermodynamically more stable product, but is kinetically less favorable. Because of extensive chain transfer the poljunerization of DXL is not living. However, if a fimctionalized acetal is added to the monomer, telechelic polymers, ega,op-bisacrylate ofpoly(DXL) (318), are obtained. Similarly, addition of trimethylamine to growing poly(DXL) initiated with triethyloxonium hexafluoroantimonate yields telechelics with one trimethylammonium and one ethoxy end group (319). 

All these cationic deactivation processes were performed with oxolane as the monomer and with various initiators such as triethyloxonium tetrafluoroborate and benzoyl, acetyl or propionyl hexafluoroantimonate. Efficient difunctional cationic initiators such as adipoyl- or terephthaloyl hexafluoroantimonate) can also be used 42 to synthesize bifunctional macromonomers containing at both chain ends a polymerizable double bond. 

The importance of both the cationic and anionic portions of the initiator was revealed by a study of various initiators for THF polymerization having different cations and different counter-ions. In this study, Yamashita et al. [84,85] concluded that the kp value with CH2CI2 solvent at 0°C is almost independent of counter-ion when triethyloxonium ions are used as initiators. They found much slower apparent rates when the different cation initiators, acetyl hexafluoroantimonate and 2-methyl-1,3-dioxolenium perchlorate, were used. They explained the slower rates by decreased rates of initiation. The apparent fep s can be increased to the... 

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