142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

Synthesis of Branched Polymers by Cationic Polymerization 55
Well-defined macromonomers of poly(BVE), poly(IBVE), and poly(EVE)
with w-methacrylate end group [91] were prepared by living cationic polymerization
of the corresponding monomers initiated by trifluoromethanesulfonic
acid in CH 2 Cl 2 at –30 °C in the presence of thiolane as a Lewis base. After complete
conversion, the polymers were quenched with 37 in the presence of 2,6-lutidine
or with 41 to produce macromonomers with M n up to 10,000 g mol –1 , with
narrow MWD, bearing one polymerizable methacrylate function per molecule.
The same polymers were also quenched with 38 in the presence of 2,6-lutidine
to give poly(vinyl ether)s with an allylic terminal group.
A vinyl ether with a mesogenic side group, 3-[4-cyano-4'-biphenyl)oxy]propyl
vinyl ether, was polymerized at 0 °C in CH 2 Cl 2 with trifluoromethanesulfonic
acid as an initiator in the presence of dimethylsulfide [92].
3-[4-cyano-4'-biphenyl)oxy]propyl vinyl ether
Three macromonomers were obtained after quenching with 37, 39, and 40 respectively.
All had a well defined structure as evidenced by SEC and NMR analyses,
with DP n close to 6 and narrow MWD (M w /M n =1.09–1.13) and with F n very
close to 1.
Macromonomers of poly(octadecyl vinyl ether) were prepared by cationic
polymerization although this technique is difficult since the corresponding
ODVE monomer has a high melting point and poor solubility at low temperature
[93]. The polymerization was initiated by the trimethylsilyl iodide/1,1-diethoxyethane
system in the presence of ZnI 2 (initiator solution was prepared at –
40 °C) and was carried out in toluene at 0 or 10 °C. Linearity of M n with conversion
was observed up to 6000 g mol –1 . At higher M n , deviation was observed and
this was assigned to transfer to the monomer. However, although transfer leads
to dead chains with a terminal unsaturation, it was shown that upon addition of
37 as a capping agent, all the chains were quenched irrespective of their end
group. Actually, the dead chains could also react with the alcoholic quencher after
their protonation by HI released in the reaction of the same quencher with
the active chains. Thus, although controlled polymerization was not achieved,
quantitative end-functionalization of poly(ODVE) with 37 could be obtained.
Short macromonomers (M n