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

50 B. Charleux, R. Faust
second example [77], macromonomers with DP n up to 28 were prepared. After
reacting the terminal aldehyde with a silyl ketene acetal (1-methoxy-2-methyl-
1-trimethylsilyloxy propene) to provide a more stable ester end group, tertbutyldimethylsilyl
ether side groups were hydrolyzed to the corresponding alcohol
leading to heterotelechelic poly(vinyl alcohol) with a polymerizable styryl a
end group and an ester w end group.
(33)
Such hydrophilic macromonomers (DP n =7–9) were radically homopolymerized
and copolymerized with styrene [78] using AIBN as an initiator at 60 °C in
deuterated DMSO in order to follow the kinetics directly by 1 H NMR analysis.
The macromonomer was found to be less reactive than styrene (r M=0.9 for the
macromonomer and r S=1.3 for styrene). Polymerization led to amphiphilic
graft copolymers with a polystyrene backbone and poly(vinyl alcohol) branches.
The hydrophilic macromonomer was also used in emulsion polymerization
and copolymerized onto seed polystyrene particles in order to incorporate it at
the interface.
3.3.1.1.3
Polystyrene and Poly(p-methylstyrene)
Using functional initiator 31, polystyrene and poly(p-MeS) macromonomers
bearing a terminal methacrylate group [79] could be prepared by living cationic
polymerization in CH 2Cl 2 at –15 °C in the presence of SnCl 4 and n-Bu 4NCl. To
obtain an a end-functionality (F n) close to 1, mixing of the reagents was carried
out at –78 °C. When mixing was performed at –15 °C, the functionality was lower
than 1 which was ascribed to a side-reaction, initiation by protons eliminated
following intramolecular alkylation. The resulting oligomers could be clearly
observed by SEC analysis at low conversion. After complete conversion of the
monomers, the polymerization was quenched with methanol and macromonomers
with a chloride w end group were recovered. A polystyrene macromonomer
with DP n =18 (M w /M n =1.16 and F n =0.94) and a poly(p-MeS) macromonomer
with DP n =24 (M w /M n =1.14 and F n =0.97) were reported.
3.3.1.1.4
Poly(a-methylstyrene)
A similar procedure was also used for the synthesis of methacrylate functional
poly(a-MeS) [80]. Thus, 31 was used in conjunction with SnBr 4 in CH 2 Cl 2 at –
78 °C, to obtain the macromonomer with M n s substantially (~50%) higher than
the theoretical value. This was probably due to the formation of terminated low
MW oligomers with indanyl end group structure. The eliminated proton was as-