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

20 B. Charleux, R. Faust
omer increment. Methacrylate-capped three arm poly(p-MOS) was obtained after
quantitative end-quenching with 2-hydroxyethyl methacrylate (HEMA). Besides
formation of a well-defined trifunctional macromonomer, this reaction
could also be used to confirm the structure of the stars using 1 H NMR spectroscopy.
By integration of the characteristic peaks of the core and of the end group
respectively, F n ~3 was found. Using initiator 12 with an ester core, the same star
could be prepared. SEC and NMR analysis of the arms after separation from the
core by hydrolysis under mild alkaline conditions, confirmed uniformity of the
individual arms.
2.2.1.3
Poly(styrene) n
Six arm star polystyrenes were prepared by the core-first method using initiator
13 with six phenylethylchloride-type functions emanating from a central hexasubstituted
benzene ring [24].
(13)
Living cationic polymerization of styrene was carried out using SnCl 4 and n-
Bu 4N + Cl – in CH 2Cl 2 at –15 or –30 °C. Polystyrene stars of various MW depending
upon the amount of styrene and reaction times were characterized by NMR
and SEC equipped with a light scattering detector. M n values as determined using
both techniques were claimed to be in good agreement with each other;
moreover, narrow MWDs were found using SEC (M w /M n »1.1). On the basis of
these experimental results, the authors concluded that the hexafunctional initiator
13 was efficient to prepare well-controlled six arm star polystyrene up to
M n =90,000 g mol –1 . For higher MWs, however, the control was difficult to