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

82 N. Hadjichristidis, S. Pispas, M. Pitsikalis, H. Iatrou, C. Vlahos
2.2.1.1.5
Other Methods
Individual methods have also been devised for the preparation of miktoarm
stars. One of these approaches involves the preparation of macromonomers possessing
either central or end vinyl groups which can be used to produce miktoarm
stars either by copolymerization of the double bonds or by reacting the
double bonds with living polymer chains, thus creating active centers able to initiate
the polymerization of another monomer. All these methods are limited to
specific synthetic problems and cannot be used for the preparation of a wide
range of different structures.
2.2.1.2
Synthesis of A 2B Miktoarm Star Copolymers
One miktoarm star copolymer of the A 2B type was prepared by Mays using a
method similar to the one adopted by Pennisi and Fetters for the synthesis of
asymmetric stars [21]. According to this method living PS chains were reacted
with excess CH 3SiCl 3 to produce the monosubstituted linking agent, followed by
the removal of the excess silane by the addition of a slight excess of living PI
chains. Fractionation was performed to remove the excess PI after the linking
Scheme 5
Scheme 6