Çok yöntemli polimerizasyon ile blok kopolimer eldesi

SUMMARY Block copolymers are materials of importance because of their practical use in giving rise to an unique two- phase structure that often allows for non- linear responses in their physical and mechanical properties. In this thesis, we have investigated the synthesis and physicochemical properties of several new classes of block copolymers. Up to now, various methods have been proposed and used for the synthesis of block copolymers. These methods are generally based on the use of either telechelic oligomers in polycondensation reactions or living polymerization techniques. Due to the limitation on synthesizing block copolymers using classical single type polymerization mode, we have developed several transformation techniques. First example of the sequential combination of polymerization mechanisms involves the use of azo-linked polytetrahydrofuran as initiator for the polymerization of several vinyl monomers which makes it possible to synthesize polyether- vinyl block copolymers. The 4.4' -azobis ( 4 -cyano pentanoly chlor j rle,i when reacted with a silver salt of a low nucleophiiic counter- ion in the presence of tetrahdyrof uran at both ends by an addition mechanism. Accordingly, in this reaction stage a macroinitiator is obtained based on polytetrahdyrofuran and possesing one reactive azo group in the main chain. In addition, this macroinitiator is used to initiate the free radical polymerization of different mesogenic methaorylate monomers. A successful application of transformation approach described above to prepare block copolymers of structurally different monomers prompted us to examine the possibility of using other polymerization modes in a similar way. A promising pathway was opened by the so-called activated monomer to radical transformation polymerization. VI