Polytetrahydrofuran living cation polymer

Anionic polymerization frequently has been used to prepare well-defined living polymers such as polystyrene, poly(a-methylstyrene), polydienes, which may be transformed by two methods into block copolymers with cationically polymerizable monomers. When a living anionic polymer is mixed with a stoichiometric amount of a living cationic polymer the cationic and anionic species may couple. For example, anionic living polystyrene (St) or poly (a-methylstyrene) (MSt) were reacted with living cationic polytetrahydrofuran (THF). In the latter system the coupling efficiency was low, probably because of proton or hydride transfer 132) ... 

Polystyrene-polytetrahydrofuran block copolymers121122 are an interesting case of coupling between functional polymers The mutual deactivation of living anionic polystyrene and living cationic polyoxolane occurs quantitatively to yield polystyrene-polyoxolane block copolymers. Since either of the initial polymer species can be mono- or difunctional, diblock, triblock or multiblock copolymers can be obtained. 

Another way of synthesizing block copolyers it to have two polymers which possess mutually reacting chain ends. A picturesque example is the mutual deactivation of living" cationic polytetrahydrofuran and of "living" anionic polystyrene.12... 

Random copolymers of PS and a small quantity of 4VP ( 1% mol) were prepared by radical polymerization and used as the backbone for the grafting of the polytetrahydrofuran dication, prepared by living cationic polymerization [69]. The polymers were characterized by SEC. As an extension of this work the terminal hydroxyl groups of the graft copolymers were tosylated and 2-methyl oxa-zoline (MeOz) was added. Heating the mixture at 110 °C led to the polymerization of the MeOz. 

Nitroxide attached to macromolecules also induces the living radical polymerization of St. Yoshida and Sugita [252] prepared a polymeric stable radical by the reaction of the living end of the polytetrahydrofuran prepared by cationic polymerization with 4-hydroxy-TEMPO and studied the living radical polymerization of St with the nitroxide-bearing polytetrahydrofuran chain. The nitroxides attached to the dendrimer have been synthesized (Eq. 69) to yield block copolymers consisting of a dendrimer and a linear polymer [250,253]. 

The living polymer technique has been applied recently in studies of equilibria tetrahydrofuran polytetrahydrofuran. This polymerization proceeds by a cationic mechanism (15) the propagation being described by the equation... 

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