Polystyrene, living polymer ethylene oxide termination

It has been shown recently (10) that such block structures could be tailored precisely by the general method summarized hereabove. It is indeed possible to convert the hydroxyl end-group of a vinyl polymer PA (f.i. polystyrene, or polybutadiene obtained by anionic polymerization terminated with ethylene oxide),into an aluminum alcoholate structure since it is well known that CL polymerizes in a perfectly "living" manner by ring-opening insertion into the Al-0 bond (11), the following reaction sequence provides a direct access to the desired copolymers, with an accurate control of the molecular parameters of the two blocks ... 

The chemical route to an azo-tipped polymer is illustrated in Fig. 6 taking polystyrene as an example. Anionic polymerization is preferred as the molecular weight and molecular weight distribution can be accurately controlled. Termination of the living chains with ethylene oxide gives the hydroxy polymer which reacts with a separately prepared azo acid chloride to give the required functionalization in high yield (75-80/S). 

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