Hydroxyl functionalized, anionic polymerization using protected

Five experimental criteria have been described for the evaluation of protected, functionalized alkyllithium initiators for anionic polymerization. Several alkoxy- and t-butyldimethylsiloxy-protected, hydroxyl-functionalized initiators have been evaluated using these criteria for the polymerization of styrene, isoprene and butadiene. All of the initiators satisfied the criteria for diene polymerization, but inefficient initiation and broader molecular weight distributions were observed for styrene polymerization, especially in cyclohexane. 

The usefulness of l-alkoxy- and t-butyldimethylsiloxy-functionalized alkyllithium initiators for anionic polymerization have been evaluated using five experimental criteria. All of these criteria must be satisfied for an initiator to be generally useful. These protected hydroxyl-flmctionalized initiators are all useful for the polymerization of butadiene and styrene monomers. Inefficient initiation of styrene polymerization was observed in cyclohexane, but not in benzene. 

Thus, the protective strategy in conjunction with living anionic polymerization successfully works to afford well-defined functional polystyrenes substituted with alcoholic and phenolic hydroxyl groups, diols, and triols. The silyl ether-, cyclic acetal-, and ortho ester-protected functionalities are effective for this purpose. This strategy may possibly be applied to other useful functional styrene derivatives and will be discussed in the next section. 

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