Polystyrene, living polymer synthesis procedure

Ion coupling of anionic and cationic living polymers is an interesting procedure for the synthesis of a well-defined block copolymer. Attempted coupling of the polystyrene anion with the poly-THF cation initiated by triethyloxonium tetrafluoro-borate yielded a block copolymer mixed with homopolymers394. The block ef-... 

Two related procedures have been developed to effect this transformation. Both Involve the Initial synthesis of mono- or dlfunctlonal living anionic polymers of styrene, butadiene, or block copolymers of both. They are then reacted via Grlgnard Intermediates (7 ) with either excess bromine or with excess m-xylylyl dlbromlde (8-10) to yield polymers with reactive halide terminal groups (benzyllc or allyllc depending upon the polymer and terminating agent). The reactions for polystyrene are shown In equations 2 and 3. 

Despite a number of investigations, the efficient synthesis of co-epoxide-functionalized polymers in hydrocarbon solution with lithium as counterion at room temperature had not been reported. Takenaka et developed an efficient synthesis of epoxide-functionalized polystyrenes and poly-isoprenes by terminating the corresponding living polymeric anions with (2-bromoethyl)oxirane at -78 °C in THE as shown in eqn [27]. Termination of either PSLi or PlLi by inverse addition to 2-3 equivalents of (2-bro-moethyl)oxirane reportedly produced the corresponding epoxy-functionalized polymers in quantitative yields as determined by NMR and TLC-FID chromatography. However, the requirements of -78 °C and THF as solvent limit the usefulness of this procedure. 

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