Summary: The end coupling of living PSLi chains in hydrocarbon media by the addition of monoalkylbromides has been examined. A very selective PS–PS coupling reaction was obtained with neo‐pentylbromide (94%) at a ratio of PSLi/alkylbromide equal to 1 while the secondary and tertiary bromine derivatives yield only very limited coupling. The coupling mechanism is likely to involve a lithium‐bromine interchange at the PS chain end, generating polystyryl‐bromide which then reacts selectively with the remaining polystyryllithium chains.
