Dibromomaleimide Derivative as an Efficient Polymer Coupling Agent for Building Topological Polymers

The dibromomaleimide derivative, N ‐(4‐bromobutyl)‐dibromomaleimide (dBMIB), is found to be a highly efficient coupling agent to dimerize thiol‐terminated hydrophilic polymers by substituent reaction. When mono‐thiol poly(ethylene oxide) (PEO 45 ‐SH) is mixed with dBMIB in an equivalent molar feed in water, a dimer of PEO 45 with a maleimide unit located at the chain center, (PEO 45 ) 2 MIB, is obtained quantitatively. The dBMIB is also used to dimerize thiol‐ terminated poly( N ‐(2‐acryloyloxyethyl) pyrrolidone) and poly( N , N ‐dimethyl acrylamide). Moreover, the butylene bromide of (PEO 45 ) 2 MIB is transferred into a butylene azide, which is allowed to react with alkynyl‐terminated polystyrene to give a A 2 B miktoarm star polymer via a copper‐catalyzed azide–alkyne cycloaddition coupling reaction.