Macromolecular star architectures, with several polymer chains connected to a central core, are interesting due to their well-defined and compact structure, a high density of functional groups, and unique properties in solution and in the melt. However, adding a characteristic of dynamics (e.g., the potential for controlled degradability) to star polymers is highly desirable in many applications, including coatings, drug-delivery, and biotherapeutics. Both supramolecular and dynamic-covalent chemistry impart dynamics and reorganizability to the polymeric materials. While retaining the benefits of reversibility, the higher strength of many dynamic-covalent bonds, as compared to supramolecular interactions, leads to increased structural stability. The research to bediscussed here demonstrates the �arm-first� route to star polymers by dynamic-covalent crosslinking of well defined functional block copolymers synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Three different types of dynamic-covalent chemistries, namely boronic ester formation, Diels-Alder cycloaddition, and disulfide chemistry were utilized for synthesis of the core-crosslinked stars. The reversibility of the stars induced by specific stimuli (addition of a competing mono/multifunctional diol in case of the boronic ester linkages, heating/cooling in case of the Diels-Alder linkages, and reduction/oxidation in case of disulfide linkages) was further studied over multiple cycles.

Dynamic-covalent star nanostructures prepared from functional block copolymers obtained by RAFT polymerization

246th National Meeting (2013)

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