Mechanically linked supramolecular polymer architectures derived from macromolecular [2]rotaxanes: Synthesis and topology transformation

•This review article focuses on dynamic macromolecular systems having mechanically linked polymer chains.•Topology changes from linear to cyclic, branched, and star ones in rotaxane-linked polymer systems were achieved.•Rotaxane cross-linkers endowed cross-linked polymers with toughness via radical polymerization of vinyl monomers.

This review article deals with the construction and function of dynamic macromolecular systems having mechanically linked polymer chains which can undertake a topology transformation to induce structure and property changes. Synthesis of a macromolecular [2]rotaxane (M2R) possessing a macromolecular switch function is first described, which is a structure-definite ideal polyrotaxane consisting of one polymer axle and one macrocycle wheel. Its application to the synthesis of rotaxane cross-linked polymers (RCP) and topology-transformable polymers is discussed along with their properties, where the rotaxane-linking of polymer chains plays a crucial role. The M2R-based cross-linker is prepared and applied to the synthesis of RCPs by adding it into radical polymerization systems of vinyl monomers. RCPs have high stretchability and toughness. Rotaxane-linked block copolymers and cyclic polymers synthesized by introducing polymer chains onto the wheel and axle components of M2R are subjected to the topology transformation using the switch function of M2R to cause remarkable structure and property changes.

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