Chemistry of Sulfur Chain and Design of Dynamic Soft Materials Using Rotaxane

The present article deals with the structural characteristics and synthetic methods of rotaxanes, polyrotaxanes, and polyrotaxane networks having cyclodextrin and crown ether as the wheel components, following to the description of the importance of the rotaxane cross-links in the light of stimuli-responsive polymer materials. The formation of rotaxane structure usually requires the enthalpy gain capable of compensating the entropy loss arising from the assembly of the rotaxane components. In particular, the structures and synthetic methods of rotaxane-crosslinked polymers are discussed from viewpoints of controllability of the cross-link density and versatility of the matrix polymers.