Switchable Polymer Materials Controlled by Rotaxane Macromolecular Switches

Abstract

The synthesis and dynamic nature of macromolecular systems controlled by rotaxane macromolecular switches are introduced to discuss the significance of rotaxane linking of polymer chains and its topological switching. Macromolecular switches have been synthesized from macromolecular [2]rotaxanes (M2Rs) using sec-ammonium salt/crown ether couples. The successful synthesis of M2Rs possessing a single polymer axle and one crown ether wheel, constituting a key component of the macromolecular switch, has allowed us to develop various unique applications such as the development of topology-transformable polymers. Polymer topological transformations (e.g., linear−star and linear−cyclic) are achieved using rotaxane-linked polymers and rotaxane macromolecular switches. The pronounced dynamic nature of these polymer systems is sufficiently interesting to design sophisticated stimuli-responsive molecules, polymers, and materials.

Stereodynamics of E/Z isomerization in rotaxanes through mechanical shuttling and covalent bond rotation

“… 10 At present, the study of the stereochemistry of MIMs, i.e., mechano-stereochemistry, represents one of the most intellectually challenging lines of research in fundamental chemistry. This area is teeming with opportunities, not only as a consequence of the vastness of its scope but also for the growing role of MIMs in the development of new catalysts, 11 , 12 , 13 , 14 advanced materials, 15 , 16 , 17 , 18 and molecular machines. 1 , 19 , 20 , 21 , 22 , 23 …”

Maleimide Chemistry: Enabling the Precision Polymer Synthesis

“…Moreover, in order to improve the efficiency of the cyclization, some elegant approaches have been developed, such as electrostatic self‐assembly and covalent fixation (ESA‐CF), [ 41 ] and rotaxane protocol. [ 42 ] Metal‐free RAFT polymerization has shown some advantages in generating the polymers with controllable MW and broad selection of monomers. Importantly, it can also provide polymers with thiol end group after aminolyzing the thiocarbonate terminal.…”

Thermally Responsive Poly(ethylene oxide)‐Based Polyrotaxanes Bearing Hydrogen‐Bonding Pillar[5]arene Rings**

“…This method of assembly allows for some forms of molecular motion, which endows these supramolecules with unique mechanical and thermal properties. [1][2][3][4][5][6][7] Polyrotaxanes, in which many macrocycles are threaded onto a polymer chain and trapped by terminal bulky stoppers, have recently attracted considerable interest for their simple structures and properties different from conventional polymers. [8][9][10][11][12][13] Poly(ethylene oxide)s (PEOs) are a class of polymers, which exhibit crystalline and thermoplastic behavior, as well as high solubility in both water and organic solvents.…”

“…Topological materials are assembled from geometrically confined or interlocked components instead of rigid covalent bond frameworks. This method of assembly allows for some forms of molecular motion, which endows these materials with unique mechanical and thermal properties [1–7] . Polyrotaxanes, in which many macrocycles are threaded onto a polymer chain and trapped by terminal bulky stoppers, have recently attracted considerable interest for their simple structures and properties different from conventional polymers [8–13] …”