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Home  >  Journal list  >  Polymer Journal  >  Vol.50  No.1 (2018)  >  pp.127-147

Polymer Journal
<<Previous article Vol.50  No.1 (2018)   pp.127 - 147 Next article>>

Topology-transformable polymers: linear–branched polymer structural transformation via the mechanical linking of polymer chains

Toshikazu Takata & Daisuke Aoki
Toshikazu Takata
Department of Chemical Science and Engineering, Tokyo Institute of Technology and JST-CREST, Tokyo, Japan
Daisuke Aoki
Department of Chemical Science and Engineering, Tokyo Institute of Technology and JST-CREST, Tokyo, Japan

In this review article, we discuss the synthesis and dynamic nature of macromolecular systems that have mechanically linked polymer chains capable of undergoing a topology transformation driven by a rotaxane molecular switch. The rotaxane linking of polymer chains plays a crucial role in these systems. A linear polymer possessing a crown ether/sec-ammonium salt-type [1]rotaxane moiety at the axle chain terminal was prepared via the rotaxane linking of a single polymer chain. A linear–cyclic polymer topology transformation was achieved via the movement of the wheel component from one end to the other end of the axle component using the rotaxane macromolecular switch function. The successful synthesis of a macromolecular [2]rotaxane (M2R) possessing a single polymer axle and one crown ether wheel led to a variety of unique applications, such as the development of topology-transformable polymers and the synthesis of rotaxane crosslinked polymers (RCPs). The introduction of a polymer chain to the wheel component of M2R (rotaxane linking of two polymer chains) produced a rotaxane-linked AB block copolymer that transformed its topology from linear to branched. Furthermore, a rotaxane-linked three-component polymer and an ABC triblock copolymer were synthesized and transformed to the corresponding 3-arm star (co)polymers, and the transformation was confirmed by measuring the hydrodynamic volume change. The structural transformation of 4-arm and 6-arm star polymers was also accomplished using the dynamic mobility of a similar rotaxane. As a useful application, M2R-based vinylic crosslinkers (RCs) were prepared and applied to the synthesis of RCPs, whereby the addition of RCs into radical polymerization systems of vinyl monomers afforded polymers with excellent toughness by enhancing both of tradeoff properties that cannot be achieved using typical covalent crosslinkers.

Engineering, Supramolecular polymers

Received: July 31, 2017 , Revised: August 06, 2017
Accepted: August 07, 2017 , Published online: October 25, 2017

NatureAbstract (Nature)


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