Synthesis and Star/Linear Topology Transformation of a Mechanically Linked ABC Terpolymer

Abstract

The synthesis of an ABC star terpolymer containing one polymer chain connected mechanically through a rotaxane linkage and its topology transformation to a linear structure are reported. Pseudo[2]­rotaxane, which was designed as the key trifunctional species for the star polymer synthesis, comprised a sec-ammonium axle with ethynyl and hydroxy groups and a crown ether wheel with a trithiocarbonate group. Stepwise polymer connections to the pseudo[2]­rotaxane using the three groups afforded a rotaxane-linked ABC star terpolymer. The topology transformation from star to linear by the removal of the attractive interaction between the axle and wheel components yielded a linear ABC terpolymer via the wheel shifting to the axle end. The spectroscopic and solution property changes clearly indicated the occurrence of the polymer topology change.

Stimuli-Responsive Molecular and Macromolecular Systems Controlled by Rotaxane Molecular Switches

“…71 A pseudo [2]rotaxane initiator (3F) capable of linking three polymer chains through the rotaxane linkage was designed as the key trifunctional compound for the star polymer synthesis (Scheme 10). 72 Living ring-opening polymerization of VL initiated with 3F and successive propagation end-capping was followed by the reversible additionfragmentation chain transfer (RAFT) polymerization of styrene to give the corresponding two polymer chain-tethering [2]rotaxane PVL 33 -rot-PS 49 . Final polymer connection via click reaction with azide-terminated poly-(ethylene oxide) afforded a rotaxane-linked ABC star terpolymer PEO 45 -b-PVL 33 -rot-PS 49 _A.…”

“…Final polymer connection via click reaction with azide-terminated poly-(ethylene oxide) afforded a rotaxane-linked ABC star terpolymer PEO 45 -b-PVL 33 -rot-PS 49 _A. 72 The strong interaction of sec-ammonium/DB24C8 fixed the rotaxane-linked structure at the center of the axle polymer chain to connect the arm polymer chains. However, N-acetylation of the sec-ammonium moiety of PEO 45 -b-PVL 33 -rot-PS 49 _A resulted in transforming the initial polymer topology from star to linear shape (PEO 45 -b-PVL 33 -rot-PS 49 _U) via the emergence of the urethane/crown ether interaction at the end of the axle polymer PVL chain.…”

“…The peak top shift of the GPC profile to higher molecular weight region strongly supported the structure and dynamic nature of the topology-transformable ABC terpolymer ( Figure 15). 72 3.3 Cyclic Polymer and Reversible Linear-Cyclic Topology Transformation. The topology-transformable structure of rotaxane-linked polymers makes possible the synthesis of cyclic polymer from linear polymer.…”

“…Synthetic strategy of cyclic polymer via topology transformation of M1R as linear polymer. Synthesis of rotaxane-linked ABC star terpolymers 72.…”

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

“…32,33 To extend the capability and applicability of the topology-transformable systems based on M2R, we synthesized a topology transformable ABC terpolymer. 82 A pseudo [2]rotaxane initiator (3F) capable of linking three polymer chains by the rotaxane linkage was designed as the key trifunctional compound for the star polymer synthesis (Scheme 12).…”