A simple and efficient method to generate macrocyclic structures has been developed based on the dynamic behavior of the linker bis(2,2,6,6‐tetramethylpiperidin‐1‐yl)disulfide (BiTEMPS). The prime linear structure was transformed into a (macro)cycle using the following sequence: 1) thiol–ene reaction with a BiTEMPS derivative to afford the linear precursor, then 2) an entropy‐driven transformation induced by diluting and heating. The radicals generated from BiTEMPS upon heating are highly tolerant toward a variety of chemical species, including oxygen and olefins, but they exhibit high reactivity in exchange reactions, which can be applied to the topology transformation of various skeletons. The advantages of the present method, namely, its procedural simplicity and substrate versatility, are demonstrated by the gram‐scale synthesis of cyclic compounds with low and relatively high molecular weight.

End-functionalized polymers were synthesized by simply heating a mixture of a macrocyclic compound with one bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) moiety and bifunctional acyclic BiTEMPS compounds as sources of repeat units and terminal groups, respectively.

Recent advances in polymer chemistry have made the synthesis of polymers with various topologies possible, albeit effective synthetic routes to cyclic polymers remain limited. In this study, cyclic polymers were synthesized via a simple heat-induced ring-expansion polymerization of macrocyclic monomers with one bis­(2,2,6,6-tetramethylpiperidin-1-yl)­disulfide (BiTEMPS) linkage. The cyclic topology of the resulting products was confirmed by a variety of analytical techniques, including electrospray ionization time-of-flight mass spectrometry, proton nuclear magnetic resonance, size exclusion chromatography (SEC), and SEC equipped with multiangle light scattering. Furthermore, the synthesis of cyclic random copolymers and functionalized cyclic polymers was also accomplished. This method represents a simple route for the insertion of functional groups into cyclic copolymers, which may significantly advance their applications.

A polymer is used as a source of fertilizer. To demonstrate the viability of this concept, the chemical recycling of poly(isosorbide carbonate) (PIC) is presented as a model for the next generation of plastic-recycling systems.

The maleimide structure is highly reactive, exemplified by thiol–ene click reactions with thiols and Diels–Alder reactions with furans. Although postpolymerization modifications and macromolecular conjugations involving maleimide units have been widely studied, mostly due to their selectivity and high reactivity, little has been reported on the one‐pot postpolymerization introduction of maleimides in polymer chains. Herein, we report p‐maleimidophenyl isocyanate and its derivatives as modification agents to introduce maleimide moieties by reaction with hydroxy groups into polymer chains. The high reactivity of the resulting modification agents and of the corresponding maleimide structures once inserted in the polymer chains was examined by studying their reaction kinetics. Furthermore, these modification agents were successfully applied to the synthesis of macromonomers for graft polymerization and various block copolymers, with, for example, AB‐type, star‐shaped, and H‐shaped architectures. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2396–2406

Mechanically interlocked polymers that contain rotaxane and catenane structures have attracted much attention on account of their unique properties arising from the restricted mobility of their interlocked structure and their robustness which are comparable to those of covalent bonds. Among these polymers, mechanically interlocked cyclic polymers (MICPs) exhibit great potential as a novel type of polymer with a large movable area of the interlocked structure. However, synthetic routes to MICPs are not well developed, and it is still challenging to create MICPs. The present study has resulted in an effective method for the synthesis of MICPs from the combination of the ring-expansion polymerization (REP) of cyclic disulfide monomers with supramolecular interactions. Macrocyclic monomers (MMs) that consist of a bis(hindered amino)disulfide (BiTEMPS) linker and a supramolecular moiety, such as naphthalenediimide (NDI) and dialkoxynaphthalene (DAN), capable of forming a strong 1/1 charge-transfer complex, were synthesized as the monomers for the subsequent REP. These MMs were used in a heat-induced REP in the bulk state, which led to their swift polymerization via an intermolecular exchange reaction of BiTEMPS. The change in mechanical properties during the polymerization was monitored by rheological measurements of the increase of the storage modulus, G′. Importantly, the bulk copolymerization of the MMs containing NDI and DAN increased the hydrodynamic volume of the resulting copolymers, which is due to the spatial entanglement of the polymer chains. The change in the physical properties of the resulting polymers stands in sharp contrast to that observed in polymers with a linear topology made from the same monomers, thus supporting the formation of MICPs. The results provide guidelines for the successful design of MICPs, that is, a combination of the dynamic nature of the MMs and supramolecular interactions. Given that the present method is highly versatile, it can be expected to be applicable to various molecular skeletons and supramolecular systems.

Tetra-arm poly(ethylene glycol) (TetraPEG) gels are tough materials whose toughness originates from their uniform network structure. They can be formed by combining the termini of tetra-arm polymers via chemical reactions...

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