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.
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