Synthetic Strategy for Mechanically Interlocked Cyclic Polymers via the Ring-Expansion Polymerization of Macrocycles with a Bis(hindered amino)disulfide Linker

Biobased Cyclic Polycarbonate: Synthesis and Applications via Dynamic Bis(hindered amino)disulfide Linkers

Cyclic polymers have garnered significant interest due to their unique structure; however, their synthesis remains challenging, often hindered by low yields and limited selectivity. Considering that the cyclization step during the synthesis of cyclic polymers is presumably the most challenging, using a spontaneous and selective cyclization system is ideal. Here, we present a topology transformation from linear to cyclic, which is achieved through the error-checking ability provided by the dynamic covalent bonding between bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) and its stable radicals with a high bond exchange rate. When applying this method to biobased poly(isosorbide carbonate) (PIC), an attractive alternative to conventional petroleum-based polycarbonates, high-molecular-weight cyclic polymers were unexpectedly obtained. Since the functionalization of PICs has been traditionally limited to copolymerization techniques, we aimed to introduce dynamic covalent bonds to establish novel functionalization methods for PICs. Interestingly, the synthesis of cyclic PICs through intramolecular cyclization using dynamic covalent bonds in a heterogeneous system proceeded via a ring-expansion polymerization-like mechanism, affording high-molecular-weight cyclic polymers consisting of a PIC backbone and BiTEMPS units as dynamic units. The resulting PIC-based cyclic polymers with BiTEMPS units were applied to bond exchange reactions, providing an effective approach for the synthesis of cyclic block polymers and end-functionalized linear block polymers with a PIC skeleton. These results demonstrate the potential of dynamic covalent chemistry in polymer synthesis.

A thermally driven rotaxane-catenane interconversion with a dynamic bis(hindered amino) disulfide

We have developed a versatile and simple synthetic method to produce a [3]catenane. Heating a rotaxane with bis(hindered amino) disulfide groups at both ends spontaneously and selectively produces the [3]catenane. The successful polymerization of the obtained [3]catenane provides a platform for the synthesis of various interlocking polymers.

Polycatenanes: synthesis, characterization, and physical understanding

Chemical composition and architecture are two key factors that control the physical and material properties of polymers. Some of the more unusual and intriguing polymer architectures are the polycatenanes, which are a class of polymers that contain mechanically interlocked rings. Since the development of high yielding synthetic routes to catenanes, there has been an interest in accessing their polymeric counterparts, primarily on account of the unique conformations and degrees of freedom offered by non-bonded interlocked rings. This has lead to the synthesis of a wide variety of polycatenane architectures and to studies aimed at developing structure-property relationships of these interesting materials. In this review, we provide an overview of the field of polycatenanes, exploring synthesis, architecture, properties, simulation, and modelling, with a specific focus on some of the more recent developments.