Advanced Developments in Cyclic Polymers: Synthesis, Applications, and Perspectives

Abstract

Due to the topological effect, cyclic polymers demonstrate different and unique physical and biological properties in comparison with linear counterparts having the same molecular-weight range. With advanced synthetic and analytic technologies, cyclic polymers with different topologies, e.g. multicyclic polymers, have been reported and well characterized. For example, various cyclic DNA and related structures, such as cyclic duplexes, have been prepared conveniently by click chemistry. These types of DNA have increased resistance to enzymatic degradation and have high thermodynamic stability, and thus, have potential therapeutic applications. In addition, cyclic polymers have also been used to prepare organic–inorganic hybrids for applications in catalysis, e.g. catalyst supports. Due to developments in synthetic technology, highly pure cyclic polymers could now be produced in large scale. Therefore, we anticipate discovering more applications in the near future. Despite their promise, cyclic polymers are still less explored than linear polymers like polyolefins and polycarbonates, which are widely used in daily life. Some critical issues, including controlling the molecular weight and finding suitable applications, remain big challenges in the cyclic-polymer field. This review briefly summarizes the commonly used synthetic methodologies and focuses more on the attractive functional materials and their biological properties and potential applications.

Grubbs Catalysts Immobilized on Merrifield Resin for Metathesis of Leaf Alcohols by using a Convenient Recycling Approach

“…Robert H. Grubbs immobilized Hoveyda Grubbs catalysts on silica gel for a number of metathesis reactions . There are also some reports about using new kinds of supports, such as magnetic nanoparticle, mesoporous molecular silicas and aluminas, to immobilize Grubbs catalysts for metathesis . These results showed that the heterogeneous catalysts were recycled conveniently over a number of reaction cycles.…”

“…[13] There are also some reports about using new kinds of supports, such as magnetic nanoparticle, mesoporous molecular silicas and aluminas, to immobilize Grubbs catalysts for metathesis. [14][15][16] These results showed that the heterogeneous catalysts were recycled conveniently over a number of reaction cycles. However, they were prepared with long reaction steps and some of them had longer reaction times, lower conversions and catalytic activities than free catalysts.In sum, heterogeneous catalysts showed comparative advantages in recycling, which indicated that immobilization on proper solid support could help the Grubbs catalysts recycle efficiently.…”

Click Chemistry in Functional Aliphatic Polycarbonates

“…Compared to linear counterparts, cyclic polymers have unique physical and chemistry properties . Alkyne‐azide reaction was introduced to the synthesis of polystyrene macrocycles by Grayson et al in 2006 .…”

“…[54][55][56] Compared to linear counterparts, cyclic polymers have unique physical and chemistry properties. [57] Alkyne-azide reaction was introduced to the synthesis of polystyrene macrocycles by Grayson et al in 2006. [58] Scheme 3 presents an example of cyclic polycarbonates that were synthesized via alkyne-azide reaction.…”

Depolymerization of 1,4-polybutadiene by metathesis: high yield of large macrocyclic oligo(butadiene)s by ligand selectivity control

“…12 They can for example be employed as lubricants, 13 in optoelectronic devices, or as building blocks for specialty polymers. 14,15 However, there is a lack of inexpensive and scalable procedures for such large macrocyclic fractions. Though underexplored, their synthesis from commercial (or waste) 1,4-PB, through a metathesis-catalyzed cyclodepolymerization reaction, could constitute a practical method to create the highly unsaturated macrocycles.…”