Rhodanine-based Knoevenagel reaction and ring-opening polymerization for efficiently constructing multicyclic polymers

Ze Zhang,Long-Hai Wang,Fei Wang,Lei Xia,Xuan Nie,Wei-Qiang Huang,Zong-Yao Hao,Wen-Jian Zhang,Chun-Yan Hong,Ye-Zi You,Guang Chen

doi:10.1038/s41467-020-17474-0

Abstract

Cyclic polymers have a number of unique physical properties compared with those of their linear counterparts. However, the methods for the synthesis of cyclic polymers are very limited, and some multicyclic polymers are still not accessible now. Here, we found that the five˗membered cyclic structure and electron withdrawing groups make methylene in rhodanine highly active to aldehyde via highly efficient Knoevenagel reaction. Also, rhodanine can act as an initiator for anionic ring-opening polymerization of thiirane to produce cyclic polythioethers. Therefore, rhodanine can serve as both an initiator for ring-opening polymerization and a monomer in Knoevenagel polymerization. Via rhodanine-based Knoevenagel reaction, we can easily incorporate rhodanine moieties in the backbone, side chain, branched chain, etc, and correspondingly could produce cyclic structures in the backbone, side chain, branched chain, etc, via rhodanine˗based anionic ring-opening polymerization. This rhodanine chemistry would provide easy access to a wide variety of complex multicyclic polymers.

Highlights

Cyclic polymers have a number of unique physical properties compared with those of their linear counterparts
A controlled experiment was operated in the absence of rhodanine; there was no obvious conversion of POMT based on 1H NMR trace of reaction mixture (Supplementary Fig. 2)
The above experiments clearly indicate that rhodanine could initiate the ringopening polymerization of POMT, which is similar to those ring-opening polymerizations using trithiocarbonate, or dithiocarbonyl compounds as initiator

Summary

Introduction

Cyclic polymers have a number of unique physical properties compared with those of their linear counterparts. Via rhodanine-based Knoevenagel reaction, we can incorporate rhodanine moieties in the backbone, side chain, branched chain, etc, and correspondingly could produce cyclic structures in the backbone, side chain, branched chain, etc, via rhodaninebased anionic ring-opening polymerization. This rhodanine chemistry would provide easy access to a wide variety of complex multicyclic polymers. Knoevenagel reaction, we can incorporate rhodanine moieties in the backbone, side chain, hyperbranched chain, etc, and subsequently via rhodaninebased ring-opening polymerization, a series of multicyclic polymers can be obtained, and the cyclic position can be controlled in the main chains, hyperbranched chains, and side chains. The rhodaninebased Knoevenagel reaction and ringopening polymerization will provide a versatile scaffold towards complex multicyclic polymers

Methods

Results

Conclusion