Cyclooctadiene Is Difunctionalized Under Continuous Flow Conditions: Expanding The Scope Of Ring-opening Metathesis Polymerization (ROMP)

Since the discovery of olefin metathesis in the mid-1950s,there has been a great deal of interest in the synthesis of macromolecular materials via this versatile reaction.With the development of new catalysts and compared with radical polymerization,cationic polymerization,and anionic polymerization,ring-opening metathesis polymerization?ROMP?has the advantages of functional group tolerance?for most heteroatom functional groups?and mild reaction conditions.ROMP has become particularly powerful methods for synthesizing polymer macromolecular materials with adjustable size,shape and function.This technology has achieved great utility in the preparation of materials with biological,electronic,optical and mechanical properties.Functionalized cyclooctenes?FCOEs?are important monomers in ring-opening metathesis polymerization?ROMP?.Herein,a new library of disubstituted FCOEs bearing adjacent heteroatoms were synthesized and applied in ROMP.To address issues associated with the handling of reactive thienyl chloride intermediate,a two-step continuous flow synthesis method was developed to prepare 5-thio-6-chlorocyclooctene compounds from abundant cyclooctadiene starting materials.These newly synthesized FCOE monomers were subsequently polymerized through ROMP,giving rise to a range of functionalized polymers with high molecular weights.Furthermore,it was demonstrated that the thermal properties of these polymers could be fine-tuned by changingthefunctionalgroupsintheFCOEmonomers.This functionalization-polymerization strategy will enable the preparation of a range of polymeric materials with complex structures.In this paper,the prepared monomer was characterized and determined by ¹H NMR,¹³C NMR,mass spectrometry,FT-IR etc.The synthesized monomers were polymerized in CH₂Cl₂ solution under the Grubbs2 catalyst conditions.Subsquently,prepared polymers were characterized and determined by ¹H NMR,¹³C NMR,FT-IR etc.The thermodynamic properties of the polymers were characterized by differential scanning calorimetry?DSC?and thermogravimetric analysis?TGA?.The molecular weight and molecular weight distribution of the polymers were characterized by gel permeation chromatography?GPC?.In order to compare the thermodynamic properties before and after hydrogenation,one of the polymers was selected for hydrogenation and its thermodynamic properties were characterized.In addition,one of the monomers was selected to obtain the crystal for X-ray characterization.