Rapid and versatile polymer–polymer coupling via iodide–thiol substitution click chemistry

Abstract

A rapid and efficient coupling of iodide-terminated poly(butyl acrylate) (PBA-I) chains using a dithiol linker (HS-R-SH) to generate a coupling product (polymer-R-polymer) was developed. The coupling yield reached as high as 86% in 1 min and the coupling was nearly complete in 30 min even at room temperature. A key factor for the rapid and efficient reaction was the appropriate choice of an efficient catalyst (1,1,3,3-tetramethylguanidine) and solvent (dimethylformamide). Using polymeric (poly(ethylene glycol) (PEG)) linkers bearing one, two, and four thiols, PBA-b-PEG diblock, PBA-b-PEG-b-PBA triblock, and PBA-PEG 4-arm star block copolymers were obtained in high yields. Viscoelastic properties and microphase separation behaviors of the obtained block copolymers were also studied. The present approach offers an ultra-fast and versatile coupling process, which may be useful for designing various block copolymers and branched polymers.