Heterofunctional RAFT-derived PNIPAM via cascade trithiocarbonate removal and thiol-yne coupling click reaction
Résumé
An efficient one-pot process to functionalize the α- and ω-positions of RAFT-derived poly(N-isopropylacrylamide) (PNIPAM) by two inherently different mechanistic pathways is reported. The method relies on the RAFT polymerization of NIPAM using a new alkyne-based RAFT agent, namely 2-cyano-5-oxo-5-(prop-2-yn-1-ylamino)pentan-2-yl dodecyltrithiocarbonate (COPYDC) and the combination of thiol-yne click chemistry and thiocarbonylthio chain-end removal reactions. COPYDC was prepared in good yield and used as an efficient chain transfer agent during the RAFT polymerization of NIPAM. Well-defined polymers with controlled molar masses and narrow dispersities (Đ = 1.18–1.26) are thus obtained. Cascade thiol-yne click reaction at the alkyne α-chain end and trithiocarbonate removal at the ω-chain end are successfully achieved using benzyl mercaptan and excess AIBN. The reported method provides a facile and mild route to heterofunctional telechelic RAFT polymers with predictable molar masses and low dispersities.