RAFT polymerization of 2‐hydroxyethyl vinyl ether and dimethyl maleate

The reversible addition‐fragment chain transfer (RAFT) alternating copolymerization of 2‐hydroxyethyl vinyl ether (HEVE) and dimethyl maleate (DMM) is achieved with S‐(cyanomethyl) O‐ethyl carbonodithioate (CMX) as medaitor and 2,2′‐azobis(2‐methylpropionitrile) (AIBN) as radical initiator. The effects of monomer concentrations, comonomer feeding ratios, molar ratio of monomer to CMX and solvent on the copolymerization and copolymer structure are systematically investigated. The living feature of the HEVE and DMM copolymerization is demonstrated by the linear increasement of the molecular weights with the monomer conversions, and relatively narrow molecular weight distributions of the copolymers. With dimethyl carbonate as solvent, poly(HEVE‐alt‐DMM) with Mn = 5200 and Mw/Mn = 1.34 are synthesized at [HEVE]/[DMM]/[CMX]/[AIBN] = 100/100/3/1. The alternating structure of the copolymer is demonstrated by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) and proton nuclear magnetic resonance spectroscopy (1H NMR). The both α, ω‐end groups are mainly originated from the moiety of CMX. To further demonstrate the living feature of the alternating copolymerization, chain extension and block copolymerization are also carried out. With poly(HEVE‐alt‐DMM) as macro‐CTA (Mn = 5200, Mw/Mn = 1.34), the chain‐extension reaction has been successfully realized (Mn = 9600, Mw/Mn = 1.70), and the block copolymer with vinyl neonanoate as monomer also successfully synthesized (Mn = 9800, Mw/Mn = 1.42).