Hydrogen Bond Driven Photoinduced Sequence Control Polymerization of N-Ethylmaleimide and Methyl Methacrylate

The photo copolymerization of N-ethylmaleimide (NEM) and methyl methacrylate (MMA) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFP) and dichloromethane (DCM) was reported. The polymerization was carried out by Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization method using 2-(2-cyanopropyl) dithiobenzoate (CPDB) as the initiation-regulation dual functional agent. The copolymerization behavior of this monomer pair was investigated in detail at different reaction conditions. The structures of the copolymers were characterized by ¹H-NMR and MALDI-TOF-MS. Results revealed that fluoroalcohols were quite effective in affording the copolymers with controlled molecular weights and adjustable MMA contents compared with the normal solvent DCM, due to the hydrogen-bonding interaction. When the molar ratio between HFP and monomer was 1∶1, the reaction rate of NEM was similar to that of MMA, and NEM and MMA were written alternately to the polymer chain to form an alternate copolymer with a well-defined sequence structure.