Synthesis of PMMAzo polymers
The PMMAzo polymers were obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization where 4-cyanopentanoic acid dithiobenzoate (CPADB) and 4,4’-azobis(4-cyanovaleric acid) (ACVA) were used as the RAFT agent and the initiator, respectively. For example, AzoMA (250.0 mg, 0.63 mol), CPADB (3.26 mg, 0.012 mmol), ACVA (0.656 mg, 0.004 mmol) and dried tetrahydrofuran (1.5 mL) were added into a 5 mL ampoule bottle. The reaction tube was flame-sealed under an argon atmosphere after deoxygenated with three freeze thaw cycles. Then the polymerization was carried out at 70 oC for 9 h. Polymers of other molecular weights were obtained by changing the molar ratio of monomers and RAFT reagents.