Synthesis and Photoresponsive Behaviors of Well-Defined Azobenzene-Containing Polymers via RAFT Polymerization

The well-defined photoresponsive polymethacrylate containing azo chromophore, poly{1‘-octyloxy-4‘-(6-methacryloxy)hexyloxy-5‘-phenylmethaneone-(2-phenyl)azobenzene (AHMA)} (PAHMA), was prepared via reversible addition−fragmentation chain transfer (RAFT) polymerization in anisole solution using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the RAFT agent and 2,2‘-azobis(isobutyronitrile) (AIBN) as an initiator. The kinetic plots of polymerization were first-order and the molecular weights (Mn(GPC)s) of the homopolymer (PAHMA) with relatively low polydispersity index values (PDIs ≤ 1.37) increased with monomer conversions throughout the polymerization processes. Furthermore, the kinetic plots of chain extension with both methyl methacrylate (MMA) and styrene (St) using the obtained PAHMA as a macro-RAFT agent were also first-order. The Mn(GPC)s of the diblock copolymers, PAHMA-b-PMMA and PAHMA-b-PS, increased with the respective monomer conversions. These results indicated that most of the PAHMA chains wer...