Synthesis and characterization of a temperature-responsive amphiphilic block copolymer containing a liquid crystalline unit

To create a stimuli-responsive micelle, we synthesized a novel temperature-responsive amphiphilic block copolymer, poly(ethylene glycol)-block-poly{6-[4-(4-pyridylazo)phenoxy]-hexyl methacrylate} [PEG-b-P(AzoPyl)], by undertaking the RAFT polymerization of an AzoPyl monomer with a PEG mac-ro-RAFT reagent. This block copolymer possesses a liquid crystalline unit derived from a hydrophobic AzoPyl/carboxylic acid complex. The PEG-b-P(AzoPyl/decanoic acid (C ₉COOH)) complex formed a micelle structure (weight-average diameter = 68 nm). DSC results confirmed that the PEG-b-P(AzoPyl/C ₉COOH) micellar solution exhibited thermodynamic phase-transition behavior.