Luminescent Boron Quinolate Block Copolymers via RAFT Polymerization

The preparation of well-defined luminescent organoboron quinolate block copolymers via sequential RAFT polymerization is reported. Boron-containing block copolymers with PS, P(St-alt-MAh), and PNIPAM as the second block were successfully synthesized. The photophysical properties of the block copolymers were studied by UV-vis and fluorescence spectroscopy. Independent of the second block, the boron quinolate block copolymers that contain the parent 8-hydroxyquinolato ligand (PM1-b-PS, PM1-b-PNI-PAM, PM1-b-P(St-alt-MAh)) are green luminescent, whereas a polymer with 5-(4-dimethylaminophenyl)-8-hydroxyquinolate as the ligand (PM2-b-PS) shows red luminescence. The P(St-alt-MAh)-based block copolymer was further modified with photoactive azobenzene groups. The self-assembly behavior of the amphiphilic block copolymers was studied by transmission electron microscopy (TEM) and dynamic light scattering (DLS). In water, PM1-b-PNIPAM forms spherical micelles. The azobenzene-modified P(St-alt-AbMA)-b-PM1 exhibits a solvent-dependent self-assembly behavior in basic solutions, and large spindle-shaped aggregates and spherical micelles were observed.