Benzothiadiazole-based donor-acceptor nanoparticles with solvatochromic and thermoresponsive properties

Water-soluble benzothiadiazole (BT)-based nanoparticles (NPs) with solvatochromic and thermoresponsive properties were synthesized by a one-pot procedure involving the self-assembly and selective cross-linking of a block copolymer composed of 4-bromophenyl vinyl sulfide and N-isopropylacrylamide. In situ Suzuki coupling reaction of the block copolymer with a BT-based diboronic acid afforded core cross-linked NP(BT)s having a BT-based acceptor unit between neighboring phenyl (weak donor) groups in the core. The cross-coupling polymerization of the BT-based diboronic acid and a dibromo compound in the block copolymer micelles provided NP([BT-Th]l)s or NP([BT-dTh]l)s with a π-conjugated BT-based acceptor/thiophene- or dithiophene-donor arrangement in the core, respectively. The emission of core cross-linked NPs could be tuned from blue to red by varying the solvent and the core structure. The effects of the core structure on the thermoresponsive properties were also investigated.