Coordination-induced assemblies of quantum dots in amphiphilic thermo-responsive block copolymer micelles: morphologies, optical properties and applications

Abstract

Nanostructured hybrid materials composed of functional block copolymers (BCPs) and inorganic nanoparticles (NPs) have attracted growing interest. In this paper, quantum dot/block copolymer (QD/BCP) hybrid assemblies with precise control of dispersion and localization of QDs into/on the thermo-responsive BCP micelles were constructed by the coordination effect. A series of BCPs with a poly(N-isopropylacrylamide) (PNIPAm) block and a polystyrene (PSt) block was synthesized by RAFT polymerization, and a monomer unit containing an 8-hydroxyquinoline (HQ) group with strong coordination interaction with QDs was introduced into the hydrophobic PSt blocks, hydrophilic PNIPAm blocks and the interface of the hydrophilic and hydrophobic blocks. The QD/BCP assemblies were built through locating the QDs in the core (CDMs), shell (SDMs) and the interface (IDMs) between the core and the shell in the BCP micelles via a coordination-driven assembly process. The resulting hybrid assemblies possess special dual-emitting properties in the case of introducing only one emitting element (QDs). The dual-emission comes from the inherent emissions of the QDs (red-emission) and the HQ–Zn complex (green-emission) on the surface of the QDs. The optical properties of the QD/BCP hybrid assemblies have the characteristics of temperature response. The SDM hybrid assembly can be applied to the selective detection of 2,4,6-trinitrophenol (TNP) and Hg²⁺ ions.