Thermoresponsive random and block copolymers based on diethylene glycol methacrylate and a novel thiolated methacrylic monomer for the coating of semiconductor nanoparticles

摘要

The synthesis of smart polymers functionalized with thiol groups offers the possibility to connect the macromolecular structure to the surface of semiconductor nanoparticles, thus combining the amazing properties of the inorganic core and the smart properties of the polymeric coating. With this aim, anew methacrylic monomer containing a protected thiol group 2-(2-acetylthioetoxy)ethyl methacrylate (AcSEOMA) was synthesized. By the atom transfer radical polymerization of AcSEOMA with 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA), thermoresponsive p(MEO(2)MA-co-AcSEOMA) random and p[(MEO(2)MA-co-AcSEOMA)-b-MEO(2)MA] block copolymers were prepared. After thiol deprotection, both random and block copolymers, exhibited lower critical solution temperature (LCST) modulated by the pH. These new multi-thiolated copolymers easily replaced the hydrophobic ligand at the Quantum Dot (QD) surface leading to stable amphiphilic photoluminescent nanoparticles. Moreover, QD@polymer photoluminescence was closely related to the thiol content and its distribution along the polymer chains. In addition, functionalization with block copolymers, conduced to a noticeable increase of hybrid water solubility (ca. 15 mg mL(-1)). Finally, the polymer coating triggered a remarkable increase of nanohybrids fluorescence at acidic pH and high temperature (above the LCST). All these hybrids materials are promising for possible applications as biosensors and in the optoelectronics field. (C) 2016 Elsevier Ltd. All rights reserved.