Synthesis and Characterization of Thermo-Responsive 2-(2-methoxyethoxy)Ethyl 2-Methylacrylate Copolymer Co- Oligo(ethyleneglycol) Methyl Ether Methacrylate Stabilized Nanoparticles

Water/oil interfaces are extensively used to assemble biomimetic systems. Thermoresponsive particles are of great interest in studying such systems. Here, we demonstrate programmable partition coefficient using a system of gold or silver nanoparticles sterically stabilized with a thermoresponsive copolymer consisting of di(ethylene glycol) methyl ether methacrylate (x = MeO2MA) and poly(ethylene glycol) methyl ether methacrylate (y = OEGMA). A characterization of the polymer-coated nanoparticles and a synthesis method for capped silver nanoparticles are presented. Characterization and comparison between gold and silver thermoresponsive NPs demonstrate that thermoresponsive behavior is due to polymer coating, not core. Both particle species decreased in size from about 50 nm to about 35 nm over a temperature range from 20ºC to 40ºC. In the presence of 0.15 M NaCl, reversible aggregation was observed in both species at 28ºC. We measure partition coefficient of Au@(MeO2MAx-co-OEGMAy) NPs in a water-toluene system at room temperature as a function of copolymer ratio (x:y) and ionic strength. Data show that Ko/w increases as a function of salt concentration and linearly as a function of increase in OEGMA content of polymer. NaCl concentrations on the order of mM were sufficient for observation of interface crossing.