Iron oxide nanoparticles have gained a lot of interest in the biomedical field with applications such as hyperthermia, drug delivery, cell labeling or as contrast agents. In combination with thermoresponsive polymer shells, e.g. poly(N-isopropylacrylamide) or poly(ethylene glycol), they can be further tuned to generate multiresponsive materials displaying a switchable shell collapse and expansion, triggered by thermal actuation. This opens exciting opportunities for superparamagnetic iron oxide particles, which can produce heat locally through interaction with alternating magnetic fields, to be used as building blocks for e.g. thermoresponsive membranes or triggered release vehicles. We prepared monodisperse and monocrystalline iron oxide nanoparticles in the size range of 3-12 nm in reproducible manner by thermal decomposition of iron pentacarbonyl in the presence of oleic acid.1 Thermoresponsive polymers (Mn: 5000-20000 g/mol) were modified with nitrocatechols2,3 and subsequently used for “grafting to” reactions with the oleic acid coated iron oxide nanoparticles. Dispersant densities of up to 0.8 chains/nm2 were achieved by this method, which is limited by the coil size of the applied polymer. Higher grafting densities were achieved with a ”grafting from” approach using surface initiated ATRP or a multistep “grafting to” reaction (up to 3 chains/nm2).4 The generated core shell structures display magnetic and thermoresponsive properties (LCST). The thermoresponsive behavior of the shell was monitored by DLS and SAXS.5 The combination of the techniques allowed for investigating both aggregation and internal shell structure as function of temperature stimuli. (1) Park, J.; An, K.; Hwang, Y.; Park, J.-G.; Noh, H.-J.; Kim, J.-Y.; Park, J.-H.; Nong-Moon Hwang; Hyeon, T. Nat. Mater., 2004, 3, 891 - 895 (2) Amstad, E.;Gillich, T.; Bilecka, I.; Textor, M.; Reimhult, E. Nano Lett., 2009, 9 (12), 4042–4048 (3) Amstad, E.; Gehring, A. U.; Fischer; H.; Nagaiyanallur, V. V.; Hähner, G.; Textor, M.; Reimhult, E. J. Phys. Chem. C, 2011, 115 (3), 683–691 (4) Zirbs, R.; Lassenberger, A; Vonderhaid, I.; Reimhult, E. Nanoscale submitted (5) Grünewald, T. A.; Lassenberger, A.; van Oostrum, P. D. J.; Rennhofer, H.; Zirbs, R.; Capone, B.; Vonderhaid, I.; Amenitsch, H.; Lichtenegger, H. C., Reimhult, E. Chem. Mater. submitted

Synthesis and Investigation of thermoresponsive core shell nanoparticles

250th National Meeting (2015)

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