Magnetic nanoparticles are of huge interest in various areas of science, e.g. chemistry, biology, bio-chemistry, medicine or sensor technology.1 The requirements for particles are as multifaceted as the areas, in which they are applied. For chemical applications, the particles need to be rapidly separable, inert and stable against harsh environment (temperature, challenging pH-values, solvents).2 In contrast to this, medical, biological or sensor applications usually insist on dispersion stability in aqueous solutions, compatibility with biological relevant media, high saturation magnetization and/or the possibility for further modification.3, 4 Most of the different requirements are achieved using carbon coated ferromagnetic nanoparticles in combination with a covalently attached and controlled surface modification. The graphene-like coating enables a chemically stable and inert platform for atom transfer radical polymerization (ATRP).5 Surface initiated ATRP (SI-ATRP: polymer-growth from the surface) is feasible with a plethora of different monomers (desired functionality) and the polymerization can be well controlled (layer thickness and block-co-polymerization).4-6 Charged monomers (e.g. 3-Sulfopropyl methacrylate potassium salt (SPM)) can lead to highly stable dispersions and the stability can be tuned by the number of repeating units.4,5 Using poly(ethylene glycol) methacrylate (PEGMA) as monomer the highly lipophilic graphene layers can be turned into a hydrophilic and antifouling surface. Most challenging modifications require amphiphilic properties (dispersion stability vs. fast separation or lipophilicity vs. hydrophilicity). Such requirements need a coating with smart polymers, which can change their properties upon external trigger (temperature, pH etc.). By using N-isopropylacrylamine (NIPAM) as building block, the particles can reversibly change between hydrophilicity and hydrophobicity by temperature change.7 Here we show the promising potential of SI-ATRP on magnetic colloids to design a desired nanomaterial for various applications. [1] A.H. Lu et al., Angew. Chem. Int. Ed, 2007, 46, 1222. [2] A. Schaetz et al., Chem. Eur. J., 2010, 16, 8950. [3] Q. A. Pankhurst et al., J. Phys. D. Appl. Phys., 2003, 36, R167. [4] C.J. Hofer et al., Chem. Comm., 2015, 51, 1825. [5] M. Zeltner et al., J. Mater. Chem., 2012, 22, 12064. [6] R. Barbey et al., Chem. Rev., 2009, 109, 5437. [7] M. Zeltner et al., J. Mater. Chem., 2011, 21, 2991.

Multifunctional colloidal magnetic nanoparticles by surface initiated atom transfer radical polymerization

250th National Meeting (2015)

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