Phase Transisions in Superparamagnetic Polymer Brush Particles

Nanostructured inorganic / organic hybrid materials play an outstanding role in modern technology. We present results on the synthesis and characterization of novel thermo- and magnetoresponsive polymer brush coated particles. The investigated system is composed of nanocrystalline magnetite (Fe$_{3}$O$_{4})$ as an inorganic core and a covalently anchored polystyrene (PS) shell. In cyclohexane, a thermoresponsive magnetic fluid is obtained due to a critical solution behaviour of the PS arms. cyclohexane. Beside the phase transition of Fe$_{3}$O$_{4}$@PS particles, the well known coil-to-globule transition of Fe$_{3}$O$_{4}$@PS particles in cyclohexane is investigated. Both phenomena are compared to the behaviour of linear polymeric arms. The presented results show that magnetic brush particles are well-suited as a model system for the investigation of temperature transitions of surface-attached polymers.