Yüzey kaplamalı demiroksit nanoparçacıklarının polimer karşımlarında seçimli dağılımı

Iron oxide nanoparticles display size dependent superparamagnetic behavior that is exploited in various areas of science and technology. Spatial positioning of these nanoparticles is of special interest to generate novel structures with tailored properties and for device fabrications. Phase separated morphology of immiscible polymer blends and block copolymers can create features from nanometer to micron scale. In this study, selective dispersion of different surface modified iron oxide nanoparticles (SPIO) in the blends of PS and PEG were investigated by AFM. Surface of iron oxide nanoparticles were modified by two different methods in order to prevent agglomeration and to provide compatibility with the selected domain of the polymer blend. In the first part, lauric acid (LA) and hexadecyltrimethoxysilane (HDMS) coated hydrophobic SPIOs dispersed well both in PS and PEG homopolymers but LA coated MNPs preferred PEG phase instead of PS in the blend. Ligand exchange mechanism was proved as a reason of this unexpected selectivity. HDMS coated MNPs mainly dispersed at the interface of the blend and formed larger clusters in the PEG domain of PS/PEG blend. Lastly, methoxy(polyetyleneoxy)propyltrimethoxysilane PEG-Si coated hydrophilic SPIOs dispersed in the PEG phase, as expected. In the second part, synthesis of PS and PMMA by ATRP from surface of SPIOs was achieved and their blends with immiscible homopolymers were investigated by AFM. In all combinations, phase-separation of polymers occurred and selective dispersion was achieved. In addition, PMMA-b-PS was also grafted from the surface of iron oxide and preliminary studies about phase separation were performed by AFM.