Effective surface modification by stimuli-responsive polymers onto the magnetite nanoparticles by layer-by-layer method

Effective surface modification of poly(N-isopropylacrylamide)-based temperature-responsive polymers onto the magnetite nanoparticles was investigated. To achieve this purpose, layer-by-layer method was applied. This technique is based on sequential chemical reactions between the temperature-responsive polymers with carboxyl groups and other another polymers with amino groups. After the polyion complex formation, carbodiimide chemistry was used to cross-link both the functional polymers. As a result, we could confirm the successful preparation using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and the dispersion measurement of the modified magnetite nanoparticles. The thickness was tunable be the number of the layer-by layer reaction. As expected, the magnetite nanoparticles show the very sensitive temperature-responsive behavior.