Loading of PNIPAM Based Microgels with CoFe2O4 Nanoparticles and Their Magnetic Response in Bulk and at Surfaces.
The present paper addresses the loading of thermoresponsive poly-N-isopropylacrylamide (PNIPAM) based microgel particles with magnetic nanoparticles (MNP: CoFe2O4@PAA (PAA = poly(acrylic acid))) and their response to an external magnetic field. The MNP uptake is analyzed by transmission electron microscopy (TEM). Obviously, the charge combination of MNP and microgels plays an important role for the MNP uptake, but it does not explain the whole uptake process. The MNP uptake results in changes of size and electrophoretic mobility, which is investigated by dynamic light scattering (DLS) and a Zetasizer. The microgels loaded with MNP preserve their thermosensitivity, and they show magnetic separability and are considered as magnetic microgels. After adsorption at a surface the magnetic microgels are studied with a scanning force microscope and indentation experiments. The magnetic microgels show an elongation along the magnetic field parallel to the surface while the height of the microgels (perpendicular to the surface and to the magnetic field) is compressed. This result is in good agreement with simulations of volume change of ferrogels in a magnetic field.
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
Sebastian
S
Backes
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
Marcus U
MU
Witt
Department für Chemie, Institut für Physikalische Chemie, Universität zu Köln , Luxemburger Str. 116, 50939 Köln, Germany.
Eric
E
Roeben
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
Lucas
L
Kuhrts
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
Sarah
S
Aleed
Department für Chemie, Institut für Physikalische Chemie, Universität zu Köln , Luxemburger Str. 116, 50939 Köln, Germany.
Annette M
AM
Schmidt
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin , Straße des 17. Juni 124, 10623 Berlin, Germany.
Regine
R
von Klitzing