Abstract
Magnetic nanocomposites, showing extremely small coercivity and hysteresis loop, were synthesized using amphiphilic polyurethane networks based on amphiphilic urethane acrylate nonionomer (UAN) precursor chains. Three kinds of UAN gel films were synthesized through UV‐curing of UAN chains in the absence of a solvent, or crosslinking polymerization of UAN/water and UAN/DMAc mixtures. Even though these gel films were synthesized with the same UAN, these UAN gel films had very different microstructures depending on the preparation conditions; as a consequence, magnetic composites prepared with these crosslinked films exhibited very different size and morphology of magnetic nanoparticles. Atomic force microscopy and mechanical property measurements showed that UAN gel film (UANH) synthesized with UAN/water mixture had the highly microphase‐separated structures whereas the gel films synthesized via UV‐curing (UANV) or polymerization of UAN/DMAc mixture (UAND) had relatively homogeneous structures. The largest ellipsoidal particles were formed in UANH gel films and the smallest ellipsoidal particles and rod‐shaped particles were made up in UANV gel and UAND gel film, which was confirmed by transmission electron microscopy.
Transmission electron micrograph of magnetic composite film prepared with UANV.
magnified imageTransmission electron micrograph of magnetic composite film prepared with UANV.