Ring-opening polymerization of cyclic esters mediated by base/(thio)urea binary catalysts toward sustainable polyesters

Key Words:Dispersions;Characterization - Fabrication - Fourier transform infrared spectroscopy - Iron compounds - Magnetic properties - Magnetism - Morphology - Nanocrystals - Single crystals - Transmission electron microscopy - X ray diffraction;Different sizes - Dipolar interaction - Fabrication and characterizations - Face centered cubic structure - High temperature - Magnetic property measurement systems - Mineral processing - Synthesized materials

Abstract:Monodisperse Fe<inf>3</inf>O<inf>4</inf>nanocrystals with different size and morphology have been successfully fabricated by a facile high temperature reflow method. The presented materials were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), selection area electron diffraction (SAED) and magnetic property measurement system (MPMS). The results showed that the as-prepared materials have face-centered cubic structures. Oleic acid plays a key role in the dispersion of Fe<inf>3</inf>O<inf>4</inf>nanocrystals. The cubic and octahedral nanocrystals are enclosed by {1 0 0} and {1 1 1} lattice planes. The MPMS measurements show that magnetic properties are closely related to the sizes of the materials, and there is a stronger dipolar interaction between Fe<inf>3</inf>O<inf>4</inf>nanocrystals with larger sizes. The controllable magnetic property and good dispersion endow the as-synthesized materials with great potential applications in magnetic fluid fields including sealing, medical equipment, mineral processing and other aspects.<br/> &copy; 2018 Elsevier B.V.

Volume:439

Translation or Not:no