Synthesis And Properties Of Thermoresponsive Magnetic Polymer Composites And Their Electrospun Nanofibers

The thermoresponsive magnetic polymer composites and nanofibers were fabricated. Their thermal and magnetic properties were also investigated. Fe3O4 nanoparticles were prepared by coprecipitation method. Further condensation reaction was used to fabricate the double-layer lauric acid modified Fe3O4 (DLF) nanoparticles dispersed well in water. Thermal properties of poly(N-isopropylacrylamide) (PNIPAAm) and DLF/PNIPAAm composites and their aqueous solutions were measured by TGA and DSC. With the increasing of DLF content, the interaction between DLF and PNIPAAm caused the lower critical solution temperature (LCST) of polymer solution to shift from 33 to 31.25 degrees C. The effects of concentration and pH on LCST were also studied. The DLF/PNIPAAm nanofibers were fabricated by electrospinning. Their diameters were around 100-250 nm. Magnetization curves of DLF/PNIPAAm composite and nanofibers were overlapped and the saturated magnetizations were the same. Magnetic attraction behaviors of DLF/PNIPAAm polymer solution at temperatures below and above LCST were different. Aggregation of DLF/PNIPAAm above LCST enhanced magnetic moment density as well as magnetic attraction ability. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 848-856