γ-Fe 3 O 4 doped polyimide films with different weight percentages (1, 5, and 10 wt % of Fe 3 O 4 ) have been prepared and the effect of nonmagnetic γ-Fe 3 O 4 content on the structural and magnetic properties has been studied. X-ray diffraction (XRD) studies revealed that the nanopowders obtained are magnetite. The calculated grain sizes from XRD data have been verified using scanning electron microscopy (SEM). SEM micrographs show that the powders consist of nanometer-sized grains. Magnetic hysteresis loops were measured at room temperature with a maximum applied magnetic field. As the γ-Fe 3 O 4 content increases, the measured magnetic hysteresis curves become more and more narrow and the saturation magnetization and remanent magnetization both decreased. The prepared nanocomposites were identified in terms of their structure, morphology, and magnetic and thermal properties. These studies showed that the particles seem to be dispersed randomly, although the particles do appear to form aggregates at increasing particle loadings.

The present study relates to a heterogeneous polyimide-supported transition metal complex catalyst for hydrosilylation reactions, which is prepared by functionalizing a heat-and acid-resistant polyimide resin with a homogeneous metal catalyst of ruthenium (II) complex. The heterogeneous polyimide-supported transition metal complex catalyst of the invention provides superior catalytic activity, selectivity and stability in the hydrosilylation of acetophenone. Further, the catalyst has strong resistance against heat and acid. Besides, the catalyst of the invention may provide the following advantage which are critical in industrial use: it can be easily separated from the reaction product, which eases recycling of the catalyst.