Adduct Interaction Between Molybdenum Compounds And Polymer Materials And Its Characterization

A novel molecule-ion adduct of ammonium molybdate tetrahydarte (AMT) withβ-cyclodextrin (CD) was prepared in this work. Significant differences in spectral properties between AMT and the adduct AMT-β-CD were observed by a series of experimental probes, such as powder X-ray diffraction, Fourier transformation infrared spectroscopy and Raman spectroscopy. Field emission scanning electron microscopy showed that although the crystal growth of AMT?β-CD was dominated by the molecular stacking of AMT, the size and morphology of the adduct were rather different from those seen in free AMT. The difference in stacking forms was attributed to the contribution of the molecule-ion interaction between AMT andβ-CD. A drastic improvement in thermal stability of AMT andβ-CD after adduct was observed by thermogravimetry analysis, which was confirmed by controlled sintering measurements. This revealed that the adduct interaction between them played an important role in mediating the thermal decomposition process of the adducted components. Furthermore, our results indicated that AMT and its adduct had a different performance in the catalytic desulfurization of thiophene and its derivatives. The fact that the catalytic efficiency of AMT was decreased after adduct implied there was a complexation between AMT andβ-CD. Besides, several unusual molecular ions: NH₃⁺, NH₂⁺ and NH⁺ were simultaneously found in a gas chromatography coupled to time-of-flight mass spectrometry of free AMT.An adduct behaviour of AMT with polytetrafluoroethylene (PTFE) resulted in three significant benefits: a) a much lower degradation temperature (ΔT_m, 82 K) of the PTFE in the adduct and a much lower final residual mass (ΔRM, 39%) of the adduct compared to the theoretical prediction, b) the formation of MoO₃ and MoO₂ nanoparticles, and c) the shuttle-shaped MoO₂ nanoparticles coated with graphite exhibits superior soft magnetic property. The much earlier degradation suggested that there was a strong mutual effect between AMT and PTFE. The much lower residual mass implied that the intervention of a chemical reaction was responsible for the effect in nitrogen. Actually, Raman spectra revealed that the adducted PTFE was degraded into a graphite structure at this atmosphere, and the presence of the graphite layer led to the reduction of AMT into shuttle-shaped MoO₂ nanoparticles at 837 K to a complete extent. Controlled sintering measurements in air indicated that the AMT in the presence of PTFE producedα-MoO₃ nanoparticles, instead of MoO₂. Further, our results indicated that the MoO₃ nanoparticles obtained had a positive response to the heterogeneous catalytic oxidation of thiophene in the presence of hydrogen peroxide. We believe that the present work is not only of relevance for applications in the degradation of polymer materials, but also will attract the attention of many groups studying the preparation and magnetic property of transition metal oxide nanoparticles and their practical application in heterogeneous catalytic reactions.