Controlled reactivity of metastable n-Al@Bi(IO3)3 by employment of tea polyphenols as an interfacial layer

Abstract It has been demonstrated in this paper that the tea polyphenols (TP) can easily adhere to the surface of particles through self-polymerization, even these particles are very hydrophobic. In this paper, a method of in-situ polymerization of TP has been used to coat n-Al powder. Then, Bi(IO3)3 crystal is grown on TP as an interfacial layer to obtain core-shell iodine-based MICs (n-Al@TP@Bi(IO3)3). Various characterization techniques are used to investigate the prepared core-shell MICs, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermal analysis, mass spectrum (MS), bomb calorimetry and high-speed camera. The results show that the obtained novel MICs are uniformly and densely distributed. The n-Al@TP@Bi(IO3)3 has higher reactivity and heat release than the traditional mechanical mixture, and the initial reaction temperature is reduced by about 30 °C caused by the decomposition-promoting effect of the decomposition product of TP (carbon) on Bi(IO3)3. and the volume reaction heat of n-Al@TP@Bi(IO3)3 (21.246 kJ cm−3) enhances by 11.3%. The results of combustion experiments show that the burning rate of n-Al@TP@Bi(IO3)3 is above 3.4 m s−1, which is 4 times that of Al/ Bi(IO3)3 (0.9 m s−1). Moreover, the combustion efficiency is higher and the agglomeration of the condensed combustion products is greatly decreased. Various other core-shell structured MICs with tunable reactivity could be easily prepared by using similar interfacial binding materials by using our strategy as a guidance.