Constructing the combination bridge of aluminum hydride (AlH3) and polyvinylidene fluoride (PVDF) through the self-assembly of dopamine: Improving the stability and ignition properties of AlH3

Abstract

Surface coating is an important method to solve the poor stability of aluminum hydride (AlH3). To overcome the difficulty of uneven coating of fluorine-containing polymers on the surface of AlH3, this study utilizes the adhesion properties of polydopamine (PDA) to establish a bridge between the oxide layer of AlH3 (Al2O3) and polyvinylidene fluoride (PVDF), so that Polyvinylidene fluoride (PVDF) was uniformly coated on the AlH3 surface, and a dual-core shell structure AlH3@PDA@PVDF composite was successfully prepared. Molecular dynamics simulations reveal significantly higher binding energy per unit area for γ-Al2O3@PDA/PVDF (1.2270 Kcal·mol−1·Å−2) compared to γ-Al2O3/PVDF (0.6644 Kcal·mol−1·Å−2), affirming that PDA can effectively enhance the interfacial interaction between AlH3 and PVDF. The morphology characterization and performance testing of raw AlH3 and AlH3@PDA@PVDF composite were carried out through SEM, XPS, FT-IR, DSC, VST, etc. The results indicate that through the interface modification of AlH3 by PDA, PVDF with a hydrophobic surface can be evenly coated on the surface of AlH3, causing the water contact angle (WCA) of the AlH3@PDA@PVDF composite to increase from 41° for the raw AlH3 to 124°. Furthermore, the total decomposition time of the AlH3@PDA@PVDF composite (2326 min) is improved by 1.8 times than that of the raw sample (1277 min), and its apparent activation energy (117.75 kJ·mol−1) was also higher than that of the raw sample (99.88 kJ·mol−1), indicating that coating with PDA and PVDF can improve the stability of AlH3. Ignition experiments demonstrate that the AlH3@PDA@PVDF composite has superior ignition reaction performance compared with the raw AlH3. Especially, adding a small amount of AlH3@PDA@PVDF composite can also significantly catalyze the thermal decomposition process of ammonium perchlorate (AP), reducing its high-temperature decomposition temperature from 405.37 °C to 352.20 °C.