Preparation of PDA@AP composite particles by two-step method and its application in glycidyl azide polymer-energetic thermoplastic elastomer propellants

Polydopamine (PDA) has been widely used in the field of energetic materials; however, there are few reports on the ammonium perchlorate (AP) coating of PDA. In this article, to improve the mechanical properties of the GAP-ETPE-based propellant, a two-step method was used to coat the AP with PDA and used in glycidyl azide polymer (GAP) based propellant. SEM, EDS, XRD, and XPS were used to analyze the morphology and composition of PDA@AP, while contact angle testing and calculation were performed to measure the wettability and surface energy of both PDA@AP and GAP-ETPE. In addition, the tensile strength and elongation of the propellant were measured. The results showed that the PDA@AP composite particles were successfully prepared. The crystal form remained unchanged during the preparation process. The wettability of PDA on AP was improved through the coating of PDA, leading to an increase in the surface energy of AP and enhancing the adhesion between AP and GAP. Mechanical performance testing shows that using PDA@AP in propellants increased the tensile strength of the propellant from 1.2 to 1.8 MPa, while the elongation at break decreased from 208% to 155%. The "dewetting ratio" has also decreased from 2.88 to below 2.5.