Fluoropolymer Functionalization for Enhanced Interfacial Adhesion and Mechanical Properties in Polymer Bonded Explosives

Abstract

The poor interfacial adhesion between energetic crystals and polymer matrices results in undesirably low mechanical properties, limiting the application of energetic composites. To address this issue, we employed a covalent functionalization strategy using fluoropolymers, bridged by mussel-inspired polydopamine (PDA), to obtain strong interfacial adhesion. In-depth characterizations confirmed the successful grafting of fluoropolymers onto the surface of energetic crystals. Remarkably, both experimental results and numerical simulations revealed that the covalent functionalization and fluorine-containing binder system significantly increased the number of hydrogen bonds and interfacial interactions, thereby enhancing the interfacial adhesion between energetic crystals and the polymer matrix. Energetic composites with fluoropolymer functionalization exhibited substantial interfacial enhancement effects. The mechanical properties of the composites improved with increasing grafted fluoropolymer content. The composites based on energetic crystals with 2 wt% grafted fluoropolymer exhibited optimal performance, with compressive and tensile fracture energies increased by 97.7% and 182.0%, respectively, compared to the unmodified composites. Additionally, computational simulations provided fundamental insights into how the interfacial structure affects the mechanical properties of energetic composites, confirming that the covalent functionalization and fluorine-containing binder system enhance interfacial adhesion by increasing hydrogen bond numbers and interfacial interactions.

Keywords: Polymer Bonded Explosives, Interfacial Adhesion, Fluoropolymer Functionalization