Construction of Novel Neutral Polymer Bonding Agent by Grafting Multifunctional Pendants for Strengthening the Mechanical Properties of F2313/DAAF-based PBX

The weaker interface interaction between fluoropolymer binder matrix (F2313) and 3,3ʹ-diamino-4,4ʹ-azoxyfurazan (DAAF) energetic solid particles tends to the formation of “de-wetting” during fabrication, transportation, and storage, causing solid grain collapse, further leading to unsatisfactory explosion effect on the polymer bonded explosive (PBX). Adding neutral polymer bonding agent (NPBA) modified with multiple polar groups is currently the most effective way for reinforcing the composite interface of PBX to inhibit de-wetting. In this contribution, a series of novel NPBA, named 3%FTDI-NPBA, 5%FTDI-NPBA, and 10%FTDI-NPBA, were designed for an F2313/DAAF system by grafting multifunctional FTDI pendants consisting of perfluorobutyl and urethane groups on the side chains of classical NPBA-1. The chemical structure, thermal stability, interfacial properties, and bonding performances of all FTDI-NPBA were systematically investigated. As expected, the introduction of multifunctional pendants could effectively bridge the interface gap between F2313 and DAAF. F2313/DAAF/5%FTDI-NPBA exhibited the best mechanical properties with the Brazilian Disk strength and modulus of 8.16 ± 0.02 MPa and 5.76 ± 0.02 GPa, respectively, 29.52% and 12.50% higher than the system with NPBA-1. Our multifunctional pendants grafting strategy will provide a viable guide for optimizing NPBA.