Preparation of agglomeration-free composite energetic microspheres taking PMMA-PVA with honeycomb structure as template via the molecular collaborative self-assembly

Abstract

ABSTRACT We proposed with excitement a novel molecular co-assembly (MCSA) that can effectively overcome the agglomeration of energetic materials. Through the coordinated self-assembly of polymethyl methacrylate-polyvinyl acetate (PMMA-PVA) with honeycomb-like structure and nanoparticles, a controlled and orderly distribution of nitroamine explosive (cyclotetramethylenetetranitramine, HMX; cyclotrimethylenetrinitramine, RDX; and hexanitrohexaazaisowurtzitane, CL-20) structure was achieved, above all, resolving the agglomeration problem availably. The modification ability of PMMA to RDX, HMX, and CL-20 at different temperatures was simulated by Materials Studio, which provided guidance for the ambient temperature of collaborative self-assembly. In order to compare the priority of the morphology and performance, RDX/PMMA-PVA, HMX/PMMA-PVA, and CL-20/PMMA-PVA composite particles with the same PMMA content were also fabricated by water suspension coating method, respectively. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier-transform infrared (FT-IR) spectra, and differential scanning calorimeter (DSC). Moreover, the safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The solid spherical PBX prepared via collaborative self-assembly all exhibited a perfect spherical structure, smooth, and flat coating, without any agglomeration. They had the same crystalline structure as the uncoated explosives, simultaneously demonstrating lower impact sensitivity and higher energy performance. The application of collaborative self-assembly technology has broken through the key technical bottleneck of the shell material being easy to form a separate phase in the desensitization coating of explosives, availably resolved the problems of particle exposure and low coverage during the coating, thus possessing vital significance for reference in the design and fabrication of PBXs with core-shell structure.