Core-Shell Structured HMX@Polydopamine Energetic Microspheres: Synergistically Enhanced Mechanical, Thermal, and Safety Performances.

Congmei Lin,Feiyan Gong,Xu Zhao,Jiang Li,Chengcheng Zeng,Yubin Li,Shaoyun Guo,Zhijian Yang

doi:10.3390/polym11030568

Congmei Lin, Feiyan Gong + Show 6 more

Open Access

https://doi.org/10.3390/polym11030568

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Journal: Polymers	Publication Date: Mar 26, 2019
Citations: 59	License type: CC BY 4.0

Affiliation: China Academy of Engineering Physics, Sichuan University

Abstract

The solid–solid phase transition, poor mechanical properties, and high sensitivity has impeded further practical applications of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based polymer bonded explosives (PBXs). To address these issues together, a facile and effective route was employed to achieve a coating of polydopamine (PDA) on the surface of explosive crystals via in situ polymerization of dopamine. Additionally, PBXs based on HMX@PDA microcapsules were prepared with a fluoropolymer as polymer binder. Improved storage modulus, static mechanical strength and toughness, and creep resistance has been achieved in as-prepared PDA modified PBXs. The β-δ phase transition temperature of as-obtained PBXs based on conventional HMX (C-HMX)@PDA was improved by 16.3 °C. The friction sensitivity of the C-HMX based PBXs showed a dramatic drop after the PDA coating. A favorable balance proposed in this paper among thermal stability, mechanical properties, and sensitivity was achieved for C-HMX based PBXs with the incorporation of PDA.

Highlights

Energetic materials (EMs) contain high chemical energy, in which organic small molecular crystals act as functional materials
We demonstrate a facile in situ polymerization approach to synthesize core-shell microparticles with a high-energy HMX core and a PDA shell
PDA coated HMX crystals were synthesized via a facile in situ polymerization of dopamine on the surface of HMX

Summary

Introduction

Energetic materials (EMs) contain high chemical energy, in which organic small molecular crystals act as functional materials. Due to the difficulty in controlling the mass transfer, the polymer binder cannot be completely coated onto explosive crystals at the large-scale production by the in situ polymerization Another limitation for the application of HMX energetic crystal is that it undergoes a solid–solid β-δ phase transition under thermal shock, which is harmful for the long-term storage and transportation. Another technique is the fabrication of core-shell microparticles, such as HMX@nano-TATB composites [19] It significantly changes the surface morphology of HMX and the interface adhesion state between particles and polymer binder, resulting in the enhancement of mechanical properties. The strong chemical adhesion to form the robust and compact core-shell structure and high rigidity of polydopamine (PDA) enables it to provide a great potential to efficiently reduce the sensitivity and improve the thermal stability and mechanical properties of energetic materials without a sacrifice of detonation power. The amount of PDA in core-shell microparticles is varied to investigate the dependence of the comprehensive properties on the degree of coating

Materials

Sample Preparations

Material Characterizations

Results and Discussion

Conclusions