Inhibition of dissolution‐induced crystal transformation of ϵ‐Hexanitrohexaazaisowurtzitane in plasticizers by polydopamine coating**

Abstract

AbstractIn order to avoid the crystal transformation of ϵ‐Hexanitrohexaazaisowurtzitane (ϵ‐HNIW) dissolved in plasticizers, a suitable bonding agent was selected to inhibit the crystal transformation of ϵ‐HNIW. Interfacial interaction simulations were carried out using Materials Studio2017 software for selected neutral polymer bonding agent (NPBA), polyene polyamine bonding agent (LBA) and polydopamine (PDA) and ϵ‐HNIW. Results showed that the interaction order of the three polymers on the ϵ‐HNIW crystal surface is PDA>NPBA> LBA; ϵ‐HNIW@ PDA crystal phase was more stable. Therefore, ϵ‐HNIW@ PDA crystal particles were constructed by the in‐situ self‐polymerization coating technology. Scanning electron microscope (SEM) showed that the ϵ‐HNIW@ PDA was square with smooth surface. The thermal properties of ϵ‐HNIW@ PDA were investigated by differential scanning calorimetry (DSC), which showed that the coating of PDA effectively increased the transition temperature of ϵ‐HNIW crystal. Moreover, the solubility and crystal transformation mechanism and law of ϵ‐HNIW/ϵ‐HNIW@ PDA in four plasticizers were further studied and compared systematically, ϵ‐HNIW@ PDA showed significantly lower solubility compared with ϵ‐HNIW. The solubility size was ranking as isodecyl nonanoate (IDP)>dioctyl sebacate (DOS)>dioctyl adipate (DOA)>paraffin liquid (RH). Variable‐temperature X‐ray diffraction (XRD) tests showed that PDA increased the ϵ‐HNIW crystal transformation temperature by about 35 °C. The small amount of dissolution of ϵ‐HNIW by the four plasticizers had a facilitative effect on the ϵ‐HNIW crystal transformation, which was consistent with the solubility magnitude. These results indicated that PDA‐coated ϵ‐HNIW enhances crystal interfacial interaction, reduces the solubility in plasticizers, and has a significant inhibitory effect on the dissolution‐induced crystal transformation of ϵ‐HNIW.