Fabrication of ZIF‐8@Polyphosphazene core‐shell structure and its efficient synergism with ammonium polyphosphate in flame‐retarding epoxy resin

Abstract

A novel zeolitic imidazolate framework (ZIF-8) nanoparticles@polyphosphazene (PZN) core-shell architecture was synthesized, and then, ZIF-8@PZN and ammonium polyphosphate (APP) were applied for increasing the flame retardancy and mechanical property of epoxy resin (EP) through a cooperative effect. Herein, ZIF-8 was used as the core; the shell of PZN was coated to ZIF-8 nanoparticles via a polycondensation method. The well-designed ZIF-8@PZN displayed superior fire retardancy and smoke suppression effect. The synthesized ZIF-8@PZN observably raised the flame retardancy of EP composites, which could be demonstrated by thermogravimetric analysis (TGA) and a cone calorimeter test (CCT). The chemical structure of ZIF-8@PZN was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Compared with pure epoxy, with the incorporation of 3 wt% ZIF-8@PZN and 18 wt% APP into the EP, along with 80.8%, 72.6%, and 64.7% decreased in the peak heat release rate (pHRR), the peak smoke production rate (pSPR), and the peak CO production rate (pCOPR), respectively. These suggested that ZIF-8@PZN and APP generated an intumescent char layer, and ZIF-8@PZN can strengthen the char layer, resulting in the enhancement in the flame resistance of EP. K E Y W O R D S epoxy resin, flame retardancy, mechanical properties, polyphosphazene, ZIF-8

Metal‐organic frameworks derived ZnO@MOF@PZS flame retardant for reducing fire hazards of polyurea nanocomposites

“…It can be seen from Figure 1(C) that the morphology of ZnO@MOF@PZS is rougher than ZnO@MOF. The NH 2 active groups and π‐π stacking at the interface can aid to coating the PZS shell regularly on the ZnO@MOF nanoflowers 31 . To further confirm the synthesis of ZnO@MOF@PZS, the energy dispersive X‐Ray (EDX) spectroscope was used to illustrate it, and the result is shown in Figure 1(D).…”

“…Figure 3(D) shows the N 1s spectrum of ZnO@MOF@PZS, the peaks at 397.5, 398.7 and 400.8 eV are assigned to the N H, C N and P N bonds, respectively. 31 XRD, FTIR and XPS results show that ZnO@MOF@PZS composite has been successfully prepared.…”

“…The NH 2 active groups and π-π stacking at the interface can aid to coating the PZS shell regularly on the ZnO@MOF nanoflowers. 31 To further confirm the synthesis of ZnO@MOF@PZS, the energy dispersive X-Ray (EDX) spectroscope was used to illustrate it, and the result is shown in The XRD patterns of as-prepared nano ZnO and ZnO@MOF were displayed in Figure 2. For the ZnO, all the diffracted peaks are well attributed to hexagonal (Wurtzite) ultra-nano crystalline phases of ZnO.…”

“…The reduction in CO release is attributed to the porous structure of transition metal oxide particles Co 3 O 4 and ZnO produced during the combustion of Zn-Co MOF, which can adsorb combustible/toxic gases generated by the degradation of PUA. 31 The mass loss curves of the samples were shown in Figure 6(D). It is obvious that the mass loss of PUA composites containing ZnO@MOF@PZS is less than pure PUA.…”

Preparation of spherical cobalt hydroxystannate and its flame retardant and smoke suppressant effect in poly(vinyl chloride)

“…Many literature works have reported that some transition metals such as titanium, 25 nickel, 26 iron, 27,28 zinc, 29,30 and cobalt 31,32 can promote carbonization during combustion, which is beneficial to the flame retardancy of polymers. As far as we know, cobalt hydroxystannate (CHS) has almost no reports on toxic gas suppression and flame retardancy.…”