High-Performance Uniformly-Dispersed Black Phosphorene Composites with Ultrahigh Flame-Retarded Efficiency Via Iterative Dispersion Strategy

Abstract

Black phosphorus (BP) nanosheets are widely used in flame retardant polymers, but the challenge of poor dispersion in polymers increases their additions as well as raises the cost of BP-based flame retardant materials. Here, for the first time, we propose an iterative dispersion strategy, which continuously approaches the homogeneous dispersion state by separating the BP dispersion solution and aggregates in multiple cycles. A Fe and F synergistic functionalized BP (BFF) is utilized for the flame retardant and reinforcing modification of epoxy matrix (DGEBA) to verify the reliability of this strategy, noting that the F element in BFF can achieve dynamic hydrogen bonds with the epoxy-amine system during the curing process, further promoting dispersion. Therefore, epoxy thermosets with only 0.2 wt% BFF loading achieve UL-94 V-0 level with an LOI of 29.2% through the synergistic effect of iterative dispersion and dynamic hydrogen bond. The formation of hydrogen bonds between BFF and epoxy matrix also contributes to a significant increase in the mechanical properties. This work provides a reasonable and facile concept to achieve sufficient dispersion of inorganic nanosheets in polymer or organic matrices and also promote the process of industrial large-scale manufacturing of BP-based fire retardant materials.

Keywords: Iterative dispersion, Dynamic hydrogen bond, Uniform dispersion, Flame retarded efficiency