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Good dispersion and distributed nanoscaled synergists are expected to greatly enhance the performance of flame retardants. Here, a new type of iron organic‐phosphonate (FeP) nanoparticles was synthesized and utilized as the synergist for polypropylene‐based intumescent flame‐retardant system (IFR/PP). To improve the dispersion of the FeP in the IFR/PP system, a master‐batch method was used to achieve separation between the FeP particles, which included hydrogen bonding with ammonium polyphosphate (APP). To improve its compatibility with PP, the hybrid synergist FeP@APP@CS was produced by electrostatic interaction with chitosan (CS). The results showed that the FeP@APP@CS nanoparticles were homogeneously dispersed in the PP matrix and selectively located on the IFR particles, achieving compatibility between the PP and IFR. The FeP@APP@CS/IFR/PP system exhibited an enhanced limiting oxygen index (LOI) of up to 28.5%, and achieved an improved vertical burning rating of V‐0 (UL‐94), compared to the IFR/PP system. The improved flame‐retardant properties, even at low levels of IFR loading, were attributed to the homogeneous dispersion of the FeP@APP@CS throughout the IFR system and the fine synergistic effect between the FeP@APP@CS and IFR.

A two-dimensional (2D) heterogeneous coupling nanoparticle composed of graphene oxide and zirconium phosphonate (GO-ZrP) was synthesized layer by layer in a self-assembly manner. A rigid layer of zirconium phosphonate can inhibit the curling of graphene oxide and then improve its dispersion. The GO-ZrP was then applied to phenolic resin-based friction materials by blending and hot pressing to improve their friction properties. The results show that the phenolic resin-based friction materials modified by GO-ZrP possess excellent tribological, mechanical, and thermal properties. Also, the specific wear rate of the material decreased nearly fivefold with the optimal loading, while the friction coefficient was basically stable. Synergistic effects between GO and ZrP nanosheets provide good prospects for the application of 2D nanofillers in friction materials. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46543.

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