In-situ Reactive Self-Assembly of Graphene Oxide Nano-Coating in Polymer Foam Materials with Synergistic Fire Shielding Properties
Lightweight polymer foam materials that are resilient and flame retardant are critically required in various practical applications. However, it has remained a great challenge to realize high-temerpature resilience and flame reisitance in the polymer foams at an ultra-low loading of flame retardant additives. Herein we report a facile, low-cost and scalable strategy to create unprecedented high-performance polydimethylsiloxane foam materials by in-situ reactive self-assembly of graphene oxide (GO) sheets. Addiiton of 0.10 wt.% GO produces compact and ultrathin protective nano-coatings on the foam surface. Moreover, such nano-coatings are chemically bonded with the foam skeleton. As a result, the nano-coatings produce significantly improved thermal stability and high-temperature resilience as well as synergistic fire shielding properties, enabling ~57% and ~87% reduction in heat release rate and total smoke rate at 0.10 wt.% and limiting oxygen index of >31% at 0.50 wt.%. By observing the burnt surface zones, we demonstrate that the thermal decomposition of PDMS molecules transforms into inorganic nano-silica layers and promotes GO graphitization to form a compact protective char, leading to synergetic silicone/GO flame-retardant properties. The successful fabrication of the fascinating PDMS foam materials provides new perspectives for understanding and design of advanced polymer foam nanocomposite materials.