In situ complexation of bio-based ATP with copper and cobalt on graphene surfaces to improve the fire resistance of epoxy coatings

Abstract

Adenosine triphosphate (ATP), consisting of ribose, adenine and phosphate groups, can be used as a carbon, acid and gas source, respectively, in the combustion process, thereby being known as an ‘all-in-one’ intumescent flame retardant. Here, we prepared a new type of ATP-Cu/Co nanoparticles through the strong interaction between active N,O groups in the ATP structure and metal ions (Cu^2 +, Co²⁺), and combined them with reduced graphene oxide (RGO) with high barrier ability to obtain a composite flame retardant (RGO@ATP-Cu/Co). The data showed that RGO/ACC_2.0 %/EP displayed the lowest backside temperature value (164.6 °C) during flame impingement. In comparison, RGO/ACC_2.0 %/EP displayed a significantly highest expansion height and expansion rate (25.4 mm, 16.96) during the calcination process. The RGO/ACC_2.0 %/EP ultimately reached the highest limiting oxygen index (LOI, 31.7 %), residual carbon content (31.4 %), and achieved a V₀ rating for the UL-94 test. Furthermore, the peak heat release rate (PHRR), total heat release rate (THR), peak smoke production rate (PSPR), total smoke production (TSP), and peak CO production rate (PCOPR) of RGO/ACC_2.0 %/EP were reduced by 38.4 %, 45.9 %, 46.6 %, 41.3 %, and 57.5 %, respectively, compared to pure EP, which proves its excellent flame retardant properties. In addition, signal markers specific to metal oxides were identified in the RGO/ACC_2.0 %/EP residual char structure, which significantly enhanced the oxidation resistance and thermal isolation efficacy of the residual carbon.