Integrated effect of flame retardant wrapped macromolecular covalent organic nanosheet on reduction of fire hazards of epoxy resin

Abstract The original phosphorus-containing flame retardant wrapped covalent organic frameworks (FCOFs) nanosheets are prepared and then added into epoxy resin (EP) through in situ polymerization. TEM image shows that FCOFs nanosheets with a lateral size from several hundred nanometers to several micrometers are prepared. The P Ph and P O bonds support that COFs nanosheets are modified by flame retardant successfully. The peak thermal degradation rate, peak heat release rate and char residues of EP/FCOFs nanosheets-3.2 wt% decrease by 52.9% and 19.7%, −64.2%, respectively. LOI and rating of UL-94 vertical burning of EP/FCOFs nanosheets-3.2 wt% are 25.5% and V1, respectively. The volatile components during pyrolysis such as CO, carbonyl and aromatic compounds are also decreased. The char residues with increased graphitization degree, quality and integrity have been achieved due to incorporating of FCOFs nanosheets. This work provides a direction to prepare multifunctional COFs based nanocomposite.