Grafting multi-elements hybrid polymer brushes on graphene oxide for epoxy composite with excellent flame retardancy

In this paper, a silicon-oxygen coupling agent (MPS) with a double bond is hydrolyzed with graphene oxide (GO) to obtain MPS-GO. The polymerization of MPS-GO with the phosphorus-containing monomer (HEPO) is initiated with 2,2 '-Azobis(2-methylpropionitrile) (AIBN) to obtain multi-elements hybrid polymer brushes grafting graphene oxide (HM-GO). As a flame retardant, different amounts of HM-GO are added to obtain EP composites. In this system, the properties of composite flame retardant obviously increase with the increasing of HM-GO. The limiting oxygen index (LOI) value of composites with 4 wt% addition of HM-GO is 31.0%, while the LOI value of EP-0 is only 23.9%. And the peak heat release rate (PHRR) value is reduced from 515.8 W g(-1) of pure epoxy resin to 376.9 W g(-1). In addition, with the increase of HM-GO addition, the T-g value, flexural strength and flexural modulus of EP composites are improved. Through calculation, it is proved that the rising of T-g was due to the increase of crosslink density of the system. The flame retardant performance and mechanical properties of the composite materials are steadily improved, indicating that such flame retardants are dispersed well in the epoxy resin. HM-GO is an efficient macromolecular modified graphene oxide halogen-free flame retardant, which can improve both flame retardant properties and mechanical properties.

Automated summary

By hydrolyzing a silicon-oxygen coupling agent with graphene oxide and polymerizing it with a phosphorus-containing monomer, multi-elements hybrid polymer brushes grafting graphene oxide were obtained. These were added as flame retardant to epoxy composites, resulting in significantly increased flame retardant properties and mechanical properties.