Toughening, synergistic fire retardation and water resistance of polydimethylsiloxane grafted graphene oxide to epoxy nanocomposites with trace phosphorus

Polydimethylsiloxane (PDMS) short chains were grafted to graphene oxide (GO) surface by one-step synthesis to form a GO ramification, which exhibited a remarkable toughening, synergistic fire retardation, and water resistance for cured epoxy nanocomposites. Small addition of 0.29 wt% of PDMS-GO with 0.3 wt% of P made the cured epoxy reach the UL94 V-0 level with LOI of 29.2, T5wt% of 339 °C, char yield of 21.4 wt%. The flexible strength was significantly increased to 101.2 MPa, and the water absorption was reduced to 0.4 wt% with static contact angle of water as 108.7° for the epoxy containing 0.29 wt% of PDMS-GO. This was due to homodisperse of PDMS-GO in epoxy matrix observed with TEM. Therefore, the epoxy containing 0.3 wt% of P and 0.29 wt% of PDMS-GO was the optimal formula with the balanced performance in fire-retardation, toughness, and water resistance and is expected to satisfy electronic applications.