▎ 摘　　要

The new hydrophobic octylamine-based polybenzoxazines (POPBOs) and flexible aliphatic chain donating hexa-methylene diamine-based polybenzoxazines (PHPBOs) have been synthesized through Mannich reaction, and were analyzed by FT-IR, H-1, C-13, and DEPT-135 C-13 NMR sepctra. Additionally, the graphene nanosheets (GNs) were synthesized via one-pot hydrothermal method through Ullmann reaction, and were evaluated using FT-IR, PXRD, SEM, and HR-TEM analyses. The pristine POPBOs/PHPBOs polymers and of various amounts of (1%, 2%, 3%, and 5%) GNs-dispersed POPBOs/PHPBOs polymers nanocomposites (NCs) were prepared by thermally curing at elevated temperatures, and they were fabricated into medium-temperature proton exchange membrane fuel cells (MT-PEMFCs). The typical physico-chemical properties of the neat POPBOs/PHPBOs, and 1%, 2%, 3%, and 5% GNs dispersed POPBOs/PHPBOs NC membranes such as oxidative stability (OS), swelling ratio (SR), water uptake (WU), ion exchange capacity (IEC) and proton conductivity (PC), were valued. Interestingly, the 3 wt% GNs-loaded POPBOs/PHPBOs NCs exhibited the highest IEC, tensile stress, and elongation break values of 4.41 mmol g(-1), 0.33 MPa and 35.7% respectively, at room temperature. In addition, the 3 wt% GNs-loaded POPBOs/PHPBOs NCs showed the PC value around 7.2 x 10(-2) S cm(-1) at 120 degrees C. Additionally, the Single cell test of the bare and 3% GNs-loaded POPBOs/PHPBOs amphiphilic membranes displayed the power density and voltage value of 0.854 W cm(-2) and 0.93 V at 120 degrees C, respectively, under fully anhydrous condition. The NCs demonstrated admirable OS with a value of 73.4% degradation after being immersed in Fenton reagent for 6 hours at 100 degrees C.