This study intends to provide new TiO 2 /phosphorous-functionalized cellulose acetate (Ph-CA) nanocomposite membranes for direct methanol fuel cells (DMFCs). A series of TiO 2 /Ph-CA membranes were fabricated via solution casting technique using a systematic variation of TiO 2 nanoparticle content. Chemical structure, morphological changes, and thermal properties of the as-fabricated nanocomposite membranes were investigated by FTIR, TGA, SEM, and AFM analysis tools. Further, membranes' performance, mechanical properties, water uptake, thermal-oxidative stability, and methanol permeability were also evaluated. The results clarified that the ion-exchange capacity (IEC) of the developed nanocomposite membranes improved and reached a maximum value of 1.13 and 2.01 m eq /g at 25 and 80 °C, respectively, using TiO 2 loading of 5 wt % compared to 0.6 and 0.81 m eq /g for pristine Ph-CA membrane at the same temperature. Moreover, the TiO 2 /Ph-CA nanocomposite exhibited excellent thermal stability with appreciable mechanical properties (49.9 MPa). The developed membranes displayed a lower methanol permeability of 0.98 × 10 −16 cm 2 s −1 compared to 1.14 × 10 −9 cm 2 s −1 for Nafion 117. The obtained results suggested that the developed nanocomposite membranes could be potentially applied as promising polyelectrolyte membranes for possible use in DMFCs.

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