Nanocellulose/poly(methacryloyloxyethyl phosphate) composites as proton separator materials

The present study discloses a new type of nanocomposite membranes consisting of cross-linked poly(methacryloyloxyethyl phosphate) (PMOEP) and bacterial cellulose (BC) prepared by the in situ free radical polymerization of MOEP within the BC network under green reaction conditions. Homogeneous and translucent PMOEP/BC nanocomposite membranes with 52, 61 and 78 wt% of BC have good thermal and viscoelastic stability up to 180 °C with storage modulus higher than 200 MPa, good mechanical properties (Young’s modulus = 7.8–13.5 GPa), and high ion exchange capacity (1.95–3.38 mmol [H + ] g −1 ). The protonic conductivity of these nanocomposite membranes increases with increasing PMOEP content and relative humidity (RH), reaching values higher than 0.1 S cm −1 at 98 % RH, with activation energy close to 15 kJ mol −1 , from room temperature up to 94 °C. These values are comparable to, or higher than, data typically found for a commercial Nafion ® membrane, further confirming the potential of these proton separator materials as a green alternative for application in fuel cells.