title: Nanostructured bacterial cellulose-poly(4-styrene sulfonic acid) composite membranes with high storage modulus and protonic conductivity.
abstract: The present study reports the development of a new generation of bio-based nanocomposite proton exchange membranes based on bacterial cellulose (BC) and poly(4-styrene sulfonic acid) (PSSA), produced by in situ free radical polymerization of sodium 4-styrenesulfonate using poly(ethylene glycol) diacrylate (PEGDA) as cross-linker, followed by conversion of the ensuing polymer into the acidic form. The BC nanofibrilar network endows the composite membranes with excellent mechanical properties at least up to 140 °C, a temperature where either pure PSSA or Nafion are soft, as shown by dynamic mechanical analysis. The large concentration of sulfonic acid groups in PSSA is responsible for the high ionic exchange capacity of the composite membranes, reaching 2.25 mmol g(-1) for a composite with 83 wt % PSSA/PEGDA. The through-plane protonic conductivity of the best membrane is in excess of 0.1 S cm(-1) at 94 °C and 98% relative humidity (RH), decreasing to 0.042 S cm(-1) at 60% RH. These values are comparable or even higher than those of ionomers such as Nafion or polyelectrolytes such as PSSA. This combination of electric and viscoelastic properties with low cost underlines the potential of these nanocomposites as a bio-based alternative to other polymer membranes for application in fuel cells, redox flow batteries, or other devices requiring functional proton conducting elements, such as sensors and actuators.
authors.affiliation: Department of Materials & Ceramic Engineering, CICECO, University of Aveiro , 3810-193 Aveiro, Portugal.
authors.forename: Tiago D O
authors.initials: TD
authors.lastname: Gadim
authors.forename: Andrea G P R
authors.initials: AG
authors.lastname: Figueiredo
authors.forename: Nataly C
authors.initials: NC
authors.lastname: Rosero-Navarro
authors.forename: Carla
authors.initials: C
authors.lastname: Vilela
authors.forename: José A F
authors.initials: JA
authors.lastname: Gamelas
authors.forename: Ana
authors.initials: A
authors.lastname: Barros-Timmons
authors.forename: Carlos Pascoal
authors.initials: CP
authors.lastname: Neto
authors.forename: Armando J D
authors.initials: AJ
authors.lastname: Silvestre
authors.forename: Carmen S R
authors.initials: CS
authors.lastname: Freire
authors.forename: Filipe M L
authors.initials: FM
authors.lastname: Figueiredo
mesh_terms: D001419:Bacteria / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry*; D004553:Electric Conductivity; D006813:Humidity; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared; D013451:Sulfonic Acids / Q000737:chemistry*; D013696:Temperature; D013818:Thermogravimetry
chemical_list: D008567:Membranes, Artificial; D011108:Polymers; D011522:Protons; D013451:Sulfonic Acids; C437167:poly(ethylene glycol)diacrylate; D011092:Polyethylene Glycols; D002482:Cellulose; C077114:styrenesulfonic acid polymer