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A new membrane was synthesized containing pure alginate, crosslinking agent (CaCl 2 ), and plasticizer (glycerol). Characterization studies of the membrane were applied to determine the characteristics and morphology using field emission scanning electron microscope, EDX, FTIR, XRD, and atomic force microscopy analysis. The half-cell performance test of the membrane was verified by several tests, including proton conductivity and methanol permeability. The best membrane had high proton conductivity (10.1 3 10 23 S cm 21 ) and very low methanol permeability (1.984 3 10 27 cm 2 s 21 ), which consequently resulted in very high selectivity (5.0907 3 10 4 Ss cm 23 ). Glycerol had a positive modification and good influence on the alginate characteristics. Furthermore, the poor mechanical properties of the alginate biopolymer were enhanced by calcium chloride and glycerol inside the polymer. V C 2018Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46666.

The high methanol crossover and high cost of Nafion® membrane are the major challenges for direct methanol fuel cell application. With the aim of solving these problems, a non-Nafion polymer electrolyte membrane with low methanol permeability and high proton conductivity based on the sodium alginate (SA) polymer as the matrix and sulfonated graphene oxide (SGO) as an inorganic filler (0.02-0.2 wt%) was prepared by a simple solution casting technique. The strong electrostatic attraction between -SO3H of SGO and the sodium alginate polymer increased the mechanical stability, optimized the water absorption and thus inhibited the methanol crossover in the membrane. The optimum properties and performances were presented by the SA/SGO membrane with a loading of 0.2 wt% SGO, which gave a proton conductivity of 13.2 × 10−3 Scm−1, and the methanol permeability was 1.535 × 10−7 cm2 s−1 at 25 °C, far below that of Nafion (25.1 × 10−7 cm2 s−1) at 25 °C. The mechanical properties of the sodium alginate polymer in terms of tensile strength and elongation at break were improved by the addition of SGO.