Effect of the scaling-up the reactions synthesis of the poly(styrene-co-acrylic acid) polyelectrolyte at laboratory level

Sulfonated styrene-acrylic acid copolymers have been used as an alternative polyelectrolyte membrane for applications in fuel cells. In this work, the raw copolymer has been prepared by a well studied solution copolymerization reaction method, but at two different capacity reactor conditions: 100 mL and 3 L. The main idea was to scale up the copolymer production for having enough material for future sulfonation reactions. The reaction conditions consisted of styrene/acrylic acid in a 94/6 % mol, BPO as radical initiator in a 0.045 % mol, divinyl benzene (DVB) as crosslinking agent at 0.25 %mol and the solvent diethyl benzene (DEB) in a 50/50 volume ratio with monomers. Temperature was kept at 90 °C and the system stirred at 200 rpm during 2 hours, for both reactors. Molecular weight of copolymers was obtained by means of GPC, glass transition (Tg) by DSC and decomposition temperature (Td) through TGA analysis.