Proton conducting electrolytes composed of chondroitin sulfate polysaccharide and citric acid

• Autor(a) principal: Santos, Filipe M.
• Data de Publicação: 2020
• Outros Autores: Barbosa, Paula C., Pereira, Rui F. P., Silva, M. Manuela, Gonçalves, Helena M. R., Nunes, Sílvia C., Figueiredo, Filipe L., Valente, Artur J. M., Bermudez, Verónica de Zea
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/91172; https://doi.org/10.1016/j.eurpolymj.2019.109453
• topic: Chondroitin sulfate; Biopolymer electrolytesIonic conductivity; Citric acid

Novel electrolytes composed of chondroitin sulfate A (CSA) and citric acid (CA) have been prepared using a clean, safe, and fast route. These electrolytes exhibit different physical-chemical properties, depending on the amount of CA. For X > 82.3%, where X is the mass ratio, in %, of CA/(CA + CSA), whitish polycrystalline powders result. Lower amounts of CA leads to the production of translucent, amorphous films, sticky for X = 75.6 and 82.0, brittle for X < 43.6 and crack-free, self-standing for 43.6 < X < 75.6%. The results obtained provide evidence that, at low pH, strong hydrogen bonding interactions take place between the anionic sulfonic and carboxylic groups of CSA and CA. CA exerts a key role, acting as a cross-linker and proton source, while simultaneously influencing sample morphology. At room temperature the highest ionic conductivity is achieved at X = 60.8%. A significant enhancement of the ionic conductivity of this sample occurs with the increase of relative humidity (RH) (from 3.1 × 10−7 to 3.7 × 10−2 S cm−1 30% for RH = 30 and ~100%, respectively).