Considering all effects, water uptake is generally recommended in the literature to be between 30-100% for electrodialysis. Firstly, the influence of the alkyl methacrylate monomers on the water uptake of the membranes was studied by fixing LiMTFSI as the lithium monomer source, with a ratio 1:1 LiMTFSI:alkyl monomer, and EGDMA, the crosslinking agent, was fixed to 2.5 wt%. As introduced before, the length and functional group size of the substituents affect the water uptake degree. In the case of the MMA-containing membrane, after 24 h of membrane immersion in excess of water, it disintegrated in small pieces, and this was therefore considered to be a non-viable composition for electrodialysis applications. Moving to the BMA monomer, the membrane was able to withstand up to 254% swelling produced by the water uptake experiment, however, the swelled membrane presented a poor handleability, being very easy to break during manipulation. Therefore this co-monomer was also discarded and not used in further tests and characterisations. The IBMA-containing membrane was also stable after water uptake, with a lower swelling degree of 90% and a higher manageability compared to the other membranes, making it possible to manipulate the material by bending and stretching it without rupture (Figure ). A relationship between alkyl monomer chain length and size and water uptake was found: while MMA co-monomer, the shortest length chain, presented the highest hydrophilicity (274% water uptake), IBMA co-monomer with the bulkiest alkyl group presented the lowest hydrophilicity with the lowest water uptake percentage (90%) under the same conditions.