A series of copolymers were designed that combined either LiMTFSI or LiSTFSI monomers with one of the three different alkyl methacrylate monomers (MMA, BMA and the biobased monomer IBMA), with different degrees of crosslinking by EGDMA. Water uptake experiments on membranes with different compositions led to the selected three membranes [P(LiMTFSI-IBMA)-2.5% EGDMA, P(LiMTFSI-IBMA)-10% EGDMA and P(LiSTFSI-IBMA)-10% EGDMA] that presented water uptake levels in the targeted range of 30-100%, sufficient mechanical strength and good handleability after swelling.