Four guanidinuium-functionalized model compounds containing different substituent groups were prepared, and the substituent effects on the overall alkaline stability of the guanidinium cations were investigated. Based on the good alkaline stability of the model compounds, novel guanidinium-based anion exchange membranes (AEMs), GPP-co-PAEK x, with controlled microblock structures were subsequently designed and synthesized in good yield via a three step reaction that included a fluorophenyl-amine reaction, methylation and nickel (0)-catalyzed coupling. Notably, the use of a hydrophilic, guanidinium cation-containing component as a raw material in the direct synthesis of AEMs via nickel(0)-catalyzed coupling avoided using hygroscopic Vilsmeier salts and is obviously different from the conventional method that involves bromomethylation or post-quaternization. The GPP-co-PAEK x membranes exhibited lower water uptake values (<= 23.4% at 60 degrees C) and hydroxide conductivities comparable to those of others reported randomly functionalized guanidinium-based AEMs with similar ion exchange capacity (IEC) values. This finding indicates that the GPP-co-PAEK x membranes with controlled microblock structures possess well-developed hydrophilic/hydrophobic nanophase separation, which was confirmed by transmission electron microscopy (TEM). Moreover, long-term alkaline stability tests demonstrated that the alkaline stability of both the hydrophilic guanidiniums groups and the copolymer backbone contributed to the good alkaline stabilities of the GPP-co-PAEK x membranes.