Base-stable amphiphilic diblock copolymers with a polydiallyl dimethyl ammonium hydroxide block were synthesized and characterized to quantify hydroxide-ion transport in the hydrated state; polystyrene was the hydrophobic block. The challenge of synthesizing a copolymer comprising blocks with very different solubility behaviors was addressed by a combination of reversible addition fragmentation chain transfer polymerization and ion metathesis. Both monomers used in the polymerization are commercially available on industrial scales. Hydroxide-ion conductivities of 0.8 mS/cm were achieved in hot-pressed membranes immersed in water at room temperature despite relatively low water uptake (4.2 water molecules per hydroxide ion). The stability of the polydimethyl ammonium hydroxide chains was investigated in 2 M NaOD at 60 degrees C. H-1 NMR spectroscopy studies showed no detectable degradation after 2000 hours. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2243-2248