A new randomly crosslinked polymer is investigated for use as an ion-exchange membrane. The polymer was produced through amination of chlorinated poly(propylene) (PP) with poly(ethyleneimine) (PEI) and quaternized with iodoethane. The synthesis of the new polymer is confirmed by FTIR H-1 and C-13 NMR. The microstructure of the polymer consists of aggregates on the order of 1 mu m. Environmentally controlled small and wide angle X-ray analysis showed a relatively featureless amorphous morphology over length scales less than 105 nm through a full range of humidity environments. Little physical swelling of the films were observed, but very high internal water uptake was observed with lambda = 50. The highest in-plane ionic conductivity with chloride as the counter ion observed was 0.29 mS cm(-1) at 90 degrees C and 95% relative humidity. Infrared spectroscopy was used to monitor the relatively rapid rate of counter-ion reaction of hydroxide with ambient CO2 to form a mixture of carbonate and bicarbonate when exposed to air. (C) 2013 Elsevier Ltd. All rights reserved.