Polyamide 12-polytetramethyleneoxide block copolymer membranes with silver nanoparticles - Synthesis and water permeation properties

The water vapor uptake in the membranes with different AgBF4 contents studied by microgravimetry allowed us to determine the sorption isotherms at 25 °C. The sigmoidal BET-II type isotherms were fairly well fitted with Park's equation, where the concave part was fitted with a Langmuir and a Henry sorption term, while the convex part was fitted with an exponential term in Park's equation that takes into account the clustering of water molecules in the polymer matrix. We suggest that at low water activity, water molecules adsorb on Langmuir sites-probably on the nanoparticle surface-and at high activities water molecules form aggregates in the polymer matrix.