New sustainable routes for gas separation membranes: The properties of poly(hydroxybutyrate-co-hydroxyvalerate) cast from green solvents

The gas separation performance of biopolymers is still scarcely characterized, mostly because their poor thermomechanical properties and high crystallinity which associated to low permeability. In this work we characterize the transport in a poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) random copolymer, that has relatively good mechanical properties, combined with renewable origin, biodegradability biocompatibility. study also compared several solvents for membrane casting, different toxicity levels. We found dimethyl carbonate allows production polymer films similar those obtained more toxic CHCl3, it leads stable samples over time. PHBV show size-sieving behaviour, as permeability decreases significantly kinetic diameter. However, strong energetic interactions CO2 matrix, confirmed by Flory-Huggins model, induce marked solubility-driven CO2/N2 CO2/CH4 selectivity, could make material potentially interesting removal processes.