Résumé
The study focuses on the effects of C-60 filler on the phase inversion process and related changes in the morphology and separation properties of cast C-60-polysulfone nanocomposite membranes. The effects of C-60 on the rejection and permeability of the cast membranes are correlated to rheological and demixing properties of the corresponding casting mixtures. The observed differences between C-60-free and nanocomposite membranes are interpreted as resulting from enthalpic and entropic C-60-polysulfone interactions that drive and are mediated by the aggregation of C-60. Only 30 nm and smaller C-60 aggregates are observed in membranes with the smallest (1% C-60/polysulfone by mass) C-60 loading. In contrast, only aggregates larger than 30 nm are found in composites with 5% and 10% C-60 loadings. A correlation between the demixing rate and permeability and a counter-correlation between permeability and rejection are observed for nanocomposite membranes for the entire C-60 loadings range studied. The observed accumulation of the filler at the surface of internal membrane pores is attributed to the expulsion of C60 aggregates to the free surface for an entropic gain. The findings have implications for the design of polymer nanocomposite membranes as well as for the lifecycle analysis of nanomaterial-enabled products. (C) 2010 Elsevier B.V. All rights reserved.