Pore size tailorability in gamma Al2O3 membranes using surfactant micellesas templates

gamma Al2O3 membranes with highly tailorable pore sizes in the range of 50- 60 Angstrom could be prepared by using surfactant micelles of varying sizes as templates. Surfactants were incorporated in the alumina sol by dissolvi ng them in water above their critical micellar concentration and using the micellar solutions to hydrolyze aluminium alkoxides. 15 mM solutions of qua ternary ammonium surfactants namely dodecyl trimethyl ammonium bromide, tet radecyl trimethyl ammonium bromide, and hexadecyl trimethyl ammonium bromid e were found to give pore sizes of 50, 55 and 60 Angstrom respectively as o btained by nitrogen adsorption BET and transmission electron microscopy (TE M) methods. These pore sizes also match closely with the micellar sizes obt ained by quasi elastic light scattering measurements. Moreover, it was also found that the total pore volume increases with increase of the amount of surfactant. Rejection of standard polyethylene glycol (PEG) solutions of di fferent molecular weights as well as some globular protein solutions of dif ferent molecular weights was determined in these membranes and the data wer e explained on the basis of the model originally developed by Sourirajan an d Matsuura and later modified by Brites and de Pinho. (C) 1999 Kluwer Acade mic Publishers.