Nano-composite polymer-aluminophosphate membranes do not have molecular sieving properties as previously claimed. The layered microporous aluminophosphate [Al3P4O16](+)center dot 3[NH3CH2CH3](-) was swollen with a surfactant and incorporated into cellulose acetate, Matrimid 5218(C), UDEL P-3500(C), PDMS, and a PDMS-6FDA-6FpDA co-polymer using simple mixing in organic solvents. It was anticipated that the addition of layered, microporous aluminophosphate to the polymer matrices would enhance the selectivity of large gas species compared to small gases through a molecular sieving effect. However, the selectivity was not improved using this technique due to insufficient exfoliation of the aluminophosphate and low dispersion of the particles into the respective polymer matrices. (C) 2007 Elsevier B.V. All rights reserved.