Full Description

The objective of this research was to fabricate near perfect polymericmicrofiltration membranes with highly ordered pore sizes, shapes, and spacing, therebyovercoming several problems associated with currently available membranes. Todate, only ceramic, silicon nitride membranes have been produced with potentiallysimilar characteristics as the ones attempted by this study.Because polymeric membranes are substantially less expensive than ceramic ones, thisconstitutes an important gap in membrane technology. Aperture Array Lithography was used in this research. In this process, a thinstencil mask, containing a regular array of circular openings (the aperture array pattern),was placed in close proximity to a substrate and is illuminated by a broad beam of highly collimated, energetic helium ions. Ions that strike the opaque regions of the mask arestopped while the ions that pass through the openings form an array of ion beamlets thatexpose portions of an ion-sensitive resist coating that is applied to the substrate. Forpositive tone resists, the exposed portions dissolve during a subsequent development step,leaving a replica of the mask pattern in the resist. This pattern is then further transferredthrough a thin polyimide membrane to form a free-standing membrane filter.Pore size distributions were measured by digital image analysis of electronmicrographs of the membrane surface obtained using a Field Emission Scanning ElectronMicroscope. Includes 11 references, figures.

Product Details

Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 5File Size: 1 file , 720 KB