COLL 122 |
| Lei Zhai1, Hyunku Ahn1, Michael Rubner2, and Robert E. Cohen3. (1) Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, (2) Department of Materials Science and Engineering, MIT, 13-5106, Cambridge, MA 02139, (3) Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 |
| Polymeric nanoporous structures in confined geometry have numerous applications in photonic structures, microfluid channels, and drug delivery systems. Polyelectrolyte multilayers with alternating porous and fully-dense regions have been assembled from poly(acrylic acid) (PAA), poly(allylamine hydrochloride) (PAH) and polystyrene sulfonate (SPS) in appropriate combinations. The porous zones were developed post-assembly, via immersion of the hetero-structures into an aqueous acidic medium followed by rinsing in deionized water. Properly assembled PAA/PAH strata exhibit a reversible, pH-gated nanoporosity while the SPS/PAH regions remain unchanged at low pH. Organic liquid crystal molecules were successfully loaded selectively into the dry nanoporous regions via a capillary force driven wicking action. We have examined the liquid cystal-filled materials in the context of Bragg stacks with tunable refractive index layers. The application of these structures as one-dimensional dielectric mirrors and vapor sensors have been investigated. Applications in drug delivery are also discussed. |
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Nanoscience and Nanotechnology
8:30 AM-11:45 AM, Monday, March 29, 2004 Marriott -- Grand Ballroom J, Oral
Division of Colloid and Surface Chemistry |