POLY 198 |
| The nanopore surface in opal films, assembled from 200 nm silica spheres, was modified with poly(acrylamide) (PAAm) or poly(N-isopropylacrylamide) (PNIPAAm) brushes using surface-initiated atom transfer radical polymerization. The polymer thickness inside the nanopores was controlled by the polymerization time and was monitored by measuring the flux of redox-active species across the opal film using cyclic voltammetry. PAAm brush thickness increased in the course of 26 hours of polymerization in a logarithmic manner from 1.3 to 8.5 nm leading to nanopores as small as 7.5 nm. The diffusion through PNIPAAm-modified opal films was studied as a function of temperature and polymer brush thickness. Nanopores modified with a thin PNIPAAm brush exhibited a positive gating behavior, where diffusion rates increased with increasing temperature. Nanopores modified with a thick PNIPAAm brush showed a negative gating behavior where diffusion rates decreased with increasing temperature. |
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General Papers: Polymers in Nanotechnology
6:00 PM-8:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Polymer Chemistry |