Paper TF-MoA8
Combined Atomic Layer Deposition and Molecular Layer Deposition for Encapsulation of Electrospun Nylon Nanofibers

Monday, October 18, 2010, 4:20 pm, Room Pecos

Electrospun nanofibers are of interest for air filtration, thermal insulation, biochemical sensing, and a range of other applications. Nanofibers can be readily electrospun from polyamide-6 (PA-6) nylon, but nylon is highly susceptible to water uptake and rapid degradation when exposed to chemical reactants, including those used in ALD. The high surface area of nanofibers makes these issues more acute and difficult to manage. We have recently investigated the deposition of Al₂O₃ and ZnO on nylon nanofibers and found distinctly different results for these two material processes. Aluminum oxide ALD from trimethylaluminum and water resulted in significant fiber degradation, whereas fibers remained intact upon ALD using diethyl zinc and water. The ZnO coating was not sufficient, however, to impede attack and degradation during subsequent exposure to Al₂O₃ ALD using TMA. We have recently explored a new MLD process in our lab using TMA and glycidol, where the resulting film is a hybrid organic-metal oxide polymer. This MLD coating onto a ZnO-coated nylon nanofiber results in only minimal reaction with the polymer under the ZnO. After 75 MLD cycles, exposing the nylon nanofibers to 25 cycles of trimethylaluminum/water results in no visible degradation, indicating successful encapsulation by the ZnO/MLD bilayer. We will present the chemistry associated with the reaction between the TMA and PA-6. Additionally, the surface chemistry of the PA-6 nanofibers after encapsulation, and the air stability of the hybrid organic-metal oxide coatings will be discussed.