Bi-layer Al2O3/ZnO atomic layer deposition for controllable conductive coatings on polypropylene nonwoven fiber mats

Abstract

Electrically conductive zinc oxide coatings are applied to polypropylene nonwoven fiber mats by atomic layer deposition (ALD) at 50–155 °C. A low temperature (50 °C) aluminum oxide ALD base layer on the polypropylene limits diffusion of diethyl zinc into the polypropylene, resulting in ZnO layers with properties similar to those on planar silicon. Effective conductivity of 63 S/cm is achieved for ZnO on Al2O3 coated polypropylene fibers, and the fibers remain conductive for months after coating. Without the Al2O3 precoating, the effective conductivity was much smaller, consistent with precursor diffusion into the polymer and sub-surface ZnO nucleation. Mechanical robustness tests showed that conductive samples bent around a 6 mm radius maintained up to 40% of the pre-bending conductivity. Linkages between electrical conductivity and mechanical performance will help inform materials choice for flexible and porous electronics including textile-based sensors and antennas.

In Situ Conductance Analysis of Zinc Oxide Nucleation and Coalescence during Atomic Layer Deposition on Metal Oxides and Polymers

“…The ALD window for DEZ/water is measured to be ∼1.7−2.0 Å/cycle between 100 and 150°C, with decreasing growth rate at T > 150°C. 8,10,11 Therefore, similar growth is expected at 100 and 150°C, but reduced growth is expected for T = 175°C.…”

“…However, ALD on polymers is often complicated by subsurface precursor diffusion, which is influenced by thermal expansion of the polymer as well as the detailed reaction between precursors and polymers. 4,9,10 Analyzing conductance in situ during ZnO ALD on different polymers and at different temperatures will therefore provide insight into nucleation and growth mechanisms needed to achieve well-controlled coatings on polymer surfaces in general.This work will demonstrate a simple in situ two-wire and four-wire conductance probe to investigate the nature of ZnO ALD nucleation and film coalescence on polymer and quartz fiber substrates. We characterize the performance of the in situ conductance probe and use it to explore chemical and physical mechanisms during nucleation of ZnO on various untreated and pretreated polymeric and ceramic fiber surfaces.…”

Water-soluble non-polymeric electrospun cyclodextrin nanofiber template for the synthesis of metal oxide tubes by atomic layer deposition

“…[1][2][3][4][5][6][7][8][9][10] In fact ALD can yield coral, 6 core-shell, 4,5,11 hollow 6,7,9 like complex nanostructures. Although various polymers are the subjects of electrospinning, the compatibility between the polymer and the ALD precursor is vital.…”

“…The other factor is the chemical compatibility, see the ALD of Al 2 O 3 on nylon-6 polymer, 2 ALD of ZnO on poly(propylene) bers with Al 2 O 3 base layer to inhibit the diffusion of diethylzinc (DEZn) into the polymer. 1 Despite of these limitations bers of various polymers are explored by our group 3,4,12 and other researchers in ALD. 6,7 polyvinyl acetate/ZnO.…”

Transformation of polymer-ZnO core–shell nanofibers into ZnO hollow nanofibers: Intrinsic defect reorganization in ZnO and its influence on the photocatalysis

“…The catalysts examined here were fabricated via a renounced and industrially applicable combination [10,11,18,28,29,[39][40][41], viz. electrospinning [42][43][44] and atomic layer deposition (ALD) [45][46][47][48][49].…”