Schematic showing the subreaction sequence resulting in the growth of ALD or MLD coatings. Films are grown in monolayer increments by alternating between two separate half reactions, i.e., “A” and “B” surface species.
A chemical tag was used for the postexamination of tensile specimens. A lipophillic end group enables the tag to adhere specifically to the hydrophobic surface of the PEN substrate; a fluorescent end group enables damage visualization via external illumination.
Tensile test data (engineering stress/strain) for a 5 nm thick layer deposited on a thick PEN substrate.
Measured crack density for a single layer (deposited on a thick PEN substrate), following tensile testing to prescribed strains.
Evolution of the damage morphology for a single 125 nm thick layer deposited on PEN. The set of images includes separate specimens tensioned to the of (a) 0%, (b) 0.9%, (c) 1.5%, (d) 7.5%, and (e) 25%.
Measured crack density for a 100 nm thick alucone layer, tensioned to prescribed strains. The insets show (a) a schematic representing the specimens in cross section and (b) the morphology of the top surface (orientation is indicated with respect to ) of a specimen tensioned to .
Cross section of multilayer coating on PEN (micrograph is oriented obliquely to the specimen).
Measured crack density for separate ALD/MLD/ALD coatings (thickness ), tensioned to prescribed strains.
Damage morphology for coatings tensioned to , including (a) 25 nm , as well as (b) 25/15/25 nm, (c) 25/192/25, and (d) 10/3/10 nm multilayers. Tearing, concluded to occur in the PEN substrate, is indicated with an arrow in (a), (b), and (d). The delamination of film layers is shown in (c). The direction of the strain applied during testing is shown in (d).
Results of numerical analysis for an ALD/MLD/ALD coating on a PEN substrate. The critical strains measured from ALD/MLD/ALD specimens, Fig. 8, are also shown in the figure.
Results of numerical analysis for an alumina/arbitrary polymer/alumina coating configuration on a PEN substrate. The results predict according to the modulus and critical energy release rate (“toughness”) of the spacer layer. The particular geometry considered is shown in inset.
Summary of results for a single layer (deposited on PEN), tensioned to prescribed strains.
Summary of results for a 100 nm thick alucone layer (deposited on PEN), tensioned to prescribed strains.
Summary of results for multilayer coatings, tensioned to prescribed strains.
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