Film Confinement Induced "Jump-Percolation" Wetting Transition in Amphiphilic Block Copolymer Films.
ACS Appl Mater Interfaces
; 9(40): 35349-35359, 2017 Oct 11.
Article
en En
| MEDLINE
| ID: mdl-28925687
ABSTRACT
We report a first-order like sharp surface wettability transition with varying film thickness dependent morphology in cast films of an amphiphilic triblock copolymer. Films composed of poly(2-(N-ethylperfluorooctanesulfonamido) ethyl methyl acrylate), poly(FOSM), and poly(N,N'-dimethyl acrylamide), poly(DMA), with thickness (h) in the transition-range, 200 < h < 300 nm, exhibited an abrupt hydrophobic to hydrophilic dynamic water contact angle transition. After an induction time, ti ≈ 40 to 180 s, water contact angle varied as θc ≈ 116° to 40° with an ultrafast contact angle decay time constant, [Formula see text] ≈ -18°/s. This behavior is a result of competing heterogeneous and antagonistic effects of bumpy poly(DMA) wetting domains against a nonwetting planar poly(FOSM) background, with a "jump percolation" wetting transition when the poly(DMA) domain density reaches unity. Outside of this film thickness range, relatively shallow decreasing water contact angle gradients were observed with a monotonically increasing poly(DMA) domain area coverage with increasing film thickness in the overall range of 40 nm (hydrophobic, θc ≈ 118°) < h < 500 nm (hydrophilic, θc ≈ 8°). The optical diffuse reflectance properties of these rough surfaces exhibit an onset of diffuse reflectance maxima correlated to the transition morphology film thickness.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
ACS Appl Mater Interfaces
Asunto de la revista:
BIOTECNOLOGIA
/
ENGENHARIA BIOMEDICA
Año:
2017
Tipo del documento:
Article
País de afiliación:
Estados Unidos