Effect of Structure Hierarchy for Superhydrophobic Polymer Surfaces Studied by Droplet Evaporation

Nastasia Okulova, Peter Johansen, Lars Christensen, Rafael J. Taboryski*

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

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    Abstract

    Super-hydrophobic natural surfaces usually have multiple levels of structure hierarchy. Here, we report on the effect of surface structure hierarchy for droplet evaporation. The two-level hierarchical structures studied comprise micro-pillars superimposed with nanograss. The surface design is fully scalable as structures used in this study are replicated in polypropylene by a fast roll-to-roll extrusion coating method, which allows effective thermoforming of the surface structures on flexible substrates. As one of the main results, we show that the hierarchical structures can withstand pinning of sessile droplets and remain super-hydrophobic for a longer time than their non-hierarchical counterparts. The effect is documented by recording the water contact angles of sessile droplets during their evaporation from the surfaces. The surface morphology is mapped by atomic force microscopy (AFM) and used together with the theory of Miwa et al. to estimate the degree of water impregnation into the surface structures. Finally, the different behavior during the droplet evaporation is discussed in the light of the obtained water impregnation levels.
    Original languageEnglish
    Article number831
    JournalNanomaterials
    Volume8
    Issue number10
    Number of pages12
    ISSN2079-4991
    DOIs
    Publication statusPublished - 2018

    Keywords

    • Cassie-Baxter
    • Contact angle hysteresis
    • Droplet evaporation
    • Hierarchical structures
    • Super-hydrophobic surfaces

    Cite this

    @article{b48161ae8a9e43778f824c7b40b46f30,
    title = "Effect of Structure Hierarchy for Superhydrophobic Polymer Surfaces Studied by Droplet Evaporation",
    abstract = "Super-hydrophobic natural surfaces usually have multiple levels of structure hierarchy. Here, we report on the effect of surface structure hierarchy for droplet evaporation. The two-level hierarchical structures studied comprise micro-pillars superimposed with nanograss. The surface design is fully scalable as structures used in this study are replicated in polypropylene by a fast roll-to-roll extrusion coating method, which allows effective thermoforming of the surface structures on flexible substrates. As one of the main results, we show that the hierarchical structures can withstand pinning of sessile droplets and remain super-hydrophobic for a longer time than their non-hierarchical counterparts. The effect is documented by recording the water contact angles of sessile droplets during their evaporation from the surfaces. The surface morphology is mapped by atomic force microscopy (AFM) and used together with the theory of Miwa et al. to estimate the degree of water impregnation into the surface structures. Finally, the different behavior during the droplet evaporation is discussed in the light of the obtained water impregnation levels.",
    keywords = "Cassie-Baxter, Contact angle hysteresis, Droplet evaporation, Hierarchical structures, Super-hydrophobic surfaces",
    author = "Nastasia Okulova and Peter Johansen and Lars Christensen and Taboryski, {Rafael J.}",
    year = "2018",
    doi = "10.3390/nano8100831",
    language = "English",
    volume = "8",
    journal = "Nanomaterials",
    issn = "2079-4991",
    publisher = "M D P I AG",
    number = "10",

    }

    Effect of Structure Hierarchy for Superhydrophobic Polymer Surfaces Studied by Droplet Evaporation. / Okulova, Nastasia; Johansen, Peter; Christensen, Lars; Taboryski, Rafael J.

    In: Nanomaterials, Vol. 8, No. 10, 831, 2018.

    Research output: Contribution to journalJournal articleResearchpeer-review

    TY - JOUR

    T1 - Effect of Structure Hierarchy for Superhydrophobic Polymer Surfaces Studied by Droplet Evaporation

    AU - Okulova, Nastasia

    AU - Johansen, Peter

    AU - Christensen, Lars

    AU - Taboryski, Rafael J.

    PY - 2018

    Y1 - 2018

    N2 - Super-hydrophobic natural surfaces usually have multiple levels of structure hierarchy. Here, we report on the effect of surface structure hierarchy for droplet evaporation. The two-level hierarchical structures studied comprise micro-pillars superimposed with nanograss. The surface design is fully scalable as structures used in this study are replicated in polypropylene by a fast roll-to-roll extrusion coating method, which allows effective thermoforming of the surface structures on flexible substrates. As one of the main results, we show that the hierarchical structures can withstand pinning of sessile droplets and remain super-hydrophobic for a longer time than their non-hierarchical counterparts. The effect is documented by recording the water contact angles of sessile droplets during their evaporation from the surfaces. The surface morphology is mapped by atomic force microscopy (AFM) and used together with the theory of Miwa et al. to estimate the degree of water impregnation into the surface structures. Finally, the different behavior during the droplet evaporation is discussed in the light of the obtained water impregnation levels.

    AB - Super-hydrophobic natural surfaces usually have multiple levels of structure hierarchy. Here, we report on the effect of surface structure hierarchy for droplet evaporation. The two-level hierarchical structures studied comprise micro-pillars superimposed with nanograss. The surface design is fully scalable as structures used in this study are replicated in polypropylene by a fast roll-to-roll extrusion coating method, which allows effective thermoforming of the surface structures on flexible substrates. As one of the main results, we show that the hierarchical structures can withstand pinning of sessile droplets and remain super-hydrophobic for a longer time than their non-hierarchical counterparts. The effect is documented by recording the water contact angles of sessile droplets during their evaporation from the surfaces. The surface morphology is mapped by atomic force microscopy (AFM) and used together with the theory of Miwa et al. to estimate the degree of water impregnation into the surface structures. Finally, the different behavior during the droplet evaporation is discussed in the light of the obtained water impregnation levels.

    KW - Cassie-Baxter

    KW - Contact angle hysteresis

    KW - Droplet evaporation

    KW - Hierarchical structures

    KW - Super-hydrophobic surfaces

    U2 - 10.3390/nano8100831

    DO - 10.3390/nano8100831

    M3 - Journal article

    VL - 8

    JO - Nanomaterials

    JF - Nanomaterials

    SN - 2079-4991

    IS - 10

    M1 - 831

    ER -