In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications

Lanhui Li, Zhibin Yan, Mingliang Jin, Xiangshen You, Shuting Xie, Zhenping Liu, Albert van den Berg, Jan C.T. Eijkel, Lingling Shui*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    4 Citations (Scopus)
    19 Downloads (Pure)

    Abstract

    We report on a simple approach for in-channel functionalization of a polydimethylsiloxane (PDMS) surface to obtain a switchable and reversible wettability change between hydrophilic and hydrophobic states. The thermally responsive polymer, poly(N-Isopropylacrylamide) (PNIPAAm), was grafted on the surface of PDMS channels by UV-induced surface grafting. PNIPAAm-grafted PDMS (PNIPAAm-g-PDMS) surface wettability can be thermally tuned to obtain water contact angles varying in the range of 24.3 to 106.1° by varying temperature at 25-38 °C. By selectively modifying the functionalized area in the microfluidic channels, multiform emulsion droplets of oil-in-water (O/W), water-in-oil (W/O), oil-in-water-in-oil (O/W/O), and water-in-oil-in-water (W/O/W) could be created on-demand. Combining solid surface wettability and liquid-liquid interfacial properties, tunable generation of O/W and W/O droplet and stratified flows were enabled in the same microfluidic device with either different or the same two-phase fluidic systems, by properly heating/cooling thermal-responsive microfluidic channels and choosing suitable surfactants. Controllable creation of O/W/O and W/O/W droplets was also achieved in the same microfluidic device, by locally heating or cooling the droplet generation areas with integrated electric heaters to achieve opposite surface wettability. Hollow microcapsules were prepared using double emulsion droplets as templates in the microfluidic device with sequential hydrophobic and hydrophilic channel segments, demonstrating the strength of the proposed approach in practical applications.

    Original languageEnglish
    Pages (from-to)16934-16943
    Number of pages10
    JournalACS Applied Materials and Interfaces
    Volume11
    Issue number18
    DOIs
    Publication statusPublished - 8 May 2019

    Fingerprint

    Emulsions
    Wetting
    Oils
    Water
    Microfluidics
    Polydimethylsiloxane
    Cooling
    Heating
    Liquids
    Fluidics
    Surface-Active Agents
    Contact angle
    Capsules
    Polymers
    Surface active agents

    Keywords

    • Droplet
    • Microcapsule
    • Microfluidics
    • Multi-emulsion
    • Reversible emulsion
    • Surface wettability
    • Thermoresponsive

    Cite this

    Li, Lanhui ; Yan, Zhibin ; Jin, Mingliang ; You, Xiangshen ; Xie, Shuting ; Liu, Zhenping ; van den Berg, Albert ; Eijkel, Jan C.T. ; Shui, Lingling. / In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications. In: ACS Applied Materials and Interfaces. 2019 ; Vol. 11, No. 18. pp. 16934-16943.
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    title = "In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications",
    abstract = "We report on a simple approach for in-channel functionalization of a polydimethylsiloxane (PDMS) surface to obtain a switchable and reversible wettability change between hydrophilic and hydrophobic states. The thermally responsive polymer, poly(N-Isopropylacrylamide) (PNIPAAm), was grafted on the surface of PDMS channels by UV-induced surface grafting. PNIPAAm-grafted PDMS (PNIPAAm-g-PDMS) surface wettability can be thermally tuned to obtain water contact angles varying in the range of 24.3 to 106.1° by varying temperature at 25-38 °C. By selectively modifying the functionalized area in the microfluidic channels, multiform emulsion droplets of oil-in-water (O/W), water-in-oil (W/O), oil-in-water-in-oil (O/W/O), and water-in-oil-in-water (W/O/W) could be created on-demand. Combining solid surface wettability and liquid-liquid interfacial properties, tunable generation of O/W and W/O droplet and stratified flows were enabled in the same microfluidic device with either different or the same two-phase fluidic systems, by properly heating/cooling thermal-responsive microfluidic channels and choosing suitable surfactants. Controllable creation of O/W/O and W/O/W droplets was also achieved in the same microfluidic device, by locally heating or cooling the droplet generation areas with integrated electric heaters to achieve opposite surface wettability. Hollow microcapsules were prepared using double emulsion droplets as templates in the microfluidic device with sequential hydrophobic and hydrophilic channel segments, demonstrating the strength of the proposed approach in practical applications.",
    keywords = "Droplet, Microcapsule, Microfluidics, Multi-emulsion, Reversible emulsion, Surface wettability, Thermoresponsive",
    author = "Lanhui Li and Zhibin Yan and Mingliang Jin and Xiangshen You and Shuting Xie and Zhenping Liu and {van den Berg}, Albert and Eijkel, {Jan C.T.} and Lingling Shui",
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    In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications. / Li, Lanhui; Yan, Zhibin; Jin, Mingliang; You, Xiangshen; Xie, Shuting; Liu, Zhenping; van den Berg, Albert; Eijkel, Jan C.T.; Shui, Lingling.

    In: ACS Applied Materials and Interfaces, Vol. 11, No. 18, 08.05.2019, p. 16934-16943.

    Research output: Contribution to journalArticleAcademicpeer-review

    TY - JOUR

    T1 - In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications

    AU - Li, Lanhui

    AU - Yan, Zhibin

    AU - Jin, Mingliang

    AU - You, Xiangshen

    AU - Xie, Shuting

    AU - Liu, Zhenping

    AU - van den Berg, Albert

    AU - Eijkel, Jan C.T.

    AU - Shui, Lingling

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    N2 - We report on a simple approach for in-channel functionalization of a polydimethylsiloxane (PDMS) surface to obtain a switchable and reversible wettability change between hydrophilic and hydrophobic states. The thermally responsive polymer, poly(N-Isopropylacrylamide) (PNIPAAm), was grafted on the surface of PDMS channels by UV-induced surface grafting. PNIPAAm-grafted PDMS (PNIPAAm-g-PDMS) surface wettability can be thermally tuned to obtain water contact angles varying in the range of 24.3 to 106.1° by varying temperature at 25-38 °C. By selectively modifying the functionalized area in the microfluidic channels, multiform emulsion droplets of oil-in-water (O/W), water-in-oil (W/O), oil-in-water-in-oil (O/W/O), and water-in-oil-in-water (W/O/W) could be created on-demand. Combining solid surface wettability and liquid-liquid interfacial properties, tunable generation of O/W and W/O droplet and stratified flows were enabled in the same microfluidic device with either different or the same two-phase fluidic systems, by properly heating/cooling thermal-responsive microfluidic channels and choosing suitable surfactants. Controllable creation of O/W/O and W/O/W droplets was also achieved in the same microfluidic device, by locally heating or cooling the droplet generation areas with integrated electric heaters to achieve opposite surface wettability. Hollow microcapsules were prepared using double emulsion droplets as templates in the microfluidic device with sequential hydrophobic and hydrophilic channel segments, demonstrating the strength of the proposed approach in practical applications.

    AB - We report on a simple approach for in-channel functionalization of a polydimethylsiloxane (PDMS) surface to obtain a switchable and reversible wettability change between hydrophilic and hydrophobic states. The thermally responsive polymer, poly(N-Isopropylacrylamide) (PNIPAAm), was grafted on the surface of PDMS channels by UV-induced surface grafting. PNIPAAm-grafted PDMS (PNIPAAm-g-PDMS) surface wettability can be thermally tuned to obtain water contact angles varying in the range of 24.3 to 106.1° by varying temperature at 25-38 °C. By selectively modifying the functionalized area in the microfluidic channels, multiform emulsion droplets of oil-in-water (O/W), water-in-oil (W/O), oil-in-water-in-oil (O/W/O), and water-in-oil-in-water (W/O/W) could be created on-demand. Combining solid surface wettability and liquid-liquid interfacial properties, tunable generation of O/W and W/O droplet and stratified flows were enabled in the same microfluidic device with either different or the same two-phase fluidic systems, by properly heating/cooling thermal-responsive microfluidic channels and choosing suitable surfactants. Controllable creation of O/W/O and W/O/W droplets was also achieved in the same microfluidic device, by locally heating or cooling the droplet generation areas with integrated electric heaters to achieve opposite surface wettability. Hollow microcapsules were prepared using double emulsion droplets as templates in the microfluidic device with sequential hydrophobic and hydrophilic channel segments, demonstrating the strength of the proposed approach in practical applications.

    KW - Droplet

    KW - Microcapsule

    KW - Microfluidics

    KW - Multi-emulsion

    KW - Reversible emulsion

    KW - Surface wettability

    KW - Thermoresponsive

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    U2 - 10.1021/acsami.9b03160

    DO - 10.1021/acsami.9b03160

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