Research ArticleMATERIALS SCIENCE

Liquid gating elastomeric porous system with dynamically controllable gas/liquid transport

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Science Advances  09 Feb 2018:
Vol. 4, no. 2, eaao6724
DOI: 10.1126/sciadv.aao6724
  • Fig. 1 Preparation and schematics of the LGEPM system.

    Gas is in brown, liquid is in yellow, and LGEPM is in green. EPM is fabricated from EM by laser cutting. Pore sizes in the EPM are rationally controllable. By impregnating a gating liquid in the EPM, LGEPM is formed. To establish a stable LGEPM system, the materials should follow a proper interfacial design. Transport of gas and liquid can be dynamically controlled by deforming the LGEPM. If both ΔPcritical (gas) and ΔPcritical (liquid) are higher than the applied pressure P, neither of them will penetrate the LGEPM. The pore size of LGEPM increases with stretching, and the critical pressure of the transport substance decreases simultaneously. When ΔPcritical (gas) is below P and ΔPcritical (liquid) is above P, only gas permeates the LGEPM. As the stretching process continues, the critical pressure continually drops. When both ΔPcritical (gas) and ΔPcritical (liquid) are lower than P, both gas and liquid flow through the LGEPM. Once the stress is released, the LGEPM recovers to its initial state. The inset shows a microscopic image of an EPM demonstrating a homogeneous pore distribution (scale bar, 500 μm).

  • Fig. 2 Influence of pore size on the transport substance and the feasibility of pore size control.

    (A) Pore size dependence of critical pressure of gas and liquid through the bare EPM. (B) Stress-strain behavior of a nonporous and a porous silicone rubber membrane. (C) Optical micrographs of a pore in EPM during stretching, with the images representing 0 to 100% strain (from left to right).

  • Fig. 3 The wettability, energy critera, and antifouling properties of LGEPM.

    (A) The CA of water, silicone oil, liquid paraffin, and Krytox 103 on silicone rubber, PDMS, and polyurethane membrane. (B) The CA of water on EPM, silicone oil–, liquid paraffin–, and Krytox 103–infused EPM. EPM is silicone rubber. (C) The energy of different configurations and the criteria for a stable and unstable LGEPM system. (D) The comparison of untreated and RB-treated bare EPM and silicone oil–infused EPM. EPM is silicone rubber.

  • Fig. 4 Static mechanical stretching of LGEPM and the critical pressure of gas and liquid during stretching.

    (A) Pore size depedence of the critical pressure of gas and liquid transported through the LGEPM at a certain flow rate (1000 μl/min). Inset is the theoretical model of the critical pressure of LGEPM with different pore sizes at different flow rates. (B) Schematic illustration of one- and two-dimensional stretch applied to the LGEPM, and upon deformation, the LGEPM elongates in the direction of stretching. Inserted figures depict the stress distribution surrounding the pore in the one- and two-dimensional stretching process. Dashed circles represent the initial size of the pores. (C) Critical pressure of gas and liquid flowing through the LGEPM as a function of one-dimensional strain. Insets are the representative optical images of LGEPM during the deformation process. Scale bar, 200 μm. (D) Critical pressure of gas and liquid flowing through the LGEPM in various pore sizes without stretch and with two-dimensional stretch (50% strain biaxially). Gating liquid in (A), (C), and (D) is silicone oil. EPM is silicone rubber.

  • Fig. 5 The durability of LGEPM during static deformation and liquid transport in a dynamic one-dimensional stretching process.

    (A) The transport of gas and liquid can be periodically controlled through the LGEPM system. (B) Transport of liquid in a dynamic deformation process. The inset is a schematic of the LGEPM system. Inserted optical images are the corresponding LGEPM systems under different deformation extent.

  • Fig. 6 Dynamic gas and liquid transport by LGEPM.

    (A) Left: Sketch of the LGEPM in dynamic gas and liquid transport (not to scale). Right: Detailed states of the LGEPM under various strains. (B) Snapshots of the stretching and releasing process. (C) Pressure control for transporting and separating gas and liquid in a dynamic process.

  • Table 1 Comparison of theoretical relationship with experimental results for various porous membrane/gating liquid/transport liquid combinations.

    The parameters are measured at room temperature (25°C). The unit of γA, γB, γAB, ΔEI, and ΔEII is mN/m. The unit of θA and θB is degrees (°). The case number is arranged on the basis of the order of solid materials.

    Case no.Solid materialsTransport liquid (A)Gating liquid (B)γAγBγABθAθBΔE1ΔE2Stable
    system?
    Theo.Exp.
    1Silicone rubberDI waterSilicone oil72.417.442.6115.225.346.5144.1YY
    2Silicone rubberDI waterLiquid paraffin72.429.641.6115.261.341.8126.2YY
    3Silicone rubberLiquid paraffinSilicone oil29.617.40.461.325.32.615.2YY
    4Silicone rubberDI waterKrytox 10372.417.753.7115.239.934.9143.3YY
    5Silicone rubberSilicone oilKrytox 10317.417.79.825.339.9−14.1−4.6NN
    6Silicone rubberLiquid paraffinKrytox 10329.617.711.061.339.9−12.410.6Y/NN
    7PDMSDI waterSilicone oil72.417.442.697.624.08.2105.8YY
    8PDMSDI waterLiquid paraffin72.429.641.697.645.519.0103.4YY
    9PDMSLiquid paraffinSilicone oil29.617.40.445.524.0−10.12.5Y/NN
    10PDMSDI waterKrytox 10372.417.753.797.639.1−7.2101.2Y/NY
    11PDMSSilicone oilKrytox 10317.417.79.824.039.1−14.1−4.6NN
    12PDMSLiquid paraffinKrytox 10329.617.711.045.539.1−25.1−2.2NN
    13PolyurethaneDI waterSilicone oil72.417.442.673.311.9−50.247.4Y/NN
    14PolyurethaneDI waterLiquid paraffin72.429.641.673.323.3−28.955.5Y/NN
    15PolyurethaneLiquid paraffinSilicone oil29.617.40.423.311.9−20.7−8.1NN
    16PolyurethaneDI waterKrytox 10372.417.753.773.337.0−67.141.3Y/NN
    17PolyurethaneSilicone oilKrytox 10317.417.79.811.937.0−15.6−6.1NN
    18PolyurethaneLiquid paraffinKrytox 10329.617.711.023.337.0−37.1−14.2NN

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/2/eaao6724/DC1

    section S1. Multiple methods to fabricate porous membranes with various pore sizes on different EMs.

    section S2. The theoretical model agrees with the experimental critical pressure at a series of flow rates.

    section S3. Deformation of EPM under one- or two-dimensional stretch.

    section S4. Critical pressure change in various LGEPM systems.

    section S5. Durability of the LGEPM system.

    section S6. Uniformity of the EPMs during deformation.

    fig. S1. The fabrication of EPM by CO2 laser cutting and its morphology.

    fig. S2. The image of a whole silicone rubber membrane with nine pores in the center.

    fig. S3. The fabrication of EPM by femtosecond laser cutting and its morphology.

    fig. S4. The fabrication of porous PDMS membrane by Si replica molding method and its morphology.

    fig. S5. The experimental and theoretical models of critical pressure of water transporting through the LGEPM at different flow rates.

    fig. S6. Stress distribution of the elastomeric multiporous membrane.

    fig. S7. Different pressure change via different deformation extent.

    fig. S8. Critical pressure change of bare silicone rubber membranes in a static stretching process.

    fig. S9. Critical pressure change of silicone oil–infused silicone rubber membranes in a static stretching process.

    fig. S10. Critical pressure change of liquid paraffin–infused silicone rubber membranes in a static stretching process.

    fig. S11. Critical pressure of water passing through different gating liquids in two types of membrane materials.

    fig. S12. The pressure of gas and liquid after cycles of stretch and relaxation.

    fig. S13. Images of nonstretched and stretched EPMs.

    fig. S14. Different pore size distribution leads to different gating performance.

    movie S1. Preparation and mechanism of LGEPM system.

    movie S2. One-dimensional stretching of EPM.

    movie S3. Dynamic deformation of LGEPM.

    movie S4. Dynamic gas and liquid separation process by LGEPM.

  • Supplementary Materials

    This PDF file includes:

    • section S1. Multiple methods to fabricate porous membranes with various pore sizes on different EMs.
    • section S2. The theoretical model agrees with the experimental critical pressure at a series of flow rates.
    • section S3. Deformation of EPM under one- or two-dimensional stretch.
    • section S4. Critical pressure change in various LGEPM systems.
    • section S5. Durability of the LGEPM system.
    • section S6. Uniformity of the EPMs during deformation.
    • fig. S1. The fabrication of EPM by CO2 laser cutting and its morphology.
    • fig. S2. The image of a whole silicone rubber membrane with nine pores in the center.
    • fig. S3. The fabrication of EPM by femtosecond laser cutting and its morphology.
    • fig. S4. The fabrication of porous PDMS membrane by Si replica molding method and its morphology.
    • fig. S5. The experimental and theoretical models of critical pressure of water transporting through the LGEPM at different flow rates.
    • fig. S6. Stress distribution of the elastomeric multiporous membrane.
    • fig. S7. Different pressure change via different deformation extent.
    • fig. S8. Critical pressure change of bare silicone rubber membranes in a static stretching process.
    • fig. S9. Critical pressure change of silicone oil–infused silicone rubber membranes in a static stretching process.
    • fig. S10. Critical pressure change of liquid paraffin–infused silicone rubber membranes in a static stretching process.
    • fig. S11. Critical pressure of water passing through different gating liquids in two types of membrane materials.
    • fig. S12. The pressure of gas and liquid after cycles of stretch and relaxation.
    • fig. S13. Images of nonstretched and stretched EPMs.
    • fig. S14. Different pore size distribution leads to different gating performance.
    • Legends for movies S1 to S4

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mp4 format). Preparation and mechanism of LGEPM system.
    • movie S2 (.mp4 format). One-dimensional stretching of EPM.
    • movie S3 (.mp4 format). Dynamic deformation of LGEPM.
    • movie S4 (.mp4 format). Dynamic gas and liquid separation process by LGEPM.

    Files in this Data Supplement: