Hierarchically textured superhydrophilic polyvinylidene fluoride membrane <i>via</i> nanocasting and post-fabrication grafting of surface-tailored silica nanoparticles

Chen, Guanhao; Ma, Zhibo; Xiao, Kang; Wang, Xiaomao; Liang, Shuai; Huang, Xia

doi:10.1039/c9en00983c

Cited by 9 publications

(8 citation statements)

References 46 publications

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“…The addition of the CNT layer contributed to a denser surface (Figure S4) and small protrusions (Figure d, i) compared to the control (PVDF). There were microsized protrusions of irregular size (varying from 1 to 10 μm) not homogeneously distributed on the surface, unlike the homogeneous and regular micronano hierarchical structures reported in the lotus leaf . In zoomed-in images (the higher-magnification inset) for the PVDF-CNT membrane, CNT fibers were found to be randomly cross-linked, coiled on the membrane surface.…”

Section: Results and Discussionmentioning

confidence: 75%

“…There were microsized protrusions of irregular size (varying from 1 to 10 μm) not homogeneously distributed on the surface, unlike the homogeneous and regular micronano hierarchical structures reported in the lotus leaf. 48 In zoomed-in images (the higher-magnification inset) for the PVDF-CNT membrane, CNT fibers were found to be randomly cross-linked, coiled on the membrane surface. Again, after fluorination these CNT fibers appears swollen (Figure 4 e, j), in (d,i)) and fluorinated of the CNT-coated PVDF (PVDF-CNT-FAS, (e,j and m)) in ×3000 magnification (first row) and in ×10000 magnification (second row), respectively.…”

Section: Resultsmentioning

confidence: 99%

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Beneficial CNT Intermediate Layer for Membrane Fluorination toward Robust Superhydrophobicity and Wetting Resistance in Membrane Distillation

Wang

Han

Yao

et al. 2020

ACS Appl. Mater. Interfaces

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Robust membrane hydrophobicity is crucial in membrane distillation (MD) to produce clean water, yet challenged by wetting phenomenon. We herein proposed a robust superhydrophobization process, by making use of a carbon nanotube (CNT) intermediate layer over commercial hydrophobic membrane, indirectly grafting the low-surface-energy material 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS), with the achieved membrane denoted as PVDF-CNT-FAS, in systematic comparison with direct grafting FAS on alkalinized PVDF denoted as PVDF-OH-FAS. Superhydrophobicity with water contact angle of 180° was easily achieved from initial hydrophilic interface for both two resultant membranes. Interestingly, the existence of a CNT intermediate layer significantly maintained the stable hydrophobicity in various harsh conditions and improved mechanical properties, at an expense of ca. 20% smaller pore size and extended membrane thickness than PVDF-OH-FAS. In the MD experiment, the PVDF-CNT-FAS exhibited no vapor flux sacrifice, giving constant flux with the control and doubled that for PVDF-OH-FAS. A mass-heat transfer modeling suggested no significant heat loss but facilitated vapor flux with the CNT layer, unlike the impeded transfer for the counterpart membrane. A superior wetting resistance against 0.4 mM SDS further confirmed the benefit of constructing the CNT intermediate layer, presumably because of its excellent slippery property. This study demonstrates the important role of the CNT intermediate layer toward robust superhydrophobic membrane, suggesting the interest of applying the functional nanomaterial for controllable interface design.

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Section: Results and Discussionmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Beneficial CNT Intermediate Layer for Membrane Fluorination toward Robust Superhydrophobicity and Wetting Resistance in Membrane Distillation

Wang

Han

Yao

et al. 2020

ACS Appl. Mater. Interfaces

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“…Therefore, as observed in Figure 3B,C, the SSM/PPY(AOT) membrane exhibited higher micro-roughness in the oxidization state than in the reduction state. Such increased roughness could inhibit complete contact between water and membrane surfaces, resulting in increased water contact angles [11,39,45].…”

Section: Reversible Wettability Switchingmentioning

confidence: 99%

Antifouling Conductive Composite Membrane with Reversible Wettability for Wastewater Treatment

Gao

Zhang

et al. 2022

Membranes

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Membrane fouling severely hinders the sustainable development of membrane separation technology. Membrane wetting property is one of the most important factors dominating the development of membrane fouling. Theoretically, a hydrophilic membrane is expected to be more resistant to fouling during filtration, while a hydrophobic membrane with low surface energy is more advantageous during membrane cleaning. However, conventional membrane materials do not possess the capability to change their wettability on demand. In this study, a stainless steel mesh–sulfosuccinate-doped polypyrrole composite membrane (SSM/PPY(AOT)) was prepared. By applying a negative or positive potential, the surface wettability of the membrane can be switched between hydrophilic and relatively hydrophobic states. Systematic characterizations and a series of filtration experiments were carried out. In the reduction state, the sulfonic acid groups of AOT were more exposed to the membrane surface, rendering the surface more hydrophilic. The fouling filtration experiments verified that the membrane is more resistant to fouling in the hydrophilic state during filtration and easier to clean in the hydrophobic state during membrane cleaning. Furthermore, Ca2+ and Mg2+ could complex with foulants, aggravating membrane fouling. Overall, this study demonstrates the importance of wettability switching in membrane filtration and suggests promising applications of the SSM/PPY(AOT) membrane.

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“…This is attributed to the wrinkled structure and high surface energy of the composite surface effectively increased its affinity with water. [42][43]…”

Section: Fabrication Of Oriented Wrinkles On Anisotropic Pda/semi-pdm...mentioning

confidence: 99%

Spontaneous Formation of Oriented Lateral Wrinkles Assisted by Shrinkage Controlled Cracking

Liu

Shan

Yang

et al. 2022

Adv Materials Inter

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tunable optical devices, [8][9] and as structured templates for surface arrays, [10][11] etc. Therefore, the fabrication of oriented wrinkles is of great importance.Wrinkling occurs to release the compressive stresses caused by the lateral stresses generated between the two layers of a rigid capping layer/soft substrate. [12][13] The lateral stresses (e.g., thermal stresses) can induce changes in the surface morphology of common bilayer or multilayer composites (e.g., aluminum (Al)/poly dimethylsiloxane (PDMS), Al/polystyrene (PS)/silicon (Si)) which can be considered as infinite-planar 2D systems compared to the wavelength of the surface wrinkles. In such systems, surface wrinkles do not have any preferred orientation (i.e., disordered wrinkles), since the direction of the lateral stresses between the layers is on average, isotropic. However, when anisotropy of the lateral stresses between layers is introduced, the lateral stresses are first concentrated and accumulate in a certain region or along edges with topographic features, the detailed process being related to how anisotropy is introduced. When these accumulated lateral stresses are released anisotropically, making a change in the wrinkled orientation. [12][13][14] Therefore, the introduction of anisotropy of the lateral stresses is essential for the formation of oriented wrinkles.Currently, there are three main approaches to introduce the anisotropy of the lateral stresses for the generation of oriented wrinkles, one is to use patterned templates. [12,[15][16][17] Wang et al. prepared oriented wrinkles on a polydopamine (PDA)/PS bilayer film patterned with microgrooves by thermal annealing where the lateral stresses were preferentially concentrated and released at the edges of the groove patterns. [12] Qian et al. placed PDMS molds with striped relief structures as a confine on the PS/polyvinilpyrrolidone (PVP)/Si surface. The PVP layer subjected to water vapor changes to a viscous state, resulting in a mismatch in the Young's modulus of PS/PVP, when the diffusion forces accumulated along the edges of the mold are dedicated to releasing the compressive stress in a specified direction and the highly oriented wrinkles will be generated. [16] The second approach is by laser or plasma treatment. [13,[18][19][20] Okayasu et al. introduced a series of parallel striped cracks with different spacing dimensions on a silicon substrate through a standard photolithography process. During the heat treatment process, the lateral stresses perpendicular to the stripe direction could be anisotropically released in strain concentrations at the Oriented wrinkled surfaces play a vital role in the preparation of functional components. However, existing methods for the fabrication of oriented wrinkle patterns are often limited by specific equipment (e.g., high vacuum systems) and cumbersome processes. In this study, an approach utilizing shrinkage controlled cracking method is proposed to introduce prefabricated topographic patterns on flat semi-crosslinked polydimethylsiloxa...

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Hierarchically textured superhydrophilic polyvinylidene fluoride membrane via nanocasting and post-fabrication grafting of surface-tailored silica nanoparticles

Abstract: The prepared hierarchical superhydrophilic membrane exhibited a remarkable antifouling capability owing to dual protection: in situ hydration layer and peripheral turbulent flow.

Cited by 9 publications

References 46 publications

Beneficial CNT Intermediate Layer for Membrane Fluorination toward Robust Superhydrophobicity and Wetting Resistance in Membrane Distillation

Beneficial CNT Intermediate Layer for Membrane Fluorination toward Robust Superhydrophobicity and Wetting Resistance in Membrane Distillation

Antifouling Conductive Composite Membrane with Reversible Wettability for Wastewater Treatment

Spontaneous Formation of Oriented Lateral Wrinkles Assisted by Shrinkage Controlled Cracking

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