Compatibilizing hydrophilic and hydrophobic polymers <i>via</i> spray coating for desalination

Meng, Junquan; Lau, Cher Hon; Xue, Yufei; Zhang, Rui; Cao, Bing; Li, Yuan

doi:10.1039/d0ta00871k

Cited by 68 publications

(30 citation statements)

References 47 publications

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“…Compared with solutionbased membrane modification such as spray-coating, [13a,18] this vapor-based modification did not involve wetting or dewetting, thus no need to overcome the large surface energy difference between the hydrophilic and hydrophobic components. [16][17][18] The asymmetric deposition of P(MAA-co-EGDA) and PHDFA was confirmed using FTIR spectroscopy. As shown in Figure 2, the absorption peaks at 1735, 1201, and 1147 cm −1 are assigned to the stretching of CO, CF 3 , and CF 2 functional groups in PHDFA, respectively.…”

Section: Fabrication and Characterization Of Janus Membranesmentioning

confidence: 99%

“…[11][12][13][14] In addition, the conflicting wettability of hydrophilic and hydrophobic components made the solvent-based methods less effective and resulted in poor interfacial compatibility. [18] To facilitate the attaching of hydrophilic coatings onto the liquid-repelling hydrophobic structure, protocols such as plasma activation, [16] chemical modification, [19] Janus membranes with excellent fouling resistance and mass transport properties are highly desired to improve the performance and efficiency in the treatment of oil-contaminated wastewater. The fabrication of Janus membranes requires control of both the membrane microstructure and the interfacial compatibility between distinct components.…”

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confidence: 99%

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Vapor‐Deposited Janus Membranes with Fouling Resistance for Desalination of Oil‐Contaminated Wastewater

Zhu

Mao

2021

Adv Materials Inter

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However, the hydrophobicity of conventional MD membranes makes them vulnerable to fouling when treating saline water containing organic compounds. [5] Taking the produced water as an example, total dissolved organic carbon up to 5 g L −1 has been reported. [6] The organic contaminants not only block membrane pores, but also lead to membrane wetting by the low-surface-tension compounds, resulting in the reduction of both permeate flux and desalination efficiency during MD operations. [5b] To alleviate the fouling problem, surfaces with ultralow surface energy were constructed to repel both water and lowsurface-tension compounds. [2b,7] The omniphobicity prevented membrane from oil fouling when treating feed solution with 10 mg L −1 oil. [8] However, the permeate flux of the omniphobic membranes declined as oil concentration increased to 80 mg L −1 , [9] indicating the limitation in improving MD fouling resistance by merely reducing membrane surface energy.Membranes with the combination of hydrophilic surface and hydrophobic structure present the advantage of repelling oil foulants while maintaining the wetting resistance. [10] Such Janus membranes have been directly fabricated by forming layers with opposite wettability via sequential electrospinning [11] or postcasting phase separation, [12] but materials available for direct asymmetric fabrication were quite limited. Asymmetric modification of the hydrophobic MD membranes has been studied as an alternative for the preparation of Janus membranes. A variety of hydrophilic polymers, including chitosan, [13] polydopamine, [14] polyvinyl alcohol, [15] and zwitterionic polymers, [16] were selectively processed onto MD membranes using solvent-based methods such as spray-and dip-coating. Chemical reaction in alkaline solution has also been reported to introduce hydrophilicity to the MD membrane surface. [17] Despite these advances, several challenges remained in the asymmetric modification of MD membranes. The hydrophilic modification usually required polymer preparation and/or processing in various solvents for long periods of time, [14,16] and post-treatments were often needed to remove the solvent residue and cure the coatings. [11][12][13][14] In addition, the conflicting wettability of hydrophilic and hydrophobic components made the solvent-based methods less effective and resulted in poor interfacial compatibility. [18] To facilitate the attaching of hydrophilic coatings onto the liquid-repelling hydrophobic structure, protocols such as plasma activation, [16] chemical modification, [19] Janus membranes with excellent fouling resistance and mass transport properties are highly desired to improve the performance and efficiency in the treatment of oil-contaminated wastewater. The fabrication of Janus membranes requires control of both the membrane microstructure and the interfacial compatibility between distinct components. This work presents a vapor-based strategy to incorporate Janus property into porous substrates without the wetting incompatibility in solut...

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Section: Fabrication and Characterization Of Janus Membranesmentioning

confidence: 99%

mentioning

confidence: 99%

Vapor‐Deposited Janus Membranes with Fouling Resistance for Desalination of Oil‐Contaminated Wastewater

Zhu

Mao

2021

Adv Materials Inter

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“…Over the last two decades, membrane-based separation technologies have attracted a great deal of attention because they have merits such as high energy efficiency, low capital investment, 1 environmentally friendly, simple operation, and small footprint. [2][3][4] However, in harsh operational conditions such as natural gas purification 5 or recovery of landfill gas, conventional polymeric membranes may undergo physical aging or plasticization that deteriorates the gas separation property. 1,6 Therefore, it is necessary to develop membranes having a better stability in extreme conditions.…”

Section: Introductionmentioning

confidence: 99%

Carbon molecular sieve hollow fiber composite membrane derived from PMDA-ODA polyimide for gas separation

Yang

Chen

2022

High Performance Polymers

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Carbon molecular sieve (CMS) membranes have excellent gas separation property over conventional polymeric membranes and superior anti-swelling property. PMDA-ODA polyimide has high thermal stability and good mechanical property. It has been extensively adopted as the precursor of CMS membrane. However, due to the insoluble nature, PMDA-ODA CMS membranes are limited to configurations like dense symmetric films or composite membranes using porous inorganic or metal substrates. In this work, CMS hollow fiber composite membranes based on an asymmetric PMDA-ODA hollow fiber were successfully prepared for the first time. The neat PMDA-ODA hollow fiber membrane was crosslinked by polyethyleneimine to alleviate pore collapsing during carbonization and then dip-coated by a PMDA-ODA PAA solution to seal the surface defects. The PDMA-ODA CMS composite hollow fiber membranes showed gas permeances of 93.4 GPU, 19.6 GPU, 6.5 GPU, and 4.7 GPU for CO2, O2, N2, and CH4, respectively, with an ideal selectivity of 14.4, 3.0, and 19.8 for CO2/N2, O2/N2, and CO2/CH4 gas pairs, respectively. The attractive gas separation property shows a great potential for industrial application.

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“…They showed that, through the force balance analysis, the thin air film via the dimple affects the droplet's bouncing regardless of the surface's wettability. Furthermore, in industrial technologies such as a solution-based process, e.g., printing or spray coating, the air film caused by the dimple can reduce the mechanical adhesion of the deposited layer or be an obstacle such as a pinhole defect to hinder electrical/chemical performance of the device [20][21][22]. To sum up, irrespective of the field that the droplet coalescence happens, the air film (dimple) becomes a significant factor that cannot be ignorable in droplet coalescence.…”

Section: Introductionmentioning

confidence: 99%

The Role of Electric Pressure/Stress Suppressing Pinhole Defect on Coalescence Dynamics of Electrified Droplet

et al. 2021

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The dimple occurs by sudden pressure inversion at the droplet’s bottom interface when a droplet collides with the same liquid-phase or different solid-phase. The air film entrapped inside the dimple is a critical factor affecting the sequential dynamics after coalescence and causing defects like the pinhole. Meanwhile, in the coalescence dynamics of an electrified droplet, the droplet’s bottom interfaces change to a conical shape, and droplet contact the substrate directly without dimple formation. In this work, the mechanism for the dimple’s suppression (interfacial change to conical shape) was studied investigating the effect of electric pressure. The electric stress acting on a droplet interface shows the nonlinear electric pressure adding to the uniform droplet pressure. This electric stress locally deforms the droplet’s bottom interface to a conical shape and consequentially enables it to overcome the air pressure beneath the droplet. The electric pressure, calculated from numerical tracking for interface and electrostatic simulation, was at least 108 times bigger than the air pressure at the center of the coalescence. This work helps toward understanding the effect of electric stress on droplet coalescence and in the optimization of conditions in solution-based techniques like printing and coating.

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Compatibilizing hydrophilic and hydrophobic polymers via spray coating for desalination

Abstract: The incompatibility between PVA and PTFE layers was overcome by spray-coating and the PVA/PTFE composite membrane showed excellent desalination properties in both PV and DCMD experiments.

Cited by 68 publications

References 47 publications

Vapor‐Deposited Janus Membranes with Fouling Resistance for Desalination of Oil‐Contaminated Wastewater

Vapor‐Deposited Janus Membranes with Fouling Resistance for Desalination of Oil‐Contaminated Wastewater

Carbon molecular sieve hollow fiber composite membrane derived from PMDA-ODA polyimide for gas separation

The Role of Electric Pressure/Stress Suppressing Pinhole Defect on Coalescence Dynamics of Electrified Droplet

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