Improved aging performance of vapor phase deposited hydrophobic self-assembled monolayers

Gnanappa, Arun Kumar; O'Murchu, Cian; Slattery, Orla; Peters, Frank; O'Hara, Tony; Aszalós-Kiss, Balázs; Tofail, Syed A. M.

doi:10.1016/j.apsusc.2010.12.052

Cited by 18 publications

(23 citation statements)

References 21 publications

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“…AFM imaging was used to further characterize the gradient t-F8H2 modification. For example, AFM results (Figure S2) demonstrated that when the deposition distance was 28 mm away from the vapor source, little t-F8H2 reacted onto the surface and the substrate was very smooth, which agrees well with the CA measurement of a slight increase to 26°. In addition, XPS demonstrated that F 1s and C 1s originating from t-F8H2 were low, 1.25 and 19.23% respectively.…”

Section: Results and Discussionsupporting

confidence: 75%

Controlling the Accumulation of Water at Oil–Solid Interfaces with Gradient Coating

Yang

Mei

et al. 2017

J. Phys. Chem. B

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In this work, we demonstrate a strategy to control the accumulation of water in the oil-solid interface using a gradient coating. Gradient chemistry on glass surface is created by vapor diffusion of organosilanes, leading to a range of contact angles from 110 to 20°. Hexadecane is placed on the gradient substrate as an oil layer, forming a "water/hexadecane/gradient solid substrate" sandwich structure. During incubation, water molecules spontaneously migrate through the micrometer-thick oil layer and result in the formation of micrometer-sized water droplets at the oil-solid interface. It turns out that water droplets at more hydrophobic regions tend to be closer to a regular spherical shape, which is attributed to their higher contact angle with the hydrophobic substrate. However, along the gradient from hydrophobic to hydrophilic, the water droplets gradually form more irregular shapes, as hydrophilic surfaces pin the edges of droplets to form a distorted morphology. It indicates that more hydrophilic surfaces containing more Si-OH groups lead to a higher electrostatic interaction with water and a higher growth rate of interfacial water droplets. This work provides further insights into the mechanism of spontaneous water accumulation at oil-solid interfaces and assists in the rational design for controlling such interfacial phenomenon.

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Section: Results and Discussionsupporting

confidence: 75%

Controlling the Accumulation of Water at Oil–Solid Interfaces with Gradient Coating

Yang

Mei

et al. 2017

J. Phys. Chem. B

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“…The substrates were then immediately placed in a vacuum chamber (Labconco) for 8 h with a vial containing 40 μL of trichloro(1 H ,1 H ,2 H ,2 H -perfluorooctyl)silane (Sigma-Aldrich). The fluorinated trichlorosilane vapor reacts with the OH groups to form hydrophobic carbon fiber surfaces. , A vapor phase deposition technique was chosen to form a hydrophobic layer with the eGDLs due to the ability of vapor to penetrate the small porous structures (∼100–600 nm pores) of the eGDL material. Liquid phase deposition techniques are not as ideal for the eGDL as the solutions may not uniformly penetrate the material due to presence of microscopic air bubbles …”

Section: Methodsmentioning

confidence: 99%

Designing Tailored Gas Diffusion Layers with Pore Size Gradients via Electrospinning for Polymer Electrolyte Membrane Fuel Cells

Balakrishnan

Shrestha

Gao

et al. 2020

ACS Appl. Energy Mater.

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We present electrospinning as a versatile technique to design and fabricate tailored polymer electrolyte membrane (PEM) fuel cell gas diffusion layers (GDLs) with a pore-size gradient (increasing from catalyst layer to flow field) to enhance the high current density performance and water management behavior of a PEM fuel cell. The novel graded electrospun GDL exhibits highly robust performance over a range of inlet gas relative humidities (RH). At relatively dry (50% RH) inlet conditions that exacerbate ohmic losses, the graded GDL lowers ohmic resistance and improves high current density performance compared to a uniform GDL with larger pores and fiber diameters. Specifically, the graded GDL facilitates a beneficial degree of liquid water retention at the catalyst layer/GDL interface due to the high capillary pressure inherent in its microstructure, thereby improving membrane hydration. Additionally, enhanced graphitization and connectivity of the graded electrospun fibers improves heat dissipation from the catalyst layer interface compared to the GDL with larger fiber diameters, thereby reducing membrane dehydration. When the inlet RH is raised to fully humid (100% RH) conditions, the graded GDL mitigates liquid water accumulation and lowers mass transport resistance. Specifically, the pore size gradient directs the removal of liquid water from the GDL, resulting in superior performance at high current densities.

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Section: Plasma Fluoropolymer (Pfp)mentioning

confidence: 99%

“…Others have used a vacuum annealing step at 100°C to slow the aging of the perfluorocyclobutane pp . Vacuum annealing cracked the outermost CF 3 of the pfp to CF 2 and CF moieties to reduce over‐layer formation and maintain their high surface energy . In order to eliminate the influence of atmospheric oxygen, an in‐situ XPS analysis has also been carried out directly on as‐deposited octafluorocyclobutane and trifluoromethane pps .…”

Section: Plasma Fluoropolymer (Pfp)mentioning

confidence: 99%

Low pressure plasma modifications for the generation of hydrophobic coatings for biomaterials applications

Siow

2018

Plasma Processes & Polymers

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This review focuses on low-pressure plasma modification methods to produce hydrophobic coatings and surface modifications on biomaterials. Plasma-deposited fluoropolymer, siloxane, and diamond-like carbon (DLC) coatings are reviewed in terms of process developments, monomers used, stability and aging properties, and their behavior in adsorption of proteins, cell attachment, and bacterial adhesion. These hydrophobic coatings are stable with correct selection of monomers and process conditions, but the plasma polymerized siloxane and fluorocarbons have been mainly applied in biochip and test kits rather than in blood-contact applications. Similarly, the surface characteristics and interfacial bonding of DLC coatings play a crucial role in their successful implementation. K E Y W O R D S aging, diamond-like carbon (DLC), fluoropolymers, hydrophobic coatings, siloxane coatings Plasma Process Polym. 2018;15:e1800059. www.plasma-polymers.com

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Improved aging performance of vapor phase deposited hydrophobic self-assembled monolayers

Cited by 18 publications

References 21 publications

Controlling the Accumulation of Water at Oil–Solid Interfaces with Gradient Coating

Controlling the Accumulation of Water at Oil–Solid Interfaces with Gradient Coating

Designing Tailored Gas Diffusion Layers with Pore Size Gradients via Electrospinning for Polymer Electrolyte Membrane Fuel Cells

Low pressure plasma modifications for the generation of hydrophobic coatings for biomaterials applications

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