Physical organic probes of interfacial wettability reveal the importance of surface dipole effects

Colorado, Ramon; Lee, T. Randall

doi:10.1002/1099-1395(200012)13:12<796::aid-poc317>3.0.co;2-#

Cited by 58 publications

(109 citation statements)

References 33 publications

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“… 16 − 18 PTFE-based films are well-recognized antiadhesive materials with desirable interfacial properties, such as low wettability, low friction, and low adhesion. 2 , 19 − 21 Consequently, the introduction of fluorocarbon segments in nanostructured thin films (1–2 nm thickness) can lead to materials with unique interfacial properties that limit the biofouling of surfaces.…”

Section: Introductionmentioning

confidence: 99%

Antifouling Coatings Generated from Unsymmetrical Partially Fluorinated Spiroalkanedithiols

Hill

Craft

Chinwangso

et al. 2021

ACS Appl. Bio Mater.

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Biofouling negatively impacts modern society on a daily basis, especially with regard to the important industries of medicine, oil, and shipping. This manuscript describes the preparation and study of model antifouling coatings generated from the adsorption of unsymmetrical partially fluorinated spiroalkanedithiols on gold. The antifouling properties of the self-assembled monolayers (SAMs) derived from the spiroalkanedithiols were compared to SAMs derived from analogous monodentate partially fluorinated and nonfluorinated alkanethiols. The antifouling properties were evaluated using in situ surface plasmon resonance spectroscopy (SPR), ex situ electrochemical quartz crystal microbalance (QCM) measurements, and ex situ ellipsometric thickness measurements. The resistance to nonspecific protein adsorption of the SAMs was evaluated with proteins having a wide range of properties and applications including protamine, lysozyme, bovine serum albumin, and fibrinogen. The results from the SPR and the QCM measurements demonstrated that in most cases, the SAM coatings derived from the partially fluorinated spiroalkanedithiols having mixed hydrocarbon and fluorocarbon tail groups exhibited better antifouling performance when compared to the SAMs derived from their single-component monodentate counterparts. The studies also revealed that while the SPR and the QCM measurements in most cases were able to distinguish the adsorption trends for the SAMs and proteins examined, the ellipsometric thickness measurements were markedly less discriminating. On the whole, these studies validate the use of unsymmetrical partially fluorinated spiroalkanedithiols for generating effective antifouling coatings on metal substrates.

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Section: Introductionmentioning

confidence: 99%

Antifouling Coatings Generated from Unsymmetrical Partially Fluorinated Spiroalkanedithiols

Hill

Craft

Chinwangso

et al. 2021

ACS Appl. Bio Mater.

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“…However, these properties are greatly influenced by the degree of fluorination on the molecular constituents. Of particular interest are the contact angle studies performed on SAMs generated from specifically fluorinated alkanethiols [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Table 1 highlights studies of the wetting properties of partially fluorinated SAMs.…”

Section: Introductionmentioning

confidence: 99%

“…Table 1 highlights studies of the wetting properties of partially fluorinated SAMs. In one example of minimally fluorinated SAMs, Lee et al demonstrated that CF 3 -termianted SAMs exhibit greater wettability toward polar contacting liquids than their hydrocarbon analogs [ 43 , 45 , 46 , 47 ]. The enhanced wettability exhibited by the CF 3 -terminated SAMs was attributed to the presence of oriented dipoles at the fluorocarbon-hydrocarbon junction, FC-HC.…”

Section: Introductionmentioning

confidence: 99%

“…The enhanced wettability exhibited by the CF 3 -terminated SAMs was attributed to the presence of oriented dipoles at the fluorocarbon-hydrocarbon junction, FC-HC. Further research examined the surface free energy as a function of the degree of terminal fluorination by analyzing SAMs generated from two series of adsorbates in which: (1) The total carbon count remains the same while the number of fluorocarbons systematically increases, F 3 C(CF 2 ) n (CH 2 ) m SH where n = 0–9 and m = 15–6 [ 46 ]; and (2) the hydrocarbon spacer remains the same while the number of fluorocarbons increases F 3 C(CF 2 ) n (CH 2 ) m SH where n = 0–9 and m = 11 [ 39 , 48 ]. Collectively, these studies led to the conclusions that the contact angles are affected by the number of fluorocarbons rather than the total chain length, and that the films become increasingly hydrophobic and oleophobic as the degree of fluorination increases.…”

Section: Introductionmentioning

confidence: 99%

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Unsymmetrical Spiroalkanedithiols Having Mixed Fluorinated and Alkyl Tailgroups of Varying Length: Film Structure and Interfacial Properties

et al. 2018

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A custom-designed series of unsymmetrical spiroalkanedithiols having tailgroups comprised of a terminally fluorinated chain and a hydrocarbon chain of varying lengths were synthesized and used to prepare self-assembled monolayers (SAMs) on gold substrates. The specific structure of the adsorbates was of the form [CH3(CH2)n][CF3(CF2)7(CH2)8]C[CH2SH]2, where n = 7, 9, and 15 (designated as F8H10-C10, F8H10-C12, and F8H10-C18, respectively). The influence of the length of the hydrocarbon chain in the bidentate dithiol on the structure and interfacial properties of the monolayer was explored. A structurally analogous partially fluorinated monodentate alkanethiol and the corresponding normal alkanethiols were used to generate appropriate SAMs as reference systems. Measurements of ellipsometric thickness showed an unexpectedly low film thickness for the SAMs derived from the bidentate adsorbates, possibly due to disruptions in interchain packing caused by the fluorocarbon chains (i.e., phase-incompatible fluorocarbon-hydrocarbon interactions), ultimately giving rise to loosely packed and disordered films. Analysis by X-ray photoelectron spectroscopy (XPS) were also consistent with a model in which the films were loosely packed; additionally, the XPS spectra confirmed the attachment of the sulfur headgroups of the bidentate adsorbates onto the gold substrates. Studies of the SAMs by polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) suggested that as the length of the hydrocarbon chain in the adsorbates was extended, a more ordered surface was achieved by reducing the tilt of the fluorocarbon segment. The wettability data indicated that the adsorbates with longer alkyl chains were less wettable than those with shorter alkyl chains, likely due to an increase in interchain van der Waals forces in the former.

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“…With HD, the odd-even effect was not only observed over the range of substrate roughness (0.2nm-2.2nm) recently reported by Thuo and co-workers but also in other rough substrates. [58][59] This behavior is contrary to the observations from water contact angle, where the odd-even effect is hypothesized to be useful in diagnosing the quality of the SAMs or interface structure.…”

Section: How Rough Is Too Rough For Odd-even Effect?mentioning

confidence: 67%

Interface driven engineering of charge transport across molecular tunneling junctions

Chen

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Molecular electronics uses organic molecules to replace inorganic electrical components in circuits. Molecular electronics is a promising field that can extend the Moore's law since scaling down transistors with molecules is comparatively easier than inorganic componnets fabricated using optical lithography. This thesis describes a platform that can be used to study molecular electronics, which is selfassembled monolayers based large area tunneling junction with Eutectic Gallium Indium as top electrode and metal thin film as bottom electrode.

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Physical organic probes of interfacial wettability reveal the importance of surface dipole effects

Cited by 58 publications

References 33 publications

Antifouling Coatings Generated from Unsymmetrical Partially Fluorinated Spiroalkanedithiols

Antifouling Coatings Generated from Unsymmetrical Partially Fluorinated Spiroalkanedithiols

Unsymmetrical Spiroalkanedithiols Having Mixed Fluorinated and Alkyl Tailgroups of Varying Length: Film Structure and Interfacial Properties

Interface driven engineering of charge transport across molecular tunneling junctions

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