Effective van der Waals surface energy of self-assembled monolayer films having systematically varying degrees of molecular fluorination

Takenaga, Mitsuru; Jo, Sadaharu; Graupe, Michael; Lee, T. Randall

doi:10.1016/j.jcis.2007.12.048

Cited by 29 publications

(21 citation statements)

References 20 publications

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“…The generality of this phenomenon is further supported by a more recent study by Takenaga et al of FSAMs derived from CF 3 (CF 2 ) n (CH 2 ) 12Àn SH (where n ¼ 0, 1, 2, 3, and 9), which found that the magnitude of the Lifshitz-van der Waals interactions (g LW ) decreases as the value of n increases. 77 In short, the studies collectively show that the surface energies decrease as the degree of uorination increases, which consequently leads the lms to become progressively more hydrophobic and oleophobic. 20,75,77 4 Effect of adsorbate architecture on electron-transfer properties…”

Section: Introductionmentioning

confidence: 94%

“…77 In short, the studies collectively show that the surface energies decrease as the degree of uorination increases, which consequently leads the lms to become progressively more hydrophobic and oleophobic. 20,75,77 4 Effect of adsorbate architecture on electron-transfer properties…”

Section: Introductionmentioning

confidence: 94%

“…Furthermore, this shi to positive values in the low-KE photoemission edge increases in magnitude with an increase in the number of terminal uorocarbon units, and also appears to mirror the inuence of the buried transition dipole upon the interfacial surface energy as described in Section 3. 20,21,75,77 In addition, Alloway and co-workers also examined SAMs derived from a series of alkanethiols terminated with a single CF 3 group (CF 3 (CH 2 ) n SH, where n ¼ 12-15) and observed that the shi in the low-KE photoemission edge of the CF 3 -terminated SAMs depended on the total number of carbons in the chain of these well-ordered lms. Surprisingly, the shi was greater for adsorbates having an odd number of carbon atoms than those having an even number of carbon atoms by $0.3 eV.…”

Section: Introductionmentioning

confidence: 99%

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The impact of fluorination on the structure and properties of self-assembled monolayer films

2013

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The adsorption of partially fluorinated amphiphiles on metal/metal oxide surfaces allows for the generation of specifically fluorinated thin-film interfaces. Such surfaces are often compared to polytetrafluoroethylene (PTFE), which exhibits a low surface energy, accompanied by biological and chemical inertness, making perfluorinated interfaces applicable to a wide range of technologies. In thinfilm research, self-assembled monolayers derived from fluorinated alkanethiols (FSAMs) serve as welldefined systems that can be used to evaluate the physical and chemical properties of interfaces produced with varying degrees of fluorination. The characteristics of these surfaces have been attributed to both the chemical composition of the individual molecular adsorbates and the consequent structural features associated with monolayers formed from these unique partially fluorinated adsorbates. Specifically, this review seeks to correlate the structural and interfacial properties of FSAMs on gold with the structure/composition of the fluorinated moiety present in the adsorbed molecules and to highlight how the degree of fluorination influences the interfacial ordering of the individual alkanethiolate chains and the vacuum energy levels of the modified metal substrate. Additionally, the thermal stability of these organic thin films is analyzed as a function of adsorbate structure. Included are highlights of some of the studies in which FSAMs, formed from a variety of new types of surfactants, were used to modify colloidal systems, to generate anti-adhesive materials, and to enhance the stability of fluorinated thin films toward low-energy electron degradation.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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The impact of fluorination on the structure and properties of self-assembled monolayer films

2013

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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%

“…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%

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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Self‐Assembled Monolayers: the Development of Functional Nanoscale Films

Jamison

Chinwangso

Lee

2011

Functional Polymer Films

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Effective van der Waals surface energy of self-assembled monolayer films having systematically varying degrees of molecular fluorination

Cited by 29 publications

References 20 publications

The impact of fluorination on the structure and properties of self-assembled monolayer films

The impact of fluorination on the structure and properties of self-assembled monolayer films

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

Self‐Assembled Monolayers: the Development of Functional Nanoscale Films

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