Odd–Even Effect in the Hydrophobicity of <i>n</i>-Alkanethiolate Self-Assembled Monolayers Depends upon the Roughness of the Substrate and the Orientation of the Terminal Moiety

Newcomb, Lucas B.; Tevis, Ian D.; Atkinson, Manza B. J.; Gathiaka, Symon; Luna, Rafael E.; Thuo, Martin M.

doi:10.1021/la5032569

Cited by 42 publications

(114 citation statements)

References 46 publications

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“…Porter's data [21] showed odd-even effect; however, the oscillation in the values of contact angle was inverted compared to what we later observed [25,26,54].…”

Section: Discussioncontrasting

confidence: 40%

“…This orientation difference with the number of CH2 units, c, has previously been implicated as a possible origin of the odd-even effect [18,25,41,48]. It is observed that the orientation of the terminal moiety should invert with the change of the substrate from Au to Ag and vice versa, based on the known structures of SAMs on these surfaces (Figure 7a It is also reported that the odd-even effect inverts when the surface is changed from Au to Ag, which is due to the inversion of the orientation of the terminal moiety and, hence, the surface dipole.…”

Section: Odd-even Effect In the Hydrophobicity Of N-alkanethiolate Samentioning

confidence: 84%

“…The lower hydrophobicities of monolayers prepared from shorter alkanethiols (n < 9) is thought to be due to disorder in the shorter chain molecules and, potentially, interaction of the probe liquid with methylene (alkyl chain) instead of methylalthough coulombic interactions between the dipole of the probe liquid and the now proximal oxidized metal surface (due to bond formation) can also be envisioned. The value of the contact angle tend to plateau off with longer n-alkyl chains, and this was attributed to increased crystallinity of the SAMs [25,26].…”

Section: The Original Studiesmentioning

confidence: 99%

“…All previous studies were performed on "as-deposited" surfaces. Graphs are reprinted with permission from (i,ii) [10], Copyright 1991 American Chemical Society; (iii) [8], Copyright 1999 American Chemical Society; (iv) [25], Copyright 2001 American Chemical Society; [22], Copyright 1994 American Chemical Society; and (v) [21], Copyright 1991 American Chemical Society.…”

Section: The Original Studiesmentioning

confidence: 99%

“…Therefore, the structure and properties of SAMs significantly depend on the substrate. [53] Template stripping can generate surfaces with roughness <1 nm [25], in which technique a glass slide or other solid support is glued to the exposed surface of a metal film deposited on silicon wafer, and then the metal film is peeled from the wafer to expose the surface that had been in direct contact with the wafer. Chen et al (2015) reported a new method, referred to as "remote mechanical annealing (ReMA)" to fabricate ultra-flat Au surface with RMS roughness as low as 0.2 nm [26].…”

Section: Substrates Roughnessmentioning

confidence: 99%

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The Porter-Whitesides Discrepancy: Revisiting Odd-Even Effects in Wetting Properties of n-Alkanethiolate SAMs

2015

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This review discusses the Porter-Whitesides discrepancy in wetting properties of n-alkanethiolate self-assembled monolayers (SAMs). About 25 years ago, Whitesides and coworker failed to observe any odd-even effect in wetting, however, Porter and his coworker did, albeit in select cases. Most previous studies agreed with Whitesides' results, suggesting the absence of the odd-even effect in hydrophobicity of n-alkanethiolate SAMs. Recent reports have, however, found the odd-even effect in hydrophobicity of n-alkanethiolate SAMs on smooth substrates, indicating that hydrophobicity, and analogous interfacial properties, of n-alkanethiolate SAMs significantly depends on the properties of substrate. Unfortunately, the Whitesides and Porter papers do not report on the quality of the surfaces used. Based on recent work, we inferred that the original discrepancy between Whitesides and Porter can be attributed to the quality of the surface. Odd-even effect of SAMs in charge transport, capacitance, friction, and SAM structure are also discussed in this review to inform the general discussion. The discrepancy between Porter's group and Whitesides' group could be due to surface roughness, morphology, oxidation, and adventitious contaminants. OPEN ACCESSCoatings 2015, 5 1035

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“…Porter's data [21] showed odd-even effect; however, the oscillation in the values of contact angle was inverted compared to what we later observed [25,26,54].…”

Section: Discussioncontrasting

confidence: 40%

Section: Odd-even Effect In the Hydrophobicity Of N-alkanethiolate Samentioning

confidence: 84%

Section: The Original Studiesmentioning

confidence: 99%

Section: The Original Studiesmentioning

confidence: 99%

Section: Substrates Roughnessmentioning

confidence: 99%

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The Porter-Whitesides Discrepancy: Revisiting Odd-Even Effects in Wetting Properties of n-Alkanethiolate SAMs

2015

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Smart Eutectic Gallium–Indium: From Properties to Applications

et al. 2022

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Eutectic gallium–indium (EGaIn), a liquid metal with a melting point close to or below room temperature, has attracted extensive attention in recent years due to its excellent properties such as fluidity, high conductivity, thermal conductivity, stretchability, self‐healing capability, biocompatibility, and recyclability. These features of EGaIn can be adjusted by changing the experimental condition, and various composite materials with extended properties can be further obtained by mixing EGaIn with other materials. In this review, not only the are unique properties of EGaIn introduced, but also the working principles for the EGaIn‐based devices are illustrated and the developments of EGaIn‐related techniques are summarized. The applications of EGaIn in various fields, such as flexible electronics (sensors, antennas, electronic circuits), molecular electronics (molecular memory, opto‐electronic switches, or reconfigurable junctions), energy catalysis (heat management, motors, generators, batteries), biomedical science (drug delivery, tumor therapy, bioimaging and neural interfaces) are reviewed. Finally, a critical discussion of the main challenges for the development of EGaIn‐based techniques are discussed, and the potential applications in new fields are prospected.

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Molecular‐Switch‐Embedded Solution‐Processed Semiconductors

Hassan

et al. 2022

Advanced Materials

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oxides, [44][45][46][47][48] inorganic nanocrystals, [49][50][51][52][53] and quantum dots. [54][55][56][57] The cornerstones in the history of these solution-processed semiconductors are as follows: 1) understanding of the fundamental physics of processes such as charge generation and transport; 2) optimization of their electronic/optoelectronic performances based on the development of new materials and/ or device architectures; 3) development of further functionalities of these materials typically by embedding other functional materials. The most frequently utilized material family in the third stage was the photochromic molecular switch, which showed binary isomerization between two distinct isomers in terms of the conjugation length (diarylethene (DAE)), trans/cis configuration (azobenzene), and ionic nature and dipole moment (spiropyran (SP) and spirooxazine (SPOx)). [58][59][60][61][62] These molecular switches are typically responsive to a light stimulus; therefore, molecular-switch-embedded solution-processed semiconductors possess possibility of realizing multifunctionality with nondestructive and effective optical control. Organic chemists have been developing sophisticated synthetic processes for delicate control of the physical properties of molecular switches, enabling broad and excellent responsivities to various external stimuli. [63][64][65][66][67][68][69][70][71] While previous reviews had analyzed the performances of molecular-switch-embedded semiconductors based on the type of molecular switch, semiconductor, or device, this review conducts an analysis purely based on the optoelectronic transition mechanism for a more comprehensive and integrated perspective. This approach may allow researchers to discover relevant molecular-switch-related operating mechanisms for their own studies. For this reason, the review is structured as follows: 1) semiconductor trap-level control, 2) semiconductor bulk-resistance control, 3) semiconductor doping control, 4) semiconductor junction control, and 5) other interesting mechanisms. Although described separately, all these mechanisms have in common the utilization of apparently different electron accepting/donating properties of two isomers of each molecular switch. In other words, researchers are tailoring expressions to fit the different environments and materials in which molecular switches are being applied. At the beginning of each subchapter, the mechanism of the corresponding method is explained along with a schematic diagram (Figure 1).Recent improvements in the performance of solution-processed semiconductor materials and optoelectronic devices have shifted research interest to the diversification/advancement of their functionality. Embedding a molecular switch capable of transition between two or more metastable isomers by light stimuli is one of the most straightforward and widely accepted methods to potentially realize the multifunctionality of optoelectronic devices. A molecular switch embedded in a semiconductor can effectively control various pa...

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Odd–Even Effect in the Hydrophobicity of n-Alkanethiolate Self-Assembled Monolayers Depends upon the Roughness of the Substrate and the Orientation of the Terminal Moiety

Cited by 42 publications

References 46 publications

The Porter-Whitesides Discrepancy: Revisiting Odd-Even Effects in Wetting Properties of n-Alkanethiolate SAMs

The Porter-Whitesides Discrepancy: Revisiting Odd-Even Effects in Wetting Properties of n-Alkanethiolate SAMs

Smart Eutectic Gallium–Indium: From Properties to Applications

Molecular‐Switch‐Embedded Solution‐Processed Semiconductors

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