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Wang J, Gadenne V, Patrone L, Raimundo JM. Self-Assembled Monolayers of Push-Pull Chromophores as Active Layers and Their Applications. Molecules 2024; 29:559. [PMID: 38338304 PMCID: PMC10856137 DOI: 10.3390/molecules29030559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/12/2024] Open
Abstract
In recent decades, considerable attention has been focused on the design and development of surfaces with defined or tunable properties for a wide range of applications and fields. To this end, self-assembled monolayers (SAMs) of organic compounds offer a unique and straightforward route of modifying and engineering the surface properties of any substrate. Thus, alkane-based self-assembled monolayers constitute one of the most extensively studied organic thin-film nanomaterials, which have found wide applications in antifouling surfaces, the control of wettability or cell adhesion, sensors, optical devices, corrosion protection, and organic electronics, among many other applications, some of which have led to their technological transfer to industry. Nevertheless, recently, aromatic-based SAMs have gained importance as functional components, particularly in molecular electronics, bioelectronics, sensors, etc., due to their intrinsic electrical conductivity and optical properties, opening up new perspectives in these fields. However, some key issues affecting device performance still need to be resolved to ensure their full use and access to novel functionalities such as memory, sensors, or active layers in optoelectronic devices. In this context, we will present herein recent advances in π-conjugated systems-based self-assembled monolayers (e.g., push-pull chromophores) as active layers and their applications.
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Affiliation(s)
- Junlong Wang
- Aix Marseille Univ, CNRS, CINaM, AMUTech, 13288 Marseille, France;
- ISEN, Université de Toulon, Aix Marseille Univ, CNRS, IM2NP, AMUtech, 83041 Toulon ou Marseille, France;
| | - Virginie Gadenne
- ISEN, Université de Toulon, Aix Marseille Univ, CNRS, IM2NP, AMUtech, 83041 Toulon ou Marseille, France;
| | - Lionel Patrone
- ISEN, Université de Toulon, Aix Marseille Univ, CNRS, IM2NP, AMUtech, 83041 Toulon ou Marseille, France;
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Liu S, Norikane Y, Kikkawa Y. Two-dimensional molecular networks at the solid/liquid interface and the role of alkyl chains in their building blocks. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2023; 14:872-892. [PMID: 37674543 PMCID: PMC10477993 DOI: 10.3762/bjnano.14.72] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/25/2023] [Indexed: 09/08/2023]
Abstract
Nanoarchitectonics has attracted increasing attention owing to its potential applications in nanomachines, nanoelectronics, catalysis, and nanopatterning, which can contribute to overcoming global problems related to energy and environment, among others. However, the fabrication of ordered nanoarchitectures remains a challenge, even in two dimensions. Therefore, a deeper understanding of the self-assembly processes and substantial factors for building ordered structures is critical for tailoring flexible and desirable nanoarchitectures. Scanning tunneling microscopy is a powerful tool for revealing the molecular conformations, arrangements, and orientations of two-dimensional (2D) networks on surfaces. The fabrication of 2D assemblies involves non-covalent interactions that play a significant role in the molecular arrangement and orientation. Among the non-covalent interactions, dispersion interactions that derive from alkyl chain units are believed to be weak. However, alkyl chains play an important role in the adsorption onto substrates, as well as in the in-plane intermolecular interactions. In this review, we focus on the role of alkyl chains in the formation of ordered 2D assemblies at the solid/liquid interface. The alkyl chain effects on the 2D assemblies are introduced together with examples documented in the past decades.
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Affiliation(s)
- Suyi Liu
- Graduate School of Science and Technology, University of Tsukuba, Ibaraki, 305-8571, Japan
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Yasuo Norikane
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
- Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki, 305-8571, Japan
| | - Yoshihiro Kikkawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
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3
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Kikkawa Y, Nagasaki M, Norikane Y. Two-dimensional self-assemblies of azobenzene derivatives: effects of methyl substitution of azobenzene core and alkyl chain length. Phys Chem Chem Phys 2022; 24:29757-29764. [PMID: 36458744 DOI: 10.1039/d2cp05097h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Elucidating the correlation between the molecular arrangement and physical properties of organic compounds is critical to facilitating the development of advanced functional materials. X-ray structural analyses are generally performed to clarify this relationship. Several attempts have been made to ascertain the links between three-dimensional (3D) crystals and their two-dimensional (2D) structures, which can be revealed by scanning tunnelling microscopy (STM) at the molecular level. Thus, 2D self-assemblies of a series of azobenzene derivatives were investigated in this study, and the effects of methyl substitution of the azobenzene core and alkyl chain length on the 2D molecular arrangements at the solid/liquid interface were revealed. Three types of azobenzene derivatives were prepared; these contained azobenzene (Az), 3-methyl azobenzene (MAz), or 3,3'-dimethyl azobenzene (DAz) as cores and alkyloxy chains of different lengths (C8-13) at their 4,4' positions. The 2D structures of the Az and DAz compounds were found to be modulated owing to the odd-even effect of the alkyl chains in a specific chain-length range; this effect was only weakly exhibited by the MAz compounds. This result suggests that only the methyl-group substitution of the azobenzene core significantly affected the 2D structures. The 2D structural features have been discussed in terms of molecular conformation, as well as their correlation with the photo-melting behaviour of the azobenzene derivatives, particularly the MAz compounds.
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Affiliation(s)
- Yoshihiro Kikkawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Mayumi Nagasaki
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Yasuo Norikane
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
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4
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Du C, Wang Z, Chen J, Martin A, Raturi D, Thuo M. Role of Nanoscale Roughness and Polarity in Odd–Even Effect of Self‐Assembled Monolayers. Angew Chem Int Ed Engl 2022; 61:e202205251. [PMID: 35580255 PMCID: PMC9400998 DOI: 10.1002/anie.202205251] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Indexed: 11/13/2022]
Abstract
The dependency of substrate roughness on wetting properties of self‐assembled monolayers (SAMs) has been studied extensively, but most previous studies used limited selection of probing liquid and range of surface roughness. These studies disregarded the limit to observation of sub‐nanometer odd–even parity effect, hence are inconclusive. In this work we report the role of solvent polarity on the roughness‐dependency of wetting behavior of SAMs by studying static con‐tact angle of a variety of probing liquids, with different polarities, on SAMs formed on Ag‐based substrate with different surface morphology. By overlapping the roughness ranges with previous studies on Au, the limitation of surface roughness (RMS=1 nm) to observation of the odd–even effect using water as probing liquid was confirmed, but other probing liquid yielded different roughness‐dependent behaviors, with more polar solvent showing more roughness‐dependent behavior. Based on these observations, we concluded that there exists a phase‐transition like behavior in SAMs due to substrate roughness and molecule chain length, but whose determination is dependent on the probing liquid.
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Affiliation(s)
- Chuanshen Du
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Zhengjia Wang
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Jiahao Chen
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
- Micro-electronic research center Iowa State University 133 Applied Sciences Complex, 1925 Scholl Road Ames IA 50011 USA
| | - Andrew Martin
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Dhruv Raturi
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Martin Thuo
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
- Micro-electronic research center Iowa State University 133 Applied Sciences Complex, 1925 Scholl Road Ames IA 50011 USA
- Biopolymer and Biocomposites Research Team Center for Bioplastics and Biocomposites Iowa State University 1041 Food Sciences Building Ames IA 50011 USA
- Department of Electrical Engineering Iowa State University 2215 Coover Hall Ames IA 50011 USA
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5
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Du C, Wang Z, Chen J, Martin A, Raturi D, Thuo M. Role of Nanoscale Roughness and Polarity in Odd–Even Effect of Self‐Assembled Monolayers. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Chuanshen Du
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Zhengjia Wang
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Jiahao Chen
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
- Micro-electronic research center Iowa State University 133 Applied Sciences Complex, 1925 Scholl Road Ames IA 50011 USA
| | - Andrew Martin
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Dhruv Raturi
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
| | - Martin Thuo
- Department of Materials Science and Engineering Iowa State University 2220 Hoover Hall Ames IA 50011 USA
- Micro-electronic research center Iowa State University 133 Applied Sciences Complex, 1925 Scholl Road Ames IA 50011 USA
- Biopolymer and Biocomposites Research Team Center for Bioplastics and Biocomposites Iowa State University 1041 Food Sciences Building Ames IA 50011 USA
- Department of Electrical Engineering Iowa State University 2215 Coover Hall Ames IA 50011 USA
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6
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Green JB, Clarke E, McDermott C, McDermott M, Zhong C, Bergren A, Poter M. On the Counter‐Intuitive Heterogeneous Electron Transfer Barrier Properties of Alkanethiolate Monolayers on Gold: Smooth versus Rough Surfaces. ELECTROANAL 2022. [DOI: 10.1002/elan.202100704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Carlson S, Becker M, Brünig FN, Ataka K, Cruz R, Yu L, Tang P, Kanduč M, Haag R, Heberle J, Makki H, Netz RR. Hydrophobicity of Self-Assembled Monolayers of Alkanes: Fluorination, Density, Roughness, and Lennard-Jones Cutoffs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13846-13858. [PMID: 34787431 DOI: 10.1021/acs.langmuir.1c02187] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The interplay of fluorination and structure of alkane self-assembled monolayers and how these affect hydrophobicity are explored via molecular dynamics simulations, contact angle goniometry, and surface-enhanced infrared absorption spectroscopy. Wetting coefficients are found to grow linearly in the monolayer density for both alkane and perfluoroalkane monolayers. The larger contact angles of monolayers of perfluorinated alkanes are shown to be primarily caused by their larger molecular volume, which leads to a larger nearest-neighbor grafting distance and smaller tilt angle. Increasing the Lennard-Jones force cutoff in simulations is found to increase hydrophilicity. Specifically, wetting coefficients scale like the inverse square of the cutoff, and when extrapolated to the infinite cutoff limit, they yield contact angles that compare favorably to experimental values. Nanoscale roughness is also found to reliably increase monolayer hydrophobicity, mostly via the reduction of the entropic part of the work of adhesion. Analysis of depletion lengths shows that droplets on nanorough surfaces partially penetrate the surface, intermediate between Wenzel and Cassie-Baxter states.
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Affiliation(s)
- Shane Carlson
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Maximilian Becker
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Florian N Brünig
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Kenichi Ataka
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Rubén Cruz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Leixiao Yu
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Peng Tang
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Joachim Heberle
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Hesam Makki
- Polymer and Color Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran 15875-4413, Iran
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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8
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Du C, Norris SR, Thakur A, Chen J, VanVeller B, Thuo M. Molecular Conformation in Charge Tunneling across Large-Area Junctions. J Am Chem Soc 2021; 143:13878-13886. [PMID: 34415163 DOI: 10.1021/jacs.1c06622] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Self-assembled monolayers are predicated on thermodynamic equilibrium; hence, their properties project accessible relaxation pathways. Herein, we demonstrate that charge tunneling correlates with conformational degrees of freedom(s). Results from open chain and cyclic head groups show that, as expected, distribution in tunneling data correlates with the orientation of the head group, akin to the odd-even effect and more importantly the degree of conformational freedom, but fluctuates with applied bias. Trends in nature of distributions in current density illuminate the need for higher statistical moments in understanding these rather dynamic systems. We employ skewness, kurtosis, and estimation plots to show that the conformational degree of freedom in the head group significantly amplifies the odd-even effect and may lead to enhanced or perturbed tunneling based on whether the head group is on an odd- or even-parity spacer.
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Affiliation(s)
- Chuanshen Du
- Department of Materials Science and Engineering, Iowa State University, 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Sean R Norris
- Department of Chemistry, Iowa State University, 3126 Hach Hall, 2438 Pammel Drive, Ames, Iowa 50011-3111, United States
| | - Abhishek Thakur
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University, 2220 Hoover Hall, Ames, Iowa 50011 United States.,Micro-Electronic Research Center, Iowa State University, 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011, United States
| | - Brett VanVeller
- Department of Chemistry, Iowa State University, 3126 Hach Hall, 2438 Pammel Drive, Ames, Iowa 50011-3111, United States
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University, 2220 Hoover Hall, Ames, Iowa 50011 United States.,Micro-Electronic Research Center, Iowa State University, 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011, United States.,Biopolymer and Biocomposites Research Team, Center for Bioplastics and Biocomposites Iowa State University, 1041 Food Sciences Building, Ames, Iowa 50011, United States
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Nolin A, Licht A, Pierson K, Lo CY, Kayser LV, Dhong C. Predicting human touch sensitivity to single atom substitutions in surface monolayers for molecular control in tactile interfaces. SOFT MATTER 2021; 17:5050-5060. [PMID: 33929468 DOI: 10.1039/d1sm00451d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The mechanical stimuli generated as a finger interrogates the physical and chemical features of an object form the basis of fine touch. Haptic devices, which are used to control touch, primarily focus on recreating physical features, but the chemical aspects of fine touch may be harnessed to create richer tactile interfaces and reveal fundamental aspects of tactile perception. To connect tactile perception with molecular structure, we systematically varied silane-derived monolayers deposited onto surfaces smoother than the limits of human perception. Through mechanical friction testing and cross-correlation analysis, we made predictions of which pairs of silanes might be distinguishable by humans. We predicted, and demonstrated, that humans can distinguish between two isosteric silanes which differ only by a single nitrogen-for-carbon substitution. The mechanism of tactile contrast originates from a difference in monolayer ordering, as quantified by the Hurst exponent, which was replicated in two alkylsilanes with a three-carbon difference in length. This approach may be generalizable to other materials and lead to new tactile sensations derived from materials chemistry.
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Affiliation(s)
- Abigail Nolin
- Department of Materials Science & Engineering, University of Delaware, Newark, DE, USA.
| | - Amanda Licht
- Department of Materials Science & Engineering, University of Delaware, Newark, DE, USA.
| | - Kelly Pierson
- Department of Materials Science & Engineering, University of Delaware, Newark, DE, USA.
| | - Chun-Yuan Lo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Laure V Kayser
- Department of Materials Science & Engineering, University of Delaware, Newark, DE, USA. and Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Charles Dhong
- Department of Materials Science & Engineering, University of Delaware, Newark, DE, USA. and Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
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10
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Capistran BA, Blanchard GJ. Spectroscopic Analysis of Cu(II)-Complexed Thin Films to Characterize Molecular-Level Interactions and Film Behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:5089-5097. [PMID: 33856223 DOI: 10.1021/acs.langmuir.1c00849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report on the structure and dynamics of a Cu2+-complexed arachidic acid (AA) monolayer formed by Langmuir-Blodgett (LB) deposition. Infrared reflection-absorption spectroscopy (IRRAS) was used to characterize aliphatic chain -CH2 symmetric and asymmetric stretching modes and determine the chain tilt angle and order as a function of subphase pH. Monolayer structure is controlled by metal ion-amphiphile interactions. At low subphase pH (<5), film buckling at high surface pressure is observed, while for high subphase pH (≥5), monolayer buckling is not observed. This finding is correlated to monolayer structural mediation by metal ion-amphiphile interactions. Dynamics and mobility of a fluorophore incorporated into the monolayer were also affected by Cu2+-AA interactions, determined by fluorescence recovery after photobleaching (FRAP) measurements. These data are consistent with the formation of a rigid film due to Cu2+ coordination to AA headgroups, with the extent of headgroup protonation being determined by the pH of the subphase during monolayer deposition.
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Affiliation(s)
- Briana A Capistran
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Gary J Blanchard
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
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11
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Ben Amara F, Dionne ER, Kassir S, Pellerin C, Badia A. Molecular Origin of the Odd-Even Effect of Macroscopic Properties of n-Alkanethiolate Self-Assembled Monolayers: Bulk or Interface? J Am Chem Soc 2020; 142:13051-13061. [PMID: 32597648 DOI: 10.1021/jacs.0c04288] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidating the influence of the monolayer interface versus bulk on the macroscopic properties (e.g., surface hydrophobicity, charge transport, and electron transfer) of organic self-assembled monolayers (SAMs) chemically anchored to metal surfaces is a challenge. This article reports the characterization of prototypical SAMs of n-alkanethiolates on gold (CH3(CH2)nSAu, n = 6-19) at the macroscopic scale by electrochemical impedance spectroscopy and contact angle goniometry, and at the molecular level, by infrared reflection absorption spectroscopy. The SAM capacitance, dielectric constant, and surface hydrophobicity exhibit dependencies on both the length (n) and parity (nodd or neven) of the polymethylene chain. The peak positions of the CH2 stretching modes indicate a progressive increase in the chain conformational order with increasing n between n = 6 and 16. SAMs of nodd have a greater degree of structural gauche defects than SAMs of neven. The peak intensities and positions of the CH3 stretching modes are chain length independent but show an odd-even alternation of the spatial orientation of the terminal CH3. The correlations between the different data trends establish that the chain length dependencies of the dielectric constant and surface hydrophobicity originate from changes in the polymethylene chain conformation (bulk), while the odd-even variation arises primarily from a difference in the chemical composition of the interface related to the terminal group orientation. These findings provide new physical insights into the structure-property relation of SAMs for the design of ultrathin film dielectrics as well as the understanding of stereostructural effects on the electrical characteristics of tunnel junctions.
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Affiliation(s)
- Fadwa Ben Amara
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Eric R Dionne
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Sahar Kassir
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Christian Pellerin
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Antonella Badia
- Département de chimie, FRQNT Quebec Centre for Advanced Materials, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC H3C 3J7, Canada
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12
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Chang B, Martin A, Gregory P, Kundu S, Du C, Orondo M, Thuo M. Functional Materials through Surfaces and Interfaces. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Kikkawa Y, Tsuzuki S, Kashiwada A, Hiratani K. Self-assembled 2D patterns of structural isomers in isobutenyl compounds revealed by STM at solid/liquid interface. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.10.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chen J, Wang Z, Oyola-Reynoso S, Thuo MM. Properties of Self-Assembled Monolayers Revealed via Inverse Tensiometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13451-13467. [PMID: 28777587 DOI: 10.1021/acs.langmuir.7b01937] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembled monolayers (SAMs) have emerged as a simple platform technology and hence have been broadly studied. With advances in state-of-the-art fabrication and characterization methods, new insights into SAM structure and related properties have been delineated, albeit with some discrepancies and/or incoherencies. Some discrepancies, especially between experimental and theoretical work, are in part due to the misunderstanding of subtle structural features such as phase evolution and SAM quality. Recent work has, however, shown that simple techniques, such as the measurement of static contact angles, can be used to delineate otherwise complex properties of the SAM, especially when complemented by other more advanced techniques. In this article, we highlight the effect of nanoscale substrate asperities and molecular chain length on the SAM structure and associated properties. First, surfaces with tunable roughness are prepared on both Au and Ag, and their corresponding n-alkanethiolate SAMs are characterized through wetting and spectroscopy. From these data, chain-length- and substrate-morphology-dependent limits to the odd-even effect (structure and properties vary with the number of carbons in the molecules and the nature of the substrate), parametrization of gauche defect densities, and structural phase evolution (liquidlike, waxy, crystalline interfaces) are deduced. An evaluation of the correlation between the effect of roughness and the components of surface tension (polar-γp and dispersive-γd) reveals that wetting, at nanoscale rough surfaces, evolves proportionally with the ratio of the two components of surface tension. The evolution of conformational order is captured over a range of molecular lengths and parametrized through a dimensionless number, χc. By deploying a well-known tensiometry technique (herein the liquid is used to characterize the solid, hence the term inverse tensiometry) to characterize SAMs, we demonstrate that complex molecular-level phenomena in SAMs can be understood through simplicity.
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Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
| | - Martin M Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011, United States
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Chen J, Chang B, Oyola-Reynoso S, Wang Z, Thuo M. Quantifying Gauche Defects and Phase Evolution in Self-Assembled Monolayers through Sessile Drops. ACS OMEGA 2017; 2:2072-2084. [PMID: 31457561 PMCID: PMC6640986 DOI: 10.1021/acsomega.7b00355] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/04/2017] [Indexed: 05/31/2023]
Abstract
Self-assembled monolayers (SAMs) are widely used in surface modifications, specifically in tuning the surface chemistry of materials. The structure and properties of SAMs have been extensively studied often with sophisticated tools, even for the simplest n-alkanethiolate SAMs. In SAMs, especially in linear n-alkanethiolates, the properties are dependent on the chain length, which is best manifested in the so-called odd-even effect, a simple yet not fully understood phenomenon. One main challenge is fully delineating the origin of length-dependent properties, which can be due to the structure (ideal SAMs), defect evolution, or substrate-molecule effects. This study demonstrates that utilizing the wetting behavior of polar (water) and nonpolar (hexadecane (HD)) solvents on n-alkanethiolate SAMs formed on ultraflat gold and silver surfaces, the evolution of chain-length-dependent gauche defects can be revealed and parameterized through a newly defined dimensionless number (χ). The observation of the odd-even effect in hydrophobicity, however, depends on the thiol chain length, and it was only observed on longer-chain (>C8) molecules. The trend in this odd-even effect demonstrates that there are three main transitions in the nature of wetting, hence structure, across n-alkanethiols. From wetting with HD, the role of dispersive components in wetting reveal that the SAMs are dynamic, which we attribute to rotations associated with previously reported evolution in gauche defects and changes in packing density. Therefore, from re-expression of the Young-Dupre equation, we define a new dimensionless number associated with molecular conformations, whose periodicity mirrors the energetics of Goodman's conformations of n-alkanes in unbound states and associated four- or two-twist turns. Therefore, we infer that the evolution in surface energy is largely due to molecular conformations and associated relaxations of the bound thiolates.
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Affiliation(s)
- Jiahao Chen
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Division
of Materials Science and Engineering, Ames
Laboratory, Ames, Iowa 50011, United
States
- Micro-Electronic
Research Center, Iowa State University, 133 Applied Sciences Complex I,
1925 Scholl Road, Ames, Iowa 50011, United States
| | - Boyce Chang
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Division
of Materials Science and Engineering, Ames
Laboratory, Ames, Iowa 50011, United
States
| | - Stephanie Oyola-Reynoso
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
| | - Zhengjia Wang
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
| | - Martin Thuo
- Department
of Materials Science and Engineering, Iowa
State University, 2220 Hoover Hall, Ames, Iowa 50011, United
States
- Micro-Electronic
Research Center, Iowa State University, 133 Applied Sciences Complex I,
1925 Scholl Road, Ames, Iowa 50011, United States
- Biopolymer
and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University, 1041 Food Sciences Building, Ames, Iowa 50011, United States
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16
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Vilan A, Aswal D, Cahen D. Large-Area, Ensemble Molecular Electronics: Motivation and Challenges. Chem Rev 2017; 117:4248-4286. [DOI: 10.1021/acs.chemrev.6b00595] [Citation(s) in RCA: 243] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Ayelet Vilan
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
| | | | - David Cahen
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
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17
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Kikkawa Y, Tsuzuki S, Taguchi K, Kashiwada A, Hiratani K. Odd–even effect in two dimensions induced by the bicomponent blends of isobutenyl compounds. Phys Chem Chem Phys 2017; 19:13579-13584. [DOI: 10.1039/c7cp02064c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The bicomponent blends in isobutenyl compounds showed 2D structural modulation due to odd–even effect as well as blend ratio-dependent 2D structural change.
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Affiliation(s)
- Yoshihiro Kikkawa
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
| | - Seiji Tsuzuki
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
| | - Kazuhiro Taguchi
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
| | - Ayumi Kashiwada
- Department of Applied Molecular Chemistry
- College of Industrial Technology
- Nihon University
- Narashino
- Japan
| | - Kazuhisa Hiratani
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
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18
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Chen J, Liu J, Tevis ID, Andino RS, Miller CM, Ziegler LD, Chen X, Thuo MM. Spectroscopic evidence for the origin of odd–even effects in self-assembled monolayers and effects of substrate roughness. Phys Chem Chem Phys 2017; 19:6989-6995. [DOI: 10.1039/c6cp07580k] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper reports the effects of substrate roughness on the odd–even effect in n-alkanethiolate self-assembled monolayers (SAMs) probed by vibrational sum frequency generation (SFG) spectroscopy.
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Affiliation(s)
- Jiahao Chen
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
- Microelectronic Research Centre
| | - Jian Liu
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | - Ian D. Tevis
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
| | - Richard S. Andino
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | | | | | - Xin Chen
- Department of Chemistry and the Photonics Centre
- Boston University
- Boston
- USA
| | - Martin M. Thuo
- Department of Materials Science and Engineering
- Iowa State University
- Ames
- USA
- Microelectronic Research Centre
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19
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Wang Z, Chen J, Gathiaka SM, Oyola-Reynoso S, Thuo M. Effect of Substrate Morphology on the Odd-Even Effect in Hydrophobicity of Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10358-10367. [PMID: 27642814 DOI: 10.1021/acs.langmuir.6b01681] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Surface roughness, often captured through root-mean-square roughness (Rrms), has been shown to impact the quality of self-assembled monolayers (SAMs) formed on coinage metals. Understanding the effect of roughness on hydrophobicity of SAMs, however, is complicated by the odd-even effect-a zigzag oscillation in contact angles with changes in molecular length. We recently showed that for surfaces with Rrms > 1 nm, the odd-even effect in hydrophobicity cannot be empirically observed. In this report, we compare wetting properties of SAMs on Ag and Au surfaces of different morphologies across the Rrms ∼ 1 nm limit. We prepared surfaces with comparable properties (grain sizes and Rrms) and assessed the wetting properties of resultant SAMs. Substrates with Rrms either below or above the odd-even limit were investigated. With smoother surfaces (lower Rrms), an inverted asymmetric odd-even zigzag oscillation in static contact angles (θs) was observed with change from Au to Ag. Asymmetry in odd-even oscillation in Au was attributed to a larger change in θs from odd to even number of carbons in the n-alkanethiol and vice versa for Ag. For rougher surfaces, no odd-even effect was observed; however, a gradual increase in the static contact angle was observed. Increase in the average grain sizes (>3 times larger) on rough surfaces did not lead to significant difference in the wetting properties, suggesting that surface roughness significantly dominated the nature of the SAMs. We therefore infer that the predicted roughness-dependent limit to the observation of the odd-even effect in wetting properties of n-alkanethiols cannot be overcome by creating surfaces with large grain sizes for surfaces with Rrms > 1 nm. We also observed that the differences between Au and Ag surfaces are dominated by differences in the even-numbered SAMs, but this difference vanishes with shorter molecular chain length (≤C3).
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Affiliation(s)
- Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-Electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
| | - Symon M Gathiaka
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego , Pharmaceutical Sciences Building, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-Electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
- Biopolymer and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University , 1041 Food Sciences Building, Ames, Iowa 50011 United States
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20
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Wang Z, Chen J, Oyola-Reynoso S, Thuo M. Empirical Evidence for Roughness-Dependent Limit in Observation of Odd-Even Effect in Wetting Properties of Polar Liquids on n-Alkanethiolate Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8230-7. [PMID: 27448027 DOI: 10.1021/acs.langmuir.6b02159] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Substrate roughness influences the wetting properties of self-assembled monolayers (SAMs), but details on this dependency at the sub-nanometer level are still lacking. This study investigates the effect of surface roughness on interfacial properties of n-alkanethiolate SAMs, specifically wetting, and confirms the predicted limit to the observation of the odd-even effect in hydrophobicity. This article studies static contact angles of polar and nonpolar probe liquids on a series of n-alkanethiolate SAMs on surfaces with tunable roughness. We prepared Ag surfaces with root-mean-square roughness (Rrms) of ∼0.6-2.2 nm and compared the wetting properties of n-alkanethiolate SAMs fabricated on these surfaces. We measured the static contact angles, θs, formed between SAM and probe liquids [water, glycerol, and hexadecane]. Hexadecane showed an odd-even effect on all surfaces irrespective of the degree of roughness. Polar liquids (water and glycerol), however, showed a dependency on the roughness of the substrate with an odd-even effect observable only on smooth, but not rougher (Rrms ≥ 1.15 nm), surfaces. These results confirm that the previously predicted limit to observation of the odd-even effect in hydrophobicity (here extended to polar liquids) is real. From the results with glycerol, we infer that this limit is not limited just to hydrophobicity but may extend to other polar liquids. Results from hexadecane, however, suggest that this limit may not be a universal property of the SAM.
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Affiliation(s)
- Zhengjia Wang
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Jiahao Chen
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
| | - Stephanie Oyola-Reynoso
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University , 2220 Hoover Hall, Ames, Iowa 50011 United States
- Micro-electronic Research Center, Iowa State University , 133 Applied Sciences Complex I, 1925 Scholl Road, Ames, Iowa 50011 United States
- Biopolymer and Biocomposites Research Team, Center for Bioplastics and Biocomposites, Iowa State University , 1041 Food Sciences Building, Ames, Iowa 50011 United States
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