Grafting of Benzylic Amide Macrocycles onto Acid-Terminated Self-Assembled Monolayers Studied by XPS, RAIRS, and Contact Angle Measurements

Stability of self-assembled monolayers on gold under various environmental conditions is a crucial component in many biological, chemical and mechanical surface-functionalizations. In this study, we investigate the effects of relative humidity, ambient conditions (air, nitrogen-purged) and temperature on the structural stability of alkanethiols on gold at different chain length using contact angle measurements and time-of-flight secondary ions mass spectroscopy (TOF-SIMS). The ability of self-assembled monolayers functioning under these conditions is critical in protecting gold metal surfaces especially, from surface contamination. This in turn, affects the bonding conditions required in wafer level bonding process which is a key fabrication step in microelectromechanical (MEMs) and nanoelectromechanical (NEMs) systems. Such findings are particularly important in bioMEMs or bioNEMs since gold is one of the most common microfabrication material used in MEMs drug delivery devices due to its superior biocompatibility and reduced biofouling.

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Contact Angle Analysis During the Electro-oxidation of Self-Assembled Monolayers Formed by n-Octadecyltrichlorosilane

Advanced Functional Materials ◽

10.1002/adfm.201000077 ◽

2010 ◽

Vol 20 (19) ◽

pp. 3252-3259 ◽

Cited By ~ 8

Author(s):

Nicole Herzer ◽

Jurriaan H. K. van Schaik ◽

Stephanie Hoeppener ◽

Ulrich S. Schubert

Keyword(s):

Contact Angle ◽

Self Assembled Monolayers ◽

Assembled Monolayers ◽

Electro Oxidation ◽

Self Assembled ◽

Contact Angle Analysis

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Reconfigurable Hydrophobic/Hydrophilic Surfaces Based on Self-Assembled Monolayers

MRS Proceedings ◽

10.1557/proc-774-o5.8 ◽

2003 ◽

Vol 774 ◽

Cited By ~ 4

Author(s):

Joanne Deval ◽

Teodoro A. Umali ◽

Brandee L. Spencer ◽

Esther H. Lan ◽

Bruce Dunn ◽

...

Keyword(s):

Contact Angle ◽

Surface Water ◽

Water Contact Angle ◽

Self Assembled Monolayers ◽

Ionic Surfactant ◽

Initial Surface ◽

Lauryl Sulfate ◽

Water Contact ◽

Assembled Monolayers ◽

Self Assembled

AbstractThe fabrication of micron-scale channels and reaction chambers using micromachining techniques has created devices with large surface to volume ratios. As a result, surface properties play a major role in determining the behavior of micromachined devices. In this work, we present strategies that can be used to reconfigure surfaces from hydrophobic to hydrophilic or from hydrophilic to hydrophobic. The reversible nature of the surface is made possible by using deposition and removal of biomolecules or amphiphiles on self-assembled monolayers (SAMs). When the initial surface was hydrophobic (using a CH3-terminated SAM on the surface, water contact angle ∼100), it was rendered hydrophilic (water contact angle ≤60°) using monolayer adsorption of avidin protein. To retrieve the hydrophobicity, the avidin was subsequently removed using non-ionic surfactant octyl-β-D-glucopyranoside. Moreover, by incorporating a biotinylated poly(ethyleneglycol), the avidin-coated surface was resistant to further non-specific adsorption. If the initial surface was hydrophilic (using a CO2H-terminated SAM on the surface, water contact angle ≤20°), it was rendered hydrophobic (water contact angle >90°) using monolayer amphiphilic octadecylamine adsorption. The hydrophilicity was restored after subsequently removing the amphiphile using anionic surfactant sodium lauryl sulfate. Both types of surfaces showed excellent reversibility and demonstrated the ability to control surface wettability.

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Origin of the Contact Angle Hysteresis of Water on Chemisorbed and Physisorbed Self-Assembled Monolayers

Langmuir ◽

10.1021/la3026717 ◽

2012 ◽

Vol 28 (41) ◽

pp. 14609-14617 ◽

Cited By ~ 53

Author(s):

Nataly Belman ◽

Kejia Jin ◽

Yuval Golan ◽

Jacob N. Israelachvili ◽

Noshir S. Pesika

Keyword(s):

Contact Angle ◽

Contact Angle Hysteresis ◽

Self Assembled Monolayers ◽

Assembled Monolayers ◽

Self Assembled

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Use of Self-Assembled Monolayers of Different Wettabilities To Study Surface Selection and Primary Adhesion Processes of Green Algal (Enteromorpha) Zoospores

Applied and Environmental Microbiology ◽

10.1128/aem.66.8.3249-3254.2000 ◽

2000 ◽

Vol 66 (8) ◽

pp. 3249-3254 ◽

Cited By ~ 133

Author(s):

Maureen E. Callow ◽

J. A. Callow ◽

Linnea K. Ista ◽

Sarah E. Coleman ◽

Aleece C. Nolasco ◽

...

Keyword(s):

Contact Angle ◽

Photoelectron Spectroscopy ◽

Contact Angles ◽

Self Assembled Monolayers ◽

Use Of Self ◽

Oh Groups ◽

X Ray ◽

Green Algal ◽

Assembled Monolayers ◽

Self Assembled

ABSTRACT We investigated surface selection and adhesion of motile zoospores of a green, macrofouling alga (Enteromorpha) to self-assembled monolayers (SAMs) having a range of wettabilities. The SAMs were formed from alkyl thiols terminated with methyl (CH3) or hydroxyl (OH) groups or mixtures of CH3- and OH-terminated alkyl thiols and were characterized by measuring the advancing contact angles and by X-ray photoelectron spectroscopy. There was a positive correlation between the number of spores that attached to the SAMs and increasing contact angle (hydrophobicity). Moreover, the sizes of the spore groups (adjacent spores touching) were larger on the hydrophobic SAMs. Video microscopy of a patterned arrangement of SAMs showed that more zoospores were engaged in swimming and “searching” above the hydrophobic sectors than above the hydrophilic sectors, suggesting that the cells were able to “sense” that the hydrophobic surfaces were more favorable for settlement. The results are discussed in relation to the attachment of microorganisms to substrata having different wettabilities.

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Surface Dipoles Influence the Wettability of Terminally Fluorinated Organic Films

MRS Proceedings ◽

10.1557/proc-546-237 ◽

1998 ◽

Vol 546 ◽

Cited By ~ 7

Author(s):

Ramon Colorado ◽

Michael Graupe ◽

Mitsuru Takenaga ◽

Thomas Koini ◽

T. Randall Lee

Keyword(s):

Contact Angle ◽

Organic Thin Films ◽

Dipole Interaction ◽

Contact Angles ◽

Aprotic Solvents ◽

Angle Measurements ◽

Infrared Reflection ◽

Contact Angle Measurements ◽

Assembled Monolayers ◽

High Degree

AbstractThe correlation of differences in the wettabilities of partially fluorinated self-assembled monolayers (SAMs) to changes in the chemical structure and composition of the films was explored by contact angle goniometry and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). SAMs of simple alkanethiols (CH3(CH2)nSH with n = 9-15) and their CF3-terminated analogs (CF3(CH2)nSH with n = 9-15) were prepared by adsorption from solution onto evaporated gold. Advancing contact angles of hexadecane were measured on both the terminally fluorinated surfaces and the hydrocarbon surfaces. These data were compared to those obtained using a series of polar aprotic contacting liquids. As expected, the contact angles of hexadecane were higher on the CF3-terminated SAMs than on the CH3-terminated SAMs. The contact angles of the polar aprotic solvents, however, were measurably lower on the CF3- terminated SAMs than on the CH3-terminated SAMs. These observations were rationalized on the basis that the introduction of the CF3 terminal groups yields oriented surface dipoles that interact with the dipoles of the polar contacting liquids. Further support for this model was provided by the observation of an inverse parity (“odd-even”) effect in the wettabilities of the polar aprotic solvents on the CF3-terminated surfaces. Analysis by PM-IRRAS revealed that both types of films consist of predominately trans-extended alkyl chains with relatively few gauche defects in a densely packed arrangement. The high degree of order is consistent with the detection of the parity effect, where small changes in the orientation of the tail groups can be sensed by contact angle measurements only in highly ordered organic thin films. The significance of the dipole-oriented dipole interaction in describing interfacial wettabilities is discussed.

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Fluorescent Self-Assembled Monolayers of Umbelliferone: A Relationship between Contact Angle and Fluorescence

Langmuir ◽

10.1021/la401536p ◽

2013 ◽

Vol 29 (33) ◽

pp. 10423-10431 ◽

Cited By ~ 7

Author(s):

Luc Séro ◽

Lionel Sanguinet ◽

Séverine Derbré ◽

Frank Boury ◽

Guillaume Brotons ◽

...

Keyword(s):

Contact Angle ◽

Self Assembled Monolayers ◽

Assembled Monolayers ◽

Self Assembled

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Mixed Self-Assembled Monolayers of Alkanethiolates on Ultrasmooth Gold Do Not Exhibit Contact-Angle Hysteresis

Journal of the American Chemical Society ◽

10.1021/ja044623e ◽

2005 ◽

Vol 127 (1) ◽

pp. 4-5 ◽

Cited By ~ 50

Author(s):

Pooja Gupta ◽

Abraham Ulman ◽

Stephanie Fanfan ◽

Alexander Korniakov ◽

Katja Loos

Keyword(s):

Contact Angle ◽

Contact Angle Hysteresis ◽

Self Assembled Monolayers ◽

Assembled Monolayers ◽

Self Assembled

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Differences in ITO Surfaces According to the Formation of Aromatic Rings and Aliphatic Self-Assembled Monolayers for Organic Light-Emitting Diode Applications

Nanomaterials ◽

10.3390/nano11102520 ◽

2021 ◽

Vol 11 (10) ◽

pp. 2520

Author(s):

Myung-Gyun Baek ◽

Sang-Geon Park

Keyword(s):

Contact Angle ◽

Work Function ◽

Light Emitting Diode ◽

Substrate Surface ◽

Self Assembled Monolayers ◽

Light Emitting ◽

Organic Light Emitting Diode ◽

Organic Light ◽

Assembled Monolayers ◽

Self Assembled

In this study, we investigated the effects on the characteristic changes in OLED devices of using self-assembled monolayers with different functional groups as the hole injection layer, resulting in changes in their performance. Thus, we confirmed that it is possible to control the wetting properties, surface roughness, and work function of the indium tin oxide (ITO) surface by introducing self-assembled monolayers (SAMs). The contact angle measurements confirmed that the substrate surface contact angle tended to increase with SAM deposition. In addition, AFM measurements confirmed that the substrate surface roughness tended to decrease when SAM was deposited on the surface. Finally, it was confirmed through the work function measurement results that the work function increased when the ITO surface was modified by SAM. Furthermore, compared to OLEDs using only the ITO anode, the SAM-modified device showed a higher current density (359.68 A/cm2), improved brightness (76.8 cd/cm2), and a smaller turn-on voltage (7 V). This approach provides a simple route for fabricating organic light-emitting diode applications.

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