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

2000 ◽  
Vol 66 (8) ◽  
pp. 3249-3254 ◽  
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.

scholarly journals X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

2012 ◽  
Vol 3 ◽  
pp. 12-24 ◽  
Author(s):  
Hicham Hamoudi ◽  
Ping Kao ◽  
Alexei Nefedov ◽  
David L Allara ◽  
Michael Zharnikov
Keyword(s):  
Chain Length ◽  
Photoelectron Spectroscopy ◽  
Self Assembled Monolayers ◽  
Phenylene Ethynylene ◽  
X Ray ◽  
Molecular Length ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Gold Thiolate

Self-assembled monolayers (SAMs) of nitrile-substituted oligo(phenylene ethynylene) thiols (NC-OPEn) with a variable chain length n (n ranging from one to three structural units) on Au(111) were studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and near-edge absorption fine-structure spectroscopy. The experimental data suggest that the NC-OPEn molecules form well-defined SAMs on Au(111), with all the molecules bound to the substrate through the gold–thiolate anchor and the nitrile tail groups located at the SAM–ambient interface. The packing density in these SAMs was found to be close to that of alkanethiolate monolayers on Au(111), independent of the chain length. Similar behavior was found for the molecular inclination, with an average tilt angle of ~33–36° for all the target systems. In contrast, the average twist of the OPEn backbone (planar conformation) was found to depend on the molecular length, being close to 45° for the films comprising the short OPE chains and ~53.5° for the long chains. Analysis of the data suggests that the attachment of the nitrile moiety, which served as a spectroscopic marker group, to the OPEn backbone did not significantly affect the molecular orientation in the SAMs.

scholarly journals Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

2017 ◽  
Vol 13 ◽  
pp. 648-658 ◽  
Author(s):  
Loïc Pantaine ◽  
Vincent Humblot ◽  
Vincent Coeffard ◽  
Anne Vallée
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembled Monolayers ◽  
Gold Surfaces ◽  
Water Contact ◽  
X Ray ◽  
Infrared Reflection Absorption Spectroscopy ◽  
Infrared Reflection ◽  
End Groups ◽  
Assembled Monolayers ◽  
Self Assembled

Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces have successfully reacted with ArSO2NHOSO2Ar (Ar = 4-MeC6H4 or 4-FC6H4) resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA) measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS).

The Effect of Self-Assembled Monolayers on Interfacial Fracture

2004 ◽  
Vol 73 (5) ◽  
pp. 860-870 ◽  
Author(s):  
Alberto W. Mello ◽  
Kenneth M. Liechti
Keyword(s):  
Crack Growth ◽  
Photoelectron Spectroscopy ◽  
Cohesive Zone ◽  
Self Assembled Monolayers ◽  
Mixed Mode Fracture ◽  
Silane Coupling Agents ◽  
X Ray ◽  
Atomic Force ◽  
Assembled Monolayers ◽  
Self Assembled

This paper describes a series of experiments and analyses that were used to examine crack growth near sapphire/epoxy interfaces. Adhesion of the epoxy to the sapphire was enhanced by coating the sapphire with mixtures of two silane coupling agents that form self-assembled monolayers. A new biaxial loading device was used to conduct a series of mixed-mode fracture experiments. Crack opening interferometry, atomic force microscopy, and angle-resolved X-ray photoelectron spectroscopy allowed cohesive zone sizes, fracture surface topographies, and loci of fracture to be established. The experiments were complemented by finite element analyses that accounted for the rate- and pressure-dependent yielding of the epoxy. The analyses also made use of traction-separation laws to represent the various interphases that were produced by the mixed monolayers. The intrinsic toughness (defined as the area underneath the traction-separation curve) of the bare sapphire interfaces was independent of mode-mix and lower than values from previous experiments with glass/epoxy and quartz/epoxy specimens. The increase in overall toughness with mode-mix was completely accounted for by viscoplastic dissipation in the epoxy outside the cohesive zone. The minimum toughness of the coated sapphire interfaces was about five times higher than the mode-mix independent intrinsic toughness of the uncoated specimens. The increase in overall toughness with mode-mix was almost completely accounted for by increases in the intrinsic toughness as the traction-separation law varied with mode-mix. As a result, viscoplastic dissipation outside the cohesive zone was minimal. Atomic force fractography and X-ray photoelectron spectroscopy indicated that the crack growth mechanisms and the loci of fracture in the coated and uncoated specimens were quite different.

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