Structure Of Self-assembled Monolayers Research Articles

The Effect of Physicochemical Properties of Perfluoroalkylsilanes Solutions on Microtribological Features of Created Self-Assembled Monolayers.

The presented article shows the influence of concentration of perfluoroalkylsilanes in solutions on tribological properties of self-assembled monolayers (SAMs) deposited on three surfaces with different silicon content in the millinewton load range. The SAMs were created using the liquid phase deposition (LPD) method with 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (FDTS) and (3, 3, 3-trifluoropropyl) trichlorosilane (FPTS) solutions, for which viscosity and surface tension were estimated. Deposited layers were analyzed in terms of thickness, coverage, wettability, structure and coefficient of friction. The obtained results demonstrated that SAMs created on the silicon-incorporated diamond-like carbon (Si-DLC) coatings possess the best microtribological properties. Systems composed of perfluoroalkylsilane SAM structures deposited on Si-DLC coatings are highly promising candidates as material for microelectromechanical applications.

Vibrational sum-frequency generation study of molecular structure, sterical constraints and nonlinear optical switching contrast of mixed alkyl-azobenzene self-assembled monolayers

AbstractSelf-assembled monolayers (SAMs) of azobenzene (AB) functionalized alkyl thiols on gold diluted with simple alkyl thiols provide a straightforward way to photochromic surfaces with high and tunable photoswitching efficiency.Trans-cisisomerization of the AB molecule changes the physical properties of the surface, including the nonlinear optical (NLO) response. Vibrational sum-frequency generation (VSFG) spectroscopy as a nonlinear type of laser spectroscopy offers surface- and orientation-sensitive insight into the molecular structure of mixed SAMs. In this study, VSFG as well as ultraviolet-visible (UV/Vis) spectroscopy has been employed to investigate the morphology, molecular structure, and NLO response of mixed SAMs with systematically varied surface composition. Methylazobenzene (MeAB) has been used as the molecular switch with the methyl substituent serving as orientational VSFG marker. Both short-chain and long-chain alkyl thiol co-ligands have been used to gain insight into the interplay between SAM structure and sterical constraints that are known to limit the free switching volume. Underlining the dominating role of sterical effects for controlling photochromic properties, a strong inhibition of the photoswitching efficiency and NLO response has been observed for the SAMs with an alkyl thiol co-ligand long enough to spatially extend into the layer of the MeAB chromophore. Overall, with <12% signal change, the relative NLO switching contrasts remained low in all cases. VSFG spectral trends clearly revealed that the presumably higher photoswitching efficiency upon dilution with the co-ligand is counteracted by a loss of structural order of the chromophore.

Influence of Terminal Carboxyl Groups on the Structure and Reactivity of Functionalized m-Carboranethiolate Self-Assembled Monolayers

The structure and function of self-assembled monolayers (SAMs) at the nanoscale are determined by the steric and electronic effects of their building blocks. Carboranethiol molecules form pristine ...

Influence of an alkyl spacer on the formation and structure of 4-Fluorobenzenethiol and 4-Fluorobenzenemethanethiol self-assembled monolayers on Au(111)

Self-assembled monolayers (SAMs) prepared by adsorption of 4-Fluorobenzenethiol (p-FBT) and 4-Fluorobenzenemethanethiol (p-FBMT) on Au(111) substrates with different immersion times (ITs) at room temperature have been characterized using scanning tunneling microscopy (STM). The resulting p-FBT and p-FBMT monolayers showed substantial differences concerning their adlayer SAM structure and surface morphology. The structural quality of p-FBT-SAMs was found to depend significantly on the preparation conditions such as the IT. At short IT of ~3 h, the p-FBT-SAMs were found to mainly include disordered phase (α-phase) between the surrounding areas of the gold islands. With increasing IT, a gradual phase transition from the disordered phase (α) into ordered one (β-phase) was observed. Consequently, increasing the IT to ~ 24 h resulted in the formation of well-defined and highly ordered β-phase that is characterized by the commensurate (83×23)R30∘superstructure. In contrast to the p-FBT-SAMs, a full-coverage and close packed monolayers were formed in p-FBMT-SAMs only after very short IT of ~1 min. The upright-standing p-FBMT molecules were found to form a (3×3)R30∘structure. Despite the absence of a periodic variation in the height of the molecules within the molecular domains, we proposed a larger (23×3)R30∘unit cell containing two inequivalent p-FBMT molecules arranged in a herringbone-type structure instead of the smaller (3×3)R30∘unit cell. The considerable difference in the behavior of these closely related molecules which differ only in their structure (an additional methyl group between benzene and S group in p-FBMT), clarifies the delicate balance of the factors which define the energy and the structure of thiol SAMs.

Addition of an Eco-Friendly Corrosion Inhibitor in Self-Assembled Monolayers Coatings to Improve Pitting Corrosion Resistance of Stainless Steel

In automotive industry and equipment manufacturers, treatment by phosphatation [1] is used both as an adhesion primer before painting and as a lubricant coating [2].This treatment also offers a good protection against corrosion. However, phosphatation is quite harmfull for the environment, producing a lot of waste to be treated. With regards to toxicity, it is composed of concentrated acids, nitrates and nitrites. Eventually, OEM are working to reduce the thickness of this coating which is typically in the range 2-30 µm. The objective of our research is to propose an alternative to steel/phosphate systems by thin organic coating on 304 stainless steel, a low carbon content substrate free of Molybdene available at affordable costsTo fit with the requiered specification while being as attractive as possible, this alternative coating must present a thickness reduced to a few nanometres, be environmentally friendly, non-toxic and easy to use. It must keep the main properties of phosphatation which consist in adhesion or anti-wear. Self-assembled Monolayers (SAMs) [3] coatings were chosen with addition of Aloe Vera as an ecological corrosion inhibitor [4][5]. SAMs are tunable by adjusting either their terminal group or the length of the carbon chain to obtain the desired surface properties and corrosion resistance. Three different terminal groups combined with four carbon chain lengths have been tested to find the molecule providing the best protection against corrosion.An electrochemical study is carried out to quantify protection against pitting corrosion in a chloride-containing medium. The substrate used being a 304 stainless steel. As pitting corrosion mechanism involves both stable and unstable pits, two types of electrochemical methods are used. Pulsed potentials technic will highlighted unstable pits, while stable pits are analysed by cyclic voltammetry. These measurements are supported by surface analysis (SEM, EDS).[1] T. W. COSLETT, Treatment of iron or steel for preventing oxidation or rusting, British patent 8667 and US patent 870937, 1906 et 1907[2] J. BOGI, Phosphate conversion coatings on steel, J Mater Sci (1977) 12, 2235-2240[3] A. ULMAN, Formation and structure of self-assembled monolayers, Chem. Rev. 1996, 96, 1533-1554[4] Devarayan, Kesavan, Green Inhibitors for Corrosion of Metals: A Review, Chem Sci Rev Letts, (2012)[5] M. MEHDIPOUR, Electrochemical noise investigation of Aloe plant extract as green inhibitor on the corrosion of stainless steel in 1M H2SO4, J. Ind. Eng. Chem, (2015), 21, 318-327 Figure 1

Alkynyl Linkers as a Design Tool to Gain Control over the Self-Assembly of Meso-Substituted Porphyrins on HOPG.

Self-assembled monolayers (SAMs) fall generally into two broad categories: those that are covalently bound either to the surface or to each other and those that rely on weaker forces such as hydrogen bonding or van der Waals forces. The engineering of the structure of SAMs formed from weaker forces is an exciting and complex field that often utilizes long alkane substituents bound to core moieties. The core provides the unique optical, electronic, or catalytic property desired, while the interdigitation of the alkane chains provides the means for creating well-regulated patterns of cores on the substrate. This design technique sometimes fails because some of the alkane substituents remain extended into solution rather than become interdigitated on the substrate. One contributor to this is steric hindrance between elements of the core and of the alkane chain. It is shown that the use of an alkyne linker between the core and the alkane chain can, in the case of meso-substituted porphyrins, significantly reduce this steric barrier and allow more stable and predictable surface structures to form. In particular, 5,15-bis(1-octynyl)porphyrin and 5,15-bis(1-tetradecynyl)porphyrin are shown to form significantly more stable SAMs than their alkane-linked counterparts. Scanning tunneling microscopy is used to provide detailed surface structures. Temperature and solution concentration dependence of the surface coverage is also reported. Density functional theory (DFT) is used to determine the energetic effects associated with alkane substitution at both the meso and β positions and the beneficial energetic effects of the alkyne linker.

Self-assembled monolayers from symmetrical di-thiols: Preparation, characterization and application for the assembly of electrochemically active films

1,3-dimercaptopropan-2-ol, a symmetrical di-thiol, has been synthesized and applied as a new type of anchor molecule to prepare a self-assembled monolayer (SAM) on the gold surface. The formed monolayers were studied by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, kinetic capacitance, and contact angle measurements. The SAM structure depends on the adsorption conditions. A short incubation time of the electrode at high concentration of this di-thiol leads to the predominating binding through one thiol group of the adsorbate to the gold surface, while a long incubation at low concentration leads to the predominating binding by both thiol groups. A comparative study of the desorption and replacement of SAMs indicates a strong stability increase when the SAM molecules bond gold surface by two bonds mainly. This monolayer was used to immobilize electrochemically active p-benzoquinone moiety. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10−10 mol·cm−2 which corresponds to the functionalization of 65 ± 5% of SAM molecules. The obtained highly stable SAM with redox-active terminal group can be applied for different tasks of chemical sensing and biosensing. As an example, an application of this system for electrocatalytical oxidation of dihydronicotinamide adenosine dinucleotide (NADH) was tested.

Dependence of deposition method on the molecular structure and stability of organosilanes revealed from degrafting by tetrabutylammonium fluoride.

We probe the structure of self-assembled monolayers (SAMs) comprising organosilanes deposited on flat silica-based surfaces prepared by liquid and vapor deposition by removing the organosilane molecules gradually from the underlying substrate via tetrabutylammonium fluoride (TBAF). Removal of organosilanes from the surface involves the cleavage of all pertinent Si-O bonds that anchor the organosilane molecules to the SAM, i.e., direct organosilane-surface linkages and in-plane crosslinks between neighboring organosilanes. We gain insight into the organosilane structure and stability by monitoring the organosilane density as a function of exposure time to TBAF. Degrafting of trifunctional chloro- and methoxy-alkylsilanes deposited from solution yields similar degrafting kinetics. We observe fast degrafting for organosilane SAMs deposited from the vapor phase, indicating that SAMs prepared in this manner form more loosely packed arrays, with less in-plane connectivity, compared to their solution-deposited counterparts. Bulkier, fluorinated silanes form more stable SAMs due to their ability to readily align and form a network with few aggregates and a relatively high fraction of surface bonds. The addition of a polymer brush to an anchored organosilane molecule demonstrates that increased bond tension accelerates the degrafting process despite the increased diffusion resistance.

Defects in Self-Assembled Monolayers on Nanoparticles Prompt Phospholipid Extraction and Bilayer-Curvature-Dependent Deformations

Metal nanoparticles (NPs) functionalized with self-assembled monolayers (SAMs) of long alkanethiol ligands are subject to defects in the SAM structure due to the interplay between alkyl chain packing and the free volume available in space per ligand. We find via dissipative particle dynamics (DPD) simulations that hydrophobic contact between protruding acyl chains of phospholipids from lipid vesicles and exposed alkyl chains in SAM defects prompts NP insertion and that defects become sites for phospholipid extraction. Experiments show that AuNPs coated with cationic (11-mercaptoundecyl)trimethylammonium bromide, analogous to the models used for the simulations, attach to and acquire lipids from planar supported lipid bilayers, while AuNPs coated with anionic 11-mercaptoundecanoic acid do not. Phospholipid extraction and the structure of the ligands inserted in bilayers collectively contribute to bilayer thinning at the site of NP insertion and bilayer-curvature-dependent deformability, revealing how these typical engineered SAM-coated NPs interface with lipid-bilayer systems with potential biological consequences.

Investigating the Structure of Self-Assembled Monolayers Related to Biological Cell Membranes.

Tethered bilayer lipid membranes are solid supported lipid membranes, where the inner leaflet is covalently linked to the solid supported substrate through anchorlipids. These anchorlipids form a self-assembled monolayer, which serves as the basis of the membrane and also provides submembrane space. The molecular structure and composition of this monolayer has thus significant influence on the membrane structural and functional properties. The density of the self-assembled monolayer can be tailored by adding small molecules to the monolayer. Here, the structure of fully tethered and sparsely tethered monolayers, where the anchorlipid has been diluted with a small surface-active thiol, has been analyzed using neutral impact collision ion scattering spectroscopy, X-ray photoelectron spectroscopy, and metastable induced electron spectroscopy. Combination of these three techniques allowed description of the self-assembly process in detail. The monolayers have been characterized in terms of layer thickness and orientation of the lipids.

Formation of long-range-ordered self-assembled monolayers of dodecyl thiocyanates on Au(111) via ambient-pressure vapor deposition

The surface structure, binding condition, and reductive desorption behavior of self-assembled monolayers (SAMs) of dodecyl thiocyanate (DDTC, C12–SCN) on Au(111) formed via solution and ambient-pressure vapor depositions at 50 °C for 24 h were examined by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). STM imaging clearly revealed that adsorption of DDTC molecules on Au(111) in a 1 mM ethanol solution led to the formation of short-range-ordered dodecanethiolate (C12S) SAMs with a domain size ranging from several nanometers to 20 nm, whereas the SAMs formed via vapor deposition had long-range-ordered C12S SAMs of size exceeding 60 nm, which were characterized as having a (4 × √3)rect packing structure. XPS measurements showed that the DDTC SAMs formed via vapor deposition on Au(111) contained approximately one-fourth the amount of unbound sulfurs and CN species compared to solution-deposited SAMs. CV measurements also showed that vapor-deposited SAMs had a sharp reductive desorption peak at −1.028 V, whereas solution-deposited SAMs had two broad desorption peaks at −0.671 and −0.946 V, implying that vapor-deposited SAMs are more uniform and electrochemically stable. The present results clearly demonstrate that DDTC SAMs on Au(111) with a high degree of structural order, homogeneous interface, and high electrochemical stability can be prepared by ambient-pressure vapor deposition.

Solvent Effect on the Formation of Octaneselenocyanate Self-Assembled Monolayers on Au(111).

Solvent effect on the formation and electrochemical behavior of octaneselenolate (C8Se) self-assembled monolayers (SAMs) on Au(111) derived from the adsorption of octaneselenocyanate (C8Se-CN) molecules in various solvents at 363 K for 1 h was examined by scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM imaging clearly revealed that the formation and structure of C8Se SAMs were markedly influenced by the polarity of solvent. C8Se SAMs formed in octane were composed of liquid-like disordered phase. In contrast, C8Se SAMs formed in DMF had ordered domains but not a uniform surface, whereas C8Se SAMs formed in ethanol had uniform surface and highly ordered domains with a (2 × 2 √13) structure. It was found that the structural quality of C8Se SAMs increased with increasing solvent polarity in the order of ethanol > DMF > octane. CV measurements also showed that blocking efficiency of C8Se SAMs for electrode reaction increased with increasing the structural quality of SAMs.

Segmentation of scanning tunneling microscopy images using variational methods and empirical wavelets

In the fields of nanoscience and nanotechnology, it is important to be able to functionalize surfaces chemically for a wide variety of applications. Scanning tunneling microscopes (STMs) are important instruments in this area used to measure the surface structure and chemistry with better than molecular resolution. Self-assembly is frequently used to create monolayers that redefine the surface chemistry in just a single-molecule-thick layer. Indeed, STM images reveal rich information about the structure of self-assembled monolayers since they convey chemical and physical properties of the studied material. In order to assist in and to enhance the analysis of STM and other images, we propose and demonstrate an image-processing framework that produces two image segmentations: one is based on intensities (apparent heights in STM images) and the other is based on textural patterns. The proposed framework begins with a cartoon+texture decomposition, which separates an image into its cartoon and texture components. Afterward, the cartoon image is segmented by a modified multiphase version of the local Chan-Vese model, while the texture image is segmented by a combination of 2D empirical wavelet transform and a clustering algorithm. Overall, our proposed framework contains several new features, specifically in presenting a new application of cartoon+texture decomposition and of the empirical wavelet transforms and in developing a specialized framework to segment STM images and other data. To demonstrate the potential of our approach, we apply it to actual STM images of cyanide monolayers on Au\{111\} and present their corresponding segmentation results.

Formation and Structure of Highly Ordered Self-Assembled Monolayers by Adsorption of Acetyl-Protected Conjugated Thiols on Au(111) in Tetrabutylammonium Cyanide Solution

The surface structure and binding conditions of self-assembled monolayers (SAMs) on Au(111) derived from 1-acetylthio-4-[(phenyl)ethynyl]benzene (OPE2-SAc) without and with tetrabutylammonium cyanide (TBACN) as a deprotection reagent were examined using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). STM observation revealed that OPE2-S SAMs on Au(111) formed from direct adsorption of OPE2-SAc in 1 mM methanol solution at room temperature (RT) for 24 h were composed of short-range, ordered phase separated by a disordered phase. In contrast, adsorption of OPE2-SAc SAMs on Au(111) at a higher solution temperature of 50 °C for 24 h led to formation of a fully ordered phase with slightly increased domain size. The structural quality of OPE2-S SAMs on Au(111) was remarkably enhanced when TBACN was used. OPE2-S SAMs at RT had a well-ordered (√3 × √7)R30° structure with a domain size larger than 80 nm. The SAMs deposited at 50 °C contained very uniform and highly ordered domains w...

Computational and experimental approach to understanding the structural interplay of self-assembled end-terminated alkanethiolates on gold surfaces.

Applications of self-assembled monolayers (SAMs) on surfaces are prevalent in modern technologies and drives the need for a better understanding of the surface domain architecture of SAMs. To explore structural interaction at the interface between gold surfaces and a hydroxyl-terminated alkanethiol, 11-hydroxy-1-undecanethiol, (C11TH) we have employed a combined computational and experimental approach. Density functional theory (DFT) calculations were carried out on the thiol-gold interface using both the Perdew-Burke-Ernzerhof (PBE) and van der Waals (optB86b) density functionals. Our ab initio molecular dynamics (AIMD) simulations revealed that the interface consists of four different distinguished phases, each with different C11TH orientations. Experiments involved deposition of C11TH SAMs onto gold, with the resultant surfaces examined with X-ray photoelectron spectroscopy (XPS) and ellipsometry. Weighted average projected density of states (PDOS) of the different phases were photoionization cross section corrected and these were confirmed by experimental XPS data. Computed molecular parameters including tilt angles and the thickness of SAMs also agreed with the XPS and ellipsometry results. Hydrogen bonding arising from the terminal hydroxyl groups is the primary factor governing the stability of the four phases. Experimental results from XPS and ellipsometry along with DFT simulation results provide insights into the formation of the different orientations of SAM on Au(111) which will guide future efforts in the self-assembled SAMs architecture for other thiols or metal substrates.

Nanoparticle Assembling through Click Chemistry Directed by Mixed SAMs for Magnetic Applications

“Click” chemistry, used to promote nanoparticle assemblies, is a powerful strategy which has emerged very recently to control the spatial arrangement of nanoparticles onto surfaces. Such a strategy may be of high interest for applications such as magnetic recording media or magnetic sensors which are based on the fine control of the collective properties of nanoparticles. Nevertheless, self-assembly driven by clickable functional groups still remains to be understood. Mixed self-assembled monolayers (SAMs) of alkane–thiol molecules were used to control the spatial arrangement of nanoparticles onto gold substrates. This approach was combined with click chemistry in order to control the immobilization of nanoparticles on selective areas through specific copper catalyzed alkyne–azide cycloaddition (CuAAC) reaction. Mixed SAMs consist of co-adsorbed 11-(undec-1-ynyl)thiol (S-CC) and 12-(dodecane)thiol (S-CH3) molecules. The variation of the molar ratio between both molecules resulted in significant modulation of the structure of nanoparticle assemblies. The spatial arrangement of nanoparticles revealed the very complex structure of alkyne/methylene terminated mixed SAMs. Alkyne terminal groups could not be only studied by the usual characterization surface techniques such as PM-IRRAS and XPS. Therefore, azido-terminated nanoparticles acted as probing agents to determine the spatial distribution of alkyne groups at the surface of mixed SAMs. This approach was combined with scanning tunneling microscopy (STM) and DFT calculations to get a deeper insight into the structure of mixed SAMs of S-CC and S-CH3 molecules. Gold substrate topography, chemical affinity of molecules, intermolecular interactions and length of alkyl chains were found to be critical parameters that rule the SAM structure.

Investigation of Local Hydration Structures of Alkanethiol Self-Assembled Monolayers with Different Molecular Structures by FM-AFM.

Hydration structures play crucial roles in a wide variety of chemical and biological phenomena. However, the key factors that determine a hydration structure remain an open question. Most recent studies have focused on the electrostatic interactions between the surface charges and dipoles of water molecules, which are determined by the atomic/ionic species of the outermost solid surface, as the dominating factor. The number of studies on the correlation between the hydration structure and the atomic-scale surface corrugation has been limited. In this study, we investigated the hydration structures of alkanethiol self-assembled monolayers terminated with a hydroxyl group using frequency-modulated atomic force microscopy. We observed two molecular structures, namely, the (√3 × √3) R30° structure and the c(4 × 2) superlattice structure, and found that their hydration structures are different mainly because of the slight differences in their molecular arrangements. This result suggests that a slight difference in the molecular/atomic arrangements as well as the atomic/ionic species in the outermost solid surface strongly influences the local hydration structures.

Amyloid-β fibrils assembled on ganglioside-enriched membranes contain both parallel β-sheets and turns

Some protein and peptide aggregates, such as those of amyloid-β protein (Aβ), are neurotoxic and have been implicated in several neurodegenerative diseases. Aβ accumulates at nanoclusters enriched in neuronal lipids called gangliosides in the presynaptic neuronal membrane, and the resulting oligomeric and/or fibrous forms accelerate the development of Alzheimer's disease. Although the presence of Aβ deposits at such nanoclusters is known, the mechanism of their assembly and the relationship between Aβ secondary structure and topography are still unclear. Here, we first confirmed by atomic force microscopy that Aβ40 fibrils can be obtained by incubating seed-free Aβ40 monomers with a membrane composed of sphingomyelin, cholesterol, and the ganglioside GM1. Using Fourier transform infrared (FTIR) reflection-absorption spectroscopy, we then found that these lipid-associated fibrils contained parallel β-sheets, whereas self-assembled Aβ40 molecules formed antiparallel β-sheets. We also found that the fibrils obtained at GM1-rich nanoclusters were generated from turn Aβ40 Our findings indicate that Aβ generally self-assembles into antiparallel β-structures but can also form protofibrils with parallel β-sheets by interacting with ganglioside-bound Aβ. We concluded that by promoting the formation of parallel β-sheets, highly ganglioside-enriched nanoclusters help accelerate the elongation of Aβ fibrils. These results advance our understanding of ganglioside-induced Aβ fibril formation in neuronal membranes and may help inform the development of additional therapies for Alzheimer's disease.

Kinetics and Structure of Self-Assembled Flagellin Monolayers on Hydrophobic Surfaces in the Presence of Hofmeister Salts: Experimental Measurement of the Protein Interfacial Tension at the Nanometer Scale

In the present study, we monitor the adsorption–desorption kinetics and adsorbed layer structure of the bacterial protein flagellin in the presence of Hofmeister salts by a surface sensitive label-free optical biosensor (optical waveguide lightmode spectroscopy, OWLS). The recorded OWLS data were analyzed by a computer code using a set of coupled differential equations modeling the adsorption–desorption process. By supposing reversibly and irreversibly adsorbed protein states with different adsorption footprints, the kinetic data could be perfectly fitted. We revealed that the proteins adsorbing in the presence of kosmotropic salts had smaller footprints, leading to a more oriented and densely packed layer. Kosmotropic salts increased both the adsorption rate constant and the transition rate constants from the reversibly to the irreversibly adsorbed state. In contrast, chaotropic salts increased the desorption rate constant and led to decreased adsorbed mass and a more loosely packed film. Neither circula...

Self-assembled monolayers, the agglomeration binders of pyrolytic coke fines

The chemical composition of self-assembled monolayers on the surface of pyrolytic-coke particles were examined by a variety of characteristic tests and the results revealed that aliphatic hydrocarbons are incorporated as self-assembled monolayers on the surface of pyrolytic coke particles. The self-assembled monolayers are responsible for particulate agglomeration of pyrolytic-cokes in hot quench water and fouling propensity. The size distribution of agglomerated particles was observed by scanning electron microscopy representing the merged agglomerated particles by self-assembled monolayer. Energy-dispersive X-ray spectra revealed no heteroatoms in the chemical structure of self-assembled monolayer, while BET technique highlighted the active role of micropores to adsorb the self-assembled monolayers. Particle size analysis revealed the agglomeration process of coke fines from id: 1–5 μm to 10–40 μm. Such agglomeration increases the risk of plugging and restriction of heat transfer in process equipments. The results revealed that a reliable solution to overcome the fouling problem is preventing the formation of self-assembled monolayers.