scholarly journals Roles of Paper Composition and Humidity on the Adhesion between Paper Sheet and Glass: A Molecular Dynamics Study

2021 ◽  
Author(s):  
Hyunhang Park ◽  
Sung Hoon Lee ◽  
Elizabeth I. Morin ◽  
Andrew C. Antony
Keyword(s):  
Molecular Dynamics ◽  
Adhesion Force ◽  
Water Layer ◽  
Van Der Waals Interactions ◽  
Crystalline Cellulose ◽  
Hydroxyl Groups ◽  
Cellulose Film ◽  
Paper Sheet ◽  
Hydrogen Bond Interactions ◽  
Realistic Situation

Abstract Understanding adhesion behavior between paper materials and inorganic substrate is important to minimize surface contamination by paper fragments. In this work, we investigate adhesion mechanisms between paper sheet and glass in terms of molecular interaction. Molecular dynamics simulations are employed to calculate adhesion force between paper sheet and the silica glass surfaces. Pulling and sliding tests are simulated to find the effects of the paper compositions such as mannan, glucan, and glucuronoxylan and humidity on the adhesion. Simulation results reveal that crystalline cellulose film of mannan unit (uni-directional hydroxyl groups) shows higher adhesion than that of glucan unit (bi-directional hydroxyl groups). Also, addition of just a few glucuronoxylan (xylan) hemicellulose molecules on the cellulose film remarkably enhances adhesion force, because of carboxylic acid groups with strong polarity in xylan. In addition, introduction of humidity leads to a further increase of adhesion due to hydrogen bonds bridged by water molecules. The adhesion force is maximized around 10 H2O/nm2 because as the humidity increases, hydrogen bond interactions are saturated, whereas the Van der Waals interactions decrease due to thicker water layer. It is discussed that consideration of the capillary force for paper may result in different adhesion response that reflects more realistic situation.

scholarly journals New Insights Into the Structure of Hydroxylated and Alkylated Glycols: A Comparative X-ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

2020 ◽  
Author(s):  
Lorenzo Gontrani ◽  
Pietro Tagliatesta ◽  
Antonio Agresti ◽  
Sara Pescetelli ◽  
Marilena Carbone
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Gauche Conformation ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Diffraction Patterns ◽  
Intramolecular Hydrogen

In this study, we report a detailed experimental and theoretical investigation of three glycols, namely ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane. For the first time, the X-Ray spectra of the latter two liquids was measured at room temperature, and they were compared with the newly measured spectrum of ethane-1,2-diol. The experimental diffraction patterns were interpreted very satisfactorily with molecular dynamics calculations, and suggest that in liquid ethane-1,2-diol most molecules are found in gauche conformation, with intramolecular hydrogen bond between the two hydroxyl groups. Intramolecular H-bonds are established in the mono-alkylated diol, but the interaction is weaker. The EDXD study also evidences strong intermolecular hydrogen-bond interactions, with short O···O correlations in both systems, while longer methyl-methyl interactions are found in 1,2-dimethoxy ethane. X-Ray studies are complemented by micro Raman investigations at room temperature and at 80°C, that confirm the conformational analysis predicted by X-Ray experiments and simulations.

scholarly journals Running-in behavior of a H-DLC/Al2O3 pair at the nanoscale

Friction ◽  
2020 ◽  
Author(s):  
Pengfei Shi ◽  
Junhui Sun ◽  
Yunhai Liu ◽  
Bin Zhang ◽  
Junyan Zhang ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Substrate Surface ◽  
Friction Reduction ◽  
Van Der Waals Interactions ◽  
Strong Hydrogen Bond ◽  
Asperity Contact ◽  
Layer Formation ◽  
Transfer Layer ◽  
Dlc Film ◽  
Hydrogen Bond Interactions

AbstractDiamond-like carbon (DLC) film has been developed as an extremely effective lubricant to reduce energy dissipation; however, most films should undergo running-in to achieve a super-low friction state. In this study, the running-in behaviors of an H-DLC/Al2O3 pair were investigated through a controllable single-asperity contact study using an atomic force microscope. This study presents direct evidence that illustrates the role of transfer layer formation and oxide layer removal in the friction reduction during running-in. After 200 sliding cycles, a thin transfer layer was formed on the Al2O3 tip. Compared with a clean tip, this modified tip showed a significantly lower adhesion force and friction force on the original H-DLC film, which confirmed the contribution of the transfer layer formation in the friction reduction during running-in. It was also found that the friction coefficient of the H-DLC/Al2O3 pair decreased linearly as the oxygen concentration of the H-DLC substrate surface decreased. This phenomenon can be explained by a change in the contact surface from an oxygen termination with strong hydrogen bond interactions to a hydrogen termination with weak van der Waals interactions. These results provide new insights that quantitatively reveal the running-in mechanism at the nanoscale, which may help with the design optimization of DLC films for different environmental applications.

scholarly journals New Insights into the Structure of Glycols and Derivatives: A Comparative X-Ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1011
Author(s):  
Lorenzo Gontrani ◽  
Pietro Tagliatesta ◽  
Antonio Agresti ◽  
Sara Pescetelli ◽  
Marilena Carbone
Keyword(s):  
Molecular Dynamics ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Gauche Conformation ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Molecular Dynamics Calculations ◽  
Diffraction Patterns ◽  
Intramolecular Hydrogen

In this study, we report a detailed experimental and theoretical investigation of three glycol derivatives, namely ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane. For the first time, the X-ray spectra of the latter two liquids was measured at room temperature, and they were compared with the newly measured spectrum of ethane-1,2-diol. The experimental diffraction patterns were interpreted very satisfactorily with molecular dynamics calculations, and suggest that in liquid ethane-1,2-diol most molecules are found in gauche conformation, with intramolecular hydrogen bonds between the two hydroxyl groups. Intramolecular H-bonds are established in the mono-alkylated diol, but the interaction is weaker. The EDXD study also evidences strong intermolecular hydrogen-bond interactions, with short O···O correlations in both systems, while longer methyl-methyl interactions are found in 1,2-dimethoxy ethane. X-ray studies are complemented by micro Raman investigations at room temperature and at 80 °C, that confirm the conformational analysis predicted by X-ray experiments and simulations.

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

Molecular dynamics study on the mechanism of AFM-based nanoscratching process with water-layer lubrication

2015 ◽  
Vol 346 ◽  
pp. 84-98 ◽  
Author(s):  
Jiaqi Ren ◽  
Jinsheng Zhao ◽  
Zeguang Dong ◽  
Pinkuan Liu
Keyword(s):  
Molecular Dynamics ◽  
Water Layer

scholarly journals Adhesion of Individual Attachment Setae of the Spider Cupiennius salei to Substrates With Different Roughness and Surface Energy

2021 ◽  
Vol 7 ◽  
Author(s):  
Bastian Poerschke ◽  
Stanislav N. Gorb ◽  
Clemens F. Schaber
Keyword(s):  
Surface Energy ◽  
Glass Substrate ◽  
Adhesion Force ◽  
Adhesive System ◽  
Adhesive Contact ◽  
Contact Angles ◽  
Individual Variability ◽  
Van Der Waals Interactions ◽  
Smooth Surfaces ◽  
Cupiennius Salei

Dynamic adhesion is a key ability for animals to climb smooth surfaces. Spiders evolved, convergent to geckos, a dry adhesive system made of setae branching into smaller microtrichia ending as spatulae. Several previous studies concentrated either on the whole adhesive claw tuft on the spider´s foot that consists of attachment setae or on the single adhesive contact elements, the microtrichia with spatula-shaped tips. Here, the adhesion of single setae of the spider Cupiennius salei was examined and the morphology of the pretarsus and the fine structure of the setae were studied in further detail. Using individual setae fixed to force sensing cantilevers, their adhesion at different contact angles with a glass substrate was measured as well as their adhesive performance on substrates with different roughness and on smooth surfaces with different surface energies. The results show an individual variability of the adhesive forces corresponding to the seta morphology and especially to the seta tip shape. The tip shapes of the setae vary largely even in neighboring setae of the pretarsal claw tuft that comprises approximately 2,400 setae. Regarding surface energy of the substrate, the adhesion force on hydrophobic polytetrafluoroethylene was 30% of that on a hydrophilic glass substrate, which points to the importance of both van der Waals interactions and hydrogen bonds in spider adhesion.

Diffusion coefficients and viscosities of organic aerosol components through equilibrium and non-equilibrium molecular dynamics simulations

2021 ◽  
Author(s):  
Katerina S. Karadima ◽  
Vlasis G. Mavrantzas ◽  
Spyros N. Pandis
Keyword(s):  
Molecular Dynamics ◽  
Functional Groups ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Amorphous Solid ◽  
Good Effect ◽  
Hydroxyl Groups ◽  
Chemical Structures ◽  
Organic Particles ◽  
Non Equilibrium

<p>Organic aerosols have been typically considered to be liquid, with equilibration between gas and aerosol phase assumed to be reached within seconds. However, Virtanen et al. (Nature, 2010) suggested that particles in amorphous solid state may also occur in the atmosphere implying that mass transfer between the atmospheric particulate and gas phases may be much slower than initially thought. Experimentally, the direct measurement of the diffusion coefficients of different compounds inside atmospheric organic particles is challenging. Thus, an indirect approach is usually employed, involving viscosity measurements and then estimation of diffusion coefficients via the Stokes-Einstein equation, according to which the diffusion coefficient is inversely proportional to the medium viscosity. However, the corresponding diffusion estimates are highly uncertain, especially for highly viscous aerosols which is the most important case. Molecular simulation methods, such as molecular dynamics (MD), can be an alternative method to determine directly the diffusion rates and the viscosity of the constituents of atmospheric organic particles. MD also provides detailed information of the exact dynamics and motion of the molecules, thus offering a deeper understanding on the underlying mechanisms and interactions.</p><p>In the present work, we use equilibrium and non-equilibrium MD simulations to estimate the viscosity and diffusion coefficients of bulk systems of representative organic compounds with different chemical structures and physicochemical characteristics. Hydrophilic and hydrophobic compounds representative of primary and secondary oxidized organic products and of primary organic compounds emitted by various sources are considered. The viscosity and self-diffusion coefficients calculated by our simulations are in good agreement with available experimentally measured values. Our results confirm that the presence of carboxyl and hydroxyl groups in the molecule increases the viscosity. The number of carboxyl and hydroxyl groups, in particular, seems to have a good effect on diffusivity (the diffusivity decreases as the number of these functional groups increase), and to a lesser extent on the viscosity. We also discuss the role of the hydrogen bonds formed between these functional groups.</p>

scholarly journals Effect of Lysyllysine on non-covalent hybridization of single walled carbon nanotube by single-stranded DNA homodimer: in silico approach

2019 ◽  
Vol 9 (4) ◽  
pp. 315-321
Author(s):  
Fateme Bagherolhashemi ◽  
Mohammad Reza Bozorgmehr ◽  
Mohammad Momen-Heravi
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Electrostatic Interactions ◽  
Membered Ring ◽  
Binding Energies ◽  
Van Der Waals Interactions ◽  
Dynamics Simulation ◽  
Quantum Calculations ◽  
Single Walled Carbon Nanotube ◽  
Sensor Properties

Abstract In this work, the interactions between adenine–adenine di-nucleotide (DA2N) and carbon nanotube (CNT) in the presence of Lysyllysine (LL) was studied by the molecular dynamics simulation. Different carbon nanotubes including (5.5), (6.6) and (7.7) were used to investigate the effect of CNT type. The binding energies were calculated using the molecular mechanics-Poisson Bolzmann surface area method. The results showed that the contribution of the van der Waals interactions between DA2N and CNT was greater than that of the electrostatic interactions. The LL significantly enhanced the electrostatic interactions between the DA2N and CNT (6.6). The quantum calculations revealed that the sensor properties of the DA2N were not significantly affected by the CNT and LL. However, the five-membered ring of adenine played a more important role in the sensing properties of the DA2N. The obtained results are consistent with the previous experimental observations that can help to understand the molecular mechanism of the interaction of DA2N with CNT. Graphic abstract

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