Download or read book Structure and Dynamics of Interfacial Water at Surfaces with Varying Hydrophobicity written by Stephanie Elise Sanders and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aqueous interfaces are ubiquitous across atmospheric, biological, and technological processes. Interfacial water is thought to play an active role in many of these processes. For instance, hydrophobic coatings are used for anti-biofouling and the interaction between water molecules and the hydrophilic coatings is believed to inhibit protein adhesion. However, the precise role of water is not well understood. Interfacial water is also notoriously difficult to study experimentally since the number of water molecules at the interface is miniscule compared to the bulk and the ultrafast fluctuations of the hydrogen-bonding network require sub-picosecond time resolution. Sum-frequency generation (SFG) is a second-order nonlinear spectroscopy that is sensitive to only the vibrations of interfacial water due to the requirement of broken inversion symmetry within the dipole approximation. Using hydrophobic, hydrophilic and mixed hydrophobic/hydrophilic self-assembled monolayers, we examined the structure of the interfacial water with heterodyne-detected SFG (HD-SFG) to obtain the purely absorptive vibrational line shape. In order to probe the dynamics of the hydrogen-bonded interfacial water, we performed time resolved SFG experiments. The vibrational relaxation time was measured using IR pump- SFG probe experiments, and the spectral diffusion time was measured with interferometric 2D SFG.
Download or read book Structures and Dynamics of Interfacial Water written by Duanyun Cao and published by Springer Nature. This book was released on 2023-03-14 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis highlights the study into the structures and dynamics of interfacial water, which is a cutting edge issue in condensed matter physics. Using the first principles calculation, classical molecular dynamics simulation and the simulation of atomic force microscopy (AFM), combined with the experimental results of AFM, the book systematically studies interfacial water at the atomic scale, especially the structure and growth mechanism of two-dimensional ice on hydrophobic Au (111) surface, the structure and the interconversion of the Eigen/Zundel hydrated proton on the Au(111) and Pt(111) surfaces, the microstructure and the hydration effect of the diffusion of ion hydrates on NaCl surface. This book displays the atomic scale information about the interaction between water and surface, and achieves many innovative results. Furthermore, the research methods included in this book can be further extended to study the more complex interfacial systems.
Download or read book Structural and Dynamical Properties of Water and Polymers at Surfaces and Interfaces written by Selemon Bekele and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: All-atom molecular dynamics simulations have been carried out to study the wetting of model atactic polystyrene thin films by water droplets as a function of surface polarity, the structure and dynamics at the surface of polymer films, the properties of interfacial water molecules in contact with atactic polystyrene surfaces of varying polarity, and the spreading dynamics of water droplets of varying sizes on a completely wetting surface. The simulated contact angle of a water droplet on atactic polystyrene thin films is found to decrease monotonically with increasing degree of surface oxidation which is used as a measure of surface polarity. The number of hydrogen bonds between water molecules and the polystyrene at the interface is found to monotonically increase with polarity. The contribution of the non-dispersion interactions to the interfacial energy at the polystyrene/water interface has been determined as a function of surface polarity. The roughness of the polystyrene surface and the orientational ordering of the surface phenyl rings are found to be independent of surface polarity when the polystyrene is exposed to vacuum. Surface roughness appears to increase and orientational ordering of surface rings appears to decrease slightly with polarity when the polystyrene is in contact with water. Density profiles of polymer films as a function of distance relative to an instantaneous surface exhibit a structure indicative of a layering at the polymer/vapor interface similar to the typical layered structure observed at the polymer/substrate interface. Interfacial molecules at the polymer/vapor interface have a higher mobility compared to that in the bulk while the mobility of the molecules is lower at the polymer/substrate interface. Time correlation of the instantaneous polymer/vapor interface shows that surface fluctuations are strongly temperature dependent and are directly related to the mobility of polymer chains near the interface. Interfacial water molecules on a bare atactic polystyrene surface and those which do not make hydrogen bonds with the oxidized surfaces are found to have a faster dynamics and appear to have a universal water-water hydrogen bond relaxation time of about 5 ps. Diffusion coefficients and the relaxation times of the water molecules involved in hydrogen bonding with the surface show strong dependence on surface polarity with a hydrophobic to hydrophilic transition regime with contact angle in the range 40-50°. The spreading of water droplets on completely wetting surface is characterized by a bulk part of normal density sliding over a monolayer of high density water. The monolayer has a molecular dimension and moves ahead of the bulk part of the droplet. The monolayer motion exhibits two spreading regimes, each following a power law in time. The bulk part of the droplet initially spreads over the monolayer with increasing radius until a characteristic time t* where the monolayer changes from one power law behavior to another. For times after t* ~ 0.1- 0.5 ns, it shrinks while maintaining what appears to be a constant contact angle until it disappears altogether and only a monolayer of water remains on the substrate.
Download or read book Water in Biological and Chemical Processes written by Biman Bagchi and published by Cambridge University Press. This book was released on 2013-11-14 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified overview of the dynamical properties of water and its unique and diverse role in biological and chemical processes.
Download or read book Structures and Dynamics of Interfacial Water written by Fujie Tang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the study of the interfacial water using molecular dynamics simulation and experimental sum frequency generation spectroscopy. It proposes a new definition of the free O-H groups at water-air interface and presents research on the structure and dynamics of these groups. Furthermore, it discusses the exponential decay nature of the orientation distribution of the free O-H groups of interfacial water and ascribes the origin of the down pointing free O-H groups to the presence of capillary waves on the surface. It also describes how, based on this new definition, a maximum surface H-bond density of around 200 K at ice surface was found, as the maximum results from two competing effects. Lastly, the book discusses the absorption of water molecules at the water-TiO2 interface. Providing insights into the combination of molecular dynamics simulation and experimental sum frequency generation spectroscopy, it is a valuable resource for researchers in the field.
Download or read book Orientational Dynamics of Water at Hydrophobic Interfaces written by Florian Figge and published by . This book was released on 2018 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structures and Dynamics of Interfacial Water written by Fujie Tang and published by Springer. This book was released on 2019-06-20 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the study of the interfacial water using molecular dynamics simulation and experimental sum frequency generation spectroscopy. It proposes a new definition of the free O-H groups at water-air interface and presents research on the structure and dynamics of these groups. Furthermore, it discusses the exponential decay nature of the orientation distribution of the free O-H groups of interfacial water and ascribes the origin of the down pointing free O-H groups to the presence of capillary waves on the surface. It also describes how, based on this new definition, a maximum surface H-bond density of around 200 K at ice surface was found, as the maximum results from two competing effects. Lastly, the book discusses the absorption of water molecules at the water–TiO2 interface. Providing insights into the combination of molecular dynamics simulation and experimental sum frequency generation spectroscopy, it is a valuable resource for researchers in the field.
Download or read book Molecular Dynamics Simulation of Water Near Structured Hydrophobic Surfaces written by Sandeep Pal and published by . This book was released on 2005 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main focus of the thesis is to study the enhancement in the hydrophobicity of an already hydrophobic surface by creating surface structuring on the surface of the crystal. The local structuring and the free energy of interfacial water at the crystal/water interface is analysed by molecular dynamics simulation. An alkane crystal has been taken as the parent model for a hydrophobic surface. Surface structuring were created by either indenting pits on the surface of the crystal or by raising a protrusion on the surface of the crystal. Around all structures the water density was lower and the number of contacts between water and the surface of the crystal decreased due to surface structuring. The difference in the free energy of hydration between planar surface and the structured surface also revealed the increase in the hydrophobicity of the already hydrophobic crystal. Finally a study on the hydrophobicity of a perfluoro-n-alkane crystal is discussed in the final chapter. A qualitative comparison of the water structuring near an alkane and a perfluoro-n-alkane crystal show a higher htdrophobicity in case of a perfluoro-n-alkane crystal than an alkane crystal.
Download or read book Interfacial and Confined Water written by Ivan Brovchenko and published by Elsevier. This book was released on 2008-06-03 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water in the proximity of a surface (interfacial water) is abundant on the earth. It is involved in various physical and chemical processes and crucial for biological function. Despite numerous studies of interfacial water, systematic analysis of its properties is missing in scientific literature. This book is a first comprehensive review of experimental and simulation studies of water in various confining environments, such as hydrophilic and hydrophobic surfaces, surfaces of biomolecules, porous media, etc. Systematic analysis of interfacial and confined water is based on the firm physical ground, which accounts for variety of the thermodynamic states of water near the surface, surface phase transitions, surface critical behaviour, effect of confinement on the bulk and surface phase transitions of water, clustering and formation of a spanning hydrogen-bonded water network via percolation transition. This allows distinguishing between universal features, common for all fluids, and some specific water properties, related to intermolecular hydrogen bonds. Special attention is paid to the properties of hydration water, which covers biomolecules and enables their biological activity. This book provides readers with basic information on interfacial and confined water, which will be useful for scientists and engineers working in the fields of bioscienses, nanociences and nanotechnologies. Comprehensive review and analysis of interfacial and confined water Updates and informs practitioners and students on all the latest developments in the field Written by leading scholars and industry experts
Download or read book Understanding Modulations to Hydrophobicity by Spatially Heterogeneous Interfaces written by Bradley Dallin and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding how interfaces interact with interfacial water molecules is vital to design novel bio- and nanomaterials that can rationally tune hydrophobic interactions (i.e., water-mediated interactions that drive the association of nonpolar materials in an aqueous environment). Materials with fine-tuned hydrophobicity would be of great importance in various biological (e.g., lipid membrane self-assembly) and industrial applications (e.g., separations). However, accurately predicting hydrophobic interactions at the nanoscale poses a significant challenge due to collective interactions between interfacial water molecules and the specific physical or chemical properties on the surface. Enormous research effort using experiments, simulations, and theory has been applied to relate surface properties, interfacial water structure, and hydrophobicity. The general goal of this dissertation is to apply simulation experiments and data-centric analysis to build upon the existing literature to fundamentally understand how spatially varying physical and chemical surface properties influence hydrophobic interactions. In Chapters 2 and 3, we examine how spatially varying physical properties influence hydrophobic interactions. We developed an experimentally validated simulation methodology to directly measure hydrophobic interactions between two uniformly nonpolar, planar self-assembled monolayers (SAMs). In addition, we quantified interfacial water structure by measuring a variety of water order parameters to determine how physical properties perturb the interfacial water hydrogen bond network. Our observations showed that increased SAM order correlated with decreased interfacial water structure. These observations predicted differences in the solvation entropy of the SAM-water interface, which we confirmed using simulation and experimental measurements of hydrophobic force as a function of temperature. In Chapter 4, we explore how specific end group chemistry and surface patterns influence hydrophobicity. We deployed a more efficient method to measure relative differences in SAM hydrophobicity to evaluate many more chemistries and patterns. We quantified interfacial water structure for each of the SAMs and trained a data-centric regression model to predict SAM hydrophobicity. Strikingly, this regression model required only five water structural features to accurately predict hydrophobicity. We further examined these features to understand fundamentally how chemistry and pattern tune interfacial water structure to alter hydrophobicity. In Chapter 5, we apply the insights gained from Chapter 3 which found that changes in the local water structural properties on the surface related to macroscopic differences in hydrophobicity. Using 2D and 3D data representations of the spatially varying interfacial water properties, we developed a machine learning model that uses convolutional neural networks to rapidly predict SAM hydrophobicity. This model provides a valuable tool to virtually screen many different SAM surface properties. In Chapter 6, we combine our newly established understanding of how physical properties (Chapters 2 and 3) and chemical properties (Chapter 4) impact hydrophobicity to predict howsurface properties of a SAM-protected gold nanoparticle (GNP) alter hydrophobicity. We find that physical properties, such as GNP curvature and ligand backbone, affect hydrophobicity by altering the GNP surface topology. We also find that changing the end group chemistry has a pronounced effect on GNP hydrophobicity. We use these insights to map hydrophobicity on GNPs which serve as an accurate prediction of small molecule binding to the GNP surface. The new insights gained in these studies about the relationship between surface properties, interfacial water structure, and hydrophobicity provide a strong basis of understanding for how physically and chemically heterogeneous materials modulate hydrophobic interactions. This new understanding could be directly applied as a framework for guided bio- and nanomaterials design in the many applications involving water-mediated interactions.
Download or read book Superhydrophobic Surfaces written by Mehdi Khodaei and published by . This book was released on 2020-07 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Orientational Fluctuations of Liquid Water at Hydrophobic and Hydrophilic Interfaces written by Sucheol Shin and published by . This book was released on 2018 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Being ubiquitous in nature, liquid water interfaces host many important physical and chemical processes. Most of these processes are affected by the properties of water interfaces which depend on molecular details of the interfacial environments. It is thus fundamental to understand microscopic features of a water interface for studying the interfacial phenomena. In this work, we explore structural characteristics of various water interfaces using the methods of molecular simulations and statistical mechanics. Specifically, we describe the intrinsic molecular structure of a water interface in terms of the anisotropic, depth-dependent distribution of water’s molecular orientation. We also analyze the collective hydrogen bond network at the interface which determines the orientational fluctuations of interfacial water molecules. This dissertation consists of three separate studies on related but distinct subtopics. First, we focus on the molecular structure and dielectric properties of the liquid water–vapor interface. We present a statistical mechanical model of interfacial hydrogen bonding which is capable of predicting the orientational distribution at the interface. Using this model along with the atomistic simulations, we reveal that the hydrogen bonding interactions of non-ideal geometries are responsible for the characteristics of the interfacial dielectric properties. Then, we introduce a general computational framework that can characterize the interfacial properties of a hydrated solute from its atomistic simulation. This method utilizes the orientational structure of interfacial water molecules which reflects the microscopic informations about the solute’s surface. We demonstrate that our method is applicable with both temporal and spatial resolutions to a chemically heterogenous surface as well as an irregular surface. Therefore, it is useful especially for probing the local hydration dynamics of a protein which is correlated with the conformational fluctuations. Finally, we study the effects of surface–water interactions on water’s interfacial hydrogen bonding structure using a disordered model hydrophilic surface with tunable polarity. We investigate the relationship between the surface polarity and interfacial molecular structure using the characterization method previously introduced. Based on a mean-field model of interfacial hydrogen bonding, we also quantify the energetic component of surface–water interactions that specifically contribute to modifying the interfacial hydrogen bond network. We identify this specific energetic component as a new measure for hydrophilicity.
Download or read book Hydrogen Bond Networks written by Marie-Claire Bellisent-Funel and published by Springer. This book was released on 2014-03-14 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: The almost universal presence of water in our everyday lives and the very `common' nature of its presence and properties possibly deflects attention from the fact that it has a number of very unusual characteristics which, furthermore, are found to be extremely sensitive to physical parameters, chemical environment and other influences. Hydrogen-bonding effects, too, are not restricted to water, so it is necessary to investigate other systems as well, in order to understand the characteristics in a wider context. Hydrogen Bond Networks reflects the diversity and relevance of water in subjects ranging from the fundamentals of condensed matter physics, through aspects of chemical reactivity to structure and function in biological systems.
Download or read book Water and Peptide Structure at Hydrophobic and Hydrophilic Surfaces written by Sandra Roy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to better understand the interfacial peptide-water interaction, molecular dynamics simulations were made for both water, and an amphipathic peptide, LKa14, adsorbed at hy- drophobic and hydrophilic surfaces. Structural and orientational analyses were performed on both systems. Vibrational mode frequency and oscillator coupling were analyzed for the interfacial water. When looking at the peptide, DFT (density functional theory) ab initio calculations were performed to obtain the non linear vibrational information of the different side chains conformers. Non linear vibrational spectra derived from these results were simulated for both interfacial water and adsorbed peptide. The sum frequency vibrational spectra obtained were correlated to the orientation analysis results. Comparison with literature results were made for both spectral and orientational analysis. The results obtained of water at hydrophilic surfaces lead us to conclude that the absence of signal in the 3700 cm?1 region is due to a cancellation of strongly opposite oriented water layers rather than the absence of O?H oscillators at this vibrational frequency region. The hydrophobic and water-air simulation resulted in surprisingly strong similarity but with difference in the depth of those features. When analyzing the structure of LKa14, results showed that it retained an? helix conformation preference in bulk and adsorbedon surfaces. The hydrophobic surface results lead us to conclude a strong orientation of the leucine side chain towards the interface. Results from the adsorption of LKa14 at the hydrophilic surface proved that the adsorption process takes longer than for the hydrophobic surface. Due to results of water and peptide adsorption, we propose that the time scale of the adsorption process for peptide interaction with hydrophilic surface is partially due to the multiple, strongly orientated, water layers.
Download or read book Interfacial Dynamics written by Nikola Kallay and published by CRC Press. This book was released on 2000-01-03 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: An examination of the theoretical foundations of the kinetics and thermodynamics of solid-liquid interfaces, as well as state-of-the-art industrial applications, this book presents information on surface and colloidal chemical processes and evaluates vital analytical tools such as atomic force microscopy, surface force apparatus measurements, and p
Download or read book Interfacial Water A Physical Chemistry Perspective Volume II written by Motomu Tanaka and published by Frontiers Media SA. This book was released on 2022-07-19 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topic Editor Harada receives financial support from AGC Research Collaboration System with the title “Research on the control of biocompatibility based on the analysis of substrate surface”. The other Topic Editors declare no competing interests
Download or read book Impact of Hydrophobicity and Confinement on the Structure and Dynamics of Water at Interfaces written by Frederik Maria Zysk and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
