Water Structure at the Water-Polymer Interface

Water Structure at the Water-Polymer Interface

Author: H. Jellinek

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 191

ISBN-13: 146158681X

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This symposium was held at the l6lst ACS National Meeting, Los Angeles, March/April 1971. It represents a contribution to the discussion of problems connected with the state of water near macromolecules. Some papers are only peripheral to the problem of water structure but may become quite pertinent in specific cases. Questions concerned with water structure, rate of hydration, and similar problems are of importance for biological processes and are still not yet well understood. It is hoped that the papers presented here will be of some help in the clarification of problems in this area. H. H. G. Jellinek Department of Chemistry Clarkson College of Technology Potsdam, New York September, 1971 v CONTRIBUTORS S. Ablett, Unilever Research Laboratory, Colworth House, Sharnbrook, Bedford, England M. Anbar, Stanford Research Institute, Menlo Park, California F. W. Cope, Biochemistry Division, Aerospace Medical Research Laboratory, U. S. Naval Air Development Center, Warminster, Pennsylvania B. Crist, Camille Dreyfus Laboratory, Research Triangle Park, North Carolina F. Franks, Unilever Research Laboratory, Colworth House, Sharnbrook, Bedford, England H. R, Gloria, NASA-Ames Research Center, Moffett Field, California G. W. Gross, New Mexico Institute of Mining and Technology, Socorro, New Mexico H. R. Hansen, The Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio R. S. Kaiser, Research Laboratories, Eastman Kodak Company, Rochester, New York N. Laiken, Department of Chemistry, The University of Oregon, Eugene, Oregon C. E. Lamaze, Camille Dreyfus Laboratory, Research Triangle Park, North Carolina G. N.


Structural and Dynamical Properties of Water and Polymers at Surfaces and Interfaces

Structural and Dynamical Properties of Water and Polymers at Surfaces and Interfaces

Author: Selemon Bekele

Publisher:

Published: 2018

Total Pages: 0

ISBN-13:

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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.


Understanding the Structure of Water, Ice, and Aqueous Solutions Next to Solid Surfaces

Understanding the Structure of Water, Ice, and Aqueous Solutions Next to Solid Surfaces

Author: Emmanuel Anim-Danso

Publisher:

Published: 2015

Total Pages: 142

ISBN-13:

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[Finally, we have also performed experiments at polymer/water interface. The polymer/water interface is commonly encountered and a molecular understanding of surface restructuring in water will be useful to biomedical science. We studied how poly(n-butyl a-hydroxymethyl acrylate) (PHNB), an amphiphilic polymer, restructures in the vicinity of water using SFG and contact angle measurements. We have observed that at room temperature, the surface resists putting the more hydrophilic groups at the interface with water. Even though such a conformation is thermodynamically favorable, the polymer surface appears to be frozen due to the high polymer Tg. However, when the polymer is heated in water above its Tg (80oC), the surface restructures due to the increased segmental motions in the polymer. Our study into the molecular interactions of water and ice with solid surfaces provides insights into the increased adhesion of ice to surfaces and could lead to the design of materials that could reduce ice adhesion strength on surfaces]


Water in Biological and Chemical Processes

Water in Biological and Chemical Processes

Author: Biman Bagchi

Publisher: Cambridge University Press

Published: 2013-11-14

Total Pages: 383

ISBN-13: 1107037298

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A unified overview of the dynamical properties of water and its unique and diverse role in biological and chemical processes.


Polymer Interfaces and Emulsions

Polymer Interfaces and Emulsions

Author: Kunio Esumi

Publisher: CRC Press

Published: 2020-08-13

Total Pages: 588

ISBN-13: 1000146243

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"Presents the latest knowledge on a wide range of topics in polymer science, including the dynamics, preparation, application, and physiochemical properties of polymer solutions and colloids; the adsorption characteristics at polymer surfaces; and the adhesion properties (including acid-base) of polymer surfaces."


Fundamentals of Sum-Frequency Spectroscopy

Fundamentals of Sum-Frequency Spectroscopy

Author: Y. R. Shen

Publisher: Cambridge University Press

Published: 2016-02-18

Total Pages: 570

ISBN-13: 131647304X

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The first book on the topic, and written by the founder of the technique, this comprehensive resource provides a detailed overview of sum-frequency spectroscopy, its fundamental principles, and the wide range of applications for surfaces, interfaces, and bulk. Beginning with an overview of the historical context, and introductions to the basic theory of nonlinear optics and surface sum-frequency generation, topics covered include discussion of different experimental arrangements adopted by researchers, notes on proper data analysis, an up-to-date survey commenting on the wide range of successful applications of the tool, and a valuable insight into current unsolved problems and potential areas to be explored in the future. With the addition of chapter appendices that offer the opportunity for more in-depth theoretical discussion, this is an essential resource that integrates all aspects of the subject and is ideal for anyone using, or interested in using, sum-frequency spectroscopy.


Water at Interfaces

Water at Interfaces

Author: Jordi Fraxedas

Publisher: CRC Press

Published: 2014-04-15

Total Pages: 253

ISBN-13: 1439861056

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Water, with its simple molecular structure, reveals a complex nature upon interaction with other molecules and surfaces. Water at Interfaces: A Molecular Approach provides a broad, multidisciplinary introduction to water at interfaces, focusing on its molecular characteristics. The book considers interfaces at different length scales from single wa