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Permanent link (DOI): https://doi.org/10.7939/R3KQ4W

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Role of hydrophobic effect and hydrogen bonding in surface interactions of polymers Open Access

Descriptions

Other title
Subject/Keyword
hydrophobic
Polymer surface
surface interaction
hydrogen bonding
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Faghihnejad, Ali
Supervisor and department
Zeng, Hongbo (Chemical & Materials Engineering)
Examining committee member and department
Narain, Ravin (Chemical & Materials Engineering)
Song, Hau (Chemical & Petroleum Engineering, University of Calgary)
Liu, Yang (Civil & Environmental Engineering)
Zhang, Hao (Chemical & Materials Engineering)
Department
Department of Chemical and Materials Engineering
Specialization
Chemical Engineering
Date accepted
2013-09-16T12:03:36Z
Graduation date
2013-11
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Polymers are widely used as coatings, adhesives, biomaterials and many other applications. These successful applications rely on the physical and chemical properties of the polymer molecules and surfaces. One type of important molecular and surface interaction is hydrophobic interaction which is believed to be responsible for many interfacial and colloidal phenomena such as micelle formation, protein folding and is widely used in industrial applications such as mineral floatation. Nevertheless, direct probing of hydrophobic interaction between polymer surfaces has received only limited attention. Using polystyrene (PS) as a model polymer, the surface interactions were measured in different electrolyte solutions by a surface forces apparatus (SFA) coupled with a top-view optical microscope. A long-range attraction was observed between two PS surfaces which was found to be due to the bridging of microscopic and sub-microscopic bubbles on the PS surfaces and depended on the type and concentration of the electrolyte solutions due to ion specificity. The interaction forces in asymmetric system (PS vs. mica) were also studied and long-range repulsion was observed associated with the deformation of bubbles on PS surface. The range of the surface interactions was significantly reduced to <20 nm after degassing the solutions which indicates the important role of dissolved gases on the measured forces. Another important type of intermolecular interaction widely used for the development of new polymers is hydrogen bonding through supramolecular chemistry where the reversible interaction is used for tuning polymer properties. In this work, the surface interactions of poly(butyl acrylate) (PBA) functionalized with a quadruple hydrogen bonding group called UPy were investigated. The adhesion and mechanical properties of PBA-UPy were found to be significantly enhanced by the UPy groups and strongly depend on temperature, relative humidity in air and contact time. The PBA-UPy polymer shows self-healing capability. Interesting surface patterns (e.g. fingers, stripes) were observed associated with the separation of two PBA-UPy films. Our results provide new insights into the fundamental understanding of the molecular interaction mechanisms of polymers containing hydrogen bonding and hydrophobic groups and the development of novel functional materials.
Language
English
DOI
doi:10.7939/R3KQ4W
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
A. Faghihnejad, H. Zeng “Fundamentals of surface adhesion, friction and lubrication” in Polymer Adhesion, Friction and Lubrication, John Wiley & sons, 2013.A. Faghihnejad, H. Zeng Soft Matter, 8, 2746-59 (2012).

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