FREE ELECTRONIC LIBRARY - Dissertations, online materials

Pages:   || 2 | 3 | 4 | 5 |   ...   | 42 |

«A Study of Fundamentals in Emulsion Templating for the Preparation of Macroporous Polymer Foams By Dipl.-Chem. Nadine Graeber A dissertation ...»

-- [ Page 1 ] --

Imperial College London

Department of Chemical Engineering

A Study of Fundamentals in Emulsion

Templating for the Preparation of

Macroporous Polymer Foams

By Dipl.-Chem. Nadine Graeber

A dissertation submitted to Imperial College London

in fulfilment of the requirements for the degree of

Doctor of Philosophy

and the Diploma of Membership of Imperial College London

September 2013




I, hereby, certify that the work presented in this dissertation is the result of my own investigations, carried out at Imperial College London. Every work, which is not my own has been properly acknowledged.

Nadine Graeber September 2013 The copyright of this thesis rests with the author and is made available under a Creative Commons Attribution Non-Commercial No Derivatives licence. Researchers are free to copy, distribute or transmit the thesis on the condition that they attribute it, that they do not use it for commercial purposes and that they do not alter, transform or build upon it.

For any reuse or redistribution, researchers must make clear to others the licence terms of this work.


-iv- Acknowledgements This work was carried out in the Polymer and Composite Engineering (PaCE) Group of the Department of Chemical Engineering, Imperial College London, from March 2009 to January 2012 supervised by Professor Dr. Alexander Bismarck.

First of all, I would like to acknowledge and to thank my supervisor, Professor Dr. Alexander Bismarck for giving me the opportunity and the freedom in my scientific research and Dr.

John Hodgkinson for all the discussions about the mechanical property tests. In particular, I would like to express my deepest gratitude and special thanks to Dr. Stefan Berendts for his uncountable and numerous inspiring conversations and discussions which without the present work would be completely different. Furthermore, I am very appreciative for the correction of my ‘run-on sentences’ in this thesis. If I could do so, I would pass ’Dr.h.c.’ to you.

I have an enormous list of people who have supported, trained and taught me during this study and many other people have contributed directly or indirectly to the completion of this work. Professor Dr. Michael Gradzielski and his group (Technische Universität Berlin, Germany) is kindly acknowledged for giving me the opportunity to do the rheological measurements in his laboratory and to benefit from his outstanding knowledge. Dorith Claes and Elisa Franzman (Justus-Liebig-Universität Gießen, Germany) are kindly acknowledged for giving me the opportunity to use their ESI-MS spectrometer, Dr. Dennis Blank (Justus-Liebig-Universität Gießen, Germany) for carrying out MALDI-TOF measurements and Dr. Jan-Dirk Epping (Technische Universität Berlin, Germany) for CP and CP-MAS-NMR measurements. Dr. Bjoern Luerßen (Justus-Liebig-Universität Gießen, Germany) for the enjoyable time and accurate artistic contributions to many of the drawings in this thesis. ‘My SEM images are still untouchable!’ Countless people around the Departments of Chemical Engineering, Mechanical Engineering, Chemistry and especially George Wang (SPEL Group, Imperial College London, U.K.), Dr. Natasha Shirshova (for pointed remarks) and Sarah Payne (language support) need to be acknowledged for their help and support. Also I want to thank my countless colleagues (about 42 new and former group members) and friends in the PaCE group for their help and support during my stay in the U.K.. Their kindness and humour has left me with wonderful memories and widened my view of the world. Thank you!

Additionally, I would like to acknowledge the Engineering and Physical Science Research Council (EPSRC) for the funding. My thanks and appreciation goes also to Professor Dr.

Cosima Stubenrauch (Universität Stuttgart, Germany) and Professor Dr. Paul Luckham (Imperial College London, U.K.) for serving as my examiners.

Finally, I would like to give unlimited thanks to my Dad, my little-big sister, my unborn nanobrother (now you are a year old!), my family and friends. Nothing could stop their never ending love and nothing could replace the support from them. Thank you!

–  –  –

-viiviii- ABSTRACT This thesis describes a series of styrene (ST) and divinylbenzene (DVB) emulsion templated polymer foams prepared via low, medium and high internal phase emulsion templates (L/M/HIPE templates). The emulsion templates were stabilized using different commercially available technical surfactants and surfactant mixtures. Since the chemical nature of the chosen technical surfactants is unknown, the surfactants where characterized by means of Fourier Transform Infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy, Electro Spray Ionization Mass- (ESI-MS) and Matrix-Assisted-Laser-Desorption-IonizationTime-of-Flight-Mass Spectrometry (MALDI-TOF-MS). Additionally their adsorption at the water/ST:DVB interface was studied. The investigation regarding the preparation of surfactant stabilized emulsion templates and their polymerization products revealed that the most commonly used surfactant Span 80 is not the best suited surfactant to stabilize styrene/divinylbenzene emulsion templates which is why different surfactants were used in the thesis at hand. All successfully prepared poly(merized)HIPEs proved to have interconnected, open porous polymer foam structures. In contrast, the pore structure of polyMIPEs was open, closed or non-droplet shaped, depending on the surfactant used to stabilize the corresponding emulsion template. The mechanical compression properties of all prepared polyHIPEs were similar and independent of the HIPE formulation from which they were produced but the mechanical properties of polyMIPEs differed significantly. The influence of the surfactants on the morphology and mechanical properties of the resulting macroporous polymers will be discussed in detail.

Furthermore, the relationship between the relative density (porosity) of the polymer foams and the mechanical response under compression was investigated. The semi-empirical models developed by Gibson and Ashby were applied and additionally modified to provide a more accurate description of the mechanical behaviour over a larger relative density range of polymer foams prepared via emulsion templating (polyL/M/HIPEs). This allows a prediction of the mechanical properties as a function of the relative density of the respective polymer foams and vice versa for the specified emulsion template formulation. It is obvious that the surfactant type and the internal phase volume ratio of the emulsion template used to produce macroporous polymer foams significantly determine their resulting mechanical properties, as clear transition states for polyH/M/LIPEs were identified

-ixin which the mechanical properties of these materials changed dramatically. The effect of the surfactant on the mechanical properties and the polymer foam morphology is discussed in terms of the surfactant’s solubility in the polymer and thus in terms of its role as plasticizer.

Finally, the influence of the pore size on the mechanical properties was investigated. It was found that the preparation process (emulsification and polymerization) of the emulsion templates is very crucial for the mechanical properties of the resulting polymer foams (reproducibility). More precisely, it was found out that the emulsion templates need to ‘equilibrate’ after emulsification. It was only for these emulsions that average pore sizes and mechanical properties could be reproduced.

-xList of Communications


1. Graeber, Nadine; Hodgkinson, John M.; Bismarck, Alexander; Mechanical properties of macroporous polymer foams prepared via emulsion templating (polyH/M/LIPEs) and the impact of the internal phase ratio, Macro2012, 24th to 29th June 2012, Blacksburg, Virgina, U.S.A..

2. Graeber, Nadine; Bismarck Alexander; Impact of surfactants and Internal phase ratios on the mechanical properties of polyL/M/HIPEs, Eupoc2012, 3rd to 7th June 2012, Gargnano, Italy.

3. Graeber, Nadine; Lee, Koon-Yang; Menner Angelika; Bismarck Alexander;

Renewable Open Macroporous Nanocomposites, 2011 ICMAT, 26th June to 1st July 2011, Suntec, Singapore.

4. Graeber, Nadine; Menner Angelika; Bismarck Alexander, Polymer and Surfactant Interaction, 57th SEPAWA Congress, 2010, 13th to 15th October 2010, Fulda, Germany.

5. Graeber, Nadine; Menner, Angelika; Bismarck, Alexander; Renewable Macroporous Nanocomposites via Emulsion Templating, 2009 AIChE Annual Meeting, 2009, 8th to 13th November 2009, Nashville TN, U.S.A. (Invited talk).

6. Menner, Angelika; Graeber, Nadine; Bismarck, Alexander; Ultra permeable macroporous polymers from Pickering-high internal phase emulsions, 14th U.K.

Polymer and Colloids Forum, 2009, 14th to 16th September 2009, Hull, U.K..

Poster Presentations:

I. Graeber Nadine; Menner, Angelika; Bismarck, Alexander; New perspectives in the synthesis of macroporous polymers via emulsion templating, Macro2010: 43rd IUPAC World Polymer Congress, 11th to 16th July 2010, Glasgow, U.K..

II. Graeber Nadine; Menner, Angelika; Bismarck, Alexander; Water in oil emulsions stabilized by hydrophilic particles to produce porous materials via emulsion templating, 14th U.K. Polymer and Colloids Forum, 14th to 16th September 2009, Hull, U.K..

III. Graeber, Nadine; Manley, Shu San; Menner, Angelika; Bismarck, Alexander, Turning liquid into solid: Materials based on polyHIPEs, JCF-Spring Symposium 2009, 11th to 14th March 2009, Essen, Germany.


Manley, Shu San; Graeber, Nadine; Grof, Zdenek; Menner, Angelika; Hewitt, Geoffrey F.;

Stepanek, Frantisek; Bismarck, Alexander; New insights into the relationship between internal phase level of emulsion templates and gas-liquid permeability of interconnected macroporous polymers., Soft Matter (2009), 5(23), 4780-4787.

–  –  –

-xvxvi- List of Figures Figure 1: Schematic presentation of water-in-oil-surfactant stabilized emulsion templating................1 Figure 2: Two-dimensional schematic formulation−composition map, showing the so-called optimum formulation inversion (Adapted from Ref. [44])

Figure 3: Mechanisms of emulsion destabilization which results finally in two distinct phases (oil and water).

Figure 4: Schematic potential energy according to the DLVO-theory. The potential energy (U) results from the sum of van der Waals attraction (UA) and electrostatic repulsion (UE) during the interactions between two spherical droplets or particles depending on the droplet distance (x). U0 contains all other non-DLVO interactions, which need to be considered in case of adsorbing polymers on the surface (U0). Additionally, a shortrange Born repulsion (UB) exist which arise from the fact that each atom, molecule, particle etc. occupies a certain amount of space.

Figure 5: Various mechanisms of emulsion stabilization imparted by different emulsifiers. For example; a) adsorbed Ca2+-ions in alginates (gelation), b) short molecules emulsifier such as soaps, c) solid particles, so called Pickering or Ramsden stabilization and d) high molecular weight polymeric stabilizers.

Figure 6: Some physico-chemical properties, such as electrical conductivity, surface/interfacial tension and turbidity as a function of surfactant concentration. Additionally, the adsorption behaviour of the surfactant molecules at the interface as a function of their concentration is shown at the bottom of the figure. Surfactant concentrations higher than the critical micelle concentration (CMC) result in the formation of surfactant micelles

Figure 7: Schematic representation of an emulsion and the polymerized products if one polymerizes only the dispersed phase, the continuous phase and both phases for the preparation of colloids/beads, porous materials and composites, respectively (Adapted from Ref. [118]).

Figure 8: Morphologies of polyHIPEs: a) definition of pores and pore throats of polyHIPEs, b) the pore throats are partially covered with a thin solid film, c) closed porous structure and

d) non-droplet shaped (bicontinuous) foam morphology.

Figure 9: SEM image of a polyMIPE (left, contained an internal phase of 50 vol.-%) and a polyLIPE (right, contained an internal phase of 25vol.-% ) (Reprinted from Ref. [50]).

Figure 10: Schematic representation of particles on a planar (top) and curved (middle) interface in order to define the contact angle (θOW) of the particle in water. Hydrophilic particles (θOW 90°) being adsorbed at the liquid-liquid interface (left) curve the interface to such an extent that o/w-emulsions are obtained. Hydrophobic particles (θOW 90°) curve the interface in the direction of w/o-emulsions (right) (Adapted from Ref. [250]).....36 Figure 11: Decomposition of 2,2’-azobis(2-methylpropionitrile) (AIBN) for free radical polymerization reaction.

Figure 12: The one electron step involved in the redox reaction between cumene hydroperoxide (CHP) and Fe2+.

Figure 13: Initiator decay of peroxodisulphate (APS) in a combination with tetramethylenediamin (TMEDA) to form two radical species.

Figure 14: Basic schematic reaction for a free radical polymerization reaction of vinyl monomers, where kd, ki, kp, and kt are the rate constants of dissociation, initiation, propagation and termination by combination, respectively.

Figure 15: ST-DVB-polyHIPE with metal organic framework (MOF) crystals inside the pores (Adapted from Ref. [378]).

Figure 16: Proposed chemical structure of the surfactants used. In the case of Hypermer 2296 it is assumed that this is a mixture of sorbitan oleate (Span 80) and PIBSA.

-xviiFigure 17: Photograph of emulsification set-up used (left) and dimensions of the set-up (right);

diameter of stirrer arm (b), outer diameter of stirrer (d2), vessel height (h1), blade height (h3), inner diameter of vessel (d1) and stirrer pitch (h2) 5 mm. Fill volume of 50 mL water = 43 mm height within the vessel.

Figure 18: Definition of sample specimens from the resulting polymer foam monolith used for various characterizations throughout this thesis.

Figure 19: Comparison of pore size counting via SEM and log-normal distribution function (Equation 10) of a polyHIPE, at least 200 pores were counted. The sum of all counts is equal to 1

Pages:   || 2 | 3 | 4 | 5 |   ...   | 42 |

Similar works:

«Instructions for use Numerical Simulation of Gas Flow with Electrochemical Reaction in a Polymer Electrolyte Fuel Cell by K. M. Salah Uddin A dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy (PhD) in the Division of Mechanical and Space Engineering Hokkaido University, Japan September 2013 ABSTRACT The aim of this dissertation was to investigate the performance of Polymer Electrolyte Fuel Cell (PEFC). The investigation involved...»

«A COLD OF THE HEART: JAPAN STRIVES TO NORMALIZE DEPRESSION by George Kendall Vickery BA, College of William and Mary, 1986 Submitted to the Graduate Faculty of Arts and Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2005 UNIVERSITY OF PITTSBURGH FACULTY OF ARTS AND SCIENCES This dissertation was presented by George Kendall Vickery It was defended on August 1, 2005 and approved by Dr. Joseph S. Alter Dr. Richard Scaglion Dr....»


«Modeling SHANK2 Related Neuropsychiatric Disorders in Mice by Andrea Lynn Pappas Department of Neurobiology Duke University Date: _Approved: _ Yong-hui Jiang, Supervisor _ Rebecca Yang, Chair _ Ben Philpot _ Scott Soderling Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Neurobiology in the Graduate School of Duke University 2015 i v ABSTRACT Modeling SHANK2 Related Neuropsychiatric Disorders in Mice by Andrea Lynn...»

«EVALUATING THE EFFECTIVENESS OF ORIENTATION INDICATORS WITH AN AWARENESS OF INDIVIDUAL DIFFERENCES by Tina Renee Ziemek A dissertation submitted to the faculty of The University of Utah in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science School of Computing The University of Utah June 2010 Copyright c Tina Renee Ziemek 2010 All Rights Reserved THE UNIVERSITY OF UTAH GRADUATE SCHOOL SUPERVISORY COMMITTEE APPROVAL of a dissertation submitted by...»

«Predictive Coding: How the Human Brain Uses Context to Facilitate the Perception of Degraded Speech By Conor James Wild A thesis submitted to the Centre for Neuroscience Studies in conformity with the requirements for the degree of Doctor of Philosophy Queen’s University Kingston, Ontario, Canada August, 2012 Copyright © Conor J. Wild, 2012 Abstract The most common and natural human behaviours are often the most computationally difficult to understand. This is especially true of spoken...»

«ABSTRACT Title of document: DENOVO SYNTHESIZED FATTY ACIDS AS REGULATORS OF MILK FAT SYNTHESIS Diwakar Vyas, Doctor of Philosophy, 2011 Directed By: Professor Richard A. Erdman Department of Animal and Avian Sciences The objectives of the dissertation research were to determine the role of denovo synthesized fatty acids (DNFA) in the regulation of milk fat synthesis. Milk fat responses to increasing amounts of shortand medium-chain fatty acids (SMCFA), added in the proportion as synthesized...»

«Tel Aviv University The Lester & Sally Entin Faculty of Humanities The Shirley & Leslie Porter School of Cultural Studies SIMILARITY, VARIATION, AND CHANGE: INSTABILITY IN HEBREW WEAK VERBS THESIS SUBMITTED FOR THE DEGREE “DOCTOR OF PHILOSOPHY” by Gila Zadok Submitted to the Senate of Tel Aviv University December 2012 This work was carried out under the supervision of Prof. Outi Bat-El TABLE OF CONTENTS Abstract Acknowledgements CHAPTER 1. Introduction 1.1. Overview 1.2. Language Background...»

«Representations of Gender and Subjectivity in 21st Century American Science Fiction Television Sophie Halliday Submitted for the degree of Doctor of Philosophy University of East Anglia, School of Film, Television and Media Studies March 2014 This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that use of any information derived there from must be in accordance with current UK Copyright Law....»

«MULTIOBJECTIVE DESIGN AND INNOVIZATION OF ROBUST STORMWATER MANAGEMENT PLANS A Dissertation Presented by Karim Jeffrey Chichakly to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Specializing in Computer Science May, 2013 Accepted by the Faculty of the Graduate College, The University of Vermont, in partial fulfillment of the requirements for the degree of Doctor of Philosophy, specializing in...»

«Piedras votivas de Pampacolca Nuevos datos sobre las lajas pintadas del sur del Perú Votivsteine aus Pampacolca Neue Daten über bemalte Steinplatten aus Südperu Inauguraldissertation zur Erlangung des Grades eines Doktors der Philosophie am Fachbereich Geschichtsund Kulturwissenschaften der Freien Universität Berlin vorgelegt von Renata Faron-Bartels M.A. Berlin 2011 1. Gutachter: Prof. Dr. Jürgen Golte 2. Gutachterin: Prof. Dr. Ursula Thiemer-Sachse Tag der Disputation: 10. 11. 2009 2...»

«Tuning Magnetic Order in Transition Metal Oxide Thin Films by Alexander John Grutter A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering Materials Science and Engineering in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Yuri Suzuki, Co-Chair Professor Oscar Dubon, Co-Chair Professor Frances Hellman Professor David Attwood Fall 2013 Tuning Magnetic Order in Transition Metal...»

<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.