GROWING TO SHRINK Grafting alumina mesopores for molecular separations Renaud B. Merlet GROWING TO SHRINK Grafting alumina mesopores for molecular separations DISSERTATION to obtain the degree of doctor at the University of Twente, on the authority of the rector magnificus, prof.dr. T.T.M. Palstra, on account of the decision of the Doctorate Board, to be publicly defended on the 21st of November 2019 at 14:45. by Renaud Benoit Merlet born on the 18th of November 1986 in Paris, France This dissertation has been approved by supervisors: Prof. Dr. Ir. A. Nijmeijer and Prof. Dr. A.J.A. Winnubst This work is part of the research program “Modular Functionalized Ceramic Nanofiltration Membranes” (BL-20-10), jointly financed by the Netherlands Organization for Scientific Research (NWO) and the Institute for Sustainable Process Technology (ISPT). Cover design: Linda van Zijp Printed by: ProefschriftMaken Lay-out: ProefschriftMaken ISBN: 978-90-365-4895-3 DOI: 10.3990/1.9789036548953 © 2019 Renaud Merlet, The Netherlands. All rights reserved. No parts of this thesis may be reproduced, stored in a retrieval system or transmitted in any form or by any means without permission of the author. Alle rechten voorbehouden. Niets uit deze uitgave mag worden vermenigvuldigd, in enige vorm of op enige wijze, zonder voorafgaande schriftelijke toestemming van de auteur. Graduation Committee Chairman: Dean Prof. Dr. J.L Herek University of Twente Supervisors: Prof. Dr. Ir. A. Nijmeijer University of Twente Prof. Dr. A.J.A. Winnubst University of Science and Technology of China / University of Twente Committee Members: Prof. Dr. Ir. W.M. de Vos University of Twente Prof. Dr. Ir. J. Huskens University of Twente Prof. Dr. J.J.L.M. Cornelissen University of Twente Prof. Dr. E.J.R. Sudhölter Delft University of Technology Prof. Dr. V. Meynen University of Antwerp (Belgium) Prof. Dr. I.F.J. Vankelecom Katholieke Universiteit Leuven (Belgium) A mes grandparents GJ et Cécile TABLE OF CONTENTS SUMMARY …………………………………………………………………… 1 SAMMENVATTING ……….…………………………………………………4 1. Introduction 9 1.1. The case for the functionalization of porous ceramics ............. 11 1.2. Innovative chemistry and fabrication techniques for molecular separations ................................................................................... 13 1.3. OSN membranes and their potential ......................................... 14 1.4. Outline of dissertation chapters ................................................ 15 1.5. References ................................................................................. 18 2. Hybrid Ceramic Membranes for Organic Solvent Nanofiltration: State-of-the-Art and Challenges 21 2.1. Introduction ............................................................................... 23 2.2. The case for hybrid, ceramic-based membranes in OSN ......... 26 2.3. Surface modification of ceramic oxides ................................... 29 2.4. Graft & pore characterization ................................................... 49 2.5. Measuring performance ............................................................ 52 2.6. Transport through porous ceramic membranes ........................ 55 2.7. Conclusion ................................................................................ 70 2.8. References ................................................................................. 71 3. Growing to shrink: nano-tunable polystyrene brushes inside 5 nm mesopores 87 3.1. Introduction ............................................................................... 89 3.2. Experimental ............................................................................. 92 3.3. Results & Discussion ................................................................ 96 3.4. Conclusion .............................................................................. 112 3.5. Supporting information ........................................................... 113 3.6. References ............................................................................... 115 4. Growing to shrink: Poly(ionic liquid) brushes confined to mesopores for CO2/light gas separation 121 4.1. Introduction ............................................................................. 123 4.2. Experimental ........................................................................... 125 4.3. Results & Discussion .............................................................. 130 4.4. Conclusion .............................................................................. 143 4.5. Supplementary Information .................................................... 144 4.6. References ............................................................................... 150 5. A new and green thioether-based crosslinked membrane for nanofiltration applications 157 5.1. Introduction ............................................................................. 159 5.2. Experimental ........................................................................... 162 5.3. Results & Discussion .............................................................. 166 5.4. Conclusion .............................................................................. 176 5.5. Supporting information ........................................................... 177 5.6. References ............................................................................... 185 6. Interpreting rejection in OSNacross grafted ceramic membranes through the Spiegler-Kedem Model 189 6.1. Introduction ............................................................................. 191 6.2. The Spiegler-Kedem-Katchalsky solute transport model ....... 194 6.3. Experimental ........................................................................... 199 6.4. Results & Discussion .............................................................. 202 6.5. Conclusion .............................................................................. 212 6.6. References ............................................................................... 213 7. Evaluation of organic solvent nanofiltration membranes under industrially relevant conditions 219 7.1. Introduction ............................................................................. 221 7.2. Materials ................................................................................. 223 7.3. Methods .................................................................................. 229 7.4. Results and discussion ............................................................ 230 7.5. Conclusion .............................................................................. 237 7.6. Acknowledgements ................................................................. 238 7.7. Acronyms ................................................................................ 238 7.8. Supporting Information .......................................................... 239 7.9. References ............................................................................... 242 8. Perspectives & Reflections 247 8.1. Introduction ............................................................................. 248 8.2. A case for support diversification ........................................... 248 8.3. A universal, predictive model ................................................. 250 8.4. Grafted materials for targeted applications ............................. 251 8.5. Surface & pore modification strategies .................................. 254 8.6. Towards pilot-scale ................................................................. 256 8.7. Conclusion .............................................................................. 257 8.8. References ............................................................................... 258 LIST OF PUBLICATIONS 262 ACKNOWLEDGEMENTS 263 ABOUT THE AUTHOR 265 Summary Hybrid, ceramic-based membranes combine the stability of porous ceramic oxides with the functionality of polymers. The wide range of polymers allows for tailor-made materials matching the requirements of the target application. This thesis expands upon the materials, fabrication techniques and potential applications of hybrid, ceramic-based membranes. Chapter 2 first gives an overview of the recent progress in grafted ceramics for organic solvent nanofiltration (OSN) applications. It provides an overview of suitable organic-inorganic linking functions, reviews the strategies to tune the pore surface and compares the resulting membranes. Also discussed are the capabilities and shortcomings of both the characterization tools and the transport models used to describe this class of membranes. The link between material chemistry, grafting technique and performance is established as the challenges awaiting the researcher of hybrid, ceramic-based membranes are identified. This chapter serves to frame the advances presented in the following Chapters for the reader. Chapter 3 presents the grafting-from technique applied to the confined mesopores of ɣ-alumina. It is the first instance of controlled polymerization initiated from the surface of a high-curvature concave geometry. Polystyrene was grown inside 5 nm diameter pores to shrink to a desired degree, demonstrating the ability to tune the membrane selectivity. The parameters choices of the method used - surface-initiated, activators-regenerated-by-electron-transfer, atom-transfer radical polymerization (SI-ARGET-ATRP) – are detailed. The graft is characterized by TGA, AFM, and FTIR, and it is shown that the