POLYMERS OF INTRINSIC MICROPOROSITY (PIM)-BASED MEMBRANES FOR GAS SEPARATION YONG WAI FEN NATIONAL UNIVERSITY OF SINGAPORE 2014     POLYMERS OF INTRINSIC MICROPOROSITY (PIM)-BASED MEMBRANES FOR GAS SEPARATION YONG WAI FEN (B. Eng. (Chemical) (Hons.), University Putra Malaysia) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMICAL AND BIOMOLECULAR ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2014     DECLARATION I hereby declare that the thesis is my original work and it has been written by me in its entirety. I have duly acknowledged all the sources of information which have been used in the thesis. This thesis has also not been submitted for any degree in any university previously. ___________________ YONG WAI FEN 09 January 2014     ACKNOWLEDGEMENTS First and foremost, I especially wish to express my deepest appreciation and sincere gratitude to my supervisors, Prof. Neal Chung Tai-Shung, and Prof. Tong Yen Wah for their invaluable guidance, advice and constructive comments throughout the course of my research. Their gracious encouragement and support were my source of inspiration in leading me in the completion of my PhD project. I would like to thank my Thesis Advisory Committee (TAC) members, Prof. M.D. Srinivasan, Prof. Lu Xianmao, Prof. Chen Shing Bor, Prof. Jiang Jianwen and Prof. Wang Chi-Hwa for their valuable comments. I also wish to express my recognition to Miss Yong Yoke Ping and the members of patent administration for their kind help in the process of patent documentation. Sincere thanks to department of Chemical and Biomolecular Engineering at the National University of Singapore (NUS) for providing well-equipped laboratory facilities and professional atmosphere for research study. I would also like to acknowledge the financial support from Singapore National Research Foundation (NRF) (grant number: R-279-000-311-281) to enable the succession of this work. Special appreciation is also due to Dr. Pramoda from Institute of Material Research and Engineering, Singapore (IMRE) for her help on dynamic mechanical analysis (DMA). Additionally, I would like to convey my gratitude to my mentor, Dr. Li Fu Yun for his consistent consultation and sharing his technical expertise with me at various stages of my research period. Other than technical sharing, Dr. Li provided me lots of guidance and encouragement in my life. Special thanks to Dr. Xiao You Chang and Dr. Li Pei for their kind discussion and comments during my first research project. i   I gratefully acknowledge to all members of our research group who have assisted me in any way. Special thanks to Ms. Le Ngoc Lieu, Ms. Chua Mei Ling and Mr. Zuo Jian for their friendship and support. They have enlightened my knowledge and embarked my journey in persuading PhD in NUS. I would also like to thank all the members in Prof. Chung’s research group especially to Dr. Wang Huan, Dr. Wang Yan, Dr. Peng Na and Dr. Ong Yee Kang for providing useful help in operating laboratory equipments. I would also like to express my gratitude to my beloved family for their endless love, encouragement and support. Last but not least, my deepest gratitude goes to my fiancé, Dr. Kiu Kwong Han for his unfailing love, support and patience in waiting my completion on my PhD study. ii   TABLE OF CONTENTS ACKNOWLEDGEMENT . i TABLE OF CONTENTS . iii SUMMARY .x NOMENCLATURE xiv LIST OF TABLES . xxi LIST OF FIGURES . xxiii CHAPTER INTRODUCTION 1  1.1  Demand of alternative energy source   1.2  The important role of membrane technology for gas separation .4 1.3  Technology milestones of gas separation membranes .6 1.4  New classes of membrane materials 1.5  Polymers of intrinsic microporosity (PIMs) based membranes .12 1.6  Molecular modification of polymeric membrane 21  1.6.1  Polymer blends .21 1.6.2  Chemical modification .23 1.6.3  Thermal modification .25 1.6.4  UV modification 25 1.7  Research objectives and organization of dissertation 26 1.8  References 29 iii   CHAPTER THEORETICAL BACKGROUND 38 2.1  Gas transport mechanism .39  2.1.1  Poiseuille flow .39 2.1.2  Knudsen diffusion 40 2.1.3  Molecular sieving .40 2.1.4  Solution-diffusion 41  2.2  Gas transport in glassy polymers .43  2.2.1  Dual-mode sorption model 44 2.2.2  Factors affecting gas transport properties 46 2.2.2.1 Penetrant size and shape 46  2.2.2.2 Penetrant condensability 47  2.2.2.3 Operating pressure .47 2.2.2.4 Operating temperature .48  2.2.2.5 Polymer free volume 49 2.2.2.6 Polymer chain mobility 50  2.3  References 51 CHAPTER METHODOLOGY .53 3.1  Materials 54 3.1.1  Polymers and solvents 54 3.1.2  Diamine modification reagents 54 3.2  Polymer synthesis 56 3.2.1  Synthesis of polymer of intrinsic microporosity (PIM-1) 56 3.2.2  Synthesis of carboxylated PIM-1 (cPIM-1) .57 3.3  Membrane fabrication protocols 57 iv   3.3.1  PIM-1/Matrimid dense membranes .57 3.3.2  Diamine modified PIM-1/Matrimid dense membranes .58 3.3.3  cPIM-1/Torlon dense membranes 58 3.3.4  PIM-1/Matrimid hollow fiber membranes .59 3.3.4.1 Spinning dope formulation 59  3.3.4.2 Spinning conditions, solvent exchange and post treatment .61  3.4  Characterization of physical properties .64 3.4.1  Gel permeation chromatography (GPC) 64 3.4.2  Brunauer-Emmett-Teller (BET) .64 3.4.3  Dynamic mechanical analysis (DMA) .65 3.4.4  Polarized light microscope (PLM) .65 3.4.5  Ultraviolet absorbance spectra (UV) .65 3.4.6  Fourier transform infrared spectroscopy (FTIR) .66 3.4.7  Density measurement and fractional free volume (FFV) 66 3.4.8  Thermogravimetric analysis (TGA) .67 3.4.9  Gel content analysis .67 3.4.10  X-ray diffraction (XRD) 68 3.4.11  Tensile measurement .68 3.4.12  Field emission scanning electron microscopy (FESEM) .68 3.4.13  Positron annihilation lifetime spectroscopy (PALS) .69 3.4.14  Nuclear magnetic resonance spectroscopy (NMR) 69 3.4.15  Differential scanning calorimetry (DSC) .70 3.4.16  Contact angle measurement .70 3.5  Characterization of gas transport properties 70 3.5.1  Pure gas permeation test 70 3.5.1.1 Dense membrane 70 v   3.5.1.2 Hollow fiber membrane .72  3.5.1  Mixed gas permeation test .74 3.5.2.1 Dense membrane 74 3.5.2.2 Hollow fiber membrane .76  3.5.3  Pure gas sorption test .77 3.6  References 79 CHAPTER MOLECULAR TAILORING OF PIM-1/MATRIMID BLEND MEMBRANES FOR GAS SEPARATION .81 4.1  Introduction 82 4.2 Results and discussion .85 4.2.1 Effects of different blend compositions to the phase behavior of PIM-1/ Matrimid membranes .85 4.2.2  Transport properties of the PIM-1/Matrimid system .90 4.2.3  Model prediction of gas transport properties .94 4.3  Conclusions 98 4.4  References 100 CHAPTER HIGHLY PERMEABLE CHEMICALLY MODIFIED PIM1/MATRIMID MEMBRANES FOR GREEN HYDROGEN PURIFICATION105 5.1  Introduction 106 5.2 Results and discussion .109 5.2.1 Effects of diamine structure on the degree of cross-linking 109 5.2.2  Effects of diamine immersion duration on the degree of cross-linking 117 vi   5.2.3  Morphological evolution of diamine modified membranes .122 5.2.4  Mixed gas separation performance and the Upper bound comparison 126 5.3  Conclusions 128 5.4  References 129 CHAPTER MOLECULAR INTERACTION, GAS TRANSPORT PROPERTIES AND PLASTICIZATION BEHAVIOR OF CPIM-1/TORLON BLEND MEMBRANES 134 6.1  Introduction 135 6.2 Results and discussion .137 6.2.1 Characterization of cPIM-1 polymer .137 6.2.2  Characterization of cPIM-1/Torlon membranes 141 6.2.3  Effect of different blend compositions to the gas transport properties and plasticization .146 6.2.4  Mixed gas separation performance and the Robeson upper bound comparison .151 6.2.5  Comparison among the polymer blends incorporated with PIM-1 or cPIM-1 .153 6.3  Conclusions 156 6.4  References 157 CHAPTER HIGH PERFORMANCE PIM-1/MATRIMID HOLLOW FIBER MEMBRANES FOR CO2/CH4, O2/N2 AND CO2/N2 SEPARATION .164 7.1  Introduction 165 vii   [19] H. 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However, these raw energy sources consist of the contaminant such CO2 and trace amount of N2, H2, O2 in nature which subsequently reduce the efficiency of the process in term of permeability and selectivity. Membrane based separation emerged as one of the most ideal gas separation technologies due to its environmental friendliness, low cost, systemic simplicity and space saving features. One of the main constrains in polymeric membranes includes the Robeson upper bound trade-off for its permeability and selectivity. Therefore, the main objective of this research study is the investigation and development of next-generation high performance polymeric membranes for CO2/CH4, CO2/N2, O2/N2 and H2/CO2 separations. Accordingly, four interlinked aspects are included. The key findings of each aspect are summarized and concluded as below. Firstly, the synergistic properties of the combination of polymers of intrinsic microporosity, specifically PIM-1 and Matrimid to enhance the gas separation performance were investigated. Secondly, the properties of the PIM-1/Matrimid membranes were then modified by various diamine structures to tune from CO2-selective to H2-selective. Thirdly, the focus was on modification of PIM-1 to cPIM-1 and subsequent blending with Torlon to enhance the gas transport properties. Lastly, PIM-1/Matrimid hollow fiber membranes have been developed to fabricate the membranes as a favor industrial configuration. Interestingly, the membranes developed in these studies have shown a significantly enhanced gas separation performance that surpasses the upper bound limit. The findings of this work may provide an impetus to the development of superior polymeric membranes. 196   8.1.1 Molecular tailoring of PIM-1/Matrimid blend membranes for gas separation PIM-1, a specific polymer of intrinsic microporosity is known as one of the potential materials for membrane gas separation. The contorted ladder-like structure in PIM-1 possesses high permeability but moderate selectivity for O2/N2, CO2/N2 and CO2/CH4 separation. The most feasible and time efficient strategy of tuning the permeability and selectivity by blending PIM-1 with different compositions of Matrimid has been reported here. In this work, the physical properties, phase behavior and gas transport properties of PIM-1/Matrimid blends have been examined. The use of polarized light microscope analyses revealed that most of the PIM1/Matrimid blends were partially miscible. The inclusion of PIM-1 in the Matrimid matrix resulted in a substantial increase in gas permeability and a slight decrease in selectivity. The additions of and 10 wt% PIM-1 into Matrimid induced the permeability increments of 25% and 77% respectively, raising the original 9.6 to 12 and 17 Barrer without compromising its CO2/CH4 selectivity. For O2/N2 separation, the incorporation of a small amount of Matrimid (e.g., 5-30 wt%) into PIM-1 promoted a fair increase in selectivity and allowed the overall gas separation performance to almost reach and at some time it appeared to surpass the upper bound. In binary gas tests of CO2/CH4 (50%/50%), the 30 wt% PIM-1 in Matrimid membrane had a CO2 permeability of 50 Barrer and a CO2/CH4 selectivity of 31. 197   8.1.2 Highly permeable chemically modified PIM-1/Matrimid membranes for green hydrogen purification Polymers of intrinsic microporosity, e.g., PIM-1 are attractive materials for gas separation and energy development ascribed mainly to their superior permeability. The H2 and CO2 permeability of PIM-1 are about 1300-4000 Barrer and 3000-8000 Barrer, respectively. However, it has a relatively low H2/CO2 selectivity of 0.4-0.8. Different from the previous UV rearrangement approach, for the first time we report here a viable method to tune the intrinsic properties of PIM-1 blend membranes from CO2-selective to H2-selective via blending with Matrimid and subsequently crosslinking the mixed matrix membrane by diamines at room temperature. The ideal H2/CO2 selectivity of the membrane after modification by hr triethylenetetramine (TETA) improved dramatically from 0.4-0.8 to 9.6 with a H2 permeability of 395 Barrer. The modified membranes also show exceptional separation performance surpassing the present upper bound for H2/CO2, H2/N2, H2/CH4 and O2/N2 separations. Positron annihilation lifetime spectroscopy (PALS) and Field emission scanning electron microscopy (FESEM) reveal that the diamine cross-linking successfully alters the membrane morphology from a dense to a composite structure. X-ray diffraction (XRD) analyses and sorption data confirmed that the modified membrane has a smaller d-spacing and a decrease in diffusivity coefficient. Our results also affirmed that the spatial structure rather than the pKa value of diamines is the prevailing factor that governs the reactivity of diamines toward the PIM-1/Matrimid membrane due to the low concentration of cross-linkable polyimides distributing randomly in the polymer matrix. The fundamentals and knowledge gained throughout this study may facilitate the development of polymeric membranes for green H2 enrichment processes. 198   8.1.3 Molecular interaction, gas transport properties and plasticization behavior of cPIM-1/Torlon blend membranes Polymers of intrinsic microporosity, specifically PIM-1 has emerged as a promising material for gas separation due its uniquely high gas permeability. However, its insolubility in common polar aprotic solvents like N-Methyl-2-pyrrolidone (NMP) limits its full potential and possible industrial applications. In this study, the solubility of PIM-1 in such solvents has been modified by carboxylation via hydrolysis reaction in a short period of hr. The success of carboxylation was verified by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and water contact angles. The carboxylated PIM-1 (cPIM-1) was subsequently blended with Torlon to enhance the intrinsic permeability of Torlon rich membranes and the intrinsic selectivity of cPIM-1 rich membranes. The additions of 5, 10 and 30 wt% cPIM-1 into Torlon increase its CO2 permeability by 26%, 128% and 791% respectively from the original value of 0.541 to 0.682, 1.233 and 4.822 Barrer respectively with minor sacrifices in CO2/CH4 selectivity. These permeability improvements are attributed to the formation of charge transfer complexes (CTC) between cPIM-1 and Torlon, which promotes better interactions in the blends. In addition, all the cPIM-1/Torlon membranes exhibit a great plasticization resistance up to 30 atm. This is ascribed to the incorporation of the rigid Torlon that may lead to restrict chain mobility in CO2 environments. The overall separation performance has been driven closer to the Robeson upper bound for O2/N2, CO2/CH4, CO2/N2 and H2/N2 separations. Therefore, the newly developed membranes may have great potential for energy development and industrial applications. 199   8.1.4 High performance PIM-1/Matrimid hollow fiber membranes for CO2/CH4, O2/N2 and CO2/N2 separation Polymers of intrinsic microporosity (PIM-1) have received worldwide attention but most PIM-1 researches have been conducted on dense flat membranes. For the first time, we have fabricated PIM-1/Matrimid membranes in a useful form of hollow fibers with synergistic separation performance. The newly developed hollow fibers comprising 5-15 wt% of highly permeable PIM-1 not only possess much higher gaspair selectivity than PIM-1 but also have much greater permeance than pure Matrimid fibers. Data from positron annihilation lifetime spectroscopy (PALS), field emission scanning electron microscopy (FESEM) and apparent dense layer thickness indicate that the blend membranes have an ultrathin dense layer thickness of less than 70 nm. PIM-1 and Matrimid are partially miscible. The effect of partial miscibility on dense selective layer was studied. Defect-free hollow fibers with gas pair selectivity more than 90% of the intrinsic value can be spun directly from dopes containing wt% PIM-1 with proper spinning conditions, while post annealing and additional silicone rubber coating are needed for membranes containing 10 and 15 wt% PIM-1, respectively. Comparing to Matrimid, the CO2 permeance of as-spun fibers containing and 10 wt% PIM-1 increases 78% and 146%, respectively (e.g., from original 86.3 GPU to 153.4 GPU and 212.4 GPU) without compromising CO2/CH4 selectivity. The CO2 permeance of the fiber containing 15 wt% PIM-1 improves to 243.2 GPU with a CO2/CH4 selectivity of 34.3 after silicon rubber coating. Under mixed gas tests of 50/50 CO2/CH4, this fiber shows a CO2 permeance of 188.9 GPU and a CO2/CH4 selectivity of 28.8. The same fiber also has an impressive O2 permeance of 3.5 folds higher than the pristine Matrimid (e.g., from original 16.9 GPU to 59.9 GPU) with an O2/N2 selectivity of 6.1. The newly developed membranes may have great potential to be used for natural gas purification, air separation and CO2 capture. 200   8.2 Recommendations for future work 8.2.1 Study on long-term stability and aging retardation of thin PIM-1 based membranes The newly developed membranes have presented a great improvement in the gas separation properties with the incorporation of PIM-1 or cPIM-1. However, it should be noted that this study is solely focused on the enhancement of gas separation; the membrane stability and long-term performance investigation have not been included. The limitation in polymeric membranes is their physical aging with time which results in the reduction in permeability. Chemical and physical modification such as photoirradiation and heat treatment are simple approaches in retarding the aging effects on the PIM-1 or cPIM-1 membranes. On the other hand, thin film with an ultra-thin selective layer (e.g., thickness is less than several hundred nanometers) may contribute to the optimum gas separation performance. Since the aging properties of a thin membrane are much different than a thick membrane, it would be worthwhile to conduct a fundamental study on performance of thin and thick membranes and their stability for a minimum period of months to explore the potential for industrial applications. The PIM-1 or cPIM-1 thin film could be a free-standing thin membrane or an asymmetric hollow fiber membrane depending on the final membrane configurations. 8.2.2 PIM-1 based mixed matrix membranes Other than polymer blends to enhance the gas separation efficiency presented in this work, fabricating mixed matrix membranes by blending the polymer matrix with organic or inorganic particles is the another feasible method. The particles could be carbon, zeolite, metal, metal oxide, metal–organic framework (MOFs) and zeolitic 201   imidazolate framework (ZIF). Moreover, the mixed matrix membranes possess the advantage of enhancing the mechanical properties as compared to pristine polymeric membranes, which subsequently allow membranes to operate at elevated pressures and temperatures. The careful selection of suitable particles and their amount in the mixed matrix would be an interesting research focus. 8.2.3 Interpenetrating polymer networks (IPN) in PIM-1 and PEO-azide membranes Other than PIM-1, poly(ethylene oxide) (PEO) appears as one of the suitable candidates for CO2 capture as it has high CO2/light gas solubility selectivity and the relative inertness to CO2 plasticization [1-5]. The high solubility selectivity of PEO may overcome the shortcomings of the low selectivity of PIM-1. The polar and quadrupolar interactions between the ether oxygen (EO) unit and the CO2 molecules induce PEO or poly(ethylene glycol) (PEG) based membranes to possess a reversed selectivity of CO2 to the much smaller H2 [6]. Among various polymer modifications, interpenetrating polymer networks (IPN) is a type of enhancement for a linear polymer blend where two different polymer networks physically interact with each other without chemical bonding between them [6-9]. The presences of IPN significantly enhanced the compatibility between polymers in a polymer blend. A network polymer that encompasses a linear polymer yields a pseudo-IPN. Basically, there are two common ways in preparing a pseudoIPN structure. The first method is to polymerize the precursors of a branched polymer in the existing linear polymer while the other method is the formation of a straightchain polymer within an existing polymer network. In order to prevent the linear component extracted from the structure, the chemical bonding of the linear component within the pseudo-IPN could be induced by azido-containing monomers [10]. As a result, the formation of pseudo-IPN network between PIM-1 and PEO- 202   azide is likely to create different free volume distribution that may improve the permeability and selectivity of membranes. 8.2.4 Synthesis of new PIM structure PIM-1 is one of the recent developed polymers that display a potential market for gas separation. The exceptional high performance of PIM-1 is mainly ascribed to its kinked center of ladder-type backbone structure that promotes a high free volume and large surface area. PIMs have high sorption capacity due to the inherited polar groups and microporosity structure. Therefore, the synthesis of new PIM structure by coupling the spiro center (i.e., a tetrahedral carbon atom shared by two rings) monomer with other large moiety monomer such as 6FDA, aromatic ring and perfluoro-structure at the initiate stage may further enhance the overall gas separation performance. In additional, it would promote a great integrity in the molecular level during polymer synthesis. The chemistry and the polymerization process of each polymer are unique and deep understanding and investigation are important. 8.3 References [1] H. Lin, B.D. Freeman, Gas solubility, diffusivity and permeability in poly(ethylene oxide), J. Membr. Sci. 239 (2004) 105–117. [2] H. Lin, E. Van Wagner, B.D. Freeman, L.G. Toy, R.P. Gupta, Plasticizationenhanced H2 purification using polymeric membranes, Science 311 (2006) 639–642. [3] H. Lin, B.D. Freeman, Materials selection guidelines for membranes that remove CO2 from gas mixtures, J. Molecular Structure 739(2005) 57–74. [4] J.Z. Xia, S.L. Liu, T.S. Chung, Effect of end groups and grafting on the CO2 separation performance of poly(ethylene glycol) based membranes, Macromolecules 44 (2011) 7727–7736. 203   [5] H.Z. Chen, Y.C. Xiao, T. S. Chung, Synthesis and characterization of poly (ethylene oxide) containing copolyimides for hydrogen purification, Polymer 51 (2010) 4077–4086. [6] T. Tamai, A. Imagawa, Q. Tran-Cong, Semi-Interpenetrating Polymer Networks Prepared by in Situ Photo-Cross-Linking of Miscible Polymer Blends, Macromolecules 27 (1994) 7486–7489. [7] C. Leger, Q. T. Nguyen, J. Neel, C. Streicher, Level and Kinetics of PVP Extraction from Blends, Interpenetrating Polymer Blends, and Semiinterpenetrating Polymer Networks, Macromolecules 28 (1995) 143–151. [8] J. M. Meseguer Dueñas, D. Torres Escuriola, G. Gallego Ferrer, M. Monleón Pradas, J. L. Gómez Ribelles, P. Pissis, A. Kyritsis, Miscibility of Poly(butyl acrylate)-Poly(butyl methacrylate) Sequential Interpenetrating Polymer Networks, Macromolecules 34 (2001) 5525–5534. [9] M. Wang, K.P. Pramoda, S.H. Goh, Mechanical Behavior of Pseudo-SemiInterpenetrating Polymer Networks Based on Double-C60-End-Capped Poly(ethylene oxide) and Poly(methyl methacrylate), Chem. Mater. 2004, 16, 3452–3456. [10] S.B. Pandit, S.S. Kulkarni, V.M. Nadkarni, Interconnected interpenetrating polymer networks of polyurethane and polystyrene. 2. Structure-property relationships, Macromolecules 27 (1994) 4595–4604. 204   LIST OF PUBLICATIONS, PATENTS AND CONFERENCES Publications [1] W.F. Yong, F.Y. Li, Y.C. Xiao, P. Li, K.P. Pramoda, Y.W. Tong, T.S. Chung, Molecular engineering of PIM-1/Matrimid blend membranes for gas separation, J. of Membr. Sci., 407– 408 (2012) 47– 57. [2] W.F. Yong, F.Y. Li, Y.C. Xiao, T.S. Chung, Y.W. Tong, High performance PIM-1/Matrimid hollow fiber membranes for CO2/CH4, O2/N2 and CO2/N2 separation, J. of Membr. Sci. 443 (2013) 156–169. [3] W.F. Yong, F.Y. Li, T.S. Chung, Y.W. Tong, Highly permeable chemically modified PIM-1/Matrimid membranes for green hydrogen purification, J. Mater. Chem. A, 2013, 1, 13914–13925. [4] W.F. Yong, F.Y. Li, T.S. Chung, Y.W. Tong, Plasticization and enhanced gas transport properties of cPIM-1/Torlon blend membranes for CO2 capture, J. of Membr. Sci. 462 (2014) 119–130. Patents [1] W.F. Yong and T.S. Chung, Hollow fiber membranes consisting of Polymers of Intrinsic Microporosity for Gas Separation, US Provisional Patent Application No. 61/815,848 (2013). [2] W.F. Yong and T.S. Chung, Molecular interaction, gas transport properties and plasticization behavior of cPIM-1/Torlon blend membranes, Submitted for patent application. Award [1] W.F. Yong, 2014 North American Membrane Society (NAMS) Elias Klein Travel Supplement (USD 500), May 2014. 205   Conference papers: [1] W.F. Yong, F.Y. Li, Y.C. Xiao, P. Li, K.P. Pramoda, Y.W. Tong, T.S. Chung, PIM-1/ Matrimid blend membranes for gas separation, 2012 North American Membrane Society (NAMS) Meeting, New Orleans, US, June 2012, Oral presentation. [2] W.F. Yong, F.Y. Li, Y.C. Xiao, P. Li, K.P. Pramoda, Y.W. Tong, T.S. Chung, Molecular tailoring of PIM-1/ Matrimid blend membranes for natural gas separation and air separation, 7th International Conference in Materials for Advance Technologies (ICMAT), Singapore, June 2013, Oral presentation. [3] W.F. Yong, F.Y. Li, Y.C. Xiao, T.S. Chung, Y.W. Tong, PIM-1/Matrimid hollow fiber membranes for natural gas and air separation, American Institute of Chemical Engineers (AIChE) Annual Meeting, San Francisco, US, November 2013, Oral presentation. [4] W.F. Yong, F.Y. Li, Y.C. Xiao, T.S. Chung, Y.W. Tong, Polymers of intrinsic microporosity (PIM-1)-based Hollow Fiber Membranes for CO2 capture and air separation, 4th Trilateral Conference on Advances in Nanoscience: Energy, Water & Healthcare, Singapore, December 2013, Poster presentation. [5] W.F. Yong, M.L. Chua, L. Hao, Membranes for Natural Gas Purification, InnovFest, Singapore, April 2014, Poster presentation. [6] W.F. Yong, F.Y. Li, T.S. Chung, Y.W. Tong, Green hydrogen separation with modified polymers of intrinsic microporosity (PIM-1) membranes, North American Membrane Society (NAMS) Meeting, Houston, TX, USA, May 2014, Oral presentation. [7] W.F. Yong, T.S. Chung, Highly Permeable Polymers of Intrinsic Microporosity (PIM-1)-based Flat Dense and Hollow Fiber Membranes for Gas Separation, International Gas Union Research Conference 2014 (IGRC), Copenhagen, Denmark, September 2014, Oral presentation. 206   [...]... of gas separation performance of PIM-1/Matrimid (10:90) hollow fiber membranes before and after heat treatment .181 Table 7.5 Gas separation performance of PIM-1/Matrimid (15:85) hollow fiber membranes before and after different post-treatment methods 182 Table 7.6 Binary gas separation performance of PIM-1/Matrimid (15:85) hollow fiber membranes after silicon rubber coating .184 Table 7.7 Intrinsic. .. (4) production of hollow fiber membranes for CO2/CH4 and O2/N2 separation Firstly, the development of polymer blend membranes with enhanced gas separation properties is presented Recently, PIM-1, a type of polymers of intrinsic microporosity has been recognized as one of the potential materials for membrane gas separation due to its contorted ladder-like structure that yields superior gas permeability... technology for gas treatment and the importance of membrane technology followed by the history and development of gas membrane separations This is then followed by a review on the new class of materials for membrane fabrication, PIMs based membranes and finally the various modification methods will be discussed 1.2 The important role of membrane technology for gas separation Natural gas, biogas and H2... investigation and development of next-generation high performance polymeric membranes for CO2/CH4, CO2/N2, O2/N2 and H2/CO2 separations Specifically, this research study focuses on four aspects including the (1) fabrication of polymer blend membranes with enhanced gas separation properties, (2) development of diamine modified membranes for H2/CO2 separation, (3) fabrication of polymer blend membranes with improved... tailoring of PIM-1/Matrimid blend membranes for gas separation 197 8.1.2 Highly permeable chemically modified PIM-1/Matrimid membranes for green hydrogen purification 198 8.1.3 Molecular interaction, gas transport properties and plasticization behavior of cPIM-1/Torlon blend membranes 199 8.1.4 Highly performance PIM-1/Matrimid hollow fiber membranes for CO2/CH4, O2/N2 and CO2/N2 separation. .. the incorporation of Torlon which has a greater rigidity restricted the chain movement in the polymer matrix The overall separation performance of cPIM-1/Torlon membranes reached to the Robeson upper bound for O2/N2, CO2/CH4, CO2/N2 and H2/N2 separation Lastly, the importance of development of PIM-1/Matrimid membranes in a useful form of hollow fibers with synergistic separation performance was explored... 169 7.2.1 Miscibility studies of PIM-1/Matrimid flat sheet dense membranes 169 7.2.2  Morphology of PIM-1/Matrimid hollow fiber membranes .170 7.2.3  Effect of bore fluid compositions on inner surface morphology .172 7.2.4  Effect of take-up speed on gas separation performance 173 7.2.5  Effect of PIM-1 concentration and bore fluid chemistry on gas separation performance 174 7.2.6  Defect-free... biogas leads to lower energy content per unit volume of biogas if compared with natural gas [6] Besides, CO2 is a greenhouse gas and hence contributes severely to the global warming Despite the numerous advantages of natural gas and biogas, the prevailing challenge is removing the CO2 content in natural gas and biogas prior distributing it through the gas pipeline Other than natural gas and biogas,... Table 6.6 A comparison of PIM-1 and cPIM-1 based polymer blends 155 Table 7.1 Gas separation performance of Matrimid and PIM-1/Matrimid hollow fiber membranes at different blend ratios before post-treatment 176 Table 7.2 Intrinsic gas transport properties of PIM-1/Matrimid dense films .178 Table 7.3 R parameter and dense-selective layer thickness of PIM-1/Matrimid hollow fiber membranes .179... terminologies for membrane gas separation namely permeability and selectivity The rate of gases permeating through the membrane is termed as permeability On the other hand, selectivity indicates the intrinsic selectivity of a membrane material to the mixture of two gases A schematic illustrating the permeation of gases through a membrane is shown in Figure 1.2: Figure 1.2 Schematic diagram of membrane separation .   POLYMERS OF INTRINSIC MICROPOROSITY (PIM)- BASED MEMBRANES FOR GAS SEPARATION YONG WAI FEN NATIONAL UNIVERSITY OF SINGAPORE 2014   POLYMERS OF INTRINSIC MICROPOROSITY. milestones of gas separation membranes 6 1.4 New classes of membrane materials 8 1.5 Polymers of intrinsic microporosity (PIMs) based membranes 12 1.6 Molecular modification of polymeric. type of polymers of intrinsic microporosity has been recognized as one of the potential materials for membrane gas separation due to its contorted ladder-like structure that yields superior gas