Sieving of Hot Gases by Hyper-Cross-Linked Nanoscale-Hybrid Membranes
- Michiel J. T. Raaijmakers ,
- Mark A. Hempenius ,
- Peter M. Schön ,
- G. Julius Vancso ,
- Arian Nijmeijer ,
- Matthias Wessling , and
- Nieck E. Benes
Abstract

Macromolecular networks consisting of homogeneously distributed covalently bonded inorganic and organic precursors are anticipated to show remarkable characteristics, distinct from those of the individual constituents. A novel hyper-cross-linked ultrathin membrane is presented, consisting of a giant molecular network of alternating polyhedral oligomeric silsesquioxanes and aromatic imide bridges. The hybrid characteristics of the membrane are manifested in excellent gas separation performance at elevated temperatures, providing a new and key enabling technology for many important industrial scale applications.
Introduction
Scheme 1

Scheme a(a) Interfacial polymerization reaction of octa-ammonium POSS in water and 6-FDA in toluene. The ammonium groups are partially deprotonated to primary amines by sodium hydroxide (NaOH, pH = 9.9 ± 0.3). The reaction occurs at the water–toluene interface, with final layer polyPOSS–(amic acid) thicknesses of ∼0.1 μm after 5 min. (b) The subsequent conversion of the amic acid to cyclic imide (imidization) is performed via heat treatment at temperatures up to 300 °C.
Experimental Section
Synthesis of PolyPOSS–Imides by Interfacial Polymerization
Material Characterization
Results and Discussion
Figure 1

Figure 1. Heat treatment induced evolution of membrane layer morphology. (a and b) SEM micrograph of 0.1-μm polyPOSS–(amic acid) and polyPOSS–imide layers, on α-alumina discs with a 3 μm-thick γ-alumina layer. The homogeneous supported films exhibit no apparent crack formation due to drying stresses or heat treatment. (c and d) The AFM peak force error images of the supported polyPOSS–(amic acid) demonstrate that the film formation results in a smooth layer with hills and valleys of lateral dimensions up to 0.2 μm. The polyPOSS–imide (bottom, right) layer exhibits a similar hill-valley structure. The heat-treatment step increases the intrinsic and thermal stress-induced surface roughness.
Figure 2

Figure 2. Heat treatment induced imidization. (a) ATR-FTIR spectra of free-standing polyPOSS–(amic acid) layers prior to (top line) and after heat treatment for 2 h in air at 300 °C (bottom line), normalized for the CF3 band at 1254 cm–1. The bands at 1620 and 1570 cm–1 are assigned to N–H bending (1) and C═O stretching (2) of the amic acid group. After heat treatment, the bands at 1620 and 1570 cm–1 are replaced by bands at 1720 and 1780 cm–1 that are assigned to C═O asymmetric (3) and symmetric (4) stretching of the imide group, respectively. The sharp bands at 1125 and 1040 cm–1 can be attributed to the Si–O–Si asymmetric stretching vibrations of the polyhedral and ladder silsesquioxane structures, respectively. The results indicate complete conversion of the amic acid groups to cyclic imide groups, and suggest a concurrent partial cleavage of the POSS cage induced by the high pH during synthesis. (12) (b)ATR-FTIR band intensities of (1) and (2) normalized with respect to their initial intensities and the band intensities of (3) and (4) normalized with respect to the imide band intensity of the 300 °C-treated sample as a function of temperature. The results indicate that imidization is initiated at 140–160 °C, reaching a maximum conversion at 300 °C. (c and d) AFM adhesion images of polyPOSS–(amic acid) and polyPOSS–imide layers. The images reveal homogeneously distributed areas of several nanometers in size with varying adhesion strength that correspond to regions with different chemical compositions.
Figure 3

Figure 3. Gas permeation characteristics of polyPOSS–imide membranes. (a) Permeance as a function of gas kinetic diameter. The decrease in permeance with increasing kinetic diameter is consistent with the glassy character of the polyPOSS–imide. (b) Arrhenius plot of individual gas permeances for He, H2, CO2, N2 and CH4. For all gases, activated transport is the dominant transport mechanism. The activation energies for transport remain constant over temperatures ranging from 50–300 °C, demonstrating that the membrane does not suffer from temperature-induced chain mobility. (c) Ideal selectivity of H2/CH4, H2/N2, CO2/CH4 and H2/CO2 as a function of temperature.
Conclusion
Supporting Information
The full reaction scheme of the polyPOSS–imide; material analysis using differential scanning calorimetry, thermal gravimetric analysis, X-ray photoelectron spectroscopy and full infrared peak analysis. This material is available free of charge via the Internet at http://pubs.acs.org.
Terms & Conditions
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Acknowledgment
This research has received funding from the European Union Seventh Framework Programme FP7-NMP-2010-Large-4 under Grant Agreement no. 263007 (acronym CARENA). M.W. acknowledges support through the Alexander von Humboldt Foundation.
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- 18Villaluenga, J. P. G.; Seoane, B.; Hradil, J.; Sysel, P. J. Membr. Sci. 2007, 305, 160– 168[Crossref], [CAS], Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFeis7zO&md5=9d3034eb6eb245e1531f115518782a93Gas permeation characteristics of heterogeneous ODPA-BIS P polyimide membranes at different temperaturesVillaluenga, J. P. G.; Seoane, B.; Hradil, J.; Sysel, P.Journal of Membrane Science (2007), 305 (1+2), 160-168CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)Heterogeneous carbon mol. sieves and hypercrosslinked polystyrene microparticles adsorbent-based membranes with a (ODPA-BIS P) polyimide binder were prepd. The effect of adsorbent particles on the gas transport properties of heterogeneous membranes was studied. Permeability, diffusion and soly. coeffs. of He, CO2, O2, and N2 were estd. for homogeneous and heterogeneous membranes at a feed pressure of 1 atm for different temps. between 25° and 60°. It was obsd. that adsorbent-filled (ODPA-BIS P) polyimide membranes exhibit higher gas permeability in comparison with adsorbent-free membrane, while permselectivity is maintained. The results also showed that the adsorbents enhance significantly gas diffusivity in (ODPA-BIS P) polyimide membrane, whereas the gas soly. is clearly reduced. In both type of heterogeneous membranes, gas permeation and diffusion are thermal activated processes described by the Arrhenius equation, whereas the sorption process is exothermic. The addn. of both type of adsorbents to the (ODPA-BIS P) polyimide membrane increases the activation energy of permeability, this is mainly due to a significant increase of the heat of sorption, because the activation energy for diffusion is slightly decreased.
- 19Neyertz, S.; Gopalan, P.; Brachet, P.; Kristiansen, A.; Männle, F.; Brown, D. Soft Mater. 2014, 12, 113– 123[Crossref], [CAS], Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXms1Wgsbw%253D&md5=2ddf18eebcc5abaf66b959caa5b4f9a9Oxygen Transport in Amino-Functionalized Polyhedral Oligomeric Silsesquioxanes (POSS)Neyertz, S.; Gopalan, P.; Brachet, P.; Kristiansen, A.; Mannle, F.; Brown, D.Soft Materials (2014), 12 (1), 113-123CODEN: SMOAAE; ISSN:1539-445X. (Taylor & Francis, Inc.)The transport properties of oxygen in three amino-functionalized cubic polyhedral oligomeric silsesquioxanes (POSS) have been studied using classical mol. dynamics (MD) simulations over a timescale long enough to reach the Fickian regime for diffusion. An amt. of O2 corresponding to an applied pressure of 3 bars was inserted into mol. models of hybrid org./inorg. POSS with the chem. compn. (RSiO3/2)8, which differed by the end-groups of their org. pendant chains, i.e., R = -(CH2)3-NH-CO-X with X = -C6H4OH, -C6H5 or -C6H11. The oxygen ... POSS energies were found to be small with respect to the POSS... POSS interactions. The O2 mols. permeate the org. phase and move through combinations of oscillations within available free vols. in the matrixes and occasional jumping events. Gas mobility was more restricted in the system with the salicylic end-group and the largest hydrogen-bond network, whereas it was enhanced in the system with the cyclohexyl end-group. The most energetically-favorable sites for O2 insertion were either in the vicinity of the silica cages or close to the rings of the chain end-groups. On the other hand, the amide and hydroxyls groups engaging in H-bonds were less energetically favorable. This confirms that H-bonding networks are a hindrance for O2 transport in such systems.
- 20Lin, H.; Van Wagner, E.; Freeman, B. D.; Toy, L. G.; Gupta, R. P. Science 2006, 311, 639– 642Google ScholarThere is no corresponding record for this reference.
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Abstract

Scheme 1
Scheme 1. The Membrane Synthesis ProcessaScheme a(a) Interfacial polymerization reaction of octa-ammonium POSS in water and 6-FDA in toluene. The ammonium groups are partially deprotonated to primary amines by sodium hydroxide (NaOH, pH = 9.9 ± 0.3). The reaction occurs at the water–toluene interface, with final layer polyPOSS–(amic acid) thicknesses of ∼0.1 μm after 5 min. (b) The subsequent conversion of the amic acid to cyclic imide (imidization) is performed via heat treatment at temperatures up to 300 °C.
Figure 1

Figure 1. Heat treatment induced evolution of membrane layer morphology. (a and b) SEM micrograph of 0.1-μm polyPOSS–(amic acid) and polyPOSS–imide layers, on α-alumina discs with a 3 μm-thick γ-alumina layer. The homogeneous supported films exhibit no apparent crack formation due to drying stresses or heat treatment. (c and d) The AFM peak force error images of the supported polyPOSS–(amic acid) demonstrate that the film formation results in a smooth layer with hills and valleys of lateral dimensions up to 0.2 μm. The polyPOSS–imide (bottom, right) layer exhibits a similar hill-valley structure. The heat-treatment step increases the intrinsic and thermal stress-induced surface roughness.
Figure 2

Figure 2. Heat treatment induced imidization. (a) ATR-FTIR spectra of free-standing polyPOSS–(amic acid) layers prior to (top line) and after heat treatment for 2 h in air at 300 °C (bottom line), normalized for the CF3 band at 1254 cm–1. The bands at 1620 and 1570 cm–1 are assigned to N–H bending (1) and C═O stretching (2) of the amic acid group. After heat treatment, the bands at 1620 and 1570 cm–1 are replaced by bands at 1720 and 1780 cm–1 that are assigned to C═O asymmetric (3) and symmetric (4) stretching of the imide group, respectively. The sharp bands at 1125 and 1040 cm–1 can be attributed to the Si–O–Si asymmetric stretching vibrations of the polyhedral and ladder silsesquioxane structures, respectively. The results indicate complete conversion of the amic acid groups to cyclic imide groups, and suggest a concurrent partial cleavage of the POSS cage induced by the high pH during synthesis. (12) (b)ATR-FTIR band intensities of (1) and (2) normalized with respect to their initial intensities and the band intensities of (3) and (4) normalized with respect to the imide band intensity of the 300 °C-treated sample as a function of temperature. The results indicate that imidization is initiated at 140–160 °C, reaching a maximum conversion at 300 °C. (c and d) AFM adhesion images of polyPOSS–(amic acid) and polyPOSS–imide layers. The images reveal homogeneously distributed areas of several nanometers in size with varying adhesion strength that correspond to regions with different chemical compositions.
Figure 3

Figure 3. Gas permeation characteristics of polyPOSS–imide membranes. (a) Permeance as a function of gas kinetic diameter. The decrease in permeance with increasing kinetic diameter is consistent with the glassy character of the polyPOSS–imide. (b) Arrhenius plot of individual gas permeances for He, H2, CO2, N2 and CH4. For all gases, activated transport is the dominant transport mechanism. The activation energies for transport remain constant over temperatures ranging from 50–300 °C, demonstrating that the membrane does not suffer from temperature-induced chain mobility. (c) Ideal selectivity of H2/CH4, H2/N2, CO2/CH4 and H2/CO2 as a function of temperature.
References
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- 1(a) Niwa, S. I.; Eswaramoorthy, M.; Nair, J.; Raj, A.; Itoh, N.; Shoji, H.; Namba, T.; Mizukami, F. Science 2002, 295, 105– 107[Crossref], [PubMed], [CAS], Google Scholar1ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XksVeqsg%253D%253D&md5=3bd60569b29e11cef5dd7580d03eeb56A one-step conversion of benzene to phenol with a palladium membraneNiwa, Shu-Ichi; Eswaramoorthy, Muthusamy; Nair, Jalajakumari; Raj, Anuj; Itoh, Naotsugu; Shoji, Hiroshi; Namba, Takemi; Mizukami, FujioScience (Washington, DC, United States) (2002), 295 (5552), 105-107CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Existing phenol prodn. processes tend to be energy-consuming and produce unwanted byproducts. We report an efficient process using a shell-and-tube reactor, in which a gaseous mixt. of benzene and oxygen is fed into a porous alumina tube coated with a palladium thin layer and hydrogen is fed into the shell. Hydrogen dissocd. on the palladium layer surface permeates onto the back and reacts with oxygen to give active oxygen species, which attack benzene to produce phenol. This one-step process attained phenol formation selectivities of 80 to 97% at benzene conversions of 2 to 16% below 250° (phenol yield: 1.5 kg per kg of catalyst per h at 150°).(b) Jiang, H.; Cao, Z.; Schirrmeister, S.; Schiestel, T.; Caro, J. Angew. Chem., Int. Ed. 2010, 49, 5656– 5660Google ScholarThere is no corresponding record for this reference.(c) Choudhary, V. R.; Gaikwad, A. G.; Sansare, S. D. Angew. Chem., Int. Ed. 2001, 40, 1776– 1779Google ScholarThere is no corresponding record for this reference.
- 2(a) Wind, J. D.; Sirard, S. M.; Paul, D. R.; Green, P. F.; Johnston, K. P.; Koros, W. J. Macromolecules 2003, 36, 6433– 6441(b) Koros, W. J.; Woods, D. G. J. Membr. Sci. 2001, 181, 157– 166[Crossref], [CAS], Google Scholar2bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjt1elsQ%253D%253D&md5=156d5bc961a8652a7d9b5b8e84fb45fcElevated temperature application of polymer hollow-fiber membranesKoros, W. J.; Woods, D. G.Journal of Membrane Science (2001), 181 (2), 157-166CODEN: JMESDO; ISSN:0376-7388. (Elsevier Science B.V.)Three asym. hollow-fiber polymer membrane systems were studied for application in elevated temp., low feed pressure systems: (1) a single component polyaramide, (2) a single component polyimide, and (3) a composite polyimide on a polyimide/polyetherimide blend support. Permeation driving force was increased for the 2.2 psig feed pressure by sweeping an inert gas along the downstream side of the membrane. Both cocurrent and countercurrent sweep flow patterns were examd. with only minimal differences found. The polyaramide membrane was stable in the entire range of temps. tested (23-220°). After utilizing a silicone rubber post-treatment, the membrane exhibited a hydrogen permeance of approx. 300 GPU at 175° with a hydrogen to n-butane selectivity of 700. The polyimide-contg. membranes had superior room-temp. properties; however, the thin skins aged at elevated temps. This aging effect decreased the permeance of the membranes approx. 40% at 175° and slightly increased the permselectivity; however, the effects of aging leveled out over 200-250 h at 175° and the membrane properties became const. At this level, the polyimide membranes exhibited approx. 400 GPU of hydrogen permeance with a 660 selectivity to n-butane.
- 3(a) Guiver, M. D.; Lee, Y. M. Science 2013, 339, 284– 285Google ScholarThere is no corresponding record for this reference.(b) Carta, M.; Malpass-Evans, R.; Croad, M.; Rogan, Y.; Jansen, J. C.; Bernardo, P.; Bazzarelli, F.; McKeown, N. B. Science 2013, 339, 303– 307Google ScholarThere is no corresponding record for this reference.(c) Du, N.; Park, H. B.; Robertson, G. P.; Dal-Cin, M. M.; Visser, T.; Scoles, L.; Guiver, M. D. Nat. Mater. 2011, 10, 372– 375Google ScholarThere is no corresponding record for this reference.(d) Song, Q.; Cao, S.; Zavala-Rivera, P.; Lu, L. P.; Li, W.; Ji, Y.; Al-Muhtaseb, S. A.; Cheetham, A. K.; Sivaniah, E. Nat. Commun. 2013, 41918[Crossref], [CAS], Google Scholar3dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3snnsFajsw%253D%253D&md5=7bb941df51b3d5b4a110dab88e01aa31Photo-oxidative enhancement of polymeric molecular sieve membranesSong Qilei; Cao Shuai; Zavala-Rivera Paul; Lu Li Ping; Li Wei; Ji Yan; Al-Muhtaseb Shaheen A; Cheetham Anthony K; Sivaniah EasanNature communications (2013), 4 (), 1918 ISSN:.High-performance membranes are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. The next-generation membranes for these processes are based on molecular sieving materials to simultaneously achieve high throughput and selectivity. Membranes made from polymeric molecular sieves such as polymers of intrinsic microporosity (pore size<2 nm) are especially interesting in being solution processable and highly permeable but currently have modest selectivity. Here we report photo-oxidative surface modification of membranes made of a polymer of intrinsic microporosity. The ultraviolet light field, localized to a near-surface domain, induces reactive ozone that collapses the microporous polymer framework. The rapid, near-surface densification results in asymmetric membranes with a superior selectivity in gas separation while maintaining an apparent permeability that is two orders of magnitude greater than commercially available polymeric membranes. The oxidative chain scission induced by ultraviolet irradiation also indicates the potential application of the polymer in photolithography technology.
- 4Rezac, M. E.; Koros, W. J.; Miller, S. J. J. Membr. Sci. 1994, 93, 193– 201[Crossref], [CAS], Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXlvVagtr4%253D&md5=9679f17fa1d3be0c6b1df0554922e82cMembrane-assisted dehydrogenation of n-butane. Influence of membrane properties on system performanceRezac, Mary E.; Koros, William J.; Miller, Stephen J.Journal of Membrane Science (1994), 93 (2), 193-201CODEN: JMESDO; ISSN:0376-7388.The influence of membrane operating properties on the performance of a membrane-assisted butane dehydrogenation system was investigated. The system consisted of 2 plug-flow reactors in series with an interstage hydrogen-removal membrane. Highly productive, thermally stable polyimide-ceramic composite membranes were evaluated. The mixed-gas selectivity of the membranes was strongly influenced by the degree of hydrocarbon sorption, which in turn was controlled by the membrane temp. At temps. below the crit. temp. of butane, the mixed-gas H/hydrocarbon selectivities of the membranes were <20. As the temp. increased to >180°, the selectivity increased to >75. Under these conditions, essentially complete H removal with <2% hydrocarbon losses was achieved. The removal of H resulted in an increase in butane dehydrogenation of ∼11% with no decrease in catalytic selectivity.
- 5(a) Calle, M.; Doherty, C. M.; Hill, A. J.; Lee, Y. M. Macromolecules 2013, 46, 8179– 8189(b) Calle, M.; Lozano, A. E.; Lee, Y. M. Eur. Polym. J. 2012, 48, 1313– 1322[Crossref], [CAS], Google Scholar5bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmvFCnsrY%253D&md5=59a4f771f4a9f55531c1cb3e6f1c451aFormation of thermally rearranged (TR) polybenzoxazoles: Effect of synthesis routes and polymer formCalle, Mariola; Lozano, Angel E.; Lee, Young MooEuropean Polymer Journal (2012), 48 (7), 1313-1322CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)Thermal treatment of ortho-hydroxy contg. polyimides (HPIs) in the solid state certainly gives polybenzoxazoles (PBOs). Thermal conversion protocol, including temp. and dwell time, and the form of the sample (film or powder) det. the rearrangement reaction rate of HPI into PBO. Thermal rearrangement kinetics seems to be faster for film samples rather than for powder ones. Also, mild thermal treatment conditions (i.e., low temps. and short times) seem to result in negligible or low degrees of conversion to PBO. Also, synthetic routes of HPI do not alter in any way the thermal conversion pathway. These findings validate the widely reported imide-to-benzoxazole thermal rearrangement mechanism, and contradict the alternative rearrangement pathway, proposed recently, of HPI into poly(biphenylene bisimide) polymers.(c) Joseph, W. D.; Abed, J. C.; Mercier, R.; McGrath, J. E. Polymer 1994, 35, 5046– 5050Google ScholarThere is no corresponding record for this reference.(d) Kim, S.; Han, S. H.; Lee, Y. M. J. Membr. Sci. 2012, 403–404, 169– 178[Crossref], [CAS], Google Scholar5dhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XkvVClsr4%253D&md5=0c4b93579b5c7dfa9ea2cad270de424dThermally rearranged (TR) polybenzoxazole hollow fiber membranes for CO2 captureKim, Seungju; Han, Sang Hoon; Lee, Young MooJournal of Membrane Science (2012), 403-404 (), 169-178CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)Thermally rearranged polybenzoxazole (TR-PBO) hollow fiber membranes were prepd. using a non-solvent induced phase sepn. method intended to apply for CO2 sepn. from post-combustion flue gas. Asym. hollow fiber membranes were spun from a hydroxyl poly(amic acid) (HPAAc) precursor and subsequently converted to TR-PBO hollow fiber membranes after thermal treatment above 400°. The skin structure and porous substructure in TR-PBO hollow fiber membranes were maintained even after thermal treatment at above glass transition temp. (Tg) of precursor polymers. To fabricate defect-free hollow fiber membranes, the effects of dope compn. and thermal rearrangement conditions were investigated. Gas permeation properties of TR-PBO hollow fiber membranes measured by const. pressure method with small lab. scale test module revealed a high CO2 permeance (1940 GPU) with a CO2/N2 selectivity of 13.
- 6(a) Angelova, P.; Vieker, H.; Weber, N. E.; Matei, D.; Reimer, O.; Meier, I.; Kurasch, S.; Biskupek, J.; Lorbach, D.; Wunderlich, K.; Chen, L.; Terfort, A.; Klapper, M.; Müllen, K.; Kaiser, U.; Gölzhäuser, A.; Turchanin, A. ACS Nano 2013, 7, 6489– 6497(b) Vendamme, R.; Onoue, S. Y.; Nakao, A.; Kunitake, T. Nat. Mater. 2006, 5, 494– 501Google ScholarThere is no corresponding record for this reference.(c) Peinemann, K. V.; Abetz, V.; Simon, P. F. W. Nat. Mater. 2007, 6, 992– 996Google ScholarThere is no corresponding record for this reference.(d) Du, N.; Park, H. B.; Dal-Cin, M. M.; Guiver, M. D. Energy Environ. Sci. 2012, 5, 7306– 7322Google ScholarThere is no corresponding record for this reference.(e) Ho, B. P.; Chul, H. J.; Young, M. L.; Hill, A. J.; Pas, S. J.; Mudie, S. T.; Van Wagner, E.; Freeman, B. D.; Cookson, D. J. Science 2007, 318, 254– 258Google ScholarThere is no corresponding record for this reference.
- 7Vanherck, K.; Koeckelberghs, G.; Vankelecom, I. F. J. Prog. Polym. Sci. 2013, 38, 874– 896[Crossref], [CAS], Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVWisbbK&md5=df402ade90181a548a9bdad1fe101e5cCrosslinking polyimides for membrane applications: A reviewVanherck, Katrien; Koeckelberghs, Guy; Vankelecom, Ivo F. J.Progress in Polymer Science (2013), 38 (6), 874-896CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)A review. This review discusses many crosslinking methods for polyimide membranes that have been described in literature. Some important properties of polyimides and their synthesis reactions are first summarized. The important (commercialized) polyimide types that are now used in membrane technol., the prepn. methods available for polyimide membranes and their main applications are listed. The effects of thermal annealing of polyimide membranes are briefly discussed, before giving an extensive review of the many crosslinking methods that have been described in literature. Thermal crosslinking, UV crosslinking and a range of chem. crosslinking methods, including diol and diamine crosslinking, are discussed in detail, focusing on the actual chem. behind the crosslinking. Also, some new, not yet fully studied, crosslinking methods are listed.
- 8(a) Laine, R. M.; Roll, M. F. Macromolecules 2011, 44, 1073– 1109(b) Nischang, I.; Brüggemann, O.; Teasdale, I. Angew. Chem., Int. Ed. 2011, 50, 4593– 4596Google ScholarThere is no corresponding record for this reference.(c) Oaten, M.; Choudhury, N. R. Macromolecules 2005, 38, 6392– 6401(d) Wu, G.; Su, Z. Chem. Mater. 2006, 18, 3726– 3732(e) Zhang, C.; Babonneau, F.; Bonhomme, C.; Laine, R. M.; Soles, C. L.; Hristov, H. A.; Yee, A. F. J. Am. Chem. Soc. 1998, 120, 8380– 8391
- 9(a) Iyer, P.; Iyer, G.; Coleman, M. J. Membr. Sci. 2010, 358, 26– 32[Crossref], [CAS], Google Scholar9ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXntVGjtr4%253D&md5=b9c2581e43eaeb558dcd5aca12766310Gas transport properties of polyimide-POSS nanocompositesIyer, Pallavi; Iyer, Ganesh; Coleman, MariaJournal of Membrane Science (2010), 358 (1-2), 26-32CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)A mixed matrix membrane material was formed by mixing mol. scale inorg. cages, octaamino functional oligomeric silsesquioxane (OAPS) in a fluorine contg. polyimide, 6FDA-MDA. These materials formed a miscible blend at loadings up to 20 wt% OAPS with phase sepn. occurring with the formation of small nanoscale OAPS particles at higher loadings (∼50 wt%). The pure gas transport properties were measured as a function of OAPS loading. There was a general decrease in permeabilities for all gases studied except carbon dioxide with increasing OAPS loading. This redn. was due to decreases in both soly. and diffusivity which indicate that the OAPS cages were not accessible to gas mols. at conditions used for the study. The amino groups on the surface of the OAPS interact with CO2 resulting in slight increase in soly. and no net decrease in permeability at all OAPS loadings. An increase in permselectivities was obsd. for most gas pairs including He/CH4, CO2/CH4 and O2/N2.(b) Leu, C. M.; Chang, Y. T.; Wei, K. H. Chem. Mater. 2003, 15, 3721– 3727
- 10Dalwani, M.; Zheng, J.; Hempenius, M.; Raaijmakers, M. J. T.; Doherty, C. M.; Hill, A. J.; Wessling, M.; Benes, N. E. J. Mater. Chem. 2012, 22, 14835– 14838Google ScholarThere is no corresponding record for this reference.
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- 13Sroog, C. E. Prog. Polym. Sci. 1991, 16, 561– 694[Crossref], [CAS], Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XitlKiurg%253D&md5=cf293f2e168086245a5f3b80d498a2caPolyimidesSroog, C. E.Progress in Polymer Science (1991), 16 (4), 561-694CODEN: PRPSB8; ISSN:0079-6700.A review with 373 refs. on prepn., properties, processing, and uses of polyimides.
- 14Schön, P.; Bagdi, K.; Molnár, K.; Markus, P.; Pukánszky, B.; Julius Vancso, G. Eur. Polym. J. 2011, 47, 692– 698
- 15Colson, J. W.; Dichtel, W. R. Nat. Chem. 2013, 5, 453– 465[Crossref], [PubMed], [CAS], Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXnsVynu7Y%253D&md5=2fab1e4f83abed4420fcc72ae6c86a10Rationally synthesized two-dimensional polymersColson, John W.; Dichtel, William R.Nature Chemistry (2013), 5 (6), 453-465CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)A review. Synthetic polymers exhibit diverse and useful properties and influence most aspects of modern life. Many polymn. methods provide linear or branched macromols., frequently with outstanding functional-group tolerance and mol. wt. control. In contrast, extending polymn. strategies to two-dimensional periodic structures is in its infancy, and successful examples have emerged only recently through mol. framework, surface science and crystal engineering approaches. In this Review, we describe successful 2D polymn. strategies, as well as seminal research that inspired their development. These methods include the synthesis of 2D covalent org. frameworks as layered crystals and thin films, surface-mediated polymn. of polyfunctional monomers, and solid-state topochem. polymns. Early application targets of 2D polymers include gas sepn. and storage, optoelectronic devices and membranes, each of which might benefit from predictable long-range mol. organization inherent to this macromol. architecture.
- 16Duthie, X.; Kentish, S.; Powell, C.; Nagai, K.; Qiao, G.; Stevens, G. J. Membr. Sci. 2007, 294, 40– 49[Crossref], [CAS], Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXjvF2rurY%253D&md5=354187bddde8dfc3232805e6cccd574bOperating temperature effects on the plasticization of polyimide gas separation membranesDuthie, Xavier; Kentish, Sandra; Powell, Clem; Nagai, Kazukiyo; Qiao, Greg; Stevens, GeoffJournal of Membrane Science (2007), 294 (1+2), 40-49CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)Membrane plasticization is the process whereby penetrant dissoln. causes membrane swelling or dilation, which in turn, can increase membrane diffusivity and soly. and lead to long time frame polymer relaxation processes. In this work, the effect of temp. upon the plasticization of a rigid polyimide, poly(4,4'-hexafluoroisopropylidene diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine) (6FDA-TMPDA), by CO2 is investigated. Across the full range of temps. studied, plasticization has little effect on CO2 soly. as all results can be characterized by a std. dual mode sorption model. However, the effect upon diffusivity is significant and this can be described by both an exponential relationship with penetrant concn. and an Arrhenius relationship with temp. The polymer relaxation processes induced by plasticization are also temp. dependent. However, the total proportion of penetrant sorption assocd. with such relaxation processes is relatively unaffected by temp. This paper shows that plasticization effects are dominated by Henry's law dissoln. Conversely, while Henry's law species contribute most to diffusion at high temps., at lower temps. the movement of Langmuir component species also contributes to the total diffusion coeff.
- 17(a) Lin, W. H.; Chung, T. S. J. Membr. Sci. 2001, 186, 183– 193[Crossref], [CAS], Google Scholar17ahttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjt12mtr8%253D&md5=daf3a697459630463b5d40d51e3a55e8Gas permeability, diffusivity, solubility, and aging characteristics of 6FDA-durene polyimide membranesLin, W.-H.; Chung, T.-S.Journal of Membrane Science (2001), 186 (2), 183-193CODEN: JMESDO; ISSN:0376-7388. (Elsevier Science B.V.)We have detd. the intrinsic gas transport properties of He, H2, O2, N2, CH4, and CO2 for a 6FDA-durene polyimide as a function of pressure, temp. and aging time. The permeability coeffs. of O2, N2, CH4, and CO2 decrease slightly with increasing pressure. The pressure-dependent diffusion coeffs. and soly. coeffs. are consistent with the dual-sorption model and partial immobilization. All the gas permeabilities increase with temp. and their apparent activation energies for permeation increase with increasing gas mol. sizes in the order of CO2, O2, N2, and CH4. The percentages of permeability decay after 280 days of aging are 22, 32, 36, 40, 42, and 30% for He, H2, O2, N2, CH4, and CO2, resp. Interestingly, except for H2 (kinetic diam. of 2.89 A), the percentages of permeability decay increase exactly in the order of He (kinetic diam. of 2.6 A), CO2 (3.30 A), O2 (3.46 A), N2 (3.64 A), and CH4 (3.80 A). The apparent activation energies of permeation for O2, N2, CH4, and CO2 increase with aging because of the increases in activation energies of diffusion and the decreases in soly. coeffs. The activation-energy increase for diffusion is probably due to the decrease in polymeric molar volume because of densification during aging. The redn. in soly. coeff. indicates the available sites for sorption decreasing with aging because of the redn. of microvoids and interstitial chain space.(b) Tanaka, K.; Okano, M.; Toshino, H.; Kita, H.; Okamoto, K.-I. J. Polym. Sci., Part B: Polym. Phys. 1992, 30, 907– 914[Crossref], [CAS], Google Scholar17bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XksV2lur4%253D&md5=e2b1ec3d2b3110f15f1e956741b3cbffEffect of methyl substituents on permeability and permselectivity of gases in polyimides prepared from methyl-substituted phenylenediaminesTanaka, Kazuhiro; Okano, Masaaki; Toshino, Hiroyuki; Kita, Hidetoshi; Okamoto, KenichiJournal of Polymer Science, Part B: Polymer Physics (1992), 30 (8), 907-14CODEN: JPBPEM; ISSN:0887-6266.Permeability and soly. coeffs. for H, CO2, O, CO, N, and CH4 in polyimides prepd. from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and Me-substituted phenylenediamines were measured to investigate effects of the substituents on gas permeability and permselectivity. The Me substituents restricted internal rotation around the bonds between the Ph rings and the imide rings. The rigidity and nonplanar structure of the polymer chain and the bulkiness of Me groups made chain packing inefficient, resulting in increases in both diffusion and soly. coeffs. of the gases. Polyimides from tetramethyl-p-phenylenediamine and trimethyl-m-phenylenediamine displayed very high permeability coeffs. and very low permselectivity due to very high diffusion coeffs. and very low diffusivity selectivity, as compared with the other polyimides having a similar fraction of free space. This suggested that these polyimides had high fractions of large-size free spaces.
- 18Villaluenga, J. P. G.; Seoane, B.; Hradil, J.; Sysel, P. J. Membr. Sci. 2007, 305, 160– 168[Crossref], [CAS], Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtFeis7zO&md5=9d3034eb6eb245e1531f115518782a93Gas permeation characteristics of heterogeneous ODPA-BIS P polyimide membranes at different temperaturesVillaluenga, J. P. G.; Seoane, B.; Hradil, J.; Sysel, P.Journal of Membrane Science (2007), 305 (1+2), 160-168CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)Heterogeneous carbon mol. sieves and hypercrosslinked polystyrene microparticles adsorbent-based membranes with a (ODPA-BIS P) polyimide binder were prepd. The effect of adsorbent particles on the gas transport properties of heterogeneous membranes was studied. Permeability, diffusion and soly. coeffs. of He, CO2, O2, and N2 were estd. for homogeneous and heterogeneous membranes at a feed pressure of 1 atm for different temps. between 25° and 60°. It was obsd. that adsorbent-filled (ODPA-BIS P) polyimide membranes exhibit higher gas permeability in comparison with adsorbent-free membrane, while permselectivity is maintained. The results also showed that the adsorbents enhance significantly gas diffusivity in (ODPA-BIS P) polyimide membrane, whereas the gas soly. is clearly reduced. In both type of heterogeneous membranes, gas permeation and diffusion are thermal activated processes described by the Arrhenius equation, whereas the sorption process is exothermic. The addn. of both type of adsorbents to the (ODPA-BIS P) polyimide membrane increases the activation energy of permeability, this is mainly due to a significant increase of the heat of sorption, because the activation energy for diffusion is slightly decreased.
- 19Neyertz, S.; Gopalan, P.; Brachet, P.; Kristiansen, A.; Männle, F.; Brown, D. Soft Mater. 2014, 12, 113– 123[Crossref], [CAS], Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXms1Wgsbw%253D&md5=2ddf18eebcc5abaf66b959caa5b4f9a9Oxygen Transport in Amino-Functionalized Polyhedral Oligomeric Silsesquioxanes (POSS)Neyertz, S.; Gopalan, P.; Brachet, P.; Kristiansen, A.; Mannle, F.; Brown, D.Soft Materials (2014), 12 (1), 113-123CODEN: SMOAAE; ISSN:1539-445X. (Taylor & Francis, Inc.)The transport properties of oxygen in three amino-functionalized cubic polyhedral oligomeric silsesquioxanes (POSS) have been studied using classical mol. dynamics (MD) simulations over a timescale long enough to reach the Fickian regime for diffusion. An amt. of O2 corresponding to an applied pressure of 3 bars was inserted into mol. models of hybrid org./inorg. POSS with the chem. compn. (RSiO3/2)8, which differed by the end-groups of their org. pendant chains, i.e., R = -(CH2)3-NH-CO-X with X = -C6H4OH, -C6H5 or -C6H11. The oxygen ... POSS energies were found to be small with respect to the POSS... POSS interactions. The O2 mols. permeate the org. phase and move through combinations of oscillations within available free vols. in the matrixes and occasional jumping events. Gas mobility was more restricted in the system with the salicylic end-group and the largest hydrogen-bond network, whereas it was enhanced in the system with the cyclohexyl end-group. The most energetically-favorable sites for O2 insertion were either in the vicinity of the silica cages or close to the rings of the chain end-groups. On the other hand, the amide and hydroxyls groups engaging in H-bonds were less energetically favorable. This confirms that H-bonding networks are a hindrance for O2 transport in such systems.
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Supporting Information
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ARTICLE SECTIONSThe full reaction scheme of the polyPOSS–imide; material analysis using differential scanning calorimetry, thermal gravimetric analysis, X-ray photoelectron spectroscopy and full infrared peak analysis. This material is available free of charge via the Internet at http://pubs.acs.org.
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