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Mallik AK, Qiu H, Takafuji M, Ihara H. High molecular-shape-selective stationary phases for reversed-phase liquid chromatography: A review. Trends Analyt Chem 2018. [DOI: 10.1016/j.trac.2018.09.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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2
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Elwinger F, Dvinskikh SV, Furó I. ¹³C SPE MAS measurement of ligand concentration in compressible chromatographic beads. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:572-7. [PMID: 26053054 PMCID: PMC4832835 DOI: 10.1002/mrc.4257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/26/2015] [Accepted: 04/06/2015] [Indexed: 06/04/2023]
Abstract
A method for measuring the ligand concentration in heterogeneous materials like chromatography media is described. In this method, (13)C single pulse excitation magic angle spinning NMR experiment with broadband (1)H decoupling is used to determine the peak integrals for a butyl ligand in the spectrum of a dried chromatography medium. Within a carefully controlled protocol, those integrals compared with that of the internal reference compound dimethyl sulfone provide the required volume concentration with an accuracy of ca 2%. The effects of temperature, degree of hydration, and other experimental parameters are discussed.
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Affiliation(s)
- Fredrik Elwinger
- KTH Royal Institute of TechnologyDivision of Applied Physical ChemistryTeknikringen 36SE‐10044StockholmSweden
- GE Healthcare Bio‐Sciences ABBjörkgatan 31SE‐75184UppsalaSweden
| | - Sergey V. Dvinskikh
- KTH Royal Institute of TechnologyDivision of Applied Physical ChemistryTeknikringen 36SE‐10044StockholmSweden
| | - István Furó
- KTH Royal Institute of TechnologyDivision of Applied Physical ChemistryTeknikringen 36SE‐10044StockholmSweden
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3
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Zhang M, Qiu H. Progress in stationary phases modified with carbonaceous nanomaterials for high-performance liquid chromatography. Trends Analyt Chem 2015. [DOI: 10.1016/j.trac.2014.10.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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4
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Chandran J, Shintu L, Caldarelli S. Molecular signal suppression by in situ microextraction in nuclear magnetic resonance spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:694-698. [PMID: 25103092 DOI: 10.1002/mrc.4120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/20/2014] [Accepted: 07/08/2014] [Indexed: 06/03/2023]
Abstract
The detailed characterization of complex mixtures by NMR is often hampered by the presence of signals from uninformative compounds, the resonances of which overlap with those of the molecules of interest. We provide here a proof of principle for an approach to NMR signal suppression in complex samples using Molecularly Imprinted Polymers (MIPS). Addition of a few milligrams of polymer to a solution traps the target molecule in typical micromolar to millimolar concentration, thus achieving in situ signal suppression, without altering any other spectral features. This method minimized any manipulation or perturbation of the spectrum and was applied to a complex mixture of known compounds and to a plant extract, in both cases spiked with a compound (bisphenol A), which was subsequently removed by selective binding to a complementary MIP. What is described in this report is comparable with microextraction and may in due course be applied to a large number of analytical challenges.
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Affiliation(s)
- Jima Chandran
- Aix Marseille Université, Centrale Marseille, CNRS, iSm2 UMR 7313, 13397, Marseille, France; Research Group Biosynthesis/NMR Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745, Jena, Germany
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5
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Preparation and chromatographic evaluation of new branch-type diamide-embedded octadecyl stationary phase with enhanced shape selectivity. Anal Chim Acta 2014; 833:48-55. [DOI: 10.1016/j.aca.2014.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 04/29/2014] [Accepted: 05/02/2014] [Indexed: 11/19/2022]
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6
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Fatunmbi HO, Bruch MD. Characterization of the structural morphology of chemically modified silica prepared by surface polymerization of a mixture of long and short alkyl chains using 13C and 29Si NMR spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4974-4987. [PMID: 23530776 DOI: 10.1021/la3040853] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A series of bonded phases were prepared by the chemical modification of silica using the surface polymerization of trifunctional and difunctional ligands, and the structural morphology was characterized by solid-state nuclear magnetic resonance (NMR) spectroscopy using cross-polarization and magic angle spinning (CP/MAS). Mixed-phase surfaces were prepared using mixtures of trifunctional long-chain (C18) ligands with trifunctional and difunctional short-chain (C1) ligands, and these surfaces were compared to the corresponding single-phase surfaces consisting of only long- or short-chain ligands. For both types of mixed-phase surfaces, the incorporation of short chains increases the overall ligand density, the density of long chains, and the degree of cross-linking between ligands compared to that of the single-phase surface consisting exclusively of long chains. When the percentage of long-chain ligands in the mixture is high, a horizontally polymerized monolayer of chains is formed on the silica surface for both trifunctional and difunctional short chains. However, essentially all of the long chains adopt a trans conformation when trifunctional short chains are used, and a significant number of gauche defects are observed for the long chains when mixed with difunctional short chains. Furthermore, the ligands on the mixed-phase surface are more rigid when the short chains are trifunctional. When the percentage of trifunctional short chains is increased, some vertical polymerization occurs, caused by the molecular stacking of the highly reactive short chains near the surface. However, this does not preclude cross-linking between the ligands necessary to seal the surface, and the degree of cross-linking is quite high, suggesting that the short chains cross-link both vertically, away from the surface, and horizontally, across the surface. No such vertical polymerization is observed for the bulkier difunctional short chains. For both trifunctional and difunctional short chains, the surface chains are more mobile, with a greater number of gauche conformations among the long chains when the percentage of short-chain ligands in the reaction mixture is increased.
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Affiliation(s)
- Hafeez O Fatunmbi
- Separation Methods Technologies, Inc., 31 Blue Hen Drive, Newark, Delaware 19713, United States
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Carrara C, Lopez C, Caldarelli S. Chromatographic-nuclear magnetic resonance can provide a prediction of high-pressure liquid chromatography shape selectivity tests. J Chromatogr A 2012; 1257:204-7. [DOI: 10.1016/j.chroma.2012.07.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/09/2012] [Accepted: 07/10/2012] [Indexed: 10/28/2022]
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8
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Hentschel P, Holtin K, Steinhauser L, Albert K. Monitoring the On-line Titration of Enantiomeric Omeprazole Employing Continuous-flow Capillary Microcoil 1
H NMR Spectroscopy. Chirality 2012; 24:1074-6. [DOI: 10.1002/chir.22099] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 06/25/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Petra Hentschel
- Institute of Organic Chemistry; University of Tübingen; Tübingen 72076 Germany
| | - Karsten Holtin
- Institute of Organic Chemistry; University of Tübingen; Tübingen 72076 Germany
| | - Lisa Steinhauser
- Institute of Organic Chemistry; University of Tübingen; Tübingen 72076 Germany
| | - Klaus Albert
- Institute of Organic Chemistry; University of Tübingen; Tübingen 72076 Germany
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Mallik AK, Sawada T, Takafuji M, Ihara H. Novel Approach for the Separation of Shape-Constrained Isomers with Alternating Copolymer-Grafted Silica in Reversed-Phase Liquid Chromatography. Anal Chem 2010; 82:3320-8. [DOI: 10.1021/ac1001178] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Abul K. Mallik
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Tsuyoshi Sawada
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Makoto Takafuji
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Hirotaka Ihara
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Kühnle M, Friebolin V, Albert K, Rimmer CA, Lippa KA, Sander LC. Architecture and Dynamics of C18 Bonded Interphases with Small Molecule Spacers. Anal Chem 2009; 81:10136-42. [DOI: 10.1021/ac901911w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Mallik AK, Takafuji M, Ihara H. Tuning of the molecular packing structure of comb-shaped polymer-grafted silica by using surface-initiated ATRP to enhance the molecular-shape selectivity towards polycyclic aromatic hydrocarbons. Eur Polym J 2009. [DOI: 10.1016/j.eurpolymj.2009.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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Toussaint G, Brisbois M, Grandjean J, Cloots R, Henrist C. Hybrid lamellar silica: Combined template extraction and hydrophilic silanation. J Colloid Interface Sci 2009; 329:120-6. [DOI: 10.1016/j.jcis.2008.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 08/29/2008] [Accepted: 10/02/2008] [Indexed: 10/21/2022]
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Grynbaum MD, Meyer C, Putzbach K, Rehbein J, Albert K. Application of polymer based stationary phases in high performance liquid chromatography and capillary high performance liquid chromatography hyphenated to microcoil 1H nuclear magnetic resonance spectroscopy. J Chromatogr A 2007; 1156:80-6. [PMID: 17134714 DOI: 10.1016/j.chroma.2006.11.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 10/24/2006] [Accepted: 11/03/2006] [Indexed: 11/16/2022]
Abstract
The increased demand for chromatographic materials that are able to achieve a fast separation of large quantities of structure analogues is a great challenge. It is known that polymer based chromatographic materials have a higher loadability, compared to silica based sorbents. Unfortunately these polymer materials cannot be used under high pressure which is necessary in order to obtain high flow rates, and hence long times are needed to perform a separation. However, by immobilizing a polymer on a mechanically stable porous silica core, this problem can be circumvented and higher flows become feasible on these materials. Especially for capillary liquid chromatography hyphenated with nuclear magnetic resonance a high loadability is of great importance in order to obtain sharp, resolved, and concentrated peaks thus resulting in a good signal to noise ratio in the NMR experiment. Therefore, a highly shape selective chromatographic sorbent was developed by covalently immobilizing a poly(ethylene-co-acrylic) acid copolymer (-CH(2)CH(2)-)(x)[CH(2)CH(CO(2)H)-](y) (x=119, y=2.4) with a mass fraction of acrylic acid of 5% as stationary phase on silica via a spacer molecule (3-glycidoxypropyltrimethoxysilane). First, the loadability of this sorbent compared to C(30) is demonstrated by the HPLC separation of two xanthophyll isomers. Subsequently, it has been successfully employed in the hyphenation of capillary HPLC with microcoil (1)H NMR spectroscopy by separating and identifying a highly concentrated solution of the tocopherol homologues.
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Affiliation(s)
- Marc David Grynbaum
- Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany
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Welsch N, Meyer C, Albert K. Bilder sagen mehr als tausend Worte: Visualisierungen für Lehre und Forschung. CHEM UNSERER ZEIT 2006. [DOI: 10.1002/ciuz.200600367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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Lippa KA, Sander LC. Identification of isolated cavity features within molecular dynamics simulated chromatographic surfaces. J Chromatogr A 2006; 1128:79-89. [PMID: 16846606 DOI: 10.1016/j.chroma.2006.06.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 06/06/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
Highly ordered morphological features were characterized for molecular dynamics simulated alkyl-modified silica models that represent chromatographic materials with enhanced shape recognition capability. Deep cavities (8-10A wide) within the alkyl chains were identified for C18 polymeric models corresponding to shape-selective RPLC stationary phases. The all-trans conformational distal-end segments of these isolated cavities averaged over a 100 ps simulation time interval were observed to increase (up to 15 A) in models with an increase in both surface coverage and corresponding shape selectivity. Similar-structure cavities with significant alkyl chain ordered regions (>11A) were isolated from two independent C18 models (differing in bonding chemistry, density and temperature) that represent highly shape-selective materials. The size and depth of these ordered regions increased (up to 28 A) for the extended-length C30 alkyl phase models. These initial results offer a physical representation of alkyl-modified surfaces that may facilitate the identification of potential molecular features that may be involved in the shape-selective retentive processes, as well as illustrating the potential for such computational techniques to predict the molecular recognition capabilities of novel analyte-specific sorbents.
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Affiliation(s)
- Katrice A Lippa
- Analytical Chemistry Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
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Meyer C, Pascui O, Reichert D, Sander LC, Wise SA, Albert K. Conformational temperature dependence of a poly(ethylene-co-acrylic acid) stationary phase investigated by nuclear magnetic resonance spectroscopy and liquid chromatography. J Sep Sci 2006; 29:820-8. [PMID: 16830494 DOI: 10.1002/jssc.200500376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A polymer-based RP sorbent was prepared by immobilizing a poly(ethylene-co-acrylic acid) copolymer with an acid mass fraction of 5% on silica by using a 3-glycidoxypropyl linkage. 13C cross-polarization/magic angle spinning NMR spectroscopy of the sorbent, either in the dry state or suspended in the mobile phase, showed an increase in mobility at elevated temperatures. Alkyl chain segments with gauche conformations were more mobile than chain segments with trans conformations. The strength of the 13C-1H dipolar couplings in the alkyl chains was measured using the constant time dipolar and chemical shift pulse sequence, revealing less molecular motion for the trans conformation. Non-linear van't Hoff plots were observed for separations of shape-constrained solutes (such as geometric beta-carotene isomers and polycyclic aromatic hydrocarbons). At higher temperatures, the retention behavior was similar to that of monomeric C18 sorbents, whereas at ambient and lower temperatures, enhanced shape-selective properties were exhibited similar to those of polymeric C30 sorbents.
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Affiliation(s)
- Christoph Meyer
- Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Germany
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Srinivasan G, Meyer C, Welsch N, Albert K, Müller K. Influence of synthetic routes on the conformational order and mobility of C18 and C30 stationary phases. J Chromatogr A 2006; 1113:45-54. [PMID: 16472820 DOI: 10.1016/j.chroma.2006.01.113] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 01/23/2006] [Accepted: 01/26/2006] [Indexed: 11/30/2022]
Abstract
Silica gels modified with n-alkyl chains (n = 18, 30) are prepared by two different synthetic routes and are examined by variable temperature FTIR and solid-state NMR spectroscopy. HPLC measurements of SRM 869, cis/trans ss-carotene isomers and xanthophylls isomers confirm the dependence of the separation mechanism on the alkyl chain length and the synthetic routes. The determination of the silane functionality and degree of cross-linking of silane ligands on the silica surface is achieved by 29Si CP/MAS NMR measurements. The structural order and mobility of the alkyl chains are investigated by means of variable temperature 13C CP/MAS NMR measurements. Variable temperature FTIR studies are performed where conformational order and flexibility of the alkyl chains in C18 and C30 phases are monitored through conformational sensitive CH2 symmetric, anti-symmetric stretching and wagging modes. In addition, the chromatographic properties of the C18 and C30 phases are determined. The results derived from the FTIR, NMR and HPLC measurements are discussed in the context of the applied synthetic routes and alkyl chain lengths.
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Affiliation(s)
- Gokulakrishnan Srinivasan
- Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
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Meyer C, Busche S, Welsch N, Wegmann J, Gauglitz G, Albert K. Contact-angle, ellipsometric, and spin-diffusion solid-state nuclear magnetic resonance spectroscopic investigations of copolymeric stationary phases immobilized on SiO2 surfaces. Anal Bioanal Chem 2005; 382:1465-71. [PMID: 16001236 DOI: 10.1007/s00216-005-3363-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 05/20/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
SiO2 surfaces-silica gel particles and silica wafers-were modified by covalently immobilizing three poly(ethylene-co-acrylic acid) copolymers, (-CH2CH2-)x[CH2CH/(CO2H)-]y, with different chain lengths and mass fractions of acrylic acid. 13C solid-state NMR spectroscopy on the modified silica gel particles revealed both mobile gauche and rigid trans aligned alkyl chains in the copolymers. For copolymers attached to silica wafers via a 3-aminopropyltriethoxysilane spacer molecule, ellipsometric measurements revealed a mean value of the layer thickness distribution of 6.5 and 4.3 nm, respectively, for the more acidic and the shorter copolymers with mobile alkyl chains mostly in the gauche conformation. For the longest and least acidic copolymer with more rigid trans ordered alkyl chains, however, a mean phase thickness of 10.6 nm was found. When this copolymer was immobilized via a 3-glycidoxypropyltrimethoxysilane spacer molecule we measured a mean layer thickness of 9.9 nm. A model of the surface morphology of this immobilization strategy was derived using spin-diffusion 13C NMR measurements on the corresponding modified silica. It was thereby proven that the trans and gauche-aligned alkyl chains occur in distinct domains of certain sizes on the silica surface. The surface polarity of all modified silica wafers was also investigated by measurement of contact-angle.
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Affiliation(s)
- Christoph Meyer
- Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076, Tuebingen, Germany.
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