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Nguyen TT, Khuat HTT, Asakura S, Mizutani G, Murakami Y, Okada T. Study of the molecular orientation of steroidal side chains at polyimide surfaces using sum frequency generation vibrational spectroscopy. J Chem Phys 2021; 155:084702. [PMID: 34470358 DOI: 10.1063/5.0057145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The molecular orientation of steroidal side chains at rubbed polyimide (PI) surfaces is studied by sum frequency generation (SFG) vibrational spectroscopy. The main objective is to find a correlation between the molecular structure of the PI film and the liquid crystal alignment on the polymer. Analysis of the SFG spectra shows that rubbing of the polymer film appears to cause conformational changes in the methyl group of the polymer side chain near the steroidal structure. However, rubbing does not significantly influence the orientation of the isopropyl group at the end of the polymer side chain. This shows that the liquid crystal alignment is not correlated with the orientation of the isopropyl group.
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Affiliation(s)
- Trinh Thi Nguyen
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Hien Thi Thu Khuat
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Shinya Asakura
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Goro Mizutani
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Yoshitaka Murakami
- LCD Materials 2nd Laboratory, Display Materials Research Laboratories, JSR Corporation, Mie 510-8552, Japan
| | - Takashi Okada
- LCD Materials 2nd Laboratory, Display Materials Research Laboratories, JSR Corporation, Mie 510-8552, Japan
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Bhattacharyya D, Montenegro A, Dhar P, Mammetkuliyev M, Pankow RM, Jung MC, Thompson ME, Thompson BC, Benderskii AV. Molecular Orientation of Poly-3-hexylthiophene at the Buried Interface with Fullerene. J Phys Chem Lett 2019; 10:1757-1762. [PMID: 30908051 DOI: 10.1021/acs.jpclett.9b00498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Molecular orientation at the donor-acceptor interface plays a crucial role in determining the efficiency of organic semiconductor materials. We have used vibrational sum frequency generation spectroscopy to determine the orientation of poly-3-hexylthiophene (P3HT) at the planar buried interface with fullerene (C60). The thiophene rings of P3HT have been found to tilt significantly toward C60, making an average angle θ ≈ 49° ± 10° between the plane of the ring and the interface. Such tilt may be attributed to π-π stacking interactions between P3HT and C60 and may facilitate efficient charge transfer between donor and acceptor. Upon annealing, the thiophene rings tilt away from the interface by Δθ = 12-19°. This may be attributed to higher crystallinity of annealed P3HT that propagates all the way to the interface, resulting in more "edge-on" orientation, which is consistent with the observed red-shift by ∼6 cm-1 and spectral narrowing of the C=C stretch bands.
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Control of Molecular Ordering, Alignment, and Charge Transport in Solution-Processed Conjugated Polymer Thin Films. Polymers (Basel) 2017; 9:polym9060212. [PMID: 30970891 PMCID: PMC6432227 DOI: 10.3390/polym9060212] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/06/2017] [Accepted: 06/06/2017] [Indexed: 01/31/2023] Open
Abstract
Morphology of conjugated polymers is a critical factor that significantly affects intrinsic charge transport characteristics and in turn performance of polymer-based devices. Morphological defects including misaligned crystalline grains and grain boundaries significantly impede efficient charge hopping between transport sites, resulting in degradation of device performance. Therefore, one important challenge is to control morphology of active polymer thin-films for achieving high performance flexible electronic devices. In the past decade, significant progress has been achieved in morphology control of conjugated polymer thin-films using solution-based processing techniques. This review focuses on recent advances in processing strategies that can tune the morphologies and thus impact charge transport properties of conjugated polymer thin films. Of the available processing strategies, polymer solution treatments and film deposition techniques will be mainly highlighted. The correlation between processing conditions, active layer morphologies, and device performance will be also be discussed.
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4
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Effects of single-source multiple beam interference in vibrational sum frequency generation spectroscopy. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2014.12.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Zhang X, Zhang C, Hankett JM, Chen Z. Molecular surface structural changes of plasticized PVC materials after plasma treatment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4008-4018. [PMID: 23445444 DOI: 10.1021/la4000796] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this research, a variety of analytical techniques including sum frequency generation vibrational spectroscopy (SFG), coherent anti-Stokes Raman spectroscopy (CARS), and X-ray photoelectron spectroscopy (XPS) have been employed to investigate the surface and bulk structures of phthalate plasticized poly(vinyl chloride) (PVC) at the molecular level. Two types of phthalate molecules with different chain lengths, diethyl phthalate (DEP) and dibutyl phthalate (DBP), mixed with PVC in various weight ratios were examined to verify their different surface and bulk behaviors. The effects of oxygen and argon plasma treatment on PVC/DBP and PVC/DEP hybrid films were investigated on both the surface and bulk of films using SFG and CARS to evaluate the different plasticizer migration processes. Without plasma treatment, SFG results indicated that more plasticizers segregate to the surface at higher plasticizer bulk concentrations. SFG studies also demonstrated the presence of phthalates on the surface even at very low bulk concentration (5 wt %). Additionally, the results gathered from SFG, CARS, and XPS experiments suggested that the PVC/DEP system was unstable, and DEP molecules could leach out from the PVC under low vacuum after several minutes. In contrast, the PVC/DBP system was more stable; the migration process of DBP out of PVC could be effectively suppressed after oxygen plasma treatment. XPS results indicated the increase of C═O/C-O groups and decrease of C-Cl functionalities on the polymer surface after oxygen plasma treatment. The XPS results also suggested that exposure to argon plasma induced chemical bond breaking and formation of cross-linking or unsaturated groups with chain scission on the surface. Finally, our results indicate the potential risk of using DEP molecules in PVC since DEP can easily leach out from the polymeric bulk.
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Affiliation(s)
- Xiaoxian Zhang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Lu X, Xue G, Wang X, Han J, Han X, Hankett J, Li D, Chen Z. Directly Probing Molecular Ordering at the Buried Polymer/Metal Interface 2: Using P-Polarized Input Beams. Macromolecules 2012. [DOI: 10.1021/ma301088g] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Xiaolin Lu
- Department of Chemistry, Key
Laboratory of Advanced Textile Materials and Manufacturing Technology
of Education Ministry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Gi Xue
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Xinping Wang
- Department of Chemistry, Key
Laboratory of Advanced Textile Materials and Manufacturing Technology
of Education Ministry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Jianglong Han
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Xiaofeng Han
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
| | - Jeanne Hankett
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
| | - Dawei Li
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
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McClelland AA, López-Mejías V, Matzger AJ, Chen Z. Peering at a buried polymer-crystal interface: probing heterogeneous nucleation by sum frequency generation vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2162-2165. [PMID: 21322612 PMCID: PMC3128200 DOI: 10.1021/la105067x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Sum frequency generation vibrational spectroscopy (SFG-VS) has been applied to investigate the selective crystallization of two forms of acetaminophen (ACM) on polymer surfaces. To our knowledge, this is the first account of SFG-VS being applied to study a polymer-crystal interface. SFG elucidates the molecular-level interactions governing phase selection at this buried interface, providing insight into the process of polymer-induced heteronucleation (PIHn) in solution as well as from the vapor phase. ACM heteronucleates from supersaturated aqueous solution in the metastable orthorhombic crystal form on poly(methyl methacrylate) (PMMA) surfaces, whereas the thermodynamically stable monoclinic crystal form is observed to form on poly(n-butyl methacrylate) (PBMA) surfaces. When the ACM crystals were grown by sublimation, only the monoclinic form was observed on both PMMA and PBMA. SFG-VS results indicate that hydrogen bonds are formed between PMMA C═O groups and the orthorhombic ACM crystals at the PMMA-ACM interface. At PBMA-monoclinic ACM interfaces, no hydrogen bond formation was observed. This research demonstrates that SFG-VS can be used to probe molecular interactions at polymer-crystal interfaces. Understanding the interfacial molecular interactions will ultimately provide a rational basis for improving methods for polymorph discovery and selection based on heteronucleation on polymer surfaces.
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Probing polymer surfaces and interfaces using sum frequency generation vibrational spectroscopy - a powerful nonlinear optical technique. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11458-010-0220-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stiopkin IV, Jayathilake HD, Weeraman C, Benderskii AV. Temporal effects on spectroscopic line shapes, resolution, and sensitivity of the broad-band sum frequency generation. J Chem Phys 2010; 132:234503. [PMID: 20572717 DOI: 10.1063/1.3432776] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sum frequency generation (SFG) is a surface-selective spectroscopy that provides a wealth of molecular-level information on the structure and dynamics at surfaces and interfaces. This paper addresses the general issue of spectral resolution and sensitivity of the broad-band (BB) SFG that involves a spectrally narrow nonresonant (usually visible) and a BB resonant (usually infrared) laser pulses. We examine how the spectral width and temporal shape of the two pulses, and the time delay between them, relate to the spectroscopic line shape and signal level in the BB-SFG measurement. By combining experimental and model calculations, we show that the best spectral resolution and highest signal level are simultaneously achieved when the nonresonant narrow-band upconversion pulse arrives with a nonzero time delay after the resonant BB pulse. The nonzero time delay partially avoids the linear trade-off of improving spectral resolution at the expense of decreasing signal intensity, which is common in BB-SFG schemes utilizing spectral filtering to produce narrow-band visible pulses.
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Affiliation(s)
- Igor V Stiopkin
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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Tang H, Sun S, Wu J, Wu P, Wan X. Conformational changes in novel thermotropic liquid crystalline polymer without conventional mesogens: A Raman spectroscopic investigation. POLYMER 2010. [DOI: 10.1016/j.polymer.2010.09.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Yoon YS, Kang H, Kim BG, Lee JC. Liquid Crystal Alignment Properties of Poly-(3-thiopheneacetate)/Dialkyldimethylammonium Complexes. MACROMOL CHEM PHYS 2009. [DOI: 10.1002/macp.200900368] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Lu X, Li D, Kristalyn CB, Han J, Shephard N, Rhodes S, Xue G, Chen Z. Directly Probing Molecular Ordering at the Buried Polymer/Metal Interface. Macromolecules 2009. [DOI: 10.1021/ma901757w] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaolin Lu
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China 210093
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109
| | - Dawei Li
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China 210093
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109
| | - Cornelius B. Kristalyn
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109
| | - Jianglong Han
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China 210093
| | - Nick Shephard
- Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan 48686
| | - Susan Rhodes
- Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan 48686
| | - Gi Xue
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China 210093
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109
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Ahn D, Jeong YC, Lee S, Lee J, Heo Y, Park JK. Control of liquid crystal pretilt angles by using organic/inorganic hybrid interpenetrating networks. OPTICS EXPRESS 2009; 17:16603-16612. [PMID: 19770875 DOI: 10.1364/oe.17.016603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A new photoalignment method of controlling the pretilt angle of liquid crystals (LCs) by using organic/inorganic hybrid interpenetrating polymer networks (IPNs) is proposed and demonstrated. In the hybrid IPN alignment layer system, the competition between poly(vinyl cinnamate) (PVCi) favoring planar alignment and poly(dimethyl siloxane) (PDMS) favoring vertical alignment made it possible to achieve pretilt angle in a wide range from 0 degrees to 90 degrees, and adjust pretilt angle as a function of PDMS content. In addition, we achieved the high azimuthal anchoring energy at the intermediate pretilt angle by using PDMS as the vertical-aligning component.
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Affiliation(s)
- Dowon Ahn
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
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15
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Lu X, Han J, Shephard N, Rhodes S, Martin AD, Li D, Xue G, Chen Z. Phenolic Resin Surface Restructuring upon Exposure to Humid Air: A Sum Frequency Generation Vibrational Spectroscopic Study. J Phys Chem B 2009; 113:12944-51. [DOI: 10.1021/jp9058092] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Xiaolin Lu
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Jianglong Han
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Nick Shephard
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Susan Rhodes
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Alex D. Martin
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Dawei Li
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Gi Xue
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Zhan Chen
- Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, and Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
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Seo JH, Hwang SW, Song DH, Shin JH, Yoon TH, Kim JC, Yi MH. Liquid crystal alignment on ion-beam-treated polyimide with a long alkyl side chain: near edge X-ray absorption fine structure spectroscopy analysis. J Phys Chem B 2009; 113:2001-5. [PMID: 19161281 DOI: 10.1021/jp809090h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Liquid crystal alignment on ion-beam-treated polyimides with a long alkyl side chain was investigated using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The long alkyl side chains and the asymmetric distribution and orientational order of the pi-bonds of the polyimide surface can be determined by analyzing the angular dependent resonance intensities of the NEXAFS measurements. Herein, we demonstrate that the pretilt angle of the LC cell made by our method decreases as more long alkyl side chains are destroyed. Additionally, the tilt direction of the LC molecules can be determined from the asymmetric distribution of pi-bonds of the polyimide created by the ion beam irradiation.
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Affiliation(s)
- Joo-Hong Seo
- School of Electrical Engineering, Pusan National University, Busan, 609-735, Korea
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Jeng SC, Hwang SJ, Yang CY. Tunable pretilt angles based on nanoparticles-doped planar liquid-crystal cells. OPTICS LETTERS 2009; 34:455-457. [PMID: 19373339 DOI: 10.1364/ol.34.000455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The nanoparticles-induced vertical alignment technique was applied to generate variable liquid-crystal pretilt angles based on doping different concentrations of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in the planar-aligned liquid crystal cells. Competition between the homogeneously aligned polyimide layer and POSS-induced spontaneous vertical alignment domain generated the variable pretilt angle. Experimental results demonstrated that the pretilt angle theta(p) is a function of the doped POSS concentration and can be controlled continuously over the range of 0 degrees <theta(p)<90 degrees .
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Affiliation(s)
- Shie-Chang Jeng
- Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan
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Lu X, Shephard N, Han J, Xue G, Chen Z. Probing Molecular Structures of Polymer/Metal Interfaces by Sum Frequency Generation Vibrational Spectroscopy. Macromolecules 2008. [DOI: 10.1021/ma801680f] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Xiaolin Lu
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109, Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, and ATVB Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Nick Shephard
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109, Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, and ATVB Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Jianglong Han
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109, Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, and ATVB Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Gi Xue
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109, Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, and ATVB Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109, Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China, 210093, and ATVB Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan, 48686
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Wu WY, Wang CC, Fuh AY. Controlling pre-tilt angles of liquid crystal using mixed polyimide alignment layer. OPTICS EXPRESS 2008; 16:17131-17137. [PMID: 18852824 DOI: 10.1364/oe.16.017131] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Three approaches to controlling liquid crystal (LC) pre-tilt angle in a cell are demonstrated using a polyimide (PI) alignment layer on substrates, in the form of a mixture of horizontal (H) and vertical (V) polyimides. The concentration ratio of H- to V-PI, baking temperature, and rubbing strength influence the pre-tilt angle, and highlight parameters for controlling the pre-tilt angle of an LC cell. Finally, a variable polarization converter is demonstrated using this approach.
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Affiliation(s)
- Wei-Yen Wu
- Department of Physics, National Cheng Kung University, Tainan, Taiwan 701, Republic of China
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Palyvoda O, Bordenyuk AN, Yatawara AK, McCullen E, Chen CC, Benderskii AV, Auner GW. Molecular organization in SAMs used for neuronal cell growth. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:4097-106. [PMID: 18338909 DOI: 10.1021/la7032675] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The attachment of cells onto solid supports is fundamental in the development of advanced biosensors or biochips. In this work, we characterize cortical neuron adhesion, growth, and distribution of an adhesive layer, depending on the molecular structure and composition . Neuronal networks are successfully grown on amino-terminated alkanethiol self-assembled monolayer (SAM) on a gold substrate without adhesion protein interfaces. Neuron adhesion efficiency was studied for amino-terminated, carboxy-terminated, and 1:1 mixed alkanethiol SAMs deposited on gold substrates. Atomic force microscopy and X-ray photoelectron spectroscopy were used to measure the roughness of gold substrate and thickness of SAM monolayers. Conformational ordering and ionic content of SAMs were characterized by vibrational sum frequency generation (VSFG) spectroscopy. Only pure amino-terminated SAMs provide efficient neuronal cell attachment. Ordering of the terminal amino groups does not affect efficiency of neuron adhesion. VSFG analysis shows that ordering of the terminal groups improves with decreasing surface roughness; however the number of gauche defects in alkane chains is independent of surface roughness. We monitor partial dissociation of carboxy groups in mixed SAMs that implies formation of NH3+ neighbors and appearance of catanionic structure. Such catanionic environment proved inefficient for neuron adhesion. Surface roughness of metal within the 0.7-2 nm range has little effect on the efficiency of neuron adhesion. This approach can be used to create new methods that help map structure-property relationships of biohybrid systems.
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Affiliation(s)
- Olena Palyvoda
- Smart Sensors and Integrated Microsystems (SSIM), Electrical and Computer Engineering Department, Wayne State University, Detroit, MI 48202, USA.
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Stiopkin IV, Jayathilake HD, Bordenyuk AN, Benderskii AV. Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy. J Am Chem Soc 2008; 130:2271-5. [DOI: 10.1021/ja076708w] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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