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Ju J, Chatterjee D, Voyles PM, Bock H, Ediger MD. Vapor-to-glass preparation of biaxially aligned organic semiconductors. J Chem Phys 2023; 159:211101. [PMID: 38038197 DOI: 10.1063/5.0174819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023] Open
Abstract
Physical vapor deposition (PVD) provides a route to prepare highly stable and anisotropic organic glasses that are utilized in multi-layer structures such as organic light-emitting devices. While previous work has demonstrated that anisotropic glasses with uniaxial symmetry can be prepared by PVD, here, we prepare biaxially aligned glasses in which molecular orientation has a preferred in-plane direction. With the collective effect of the surface equilibration mechanism and template growth on an aligned substrate, macroscopic biaxial alignment is achieved in depositions as much as 180 K below the clearing point TLC-iso (and 50 K below the glass transition temperature Tg) with single-component disk-like (phenanthroperylene ester) and rod-like (itraconazole) mesogens. The preparation of biaxially aligned organic semiconductors adds a new dimension of structural control for vapor-deposited glasses and may enable polarized emission and in-plane control of charge mobility.
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Affiliation(s)
- Jianzhu Ju
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Debaditya Chatterjee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Paul M Voyles
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux, 33600 Pessac, France
| | - Mark D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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2
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Knapik-Kowalczuk J, Kramarczyk D, Jachowicz R, Paluch M. Effect of Shear Strain on the Supercooled Itraconazole. J Pharm Sci 2023; 112:1644-1652. [PMID: 36709801 DOI: 10.1016/j.xphs.2023.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023]
Abstract
This article investigated the effect of shear strain on the nematic itraconazole (ITR) from both elastic and plastic deformation regions. The rheo-dielectric technique was used for this purpose. It has been demonstrated that shear strain can change the sample color, liquid crystal alignment as well as its dielectric and thermal properties. The observed modifications depend on the shear strain value. One can distinguish four regions regarding the slope of ITR stress-strain dependence and caused changes. Proper alignment changes (obtained after the shearing procedure) can additionally affect the further recrystallization of ITR to other than the initial, i.e., second polymorphic form.
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Affiliation(s)
- Justyna Knapik-Kowalczuk
- Faculty of Science and Technology, Institute of Physics, University of Silesia in Katowice, SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland.
| | - Daniel Kramarczyk
- Faculty of Science and Technology, Institute of Physics, University of Silesia in Katowice, SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
| | - Renata Jachowicz
- Faculty of Pharmacy, Department of Pharmaceutical Technology and Biopharmaceutics, Jagiellonian University, Medyczna 9, 30-688 Kraków, Poland
| | - Marian Paluch
- Faculty of Science and Technology, Institute of Physics, University of Silesia in Katowice, SMCEBI, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland
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3
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Wolf SE, Fulco S, Zhang A, Zhao H, Walsh PJ, Turner KT, Fakhraai Z. Role of Molecular Layering in the Enhanced Mechanical Properties of Stable Glasses. J Phys Chem Lett 2022; 13:3360-3368. [PMID: 35403428 DOI: 10.1021/acs.jpclett.2c00232] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The density, degree of molecular orientation, and molecular layering of vapor-deposited stable glasses (SGs) vary with substrate temperature (Tdep) below the glass-transition temperature (Tg). Density and orientation have been suggested to be factors influencing the mechanical properties of SGs. We perform nanoindentation on two molecules which differ by only a single substituent, allowing one molecule to adopt an in-plane orientation at low Tdep. The reduced elastic modulus and hardness of both molecules show similar Tdep dependences, with enhancements of 15-20% in reduced modulus and 30-45% in hardness at Tdep ≈ 0.8Tg, where the density of vapor-deposited films is enhanced by ∼1.4% compared to that of the liquid-quenched glass. At Tdep < 0.8Tg, one of the molecules produces highly unstable glasses with in-plane orientation. However, both systems show enhanced mechanics. Both the modulus and hardness correlate with the degree of layering, which is similar in both systems despite their variable stability. We suggest that nanoindentation performed normal to the film's surface is influenced by the tighter packing of the molecules in this direction.
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4
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Surface equilibration mechanism controls the molecular packing of glassy molecular semiconductors at organic interfaces. Proc Natl Acad Sci U S A 2021; 118:2111988118. [PMID: 34645709 DOI: 10.1073/pnas.2111988118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2021] [Indexed: 12/31/2022] Open
Abstract
Glasses prepared by physical vapor deposition (PVD) are anisotropic, and the average molecular orientation can be varied significantly by controlling the deposition conditions. While previous work has characterized the average structure of thick PVD glasses, most experiments are not sensitive to the structure near an underlying substrate or interface. Given the profound influence of the substrate on the growth of crystalline or liquid crystalline materials, an underlying substrate might be expected to substantially alter the structure of a PVD glass, and this near-interface structure is important for the function of organic electronic devices prepared by PVD, such as organic light-emitting diodes. To study molecular packing near buried organic-organic interfaces, we prepare superlattice structures (stacks of 5- or 10-nm layers) of organic semiconductors, Alq3 (Tris-(8-hydroxyquinoline)aluminum) and DSA-Ph (1,4-di-[4-(N,N-diphenyl)amino]styrylbenzene), using PVD. Superlattice structures significantly increase the fraction of the films near buried interfaces, thereby allowing for quantitative characterization of interfacial packing. Remarkably, both X-ray scattering and spectroscopic ellipsometry indicate that the substrate exerts a negligible influence on PVD glass structure. Thus, the surface equilibration mechanism previously advanced for thick films can successfully describe PVD glass structure even within the first monolayer of deposition on an organic substrate.
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5
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Bishop C, Chen Z, Toney MF, Bock H, Yu L, Ediger MD. Using Deposition Rate and Substrate Temperature to Manipulate Liquid Crystal-Like Order in a Vapor-Deposited Hexagonal Columnar Glass. J Phys Chem B 2021; 125:2761-2770. [PMID: 33683124 DOI: 10.1021/acs.jpcb.0c11564] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate vapor-deposited glasses of a phenanthroperylene ester, known to form an equilibrium hexagonal columnar phase, and show that liquid crystal-like order can be manipulated by the choice of deposition rate and substrate temperature during deposition. We find that rate-temperature superposition (RTS)-the equivalence of lowering the deposition rate and increasing the substrate temperature-can be used to predict and control the molecular orientation in vapor-deposited glasses over a wide range of substrate temperatures (0.75-1.0 Tg). This work extends RTS to a new structural motif, hexagonal columnar liquid crystal order, which is being explored for organic electronic applications. By several metrics, including the apparent average face-to-face nearest-neighbor distance, physical vapor deposition (PVD) glasses of the phenanthroperylene ester are as ordered as the glass prepared by cooling the equilibrium liquid crystal. By other measures, the PVD glasses are less ordered than the cooled liquid crystal. We explain the difference in the maximum attainable order with the existence of a gradient in molecular mobility at the free surface of a liquid crystal and its impact upon different mechanisms of structural rearrangement. This free surface equilibration mechanism explains the success of the RTS principle and provides guidance regarding the types of order most readily enhanced by vapor deposition. This work extends the applicability of RTS to include molecular systems with a diverse range of higher-order liquid-crystalline morphologies that could be useful for new organic electronic applications.
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Affiliation(s)
- Camille Bishop
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
| | - Zhenxuan Chen
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Ave, Madison, Wisconsin 53705, United States
| | - Michael F Toney
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux, 115, av. Schweitzer, 33600 Pessac, France
| | - Lian Yu
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, Wisconsin 53706, United States.,School of Pharmacy, University of Wisconsin-Madison, 777 Highland Ave, Madison, Wisconsin 53705, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
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6
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Sukegawa Y, Sato K, Fujiwara W, Katagiri H, Yokoyama D. Effect of the conformer distribution on the properties of amorphous organic semiconductor films for organic light-emitting diodes. Phys Chem Chem Phys 2021; 23:14242-14251. [PMID: 34159982 DOI: 10.1039/d1cp00892g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
With the remarkable improvement in the electrical and optical properties of organic light-emitting diodes (OLEDs) in recent years, the details of the higher-order structure of vacuum-deposited amorphous organic films and its formation mechanism need to be understood. In particular, to clarify the effect of the higher-order structure on the film properties, it is necessary to analyze the molecular aggregation states in the vacuum-deposited amorphous films. Toward their deep understanding, the higher-order structure and film properties have often been discussed with relation to the surface diffusion and structural relaxation of the molecules immediately after deposition on the film surface. However, the effect of the variety of conformers, which is specific to amorphous organic materials, on the thermal and electrical properties of the films has not been deeply discussed. In this study, we focused on three structural isomers of OLED materials and discuss the effect of the conformer distribution on the molecular aggregation states and thermal and electrical properties of the vacuum-deposited films. From their comparison, we found that the properties of the film composed of a relatively small number of stable conformers are superior to those of the other two films composed of relatively large numbers of stable conformers. This superiority originates from formation of aggregates of the same conformer, which become the starting points for crystallization when the film is heated. Our detailed comparison and discussion focusing on the variety of conformers will lead to a deeper understanding of the molecular aggregation states and physical properties of amorphous organic films.
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Affiliation(s)
- Yoshihito Sukegawa
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
| | - Kaito Sato
- Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Wataru Fujiwara
- Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Hiroshi Katagiri
- Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Daisuke Yokoyama
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan. and Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan and Research Center for Organic Electronics (ROEL), Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
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7
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Heczko D, Kamińska E, Jurkiewicz K, Tarnacka M, Merkel K, Kamiński K, Paluch M. The impact of various azole antifungals on the liquid crystalline ordering in itraconazole. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112959] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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8
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Bishop C, Li Y, Toney MF, Yu L, Ediger MD. Molecular Orientation for Vapor-Deposited Organic Glasses Follows Rate-Temperature Superposition: The Case of Posaconazole. J Phys Chem B 2020; 124:2505-2513. [DOI: 10.1021/acs.jpcb.0c00625] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Camille Bishop
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Yuhui Li
- School of Pharmacy, University of Wisconsin−Madison, 777 Highland Avenue, Madison, Wisconsin 53705, United States
| | - Michael F. Toney
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Lian Yu
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- School of Pharmacy, University of Wisconsin−Madison, 777 Highland Avenue, Madison, Wisconsin 53705, United States
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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10
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Boehm BJ, Nguyen HTL, Huang DM. The interplay of interfaces, supramolecular assembly, and electronics in organic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:423001. [PMID: 31212263 DOI: 10.1088/1361-648x/ab2ac2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Organic semiconductors, which include a diverse range of carbon-based small molecules and polymers with interesting optoelectronic properties, offer many advantages over conventional inorganic semiconductors such as silicon and are growing in importance in electronic applications. Although these materials are now the basis of a lucrative industry in electronic displays, many promising applications such as photovoltaics remain largely untapped. One major impediment to more rapid development and widespread adoption of organic semiconductor technologies is that device performance is not easily predicted from the chemical structure of the constituent molecules. Fundamentally, this is because organic semiconductor molecules, unlike inorganic materials, interact by weak non-covalent forces, resulting in significant structural disorder that can strongly impact electronic properties. Nevertheless, directional forces between generally anisotropic organic-semiconductor molecules, combined with translational symmetry breaking at interfaces, can be exploited to control supramolecular order and consequent electronic properties in these materials. This review surveys recent advances in understanding of supramolecular assembly at organic-semiconductor interfaces and its impact on device properties in a number of applications, including transistors, light-emitting diodes, and photovoltaics. Recent progress and challenges in computer simulations of supramolecular assembly and orientational anisotropy at these interfaces is also addressed.
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Affiliation(s)
- Belinda J Boehm
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, SA 5005, Australia
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11
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Vapor deposition of a nonmesogen prepares highly structured organic glasses. Proc Natl Acad Sci U S A 2019; 116:21421-21426. [PMID: 31527259 DOI: 10.1073/pnas.1908445116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We show that glasses with aligned smectic liquid crystal-like order can be produced by physical vapor deposition of a molecule without any equilibrium liquid crystal phases. Smectic-like order in vapor-deposited films was characterized by wide-angle X-ray scattering. A surface equilibration mechanism predicts the highly smectic-like vapor-deposited structure to be a result of significant vertical anchoring at the surface of the equilibrium liquid, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy orientation analysis confirms this prediction. Understanding of the mechanism enables informed engineering of different levels of smectic order in vapor-deposited glasses to suit various applications. The preparation of a glass with orientational and translational order from a nonliquid crystal opens up an exciting paradigm for accessing extreme anisotropy in glassy solids.
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12
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Bishop C, Gujral A, Toney MF, Yu L, Ediger MD. Vapor-Deposited Glass Structure Determined by Deposition Rate-Substrate Temperature Superposition Principle. J Phys Chem Lett 2019; 10:3536-3542. [PMID: 31177780 DOI: 10.1021/acs.jpclett.9b01377] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We show that deposition rate substantially affects the anisotropic structure of thin glassy films produced by physical vapor deposition. Itraconazole, a glass-forming liquid crystal, was deposited at rates spanning 3 orders of magnitude over a 25 K range of substrate temperatures, and structure was characterized by ellipsometry and X-ray scattering. Both the molecular orientation and the spacing of the smectic layers obey deposition rate-substrate temperature superposition, such that lowering the deposition rate is equivalent to raising the substrate temperature. We identify two different surface relaxations that are responsible for structural order in the vapor-deposited glasses and find that the process controlling molecular orientation is accelerated by more than 3 orders of magnitude at the surface relative to the bulk. The identification of distinct surface processes responsible for anisotropic structural features in vapor-deposited glasses will enable more precise control over the structure of glassy materials used in organic electronics.
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Affiliation(s)
- Camille Bishop
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Ankit Gujral
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Michael F Toney
- Stanford Synchrotron Radiation Lightsource , SLAC National Accelerator Laboratory, Menlo Park , California 94025 , United States
| | - Lian Yu
- School of Pharmacy , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Mark D Ediger
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
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13
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Abstract
The term "organic solids" encompasses both crystals and glasses. Organic crystals are commonly grown for purification and structure determination and are being extensively explored for applications in organic electronics including field effect transistors. The ability to control the packing of one molecule relative to its neighbors is of critical importance for most uses of organic crystals. Often, anisotropic packing is also highly desirable as it enhances charge transport and optimizes light absorption/emission. When compared to crystals, the local packing in organic glasses is highly disordered and often isotropic. Glasses, however, offer two key advantages with respect to crystals. First, glasses typically lack grain boundaries and thus exhibit better macroscopic homogeneity. Second, glass composition can often be varied over a wide range while maintaining homogeneity. Besides electronic materials, many modern plastics used in a wide range of technologies are organic glasses, and the glassy state is being increasingly utilized to deliver pharmaceuticals because of higher bioavailability. In this article, we introduce vapor-deposited organic glasses as hybrid materials that combine some of the useful features of crystals and traditional liquid-cooled glasses. Physical vapor deposition produces glasses by directly condensing molecules from the gas phase onto a temperature-controlled substrate and allows film thickness to be controlled with nanometer precision. Just as liquid-cooled glasses, vapor-deposited glasses have smooth surfaces and lack grain boundaries. These attributes are critical for applications such as organic light emitting diodes (OLEDs), in which vapor-deposited glasses of organic semiconductors form the active layers. In common with crystals, vapor-deposited glasses can exhibit anisotropic packing, and the extent of anisotropy can be comparable to that of the typical organic crystal. For vapor-deposited glasses, in contrast to crystals, anisotropic packing can generally be controlled as a continuous variable. Deposition conditions can be chosen to produce glasses with significant molecular orientation (molecules "standing up" or "lying down" relative to the substrate), and π-stacking can be directed along different directions relative to the substrate. Over the last five years, we have gained a fundamental understanding of the mechanism that controls the anisotropy of vapor-deposited glasses and learned how to control many aspects of anisotropic packing. Two key elements that enable such control are the high mobility present at the surface of an organic glass and the tendency of the surface to promote anisotropic packing of molecules. In contrast to traditional epitaxial growth, for vapor-deposited glasses, the free surface (not the substrate) acts as a template that controls the structure of a growing film. The structure of any given layer is decoupled from those beneath it, thereby providing considerable freedom in producing layered glassy structures.
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Affiliation(s)
- M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Juan de Pablo
- Institute of Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, United States
| | - Lian Yu
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705, United States
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14
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Chen H, Zhang X, Cheng Y, Qian F. Preparation of smectic itraconazole nanoparticles with tunable periodic order using microfluidics-based anti-solvent precipitation. CrystEngComm 2019. [DOI: 10.1039/c8ce02149j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A microfluidics-based anti-solvent precipitation approach was developed to generate liquid crystalline nanoparticles of itraconazole in a controllable manner. The size, morphology and the structure of nanoparticles were investigated under different precipitation temperatures.
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Affiliation(s)
- Huijun Chen
- School of Pharmaceutical Sciences
- Beijing Advanced Innovation Center for Structural Biology
- the Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education)
- Tsinghua University
- Beijing 100084
| | - Xiong Zhang
- Department of Chemical Engineering
- Tsinghua University
- Beijing 100084
- P.R. China
| | - Yi Cheng
- Department of Chemical Engineering
- Tsinghua University
- Beijing 100084
- P.R. China
| | - Feng Qian
- School of Pharmaceutical Sciences
- Beijing Advanced Innovation Center for Structural Biology
- the Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education)
- Tsinghua University
- Beijing 100084
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15
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Bhardwaj V, Trasi NS, Zemlyanov DY, Taylor LS. Surface area normalized dissolution to study differences in itraconazole-copovidone solid dispersions prepared by spray-drying and hot melt extrusion. Int J Pharm 2018; 540:106-119. [DOI: 10.1016/j.ijpharm.2018.02.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/31/2018] [Accepted: 02/04/2018] [Indexed: 01/27/2023]
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16
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Teerakapibal R, Huang C, Gujral A, Ediger MD, Yu L. Organic Glasses with Tunable Liquid-Crystalline Order. PHYSICAL REVIEW LETTERS 2018; 120:055502. [PMID: 29481153 DOI: 10.1103/physrevlett.120.055502] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Indexed: 06/08/2023]
Abstract
Liquid crystals (LCs) are known to undergo rapid ordering transitions with virtually no hysteresis. We report a remarkable counterexample, itraconazole, where the nematic to smectic transition is avoided at a cooling rate exceeding 20 K/s. The smectic order trapped in a glass is the order reached by the equilibrium liquid before the kinetic arrest of the end-over-end molecular rotation. This is attributed to the fact that smectic ordering requires orientational ordering and suggests a general condition for preparing organic glasses with tunable LC order for electronic applications.
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Affiliation(s)
| | - Chengbin Huang
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
| | - Ankit Gujral
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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17
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Affiliation(s)
- M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison,
1101 University Avenue, Madison, Wisconsin 53706, USA
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18
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Liu T, Exarhos AL, Alguire EC, Gao F, Salami-Ranjbaran E, Cheng K, Jia T, Subotnik JE, Walsh PJ, Kikkawa JM, Fakhraai Z. Birefringent Stable Glass with Predominantly Isotropic Molecular Orientation. PHYSICAL REVIEW LETTERS 2017; 119:095502. [PMID: 28949582 DOI: 10.1103/physrevlett.119.095502] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 06/07/2023]
Abstract
Birefringence in stable glasses produced by physical vapor deposition often implies molecular alignment similar to liquid crystals. As such, it remains unclear whether these glasses share the same energy landscape as liquid-quenched glasses that have been aged for millions of years. Here, we produce stable glasses of 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene molecules that retain three-dimensional shapes and do not preferentially align in a specific direction. Using a combination of angle- and polarization-dependent photoluminescence and ellipsometry experiments, we show that these stable glasses possess a predominantly isotropic molecular orientation while being optically birefringent. The intrinsic birefringence strongly correlates with increased density, showing that molecular ordering is not required to produce stable glasses or optical birefringence, and provides important insights into the process of stable glass formation via surface-mediated equilibration. To our knowledge, such novel amorphous packing has never been reported in the past.
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Affiliation(s)
- Tianyi Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Annemarie L Exarhos
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Ethan C Alguire
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Feng Gao
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | - Kevin Cheng
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Tiezheng Jia
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Joseph E Subotnik
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Patrick J Walsh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - James M Kikkawa
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Zahra Fakhraai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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19
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Ngai KL, Wang LM, Yu HB. Relating Ultrastable Glass Formation to Enhanced Surface Diffusion via the Johari-Goldstein β-Relaxation in Molecular Glasses. J Phys Chem Lett 2017; 8:2739-2744. [PMID: 28585827 DOI: 10.1021/acs.jpclett.7b01192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Glasses are materials essential for modern technology; they are usually prepared by cooling liquids. Recently, novel ultrastable glasses (SGs) with extraordinary thermodynamic and kinetic stability have been created by vapor deposition at appropriate substrate temperatures. However, the underlying mechanism for the formation of SGs is still not established. For most of the molecular SGs created so far, we demonstrate that the formation of SGs is closely related to the Johari-Goldstein β-relaxation from the fact that the lowest substrate temperatures possible for the formation of SGs match the secondary glass-transition temperatures, where the β-relaxation time reaches 103 s. Theoretically the β-relaxation time via the primitive relaxation time of the coupling model has proven capable of accounting for the enhancement of molecular mobility at the surface. Thus our findings provide evidence to support that the immense enhancement of molecular diffusion at the surface is critical for the formation of SGs. The result has implications in the design and fabrication of SGs.
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Affiliation(s)
- K L Ngai
- CNR-IPCF, Universita di Pisa , Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University , Qinhuangdao, Hebei 066004, China
| | - Li-Min Wang
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University , Qinhuangdao, Hebei 066004, China
| | - Hai-Bin Yu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , WuHan, Hubei 430074, China
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20
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Antony L, Jackson NE, Lyubimov I, Vishwanath V, Ediger MD, de Pablo JJ. Influence of Vapor Deposition on Structural and Charge Transport Properties of Ethylbenzene Films. ACS CENTRAL SCIENCE 2017; 3:415-424. [PMID: 28573203 PMCID: PMC5445540 DOI: 10.1021/acscentsci.7b00041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Indexed: 06/07/2023]
Abstract
Organic glass films formed by physical vapor deposition exhibit enhanced stability relative to those formed by conventional liquid cooling and aging techniques. Recently, experimental and computational evidence has emerged indicating that the average molecular orientation can be tuned by controlling the substrate temperature at which these "stable glasses" are grown. In this work, we present a comprehensive all-atom simulation study of ethylbenzene, a canonical stable-glass former, using a computational film formation procedure that closely mimics the vapor deposition process. Atomistic studies of experimentally formed vapor-deposited glasses have not been performed before, and this study therefore begins by verifying that the model and method utilized here reproduces key structural features observed experimentally. Having established agreement between several simulated and experimental macroscopic observables, simulations are used to examine the substrate temperature dependence of molecular orientation. The results indicate that ethylbenzene glasses are anisotropic, depending upon substrate temperature, and that this dependence can be understood from the orientation present at the surface of the equilibrium liquid. By treating ethylbenzene as a simple model for molecular semiconducting materials, a quantum-chemical analysis is then used to show that the vapor-deposited glasses exhibit decreased energetic disorder and increased magnitude of the mean-squared transfer integral relative to isotropic, liquid-cooled films, an effect that is attributed to the anisotropic ordering of the molecular film. These results suggest a novel structure-function simulation strategy capable of tuning the electronic properties of organic semiconducting glasses prior to experimental deposition, which could have considerable potential for organic electronic materials design.
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Affiliation(s)
- Lucas
W. Antony
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United States
| | - Nicholas E. Jackson
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United States
- The
Institute for Molecular Engineering, Argonne
National Laboratory, Lemont, Illinois 06349, United States
| | - Ivan Lyubimov
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United States
| | - Venkatram Vishwanath
- Advanced
Leadership Computing Facility, Argonne National
Laboratory, Lemont, Illinois 06349, United States
| | - Mark D. Ediger
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Juan J. de Pablo
- Institute
for Molecular Engineering, University of
Chicago, Chicago, Illinois 60637, United States
- The
Institute for Molecular Engineering, Argonne
National Laboratory, Lemont, Illinois 06349, United States
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21
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Glor EC, Ferrier RC, Li C, Composto RJ, Fakhraai Z. Out-of-plane orientation alignment and reorientation dynamics of gold nanorods in polymer nanocomposite films. SOFT MATTER 2017; 13:2207-2215. [PMID: 28243639 DOI: 10.1039/c6sm02403c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, we develop a novel, in situ characterization method to measure the orientation order parameter and investigate the reorientation and reshaping dynamics of polymer grafted gold nanorods (AuNRs) in polymer nanocomposite (PNC) thin films. The long aspect-ratio of AuNRs results in two well-defined plasmon resonance modes, allowing the optical properties of the PNC to be tuned over a wide spectral range. The alignment of the AuNRs in a particular direction can also be used to further tune these optical properties. We utilize variable angle spectroscopic ellipsometry as a unique technique to measure the optical properties of PNC films containing AuNRs at various angles of incidence, and use effective index of refraction analysis of the PNC to relate the birefringence in the film due to changes of the plasmon coupling to the orientation order parameter of AuNRs. Polymer thin films (ca. 70 nm) of either polystyrene (PS) or poly(methyl methacrylate) (PMMA) containing PS grafted AuNRs are probed with ellipsometry, and the resulting extinction coefficient spectra compare favorably with more traditional analytical techniques, electron microscopy (EM) and optical absorbance (vis-NIR) spectroscopy. Furthermore, variable angle spectroscopic ellipsometry measures optical birefringence, which allows us to determine the in- and out-of plane order of the AuNRs, a property that is not easily accessible using other measurement techniques. Additionally, this technique is applied in situ to demonstrate that AuNRs undergo a rapid (ca. 1-5 hours) reorientation before undergoing a slower (ca. 24 hours) rod to sphere shape transition. The reorientation behavior is different depending on the polymer matrix used. In the athermal case (i.e. PS matrix), the AuNRs reorient isotropically, while in PMMA the AuNRs do not become isotropic, which we hypothesize is due to PMMA preferentially wetting the silica substrate, leaving less vertical space for the AuNRs to reorient.
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Affiliation(s)
- Ethan C Glor
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
| | - Robert C Ferrier
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Chen Li
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
| | - Russell J Composto
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA.
| | - Zahra Fakhraai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
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22
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Gómez J, Gujral A, Huang C, Bishop C, Yu L, Ediger MD. Nematic-like stable glasses without equilibrium liquid crystal phases. J Chem Phys 2017; 146:054503. [DOI: 10.1063/1.4974829] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jaritza Gómez
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ankit Gujral
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Chengbin Huang
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA
| | - Camille Bishop
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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