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Mishra VD, Pratap G, Roy A. Glassy relaxation in a de Vries smectic liquid crystal consisting of bent-core molecules. Phys Rev E 2024; 109:024703. [PMID: 38491713 DOI: 10.1103/physreve.109.024703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 02/02/2024] [Indexed: 03/18/2024]
Abstract
We report experimental investigations of a liquid crystal comprising thiophene-based achiral bent-core banana shaped molecules. The compound exhibits the following phase sequence on cooling: Isotropic (517.4 K), N (514.9 K), de Vries SmA (402 K), SmC. Practically no layer contraction was observed across the SmA to SmC transition, confirming the "de Vries" nature of the SmA phase. Interestingly, the crystallization does not occur on cooling the sample, unlike most other liquid crystals. Instead, the SmC phase undergoes a glass transition at 271 K even at a slow cooling rate. The dielectric spectroscopy studies carried out on the sample reveal the presence of a dielectric mode whose relaxation process is of the Cole-Cole type. The relaxation frequency of the mode was found to drop rapidly with decreasing temperature, confirming the glassy behavior. The variation of relaxation frequency with temperature follows the Vogel-Fulcher-Tammann equation, indicating the fragile glassy nature of the sample. This report identifies a bent-core liquid crystal exhibiting a "de Vries" SmA phase and glassy behavior at lower temperatures.
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Affiliation(s)
- Vishnu Deo Mishra
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560080, India
| | - G Pratap
- Polymer Science and Technology, CSIR-Central Leather Research Institute, Chennai 600020, India
| | - Arun Roy
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560080, India
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Hahn C, Göttker-Schnetmann I, Tzourtzouklis I, Wagner M, Müller AHE, Floudas G, Mecking S, Frey H. Nopadiene: A Pinene-Derived Cyclic Diene as a Styrene Substitute for Fully Biobased Thermoplastic Elastomers. J Am Chem Soc 2023. [PMID: 38048399 DOI: 10.1021/jacs.3c08130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
The bicyclic 1,2-substituted, 1,3-diene monomer nopadiene (1R,5S)-2-ethenyl-6,6-dimethylbicyclo[3.1.1]hept-2-ene was successfully polymerized by anionic and catalytic polymerization. Nopadiene is produced either through a facile one-step synthesis from myrtenal via Wittig-olefination or via a scalable two-step reaction from nopol (10-hydroxymethylene-2-pinene). Both terpenoids originate from the renewable β-pinene. The living anionic polymerization of nopadiene in apolar and polar solvents at 25 °C using organolithium initiators resulted in homopolymers with well-controlled molar masses in the range of 5.6-103.4 kg·mol-1 (SEC, PS calibration) and low dispersities (Đ) between 1.06 and 1.18. By means of catalytic polymerization with Me4CpSi(Me)2NtBuTiCl2 and (Flu)(Pyr)CH2Lu(CH2TMS)2(THF), the 1,4 and 3,4- microstructures of nopadiene are accessible in excellent selectivity. In pronounced contrast to other 1,3-dienes, the rigid polymers of the sterically demanding nopadiene showed an elevated glass temperature, Tg,∞ = 160 °C (in the limit of very high molar mass, Mn). ABA triblock copolymers with a central polymyrcene block and myrcene content of 60-75 mol %, with molar masses of 100-200 kg/mol were prepared by living anionic polymerization of the pinene-derivable monomers nopadiene and myrcene. This diene copolymerization resulted in thermoplastic elastomers displaying nanophase separation at different molar ratios (DSC, SAXS) and an upper service temperature about 30 K higher than that for traditional petroleum-derived styrenic thermoplastic elastomers due to the high glass temperature of polynopadiene. The materials showed good thermal stability at elevated temperatures under nitrogen (TGA), promising tensile strength and ultimate elongation of up to 1600%.
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Affiliation(s)
- Christoph Hahn
- Department of Chemistry, Johannes Gutenberg University, 55128 Mainz, Germany
- Max-Planck Graduate Center, 55128 Mainz, Germany
| | - Inigo Göttker-Schnetmann
- Chair Materials Science, Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | | | - Manfred Wagner
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Axel H E Müller
- Department of Chemistry, Johannes Gutenberg University, 55128 Mainz, Germany
| | - George Floudas
- Department of Physics, University of Ioannina, 45110 Ioannina, Greece
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
- Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece
| | - Stefan Mecking
- Chair Materials Science, Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | - Holger Frey
- Department of Chemistry, Johannes Gutenberg University, 55128 Mainz, Germany
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Skotnicki M, Czerniecka-Kubicka A, Neilsen G, Woodfield BF, Pyda M. Application of advanced thermal analysis for characterization of crystalline and amorphous phases of carvedilol. J Pharm Biomed Anal 2022; 217:114822. [PMID: 35550491 DOI: 10.1016/j.jpba.2022.114822] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 11/27/2022]
Abstract
The thermal behaviour of crystalline and amorphous carvedilol (CAR) phases was studied by advanced thermal analysis using Quantum Design Physical Property Measurement System and Differential Scanning Calorimetry. Theoretical functions describing crystalline carvedilol heat capacity at low temperatures and the Debye-Einstein function for high temperatures were obtained. Based on the experimental heat capacity values, solid and liquid baselines were established, and the state functions (H, S, G) for solid and liquid states were calculated. A comprehensive characterization of melting and glass transition processes was obtained. CAR is easily amorphizable by cooling the liquid. The residual entropy, which quantifies the extent of frozen-in disorder in the amorphous solid, for glassy CAR was estimated as 51 J·mol-1·K-1. The Kauzmann temperature (TK) was estimated based on enthalpy and entropy. Molecular motions in the amorphous phase were also studied. The activation energy for structural relaxation (Ea = 539 kJ·mol-1) and fragility parameter (m = 91) were obtained from the non-isothermal physical ageing. The isothermal physical ageing kinetics of amorphous CAR was studied by applying Kohlrausch-Williams-Watts (KWW) model. The mean molecular relaxation time constant (τKWW = 117 min) and relaxation constant (βKWW = 0.33) were obtained. CAR was classified as a fragile glass-former. Furthermore, τKWW constant for samples aged at 303.15 K is very low, thus, the physical ageing will occur during the short- and long-term storage of amorphous CAR, potentially changing its physicochemical properties during the ageing process. However, the results of molecular mobility studies (high molecular motions) show that the relationship between molecular motions in a glassy solid and its tendency to crystallization does not seem to follow an expected pattern, i.e., no crystallization occurred by thermal treatment of glassy, supercooled liquid and liquid phases of CAR as one would expect. Modern calorimetry and quantitative thermal analysis provided the fundamental kinetic and thermodynamic information about the crystalline and amorphous states of CAR.
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Affiliation(s)
- Marcin Skotnicki
- Chair and Department of Pharmaceutical Technology, Poznan University of Medical Sciences, 60-780 Poznan, Poland.
| | - Anna Czerniecka-Kubicka
- Department of Experimental and Clinical Pharmacology, Medical College of Rzeszow University, The University of Rzeszow, 35-310 Rzeszow, Poland; Interdyscyplinarny Center Preclinical and Clinical Research, The University of Rzeszow, 36-100 Werynia, Poland
| | - Grace Neilsen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Brian F Woodfield
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Marek Pyda
- Department of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland
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Drogoń A, Skotnicki M, Skotnicka A, Pyda M. Physical Ageing of Amorphous Indapamide Characterised by Differential Scanning Calorimetry. Pharmaceutics 2020; 12:pharmaceutics12090800. [PMID: 32854214 PMCID: PMC7558952 DOI: 10.3390/pharmaceutics12090800] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/14/2020] [Accepted: 08/22/2020] [Indexed: 11/16/2022] Open
Abstract
The objective of this study was to characterise amorphous indapamide (IND) subjected to the physical ageing process by differential scanning calorimetry (DSC). The amorphous indapamide was annealed at different temperatures below the glass transition, i.e., 35, 40, 45, 65, 75 and 85 °C for different lengths of time, from 30 min up to a maximum of 32 h. DSC was used to characterise both the crystalline and the freshly prepared glass and to monitor the extent of relaxation at temperatures below the glass transition (Tg). No ageing occurred at 35, 40 and 45 °C at the measured lengths of times. Molecular relaxation time constants (τKWW) for samples aged at 65, 75 and 85 °C were determined by the Kohlrausch-Williams-Watts (KWW) equation. The fragility parameter m (a measure of the stability below the glass transition) was determined from the Tg dependence from the cooling and heating rates, and IND was found to be relatively stable ("moderately fragile") in the amorphous state. Temperature-modulated DSC was used to separate reversing and nonreversing processes for unaged amorphous IND. The enthalpy relaxation peak was clearly observed as a part of the nonreversing signal. Heat capacities data for unaged and physically aged IND were fitted to Cp baselines of solid and liquid states of IND, were integrated and enthalpy was presented as a function of temperature.
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Affiliation(s)
- Agata Drogoń
- Department of Chemistry, Rzeszów University of Technology, 35-959 Rzeszów, Poland;
| | - Marcin Skotnicki
- Department of Pharmaceutical Technology, Poznań University of Medical Sciences, 60-780 Poznań, Poland;
- Correspondence: (M.S.); (M.P.)
| | - Agnieszka Skotnicka
- Department of Pharmaceutical Technology, Poznań University of Medical Sciences, 60-780 Poznań, Poland;
| | - Marek Pyda
- Department of Chemistry, Rzeszów University of Technology, 35-959 Rzeszów, Poland;
- Department of Biophysics, Poznań University of Medical Sciences, 60-780 Poznań, Poland
- Correspondence: (M.S.); (M.P.)
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Alzghoul A, Alhalaweh A, Mahlin D, Bergström CAS. Experimental and Computational Prediction of Glass Transition Temperature of Drugs. J Chem Inf Model 2014; 54:3396-403. [DOI: 10.1021/ci5004834] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ahmad Alzghoul
- Department
of Information Technology, Uppsala University, P.O. Box 337, SE- 751 05 Uppsala, Sweden
| | - Amjad Alhalaweh
- Department
of Pharmacy, Uppsala University, Uppsala Biomedical Centre, P.O. Box 580, SE-751 23 Uppsala, Sweden
| | - Denny Mahlin
- Department
of Pharmacy, Uppsala University, Uppsala Biomedical Centre, P.O. Box 580, SE-751 23 Uppsala, Sweden
| | - Christel A. S. Bergström
- Department
of Pharmacy, Uppsala University, Uppsala Biomedical Centre, P.O. Box 580, SE-751 23 Uppsala, Sweden
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Guo Q, Zheng B, Zhou S, Xu B, Qiu Y, Yu Y, Qiu J. Origin of structural relaxation dependent spectroscopic features of bismuth-activated glasses. OPTICS EXPRESS 2014; 22:15924-15931. [PMID: 24977847 DOI: 10.1364/oe.22.015924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
For the first time, we studied the effect of structural relaxation on the NIR spectroscopic properties of bismuth-activated germanium glasses below glass transition temperature. Interestingly, distinct change behavior of NIR luminescence is observed at two different heat-treatment temperature ranges corresponding to two different relaxation behavior of glass structure. Besides, when structural modified by partly substituting B(2)O(3) for GeO(2), a narrower and more thermal sensitive luminescence is observed, which is inexplicable by "inhomogeneous broadening" and we tentatively attribute it to a defect-involved reason. Fundamentally the results here not only provide us a deeper insight into the optical property of bismuth-activated materials but also increase our understanding of the glassy state, and practically it delivers some valuable guidance in designing bismuth-activated glasses with superior NIR optical properties.
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Ueno K, Angell CA. On the decoupling of relaxation modes in a molecular liquid caused by isothermal introduction of 2 nm structural inhomogeneities. J Phys Chem B 2011; 115:13994-9. [PMID: 21728285 DOI: 10.1021/jp111398r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To support a new interpretation of the origin of the dynamic heterogeneity observed pervasively in fragile liquids as they approach their glass transition temperatures T(g), we demonstrate that the introduction of ~2 nm structural inhomogeneities into a homogeneous glass former leads to a decoupling of diffusion from viscosity similar to that observed during the cooling of orthoterphenyl (OTP) below T(A,) where Arrhenius behavior is lost. Further, the decoupling effect grows stronger as temperature decreases (and viscosity increases). The liquid is cresol, and the ~2 nm inhomogeneities are cresol-soluble asymmetric derivatized tetrasiloxy-based (polyhedral oligomeric silsesquioxane (POSS)) molecules. The decoupling is the phenomenon predicted by Onsager in discussing the approach to a liquid-liquid phase separation with decreasing temperature. In the present case the observations support the notion of a polyamorphic transition in fragile liquids that is hidden below the glass transition. A similar decoupling can be expected as a globular protein is dissolved in dilute aqueous solutions or in protic ionic liquids.
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Affiliation(s)
- Kazuhide Ueno
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA
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Gi US, Min B, Lee JH, Kim JH. Preparation and characterization of paclitaxel from plant cell culture. KOREAN J CHEM ENG 2004. [DOI: 10.1007/bf02705526] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
The physical state of a dosage form, crystalline versus amorphous, is critical in determining its solid-state physical and chemical properties. This minireview describes the physics associated with the preparation and storage of amorphous solids including a review of the common theories of the glass transition and relaxation processes.
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Affiliation(s)
- Lori R Hilden
- Bristol-Myers Squibb Company, PO Box 191, New Brunswick, New Jersey 08903-0191, USA
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10
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Corsi A, Gujrati PD. Entropy crisis, ideal glass transition, and polymer melting: exact solution on a Husimi cactus. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:031502. [PMID: 14524772 DOI: 10.1103/physreve.68.031502] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2003] [Indexed: 05/24/2023]
Abstract
We investigate an extension of the lattice model of melting of semiflexible polymers originally proposed by Flory. Along with a bending penalty epsilon, present in the original model and involving three sites of the lattice, we introduce an interaction energy epsilon (p), corresponding to the presence of a pair of parallel bonds and an interaction energy epsilon (h), associated with a hairpin turn. Both these new terms represent four-site interactions. The model is solved exactly on a Husimi cactus, which approximates a square lattice. We study the phase diagram of the system as a function of the energies. For a proper choice of the interaction energies, the model exhibits a first-order melting transition between a liquid and a crystalline phase at a temperature T(M). The continuation of the liquid phase below T(M) gives rise to a supercooled liquid, which turns continuously into a new low-temperature phase, called metastable liquid, at T(MC)<T(M). This liquid-liquid transition seems to have some features that are characteristic of the critical transition predicted by the mode-coupling theory. The exact calculation provides a thermodynamic justification for the entropy crisis (entropy becoming negative), generally known as the Kauzmann paradox, caused by the rapid drop of the entropy near the Kauzmann temperature. It occurs not in the supercooled liquid, but in the metastable liquid phase since its Helmholtz free energy equals the absolute zero equilibrium free energy at a positive temperature. A continuous ideal glass transition occurs to avoid the crisis when the metastable liquid entropy, and not the excess entropy, goes to zero. The melting transition in the original Flory model, corresponding to the vanishing of the four-site interactions, appears as a tricritical point of the model.
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Affiliation(s)
- Andrea Corsi
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325, USA
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Meste ML, Champion D, Roudaut G, Blond G, Simatos D. Glass Transition and Food Technology: A Critical Appraisal. J Food Sci 2002. [DOI: 10.1111/j.1365-2621.2002.tb08758.x] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Cruz IB, Oliveira JC, MacInnes WM. Dynamic mechanical thermal analysis of aqueous sugar solutions containing fructose, glucose, sucrose, maltose and lactose. Int J Food Sci Technol 2001. [DOI: 10.1046/j.1365-2621.2001.00484.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Andersson SP, Andersson O. Relaxation Studies of Poly(propylene glycol) under High Pressure. Macromolecules 1998. [DOI: 10.1021/ma971282z] [Citation(s) in RCA: 203] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. Peter Andersson
- Department of Experimental Physics, Umeå University, S-901 87 Umeå, Sweden
| | - Ove Andersson
- Department of Experimental Physics, Umeå University, S-901 87 Umeå, Sweden
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Abstract
The purpose of this work was to characterize the solid-state properties of anhydrous paclitaxel and paclitaxel dihydrate. Paclitaxel I (anhydrous) was suspended in water for 24 h to convert it to paclitaxel.2H2O. Both forms were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). X-ray powder diffraction (XRPD) patterns were obtained at 25, 100, and 195 degrees C. Dissolution profiles of both forms were obtained in water at 37 degrees C over h. DSC of paclitaxel.2H2O showed two endothermic peaks below 100 degrees C, corresponding to dehydration. The resulting solid phase was termed "dehydrated paclitaxel.2H2O". At 168 degrees C, a solid-solid transition was observed in which dehydrated paclitaxel.2H2O was converted to a semicrystalline material called "paclitaxel I/am". The solid-solid transition was followed by melting at 220 degrees C. TGA of paclitaxel.2H2O showed a corresponding biphasic weight loss below 100 degrees C, which was equivalent to the weight of 2 mol of water. DSC of paclitaxel I showed no transitions before melting at 220 degrees C, and no weight loss was observed by TGA. Quenching of paclitaxel I from the melt produced amorphous paclitaxel with a glass transition at 152 degrees C. XRPD confirmed that paclitaxel I, paclitaxel.2H2O, and dehydrated paclitaxel.2H2O had different crystal structures. The X-ray patterns of paclitaxel I and paclitaxel I/am were similar, however the two forms of paclitaxel did not behave identically when analyzed by DSC. The bulk dissolution studies with paclitaxel I showed a rapid increase in concentration to 3 micrograms/mL in 4 h, which decreased to 1 microgram/mL after 12 h, corresponding to the solubility of paclitaxel.2H2O. The solubility of paclitaxel.2H2O was 1 microgram/mL. The data demonstrate the existence of a dihydrate form of paclitaxel that is the stable form in equilibrium with water at 37 degrees C but which dehydrates at temperatures > 45 degrees C.
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Affiliation(s)
- R T Liggins
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
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Influence of heating and cooling rates on the glass transition temperature and the fragility parameter of sorbitol and fructose as measured by DSC. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf01992837] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
Glasses can be formed by many routes. In some cases, distinct polyamorphic forms are found. The normal mode of glass formation is cooling of a viscous liquid. Liquid behavior during cooling is classified between "strong" and "fragile," and the three canonical characteristics of relaxing liquids are correlated through the fragility. Strong liquids become fragile liquids on compression. In some cases, such conversions occur during cooling by a weak first-order transition. This behavior can be related to the polymorphism in a glass state through a recent simple modification of the van der Waals model for tetrahedrally bonded liquids. The sudden loss of some liquid degrees of freedom through such first-order transitions is suggestive of the polyamorphic transition between native and denatured hydrated proteins, which can be interpreted as single-chain glass-forming polymers plasticized by water and cross-linked by hydrogen bonds. The onset of a sharp change in d<r(2)>dT(<r(2)> is the Debye-Waller factor and T is temperature) in proteins, which is controversially indentified with the glass transition in liquids, is shown to be general for glass formers and observable in computer simulations of strong and fragile ionic liquids, where it proves to be close to the experimental glass transition temperature. The latter may originate in strong anharmonicity in modes ("bosons"), which permits the system to access multiple minima of its configuration space. These modes, the Kauzmann temperature T(K), and the fragility of the liquid, may thus be connected.
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Yoshioka M, Hancock BC, Zografi G. Crystallization of indomethacin from the amorphous state below and above its glass transition temperature. J Pharm Sci 1994; 83:1700-5. [PMID: 7891297 DOI: 10.1002/jps.2600831211] [Citation(s) in RCA: 329] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The solid state crystallization of amorphous polymers, sugars, and inorganic glasses is often thought to be restricted to the region above the glass transition temperature, Tg, because insufficient molecular mobility (high viscosity) exists below Tg for nucleation and crystal growth. Here we report on the isothermal and nonisothermal crystallization of dry amorphous indomethacin in the temperature range of 20 degrees C above and below its Tg. These studies were carried out with two amorphous samples having different degrees of metastability relative to the crystalline state. It was shown that in both samples significant crystallization to the most stable polymorphic form occurred over several days when stored below Tg, and in some cases this process was preceded by the relaxation of one amorphous form to the other. At storage temperatures near to and above Tg the rates of crystallization increased as expected but a second less thermodynamically stable polymorph also appeared with the more stable crystal form. This behavior was explained by the possible relationship between the degree of metastability relative to the crystalline state of each amorphous form and the interfacial energy existing at the respective nucleation sites, in accord with the Ostwald step rule.
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Affiliation(s)
- M Yoshioka
- School of Pharmacy, University of Wisconsin Madison 53706
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Böhmer R, Ngai KL, Angell CA, Plazek DJ. Nonexponential relaxations in strong and fragile glass formers. J Chem Phys 1993. [DOI: 10.1063/1.466117] [Citation(s) in RCA: 1970] [Impact Index Per Article: 63.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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