Monotropic and enantiotropic
Polymorphic systems can be monotropic or enantiotropic, and in the case of the former, the thermodynamically-stable form is temperature invariant up to its melting, sublimation or degradation point.Thermal properties of mesophase of these liquid crystal compounds were studied to reveal that they all exhibited an enantiotropic nematic phase except for the compound bearing an OH group, i.e ...
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6 Eyl 2010 ... ... (monotropic, enantiotropic nematic/smectic), which were examined by polarized-light optical microscopy and differential scanning calorimetry.Enantiotropic polymorphism; Monotropic polymorph. In Monotropic polymorphism, a single polymorph is stable at all temperatures below the melting point, and other polymorphs are unstable. The metastable or unstable polymorphs changes to stable form at all temperature by the transition. The reversible transition is not possible in monotropic ...Mar 7, 1994 · After a basic introduction to polymorphism the most useful methods of detection of polymorphism are cited. A selection of typical DSC curves illustrates monotropic and enantiotropic solid—solid transition, allotropy, metastable—stable transition through the liquid state, pseudopolymorphic transition and mesophase transition. In addition ...
In 2012, Ha et al., synthesized azomethine liquid crystals with different terminal chain lengths. The results showed that n-octanoyloxy exhibits enantiotropic smectic A and smectic B phases in n-dodecanoyloxy derivatives, while n-tetradecanoyloxy showed enantiotropic smectic A and monotropic B phases in n-octadecanoyloxy derivatives.III behaves monotropic with regard to both enantiotropic modifications I and II. Mod. I exists in form of small lamellae, mostly of irregular forms. Mod. II consists of rhombohedron grains ...Monotropic and b enantiotropic polymorphs, where T 0 denotes the transition temperature in enantiotropic polymorphs (e.g., sulfur), where below the melting point one polymorph can reversibly ...The thermotropic LC, which can be changed to the LC state either by lowering the temperature of the liquid or by increasing the temperature of the solid and it is called the enantiotropic LC while the liquid crystal which reaches the LC phase only after a unidirectional change in temperature is called monotropic.Other articles where monotropy is discussed: allotropy: Allotropes may be monotropic, in which case one of the forms is the most stable under all conditions, or enantiotropic, in which case different forms are stable under different conditions and undergo reversible transitions from one to another at characteristic temperatures and pressures.
It was found that most of the compounds with alkyl end group exhibited enantiotropic smectic A and nematic phase; while that with alkoxyl behaved differently, some exhibited enantiotropic smectic A and nematic phase; others exhibited monotropic smectic A and enantiotropic nematic phase or unique enantiotropic nematic phase. And for both series ...Monotropic and b enantiotropic polymorphs, where T 0 denotes the transition temperature in enantiotropic polymorphs (e.g., sulfur), where below the melting point one polymorph can reversibly ...Schematic representation of the two types of polymorphs. a Monotropic and b enantiotropic polymorphs, where T 0 denotes the transition temperature in … ….
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Enantiotropic System C, Monotropic System Temperature Temperature tiotropic system on the left, at constant pressure, there are three solubility versus temperature curves: Form II is the lowest, Form I is the next higher, and the melting curve ... Fig. 3: Variation of energy with temperature for enantiotropic and monotropic systems. Curves HA, HB and HL are for enthalpy, whereas ∆Hf,A and ∆Hf,B represent enthalpy of fusion and ∆Ht
In the case of the heat of transition rule, polymorphs I and II are monotropic if the transition from form II to I is exothermic; or enantiotropic if the ...CH8C formed a monotropic cholesteric phase whereas PCOE and PCOSE exihibited enantiotropic cholesteric phases. Like in the case of CH8C, the optical pitch (λm) of PCOSE decreased with increasing ...
alex galindo Enantiotropic refers to a substance that can exist in two or more different crystal structures, depending on the temperature and pressure. Monotropic, on the ... forklift operator hourly paypst to est right now monotropic or enantiotropic. Monotropy: W hen a m etastable polymorph . is there, a polymorphic transition t o the . stable polymorph during processing can . proceed via all four mec hanism enlisted .Current Drug Discovery Technologies 1875-6220/17 $58.00+.00 © 2017 Bentham Science Publishers Daniel P. Otto1 and Melgardt M. De Villiers2,* 1Research Focus Area for ... hotels near gans creek columbia mo A series of random copolyesters containing two different aromatic ester triads and a decamethylene flexible spacer was prepared and characterized for the effect of comonomer composition on glass, crystalline and liquid crystalline state properties. The homopolymer of one of the triads was enantiotropic, but the other was not. However, a copolymer containing 90 … 24 basketballadnrew wigginshawk talk lance leipold polymorphs belong to enantiotropic or monotropic systems. These rules include the heat of transition rule, the heat of fusion rule, the entropy of fusion rule, the heat capacity marcs application Both monotropic and enantiotropic nematic phases were achieved for two homologues from the nonsubstituted (-H) series H-Dn, indicating that the lateral substitution plays an important role in ... aero physicspre writing activities examplesemployer certification pslf a monotropic system, the free energy curve of each. ... A comparison between monotropic system (a) and enantiotropic system (b). S.L. Wei et al.: Metastability in high-entropy alloys: A review.Superscript or subscript I, II, I–II, and L mean form I, form II, forms I–II transition, and liquid state, respectively. Form I is the stable form in the case of the monotropic transition, and the stable form at lower temperature in the case of enantiotropic transition. ΔH t and ΔH m are the enthalpies of polymorphic transition and …