Mechanical equilibrium, a prerequisite to unveil auxetic properties in molecular compounds

Porzio, François; Cuierrier, Étienne; Wespiser, Clément; Tesson, Stéphane; Underhill, Royale S.; Soldera, Armand

doi:10.1080/08927022.2016.1241397

Cited by 7 publications

(2 citation statements)

References 46 publications

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“…Eight simulated systems were initially set under mechanical equilibrium where hydrostatic pressure equals the stress imposed by the simulated conditions . In fact, the systems should be in thermodynamic equilibrium . It means that the system is simultaneously in mechanical, chemical, radiative, and thermal equilibria.…”

Section: Introductionmentioning

confidence: 99%

The extent of the glass transition from molecular simulation revealing an overcrank effect

et al. 2017

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A deep understanding of the transition between rubber and amorphous state characterized by a glass transition temperature, T , is still a source of discussions. In this work, we highlight the role of molecular simulation in revealing explicitly this temperature dependent behavior. By reporting the specific volume, the thermal expansion coefficient and the heat capacity versus the temperature, we actually show that the glass transition domain extends to a greater range of temperature, compared with experiments. This significant enlargement width is due to the fast cooling rate, and actually explains the difficulty to locate T . This result is the manifestation of an overcranking effect used by high-speed cameras to reveal slow-motion. Accordingly, atomistic simulation offers the significant opportunity to show that the transition from the rubber state to the glass phase should be detailed in terms of the degrees of freedom freeze. © 2017 Wiley Periodicals, Inc.

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Section: Introductionmentioning

confidence: 99%

The extent of the glass transition from molecular simulation revealing an overcrank effect

et al. 2017

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“…[ 28 ] The importance of insuring mechanical equilibrium in the development of computational procedures for predicting auxeticity in molecular systems has been noted. [ 29 ] An interesting experimental report [ 30 ] appeared recently in which a synthetic liquid crystalline elastomer (LCE) having a terpolymer (comprised of three different monomers) composition was found to exhibit auxetic behavior. This negative Poisson's ratio behavior was described as being intimately connected with the appearance of a negative liquid crystal (LC) order parameter.…”

Section: Introductionmentioning

confidence: 99%

Implications for Auxetic Response in Liquid Crystalline Polymers: X‐Ray Scattering and Space‐Filling Molecular Modeling

Verma

Griffin

2020

Physica Status Solidi (b)

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Five transverse rod (TR)-containing main-chain liquid crystalline polymers (LCPs) are examined in both the powder and fiber forms by wide angle X-ray diffraction. Data from the diffraction experiments are consistent with the site-connectivitydriven TR-reorientation mechanism for intrinsic auxetic character in these macromolecules. Shifts in peak maxima, intensity distributions in the interchain interaction region, and calculated volume increase accompanying fiber formation are all in line with expectations from considerations of this mechanism. The narrow window for experimental conditions necessary for fiber preparation and subsequent X-ray observation of this phenomenon is detailed. A close examination of space-filling Corey-Pauling-Koltun (CPK) molecular models reveals the details of local packing of rods and connected polymer chains in the quiescent nematic polymer melt prior to fiber drawing. It is found that two rod-reorientation possibilities exist each of which leads to increased interchain separation as required for auxetic response. Suggestions for future experiments and materials design for new LCPs are described.

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Environmentally Benign Blue Emissive Films from Host-Dopant Interaction of PLA–Bischalcone Combination with High UV Endurance

et al. 2021

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Mechanical equilibrium, a prerequisite to unveil auxetic properties in molecular compounds

Cited by 7 publications

References 46 publications

The extent of the glass transition from molecular simulation revealing an overcrank effect

The extent of the glass transition from molecular simulation revealing an overcrank effect

Implications for Auxetic Response in Liquid Crystalline Polymers: X‐Ray Scattering and Space‐Filling Molecular Modeling

Environmentally Benign Blue Emissive Films from Host-Dopant Interaction of PLA–Bischalcone Combination with High UV Endurance

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