Construction Of The Full Phase Diagram For The System Of Poly(γ-benzyl-<scp>l</scp>-glutamate)/dimethylformamide On The Basis Of The Complex Of Literature Data

Гинзбург, Б. М.; Шепелевский, А. А.

doi:10.1081/mb-120015749

Cited by 17 publications

(25 citation statements)

References 63 publications

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“…It has been shown experimentally 34,39 that under certain and then confirmed by subsequent data from heating/cooling DSC studies 23 and the temperature/concentration dependence of the cholesteric pitch which was found to exhibit a characteristic kink. 27 Though gels and crystalline phases are certainly to be expected at the higher concentrations, 39 we will not consider these more complicated features of the phase behaviour of the system in our current study.…”

Section: Phase Behaviour Of Solutions Of Pblg In Dmfmentioning

confidence: 64%

“…Because the molecular weight M w and density ρ PBLG of PBLG depends on the polymerization conditions, 121,122 an average prototypical molecular weight of M w = 310, 000 g mol −1 is assumed, and a value of ρ PBLG = 1.283 g cm −3 is taken for its density. 39 There is experimental evidence 24,27,36,37,40 that solutions of PBLG in some solvents (e.g., DMF or dichloromethane) exhibit a cholesteric (chiral nematic) phase rather than a nematic phase. As the difference in free energy between the two states is very small (owing to the large chiral pitches characteristic of the system), the thermodynamic properties of the cholesteric phase can be approximated by those of the nematic phase.…”

Section: Phase Behaviour Of Solutions Of Pblg In Dmfmentioning

confidence: 99%

“…In the current paper we seek to understand and describe the LC ordering exhibited by solutions of the polypeptide poly-(γ -benzyl-L-glutamate) (PBLG) in dimethylformamide (DMF) which is characterized by large regions of stable nematic order and an intriguing phase coexistence between two liquidcrystalline states with markedly different concentrations of polypeptides. 22,23,27,28,33,36,39 An essential requirement for the stabilization of a LC phase is that the molecules be highly anisotropic in shape, such as long rigid rods or thin flat discs. For this reason, rodlike [41][42][43][44][45][46][47] particles are often employed as prototype models for prolate LC molecules (see reference 48 for a relatively recent review).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding and Describing the Liquid-Crystalline States of Polypeptide Solutions: A Coarse-Grained Model of PBLG in DMF

Müller

Jackson

2014

Macromolecules

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A perturbation theory is employed to construct a free-energy functional capable of describing the isotropic and nematic phases of attractive rod-like particles. An algebraic van der Waals-Onsager equation of state is then developed to determine the global phase behaviour of prolate particles for various aspect ratios and strengths of the attractive potential. Compared with the phase diagram of their athermal analogues, the incorporation of an attractive potential is seen to stabilize the nematic state leading to an increase in the degree of orientational order of the system at high densities. The most salient feature of these fluids is the existence of regions of nematic-nematic phase separation. The simple model is used to describe the phase behaviour of solutions of a relatively rigid polypeptide, poly-(γ -benzyl-L-glutamate) (PBLG), in dimethylformamide (DMF); this system exhibits a unique phase separation between two liquidcrystalline states. The coarse-grained representation of the mesogen employed herein * To whom correspondence should be addressed 1 is a hard spherocylinder decorated with an attractive square-well potential which acts at the center of mass of the particle. A quantitative description of the experimental isotropic-nematic phase behaviour of the PBLG solutions can be achieved from the proposed model with the use of just two temperature-dependent parameters.

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Section: Phase Behaviour Of Solutions Of Pblg In Dmfmentioning

confidence: 64%

Section: Phase Behaviour Of Solutions Of Pblg In Dmfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Understanding and Describing the Liquid-Crystalline States of Polypeptide Solutions: A Coarse-Grained Model of PBLG in DMF

Müller

Jackson

2014

Macromolecules

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“…At present, one can recognize the liquid crystal behaviour in an ever-increasing number of scenarios: apart from the common examples of solutions of soaps and surfactants [3], lyotropic liquid-crystalline order in biomacromolecular systems is ubiquitous in nature, including the phase behavior exhibited by DNA [4], by stiff polymers such as polysaccharides [5], cellulose [6] and protein fibers [7] and by rod-like viruses such as the tobacco mosaic virus [8,9] or the fd virus [10,11]. The supramolecular α-helices formed from self-assembly of polypeptides in solutions are also found to give rise to a rich variety of mesogenic behaviour [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

On generalization of Van der Waals approach for isotropic-nematic fluid phase equilibria of anisotropic fluids in disordered porous medium

Holovko¹,

Shmotolokha²

2020

Condens. Matter Phys.

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A generalized Van der Waals approach is developed for anisotropic fluids in disordered porous media. As the reference system a hard spherocylinder fluid in a disordered porous medium is considered and described in the framework of the scaled particle theory with the Carnahan-Starling and Parsons-Lee corrections. The attractive part of interaction is treated in the framework of the mean field approximation in which due to orientational dependence of the excluded volume of two spherocylinders, a coupling between attractive and repulsive contributions is found. We focus on spherocylinder fluids with sufficiently long particle lengths for which the nematicnematic transition was established. It is shown that these two nematic phases have different densities and are characterized by different orientational ordering. Strong influence of the type of interparticle attraction on the phase behaviour of anisotropic fluids in disordered porous media is established. Three simple models for this purpose are considered, namely a model with the Lennard-Jones anisotropic attraction, a model with modified Lennard-Jones attraction and a model with anisotropic square-well potential. For all considered models, the phase diagram shifts to the region of lower densities and lower temperatures as the porosity decreases.cylinders when the length of a spherocylinder L 1 → ∞ and the diameter D 1 → 0 in such a way that the non-dimensional concentration C 1 = πρ 1 L 2 1 D 1 /4 is fixed, where ρ 1 = N 1 /V, N 1 is the number of spherocylinders, V is the volume of the system [16]. The application of the scaled particle theory (SPT) previously developed for a hard-sphere fluid [18,19] provides an efficient way to incorporate higher order contributions neglected in the Onsager theory [20][21][22].Another mechanism of formation of liquid crystalline matter can be connected with anisotropic attraction usually treated in molecular mean-field approaches such as the Maier-Saupe theory [23,24]. In this approach, the orientationally dependent attractive interactions are considered as the key to the orientational order in thermotropic liquid crystals controlled by the temperature. In many cases, anisotropic fluids exhibit simultaneously lyotropic and thermotropic behaviour, which can be presented in concentration-temperature phase diagrams [15,25]. Due to this, both repulsive and attractive interactions between particles should be taken into account. This leads to the Van der Waals picture of fluids [26] in which the hard molecular core is treated as the reference system that determines the fluid structure while the attractions are incorporated by the perturbation way [27][28][29]. The generalized Van der Waals theory for anisotropic fluids was formulated by Cotter [30][31][32] and by the Gelbart group [33,34]. By combining the Onsager theory with the Van der Waals approach in the group of Jackson [15,25] for the attractive hard spherocylinders, four possible pairs of coexisting fluid phases were predicted, namely vapor-liquid, vapor-nematic, liquid-nemat...

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“…A. Shepelevskii, for the first time, built and substantiated the phase diagram of a rigid polymer/solvent (for example, a synthetic polypeptide) in the entire region of the polymer concentration. [29] They interpreted all of the features and singular points of this phase diagram. It was shown that there are liquid crystalline phase and crystallosolvates on the phase diagram instead of two crystalline phases (according to the Paul Flory diagram).…”

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confidence: 99%

Foreword

Indeitsev¹,

Panarin²,

Fadin³

et al. 2013

Journal of Macromolecular Science, Part B

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Construction Of The Full Phase Diagram For The System Of Poly(γ-benzyl-l-glutamate)/dimethylformamide On The Basis Of The Complex Of Literature Data

Cited by 17 publications

References 63 publications

Understanding and Describing the Liquid-Crystalline States of Polypeptide Solutions: A Coarse-Grained Model of PBLG in DMF

Understanding and Describing the Liquid-Crystalline States of Polypeptide Solutions: A Coarse-Grained Model of PBLG in DMF

On generalization of Van der Waals approach for isotropic-nematic fluid phase equilibria of anisotropic fluids in disordered porous medium

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