Rich phase transitions in strongly confined polymer–nanoparticle mixtures: Nematic ordering, crystallization, and liquid–liquid phase separation

Roy, Supriya; Chen, Yeng-Long

doi:10.1063/5.0034602

Cited by 7 publications

(3 citation statements)

References 53 publications

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“…For tangent hard-sphere chains in the rod limit, the transition occurs at high concentrations, still lower than the solidification of the system [ 106 , 107 ]. Theories have been developed [ 108 , 109 , 110 , 111 ] and studies have been conducted [ 112 , 113 , 114 , 115 , 116 , 117 ] under various conditions on the isotropic-to-nematic transition of semi-flexible chains, as the effect on the nematic order and the phase separation of different types of blends through experimental studies [ 118 , 119 , 120 ] and computer simulations [ 117 , 121 , 122 , 123 , 124 ]. Nguyen et al studied the effect of chain stiffness and temperature on the competition between crystallization and glass formation for unentangled semi-flexible polymer melts [ 85 , 86 ].…”

Section: Introductionmentioning

confidence: 99%

Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres

et al. 2023

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The local and global order in dense packings of linear, semi-flexible polymers of tangent hard spheres are studied by employing extensive Monte Carlo simulations at increasing volume fractions. The chain stiffness is controlled by a tunable harmonic potential for the bending angle, whose intensity dictates the rigidity of the polymer backbone as a function of the bending constant and equilibrium angle. The studied angles range between acute and obtuse ones, reaching the limit of rod-like polymers. We analyze how the packing density and chain stiffness affect the chains’ ability to self-organize at the local and global levels. The former corresponds to crystallinity, as quantified by the Characteristic Crystallographic Element (CCE) norm descriptor, while the latter is computed through the scalar orientational order parameter. In all cases, we identify the critical volume fraction for the phase transition and gauge the established crystal morphologies, developing a complete phase diagram as a function of packing density and equilibrium bending angle. A plethora of structures are obtained, ranging between random hexagonal closed packed morphologies of mixed character and almost perfect face centered cubic (FCC) and hexagonal close-packed (HCP) crystals at the level of monomers, and nematic mesophases, with prolate and oblate mesogens at the level of chains. For rod-like chains, a delay is observed between the establishment of the long-range nematic order and crystallization as a function of the packing density, while for right-angle chains, both transitions are synchronized. A comparison is also provided against the analogous packings of monomeric and fully flexible chains of hard spheres.

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Section: Introductionmentioning

confidence: 99%

Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres

et al. 2023

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“…For tangent hard-sphere chains in the rod limit, the transition occurs at high concentrations, still lower than the solidification of the system [78,79]. Theories have been developed [80][81][82] and studies have been conducted [83][84][85][86][87] under various conditions on the isotropic-tonematic transition of semi-flexible chains. Nguyen et al studied the effect of chain stiffness and temperature on the competition between crystallization and glass formation for unentangled semi-flexible polymer melts [61,62].…”

Section: Introductionmentioning

confidence: 99%

Local and Global Order in Dense Packings of Semi-flexible Polymers of Hard Spheres

Martínez-Fernández¹,

Herranz²,

Foteinopoulou³

et al. 2023

Preprint

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The local and global order in dense packings of linear, semi-flexible polymers of tangent hard spheres are studied by employing extensive Monte Carlo simulations at increasing volume fractions. Chain stiffness is controlled by a tunable harmonic potential for the bending angle whose intensity dictates the rigidity of the polymer backbone as a function of the bending constant and equilibrium angle. The studied angles range from acute to obtuse ones, reaching the limit of rod-like polymers. We analyze how packing density and chain stiffness affect the ability of chains to self-organize at the local and global levels. The former corresponds to crystallinity as quantified by the Characteristic Crystallographic Element (CCE) norm descriptor, while the latter is computed through the scalar orientational order parameter. In all cases, we identify the critical volume fraction for the phase transition and gauge the established crystal morphologies, developing a complete phase diagram as a function of packing density and equilibrium bending angle. A plethora of structures is obtained, ranging from random hexagonal closed packed morphologies of mixed character and almost perfect face centered cubic (FCC) and hexagonal close-packed (HCP) crystals at the level of monomers, to nematic mesophases, with prolate and oblate mesogens at the level of chains. For rod-like chains, hysteresis is observed between the establishment of long-range nematic order and crystallization, while for right-angle chains both transitions are synchronized. A comparison is also provided against the analogous packings of monomeric and fully flexible chains of hard spheres.

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“…It has been observed that the properties of the LC-host are primarily affected by the geometry of the NPs (size, shape), their bulk and/or surface properties, and their concentration. Over the past two decades, numerous theoretical and experimental studies have been appeared regarding the influence of NPs on phase transitions, orientational order, and the response of the host liquid crystalline matrix to external fields [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Naturally, the well-known Fréedericksz transition has been studied too in certain soft-nanocomposite materials for the voltage threshold of this transition is crucial for applications.…”

Section: Introductionmentioning

confidence: 99%

Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites

Atata,

Lelidis

2023

Nanomaterials

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We explore the influence of functionalized core–shell CdSe/ZnS quantum dots on the properties of the host liquid crystal compound 4-cyano-4′-octylbiphenyl (8CB) through electrooptical measurements. Two different diameters of quantum dots are used to investigate the size effects. We assess both the dispersion quality of the nanoparticles within the mixtures and the phase stability of the resulting anisotropic soft nanocomposites using polarizing optical microscopy. The temperature-mass fraction phase diagrams of the nanocomposites reveal deviations from the linear behavior in the phase stability lines. We measure the birefringence, the threshold voltage of the Fréedericksz transition, and the electrooptic switching times of the nanocomposite systems in planar cell geometry as functions of temperature, mass fraction, and diameter of the quantum dots. Beyond a critical mass fraction of the dopant nanoparticles, the nematic order is strongly reduced. Furthermore, we investigate the impact of the nanoparticle size and mass fraction on the viscoelastic coefficient. The anchoring energy at the interfaces of the liquid crystal with the cell and the quantum dots is estimated.

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Rich phase transitions in strongly confined polymer–nanoparticle mixtures: Nematic ordering, crystallization, and liquid–liquid phase separation

Cited by 7 publications

References 53 publications

Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres

Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres

Local and Global Order in Dense Packings of Semi-flexible Polymers of Hard Spheres

Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites

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