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

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 d...

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Autores principales: Martínez-Fernández, Daniel, Herranz, Miguel, Foteinopoulou, Katerina, Karayiannis, Nikos Ch., Laso, Manuel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9919756/
https://www.ncbi.nlm.nih.gov/pubmed/36771852
http://dx.doi.org/10.3390/polym15030551
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author Martínez-Fernández, Daniel
Herranz, Miguel
Foteinopoulou, Katerina
Karayiannis, Nikos Ch.
Laso, Manuel
author_facet Martínez-Fernández, Daniel
Herranz, Miguel
Foteinopoulou, Katerina
Karayiannis, Nikos Ch.
Laso, Manuel
author_sort Martínez-Fernández, Daniel
collection PubMed
description 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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spelling pubmed-99197562023-02-12 Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres Martínez-Fernández, Daniel Herranz, Miguel Foteinopoulou, Katerina Karayiannis, Nikos Ch. Laso, Manuel Polymers (Basel) Article 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. MDPI 2023-01-20 /pmc/articles/PMC9919756/ /pubmed/36771852 http://dx.doi.org/10.3390/polym15030551 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Martínez-Fernández, Daniel
Herranz, Miguel
Foteinopoulou, Katerina
Karayiannis, Nikos Ch.
Laso, Manuel
Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title_full Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title_fullStr Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title_full_unstemmed Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title_short Local and Global Order in Dense Packings of Semi-Flexible Polymers of Hard Spheres
title_sort local and global order in dense packings of semi-flexible polymers of hard spheres
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9919756/
https://www.ncbi.nlm.nih.gov/pubmed/36771852
http://dx.doi.org/10.3390/polym15030551
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