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Marcato D, Giacometti A, Maritan A, Rosa A. Phase behaviour of semiflexible lattice polymers in poor-solvent solution: Mean-field theory and Monte Carlo simulations. J Chem Phys 2023; 159:154901. [PMID: 37843062 DOI: 10.1063/5.0171911] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/22/2023] [Indexed: 10/17/2023] Open
Abstract
We study a solution of interacting semiflexible polymers with curvature energy in poor-solvent conditions on the d-dimensional cubic lattice using mean-field theory and Monte Carlo computer simulations. Building upon past studies on a single chain, we construct a field-theory representation of the system and solve it within a mean-field approximation supported by Monte Carlo simulations in d = 3. A gas-liquid transition is found in the temperature-density plane that is then interpreted in terms of real systems. Interestingly, we find this transition to be independent of the bending rigidity. Past classical Flory-Huggins and Flory mean-field results are shown to be particular cases of this more general framework. Perspectives in terms of guiding experimental results towards optimal conditions are also proposed.
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Affiliation(s)
- Davide Marcato
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy
| | - Achille Giacometti
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, 30123 Venezia, Italy
- European Centre for Living Technology (ECLT) Ca' Bottacin, 3911 Dorsoduro Calle Crosera, 30123 Venezia, Italy
| | - Amos Maritan
- Laboratory of Interdisciplinary Physics, Department of Physics and Astronomy "G. Galilei," University of Padova, Padova, Italy and INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Angelo Rosa
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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De Filippo CA, Del Galdo S, Corsi P, De Michele C, Capone B. On the role of polydispersity on the phase diagram of colloidal rods. SOFT MATTER 2023; 19:1732-1738. [PMID: 36757264 DOI: 10.1039/d2sm01355j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The rich and complex phase diagram typical of anisotropic biological or synthetic nanoparticles, has brought a great deal of interest over the equilibrium phase behaviour of non-spherical colloids. Amongst the class of anisotropic nanoparticles, hard spherocylindrical colloids have been, over the years, extensively studied because of their optical properties, for their rich phase diagrams, and their important industrial applications, as model particles for biological systems (viruses), or for example as potential drug carriers having the ability of surviving the attacks of the immune systems. As real anisotropic nanoparticles are often polydisperse in size and/or in shape, unveiling the effect of such a perturbation over their equilibrium phase diagram is of paramount importance. This work focuses on the effects of polydispersity over the full equilibrium phase diagram of hard spherocylindrical colloids (HSCs). Previous studies showed that a polydispersity in L alters the equilibrium phase diagram of HSCs. With this work we determine, both theoretically as well as computationally, the effects due to a generic polydispersity, namely in D, in L and, in both ones, on the equilibrium phase diagram and introduce a viable theoretical generalisation of the Onsager theory that allows us to get some insight into the observed phase behaviour.
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Affiliation(s)
| | - Sara Del Galdo
- Science Department, University of Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy.
| | - Pietro Corsi
- Science Department, University of Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy.
| | - Cristiano De Michele
- Physics Department, University of Roma "La Sapienza", Piazzale Aldo Moro 2, 00186, Rome, Italy.
| | - Barbara Capone
- Science Department, University of Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy.
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Ferreiro-Córdova C, Royall CP, van Duijneveldt JS. Anisotropic viscoelastic phase separation in polydisperse hard rods leads to nonsticky gelation. Proc Natl Acad Sci U S A 2020; 117:3415-3420. [PMID: 32005711 PMCID: PMC7035602 DOI: 10.1073/pnas.1909357117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spinodal demixing into two phases having very different viscosities leads to viscoelastic networks-i.e., gels-usually as a result of attractive particle interactions. Here, however, we demonstrate demixing in a colloidal system of polydisperse, rod-like clay particles that is driven by particle repulsions instead. One of the phases is a nematic liquid crystal with a highly anisotropic viscosity, allowing flow along the director, but suppressing it in other directions. This phase coexists with a dilute isotropic phase. Real-space analysis and molecular-dynamics simulations both reveal a long-lived network structure that is locally anisotropic, yet macroscopically isotropic. We show that our system exhibits the characteristics of colloidal gelation, leading to nonsticky gels.
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Affiliation(s)
- Claudia Ferreiro-Córdova
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
- Centre for Nanoscience and Quantum Information, University of Bristol, Bristol BS8 1FD, United Kingdom
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay, France
| | - C Patrick Royall
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom;
- Centre for Nanoscience and Quantum Information, University of Bristol, Bristol BS8 1FD, United Kingdom
- H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
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Sonin AS, Churochkina NA, Kaznacheev AV, Golovanov AV. Liquid Crystals of Clay Dispersions. COLLOID JOURNAL 2019. [DOI: 10.1134/s1061933x18060170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Mao Y, Bleuel M, Lyu Y, Zhang X, Henderson D, Wang H, Briber RM. Phase Separation and Stack Alignment in Aqueous Cellulose Nanocrystal Suspension under Weak Magnetic Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8042-8051. [PMID: 29957957 DOI: 10.1021/acs.langmuir.8b01452] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Isotropic-nematic (I-N) transitions in cellulose nanocrystal (CNC) suspension and self-assembled structures in the isotropic and nematic phases were investigated using scattering and microscopy methods. A CNC suspension with a mass fraction of 7.4% spontaneously phase separated into an isotropic phase of 6.9% in the top layer and a nematic phase of 7.9% in the bottom layer. In both the phases, the CNC particles formed stacks with an interparticle distance being of ≈37 nm. One-dimensional small-angle neutron scattering (SANS) profiles due to both phases could be fitted using a stacking model considering finite particle sizes. SANS and atomic force microscopy studies indicate that the nematic phase in the bottom layer contains more populations of larger particles. A weak magnetic field of ≈0.5 T was able to induce a preferred orientation of CNC stacks in the nematic phase, with the stack normals being aligned with the field (perpendicular to the long axis of CNC particles). The Hermans orientation parameter, ⟨ P2⟩, was ≈0.5 for the nematic phase; it remained unchanged during the relaxation process of ≈10 h. The fraction of oriented CNC populations decreased during the relaxation; dramatic decrease occurred in the first 3 h. The top layer remained isotropic in the weak field. Polarized microscopy studies revealed that the nematic phase was chiral. Adjacent particles in a stack form a twisting angle of ≈0.6 °, resulting in a helix pitch distance of ≈22 μm.
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Affiliation(s)
- Yimin Mao
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg , Maryland 20899 , United States
| | - Markus Bleuel
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg , Maryland 20899 , United States
| | - Yadong Lyu
- Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg , Maryland 20899 , United States
| | - Xin Zhang
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Doug Henderson
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Howard Wang
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Robert M Briber
- Department of Materials Science and Engineering , University of Maryland , College Park , Maryland 20742 , United States
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Díaz-De Armas A, Martínez-Ratón Y. Role of length polydispersity in the phase behavior of freely rotating hard-rectangle fluids. Phys Rev E 2017; 95:052702. [PMID: 28618522 DOI: 10.1103/physreve.95.052702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Indexed: 11/07/2022]
Abstract
We use the density-functional formalism, in particular the scaled-particle theory, applied to a length-polydisperse hard-rectangle fluid to study its phase behavior as a function of the mean particle aspect ratio κ_{0} and polydispersity Δ_{0}. The numerical solutions of the coexistence equations are calculated by transforming the original problem with infinite degrees of freedoms to a finite set of equations for the amplitudes of the Fourier expansion of the moments of the density profiles. We divide the study into two parts. The first one is devoted to the calculation of the phase diagrams in the packing fraction η_{0}-κ_{0} plane for a fixed Δ_{0} and selecting parent distribution functions with exponential (the Schulz distribution) or Gaussian decays. In the second part we study the phase behavior in the η_{0}-Δ_{0} plane for fixed κ_{0} while Δ_{0} is changed. We characterize in detail the orientational ordering of particles and the fractionation of different species between the coexisting phases. Also we study the character (second vs first order) of the isotropic-nematic phase transition as a function of polydispersity. We particularly focus on the stability of the tetratic phase as a function of κ_{0} and Δ_{0}. The isotropic-nematic transition becomes strongly of first order when polydispersity is increased: The coexistence gap widens and the location of the tricritical point moves to higher values of κ_{0} while the tetratic phase is slightly destabilized with respect to the nematic one. The results obtained here can be tested in experiments on shaken monolayers of granular rods.
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Affiliation(s)
- Ariel Díaz-De Armas
- Grupo Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Madrid, Spain
| | - Yuri Martínez-Ratón
- Grupo Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Madrid, Spain
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Ferreiro-Córdova C, Wensink HH. Spinodal instabilities in polydisperse lyotropic nematics. J Chem Phys 2016; 145:244904. [DOI: 10.1063/1.4972523] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- C. Ferreiro-Córdova
- Laboratoire de Physique des Solides - UMR 8502, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - H. H. Wensink
- Laboratoire de Physique des Solides - UMR 8502, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
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Lugo-Frías R, Klapp SHL. Binary mixtures of rod-like colloids under shear: microscopically-based equilibrium theory and order-parameter dynamics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:244022. [PMID: 27115342 DOI: 10.1088/0953-8984/28/24/244022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This paper is concerned with the dynamics of a binary mixture of rod-like, repulsive colloidal particles driven out of equilibrium by means of a steady shear flow (Couette geometry). To this end we first derive, starting from a microscopic density functional in Parsons-Lee approximation, a mesoscopic free energy functional whose main variables are the orientational order parameter tensors. Based on this mesoscopic functional we then explore the stability of isotropic and nematic equilibrium phases in terms of composition and rod lengths. Second, by combining the equilibrium theory with the Doi-Hess approach for the order parameter dynamics under shear, we investigate the orientational dynamics of binary mixtures for a range of shear rates and coupling parameters. We find a variety of dynamical states, including synchronized oscillatory states of the two components, but also symmetry breaking behavior where the components display different in-plane oscillatory states.
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Affiliation(s)
- Rodrigo Lugo-Frías
- Institute für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
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