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Yuan J, Curk T. Collapse and expansion kinetics of a single polyelectrolyte chain with hydrodynamic interactions. J Chem Phys 2024; 160:161103. [PMID: 38656439 DOI: 10.1063/5.0201740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/29/2024] [Indexed: 04/26/2024] Open
Abstract
We investigate the collapse and expansion dynamics of a linear polyelectrolyte (PE) with hydrodynamic interactions. Using dissipative particle dynamics with a bead-spring PE model, long-range electrostatics, and explicit ions, we examine how the timescales of collapse tcol and expansion texp depend on the chain length N and obtain scaling relationships tcol ∼ Nα and texp ∼ Nβ. For neutral polymers, we derive values of α = 0.94 ± 0.01 and β = 1.97 ± 0.10. Interestingly, the introduction of electrostatic interaction markedly shifts α to α ≈ 1.4 ± 0.1 for salt concentrations within c = 10-4 to 10-2 M. A reduction in the ion-to-monomer size ratio noticeably reduces α. On the other hand, the expansion scaling remains approximately constant, β ≈ 2, regardless of the salt concentration or ion size considered. We find β > α for all conditions considered, implying that expansion is always slower than collapse in the limit of long polymers. This asymmetry is explained by distinct kinetic pathways of collapse and expansion processes.
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Affiliation(s)
- Jiaxing Yuan
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Tine Curk
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Garcia JU, Tree DR, Bagoyo A, Iwama T, Delaney KT, Fredrickson GH. Coarsening dynamics of ternary polymer solutions with mobility and viscosity contrasts. J Chem Phys 2023; 159:214904. [PMID: 38054518 DOI: 10.1063/5.0173992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 11/14/2023] [Indexed: 12/07/2023] Open
Abstract
Using phase-field simulations, we investigate the bulk coarsening dynamics of ternary polymer solutions undergoing a glass transition for two models of phase separation: diffusion only and with hydrodynamics. The glass transition is incorporated in both models by imposing mobility and viscosity contrasts between the polymer-rich and polymer-poor phases of the evolving microstructure. For microstructures composed of polymer-poor clusters in a polymer-rich matrix, the mobility and viscosity contrasts significantly hinder coarsening, effectively leading to structural arrest. For microstructures composed of polymer-rich clusters in a polymer-poor matrix, the mobility and viscosity contrasts do not impede domain growth; rather, they change the transient concentration of the polymer-rich phase, altering the shape of the discrete domains. This effect introduces several complexities to the coarsening process, including percolation inversion of the polymer-rich and polymer-poor phases-a phenomenon normally attributed to viscoelastic phase separation.
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Affiliation(s)
- Jan Ulric Garcia
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
- Asahi Kasei Corporation, 2-1 Samejima, Fuji, Shizuoka 416-8501, Japan
| | - Douglas R Tree
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, USA
| | - Alyssa Bagoyo
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, USA
| | - Tatsuhiro Iwama
- Asahi Kasei Corporation, 2-1 Samejima, Fuji, Shizuoka 416-8501, Japan
| | - Kris T Delaney
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
| | - Glenn H Fredrickson
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
- Department of Materials, University of California, Santa Barbara, California 93106, USA
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