Ring polymer dynamics and tumbling-stretch transitions in planar mixed flows

Young, Christopher; Qian, June R.; Marvin, Michael D.; Sing, Charles E.

doi:10.1103/physreve.99.062502

Cited by 24 publications

(21 citation statements)

References 43 publications

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“…The absence of this phase in the aforementioned work could be a consequence of approximating hydrodynamics via the RPY-tensor but it is most likely an effect of the low degree of polymerization, N = 120, employed by Young et al Further differences with Ref. [27] pertain to the solvent quality (θ-solvent in Ref. [27] vs. good quality solvent here) and to the modelling of the bonding interactions between the monomers (harmonic vs. FENEsprings, respectively).…”

Section: Resultsmentioning

confidence: 98%

“…[27] pertain to the solvent quality (θ-solvent in Ref. [27] vs. good quality solvent here) and to the modelling of the bonding interactions between the monomers (harmonic vs. FENEsprings, respectively). These details should not play an important role at sufficiently high Weissenberg numbers, however.…”

Section: Resultsmentioning

confidence: 99%

“…All polymer architectures (linear, star, dendritic, crosslinked and ring) are known to undergo tumbling under steady shear at sufficiently high shear rates [26,[66][67][68][69][70][71][72][73] . Moreover, it is known that linear chains never fully stretch under shear and they reach a stretched configuration only under so-called planar mixed flows that represent a combination of simple shear and planar extension [27,74,75] . Under simple shear, ring polymers show two dynamical modes: Tumbling (TB) and tank-treading (TT) [76] .…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic inflation of ring polymers under shear

Liebetreu

Likos

2020

Commun Mater

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Hydrodynamic interactions as modeled by Multi-Particle Collision Dynamics can dramatically influence the dynamics of fully flexible, ring-shaped polymers in ways not known for any other polymer architecture or topology. We show that steady shear leads to an inflation scenario exclusive to ring polymers, which depends not only on Weissenberg number but also on contour length of the ring. By analyzing velocity fields of the solvent around the polymer, we show the existence of a hydrodynamic pocket which allows the polymer to self-stabilize at a certain alignment angle to the flow axis. This self-induced stabilization is accompanied by transitioning of the ring to a non-Brownian particle and a cessation of tumbling. The ring swells significantly in the vorticity direction, and the horseshoe regions on the stretched and swollen ring are effectively locked in place relative to the ring's center-of-mass. The observed effect is exclusive to ring polymers and stems from an interplay between hydrodynamic interactions and topology. Furthermore, knots tied onto such rings can serve as additional "stabilization anchors". Under strong shear, the knotted section is pulled tight and remains well-localized while tank-treading from one horseshoe region to the opposite one in sudden bursts. We find knotted polymers of high contour length behave very similarly to unknotted rings of the same contour length, but small knotted rings feature a host of different configurations. We propose a filtering technique for rings and chains based on our observations and suggest that strong shear could be used to tighten knots on rings.arXiv:1909.00725v2 [cond-mat.soft]

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic inflation of ring polymers under shear

Liebetreu

Likos

2020

Commun Mater

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“…The flow properties of ring polymers in dilute solutions were recently studied using single molecule experiments and simulations [52][53][54][55]. In dilute solution extensional flow, ring polymers show reduced molecular individualism during transient stretching and a shifted coil-stretch transition (CST) compared to linear chains due to combined effects of a closed, constrained molecular topology and intramolecular hydrodynamic interactions between the two ring strands [52,53].…”

Section: Introductionmentioning

confidence: 99%

Dynamics and Rheology of Ring-Linear Blend Semidilute Solutions in Extensional Flow: Single Molecule Experiments

Zhou,

Young,

Regan

et al. 2021

Preprint

Self Cite

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Ring polymers exhibit unique flow properties due to their closed chain topology. Despite recent progress, we have not yet achieved a full understanding of the nonequilibrium flow behavior of rings in nondilute solutions where intermolecular interactions greatly influence chain dynamics. In this work, we directly observe the dynamics of DNA rings in semidilute ring-linear polymer blends using single molecule techniques. We systematically investigate ring polymer relaxation dynamics from high extension and transient and steady-state stretching dynamics in planar extensional flow for a series of ring-linear blends with varying ring fraction. Our results show multiple molecular sub-populations for ring relaxation in ring-linear blends, as well as large conformational fluctuations for rings in steady extensional flow, even long after the initial transient stretching process has subsided. We further quantify the magnitude and characteristic timescales of ring conformational fluctuations as a function of blend composition. Interestingly, we find that the magnitude of ring conformational fluctuations follows a non-monotonic response with increasing ring fraction, first increasing at low ring fraction and then substantially decreasing at large ring fraction in ring-linear blends. A unique set of ring polymer conformations are observed during the transient stretching process, which highlights the prevalence of molecular individualism and supports the notion of complex intermolecular interactions in ring-linear polymer blends. In particular, our results suggest that transient intermolecular structures form in ring-linear blends due to a combination of direct forces due to linear chains threading through open rings and indirect forces due to hydrodynamic interactions; these combined effects lead to large conformational fluctuations of rings over distributed timescales. Taken together, our results provide a new molecular understanding of ring polymer dynamics in ring-linear blends in nonequilibrium flow.

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“…We further examined the interfacial slip for short-chain branched (SCB) linear PE melts and reported the slip behavior of the SCB polymer to be quite distinct from that of the corresponding linear polymer, which was ascribed to the generally more compact and less deformed chain structures of the SCB polymer in response to the applied flow via the intrinsically fast random motions of short branches [25,27,28]. In addition, ring polymers, with their closed-loop molecular geometry, are known to exhibit a lower degree of chain stretching, weaker shear thinning, reduced interfacial slip, and hydrodynamic inflation toward the neutral direction under shear flow [26,[29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Structural and Dynamical Characteristics of Short-Chain Branched Ring Polymer Melts at Interface under Shear Flow

Jeong

Cho

et al. 2020

Polymers

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We present a detailed analysis of the interfacial chain structure and dynamics of confined polymer melt systems under shear over a wide range of flow strengths using atomistic nonequilibrium molecular dynamics simulations, paying particular attention to the rheological influence of the closed-loop ring geometry and short-chain branching. We analyzed the interfacial slip, characteristic molecular mechanisms, and deformed chain conformations in response to the applied flow for linear, ring, short-chain branched (SCB) linear, and SCB ring polyethylene melts. The ring topology generally enlarges the interfacial chain dimension along the neutral direction, enhancing the dynamic friction of interfacial chains moving against the wall in the flow direction. This leads to a relatively smaller degree of slip (ds) for the ring-shaped polymers compared with their linear analogues. Furthermore, short-chain branching generally resulted in more compact and less deformed chain structures via the intrinsically fast random motions of the short branches. The short branches tend to be oriented more perpendicular (i.e., aligned in the neutral direction) than parallel to the backbone, which is mostly aligned in the flow direction, thereby enhancing the dynamic wall friction of the moving interfacial chains toward the flow direction. These features afford a relatively lower ds and less variation in ds in the weak-to-intermediate flow regimes. Accordingly, the interfacial SCB ring system displayed the lowest ds among the studied polymer systems throughout these regimes owing to the synergetic effects of ring geometry and short-chain branching. On the contrary, the structural disturbance exerted by the highly mobile short branches promotes the detachment of interfacial chains from the wall at strong flow fields, which results in steeper increasing behavior of the interfacial slip for the SCB polymers in the strong flow regime compared to the pure linear and ring polymers.

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Ring polymer dynamics and tumbling-stretch transitions in planar mixed flows

Cited by 24 publications

References 43 publications

Hydrodynamic inflation of ring polymers under shear

Hydrodynamic inflation of ring polymers under shear

Dynamics and Rheology of Ring-Linear Blend Semidilute Solutions in Extensional Flow: Single Molecule Experiments

Structural and Dynamical Characteristics of Short-Chain Branched Ring Polymer Melts at Interface under Shear Flow

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