Probing structural and dynamical transitions in polymer globules by force

Sing, Charles E.; Einert, Thomas R.; Netz, Roland R.; Alexander‐Katz, Alfredo

doi:10.1103/physreve.83.040801

Cited by 11 publications

(20 citation statements)

References 17 publications

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“…Increasing ε above ε G causes the polymer to collapse and a globule forms. The static globule behavior from our simulations agrees with previous work [17,32,[42][43][44][45][46][47][48][49][50]60]. The value of the cohesive strength at the globule transition, ε G , depends on the system size [43].…”

Section: Description Of the Systemsupporting

confidence: 88%

“…There have been a large number of coarse-grained simulation studies on the force-induced unfolding of proteins [35], globular polymers [17,21,[36][37][38], and the diffusion of knots along a stretched chain [39][40][41]. Cohesive interactions between polymer monomers have been shown to lead to a phase transition from a liquid-like to a solid-like globule for long enough chains [42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

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Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

et al. 2011

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We study the conformational dynamics within homopolymer globules by solvent-implicit Brownian dynamics simulations. A strong dependence of the internal chain dynamics on the Lennard-Jones cohesion strength ε and the globule size N (G) is observed. We find two distinct dynamical regimes: a liquid-like regime (for ε < ε(s) with fast internal dynamics and a solid-like regime (for ε > ε(s) with slow internal dynamics. The cohesion strength ε(s) of this freezing transition depends on N (G) . Equilibrium simulations, where we investigate the diffusional chain dynamics within the globule, are compared with non-equilibrium simulations, where we unfold the globule by pulling the chain ends with prescribed velocity (encompassing low enough velocities so that the linear-response, viscous regime is reached). From both simulation protocols we derive the internal viscosity within the globule. In the liquid-like regime the internal friction increases continuously with ε and scales extensive in N (G) . This suggests an internal friction scenario where the entire chain (or an extensive fraction thereof) takes part in conformational reorganization of the globular structure.

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Section: Description Of the Systemsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

et al. 2011

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“…Notwithstanding a few studies that have probed structural relaxation of single‐chain polymer nanoglobules,106–108 we have recently reported the first systematic investigation of structural relaxation of polymer nanoparticles 109. It is well known that the properties of glasses depend on the conditions of glass formation 110.…”

Section: Polymer Nanoparticles: Our Recent Contributionsmentioning

confidence: 99%

Confined glassy properties of polymer nanoparticles

Zhang

Guo

Priestley³

2013

J Polym Sci B Polym Phys

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For nearly the past two decades, significant effort has been devoted to pursuing an understanding of the glass transition temperature and associated dynamics of polymers confined to the nanoscale. Without question, we know more about the glassy properties of confined polymers today than we knew two decades ago or even a decade ago. Much of our understanding has been obtained via studies on thin polymer films, as they are facile to process and are of substantial technological importance. Nevertheless, studies on polymers confined to other geometries are becoming increasingly more important as we pursue questions difficult to address using thin films and as technology demands the use of confined polymers beyond thin films. In this feature article, we highlight the impact of nanoscale confinement on the glassy properties of polymer nanoparticles. Although the emphasis is placed on contributions from our work, a discussion of the related literature is also presented. Our aim is to elucidate commonalities or fundamental differences in the deviations of glassy properties from the bulk for polymers confined to different geometries. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 574-586 KEYWORDS: calorimetry; confinement; fragility; glass transition; nanoparticles; structural relaxation INTRODUCTION Central to the advancement of many technologies is the miniaturization of functional devices to the nanometer length scale. As polymers continue to play a prominent role in material solutions in meeting the challenges of reducing size, they are undoubtedly being utilized at length scales that are approaching the dimensions of the unperturbed macromolecule. Furthermore, with decreasing the confining dimension to the nanoscale an increasingly larger fraction of molecules are in direct contact with interfaces. Often, the average properties or the distribution in properties away from the interfaces of a confined polymer can be strongly perturbed from the bulk. It is the deviation in properties of confined polymers relative to the bulk that is commonly referred to as the confinement effect, and in the special case when the property of interest is the glass transition temperature (T g ), the T g -confinement effect.

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“…We note that shear-induced transitions are usually referred to as globular-coil transitions [7,26,38]. However, in the grafted scenario the transition turns out to be rather a globular-stretch transition.…”

Section: Resultsmentioning

confidence: 90%

Hydrodynamic Shear Effects on Grafted and Non-Grafted Collapsed Polymers

Schwarzl

Netz

2018

Polymers

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Abstract:We study collapsed homo-polymeric molecules under linear shear flow conditions using hydrodynamic Brownian dynamics simulations. Tensile force profiles and the shear-rate-dependent globular-coil transition for grafted and non-grafted chains are investigated to shine light on the different unfolding mechanisms. The scaling of the critical shear rate, at which the globular-coil transition takes place, with the monomer number is inverse for the grafted and non-grafted scenarios. This implicates that for the grafted scenario, larger chains have a decreased critical shear rate, while for the non-grafted scenario higher shear rates are needed in order to unfold larger chains. Protrusions govern the unfolding transition of non-grafted polymers, while for grafted polymers, the maximal tension appears at the grafted end.

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Probing structural and dynamical transitions in polymer globules by force

Cited by 11 publications

References 17 publications

Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

Confined glassy properties of polymer nanoparticles

Hydrodynamic Shear Effects on Grafted and Non-Grafted Collapsed Polymers

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