Recent progress on polymer dynamics by neutron scattering: From simple polymers to complex materials

Colmenero, Juan; Arbe, Arantxa

doi:10.1002/polb.23178

Cited by 59 publications

(46 citation statements)

References 153 publications

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“…For this reason, many computational and experimental works have been performed in recent years to understand the polymer dynamics at the interface and in the interphase [127,128,328,329,[370][371][372][373][374][375][376][377][378][379][380][381][382]. While extensive works have been done to explore the chain dynamics inside PNCs, widely different and often conflicting results are reported.…”

Section: Polymer Dynamics At Interfaces and In Interphasesmentioning

confidence: 99%

Challenges in Multiscale Modeling of Polymer Dynamics

et al. 2013

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The mechanical and physical properties of polymeric materials originate from the interplay of phenomena at different spatial and temporal scales. As such, it is necessary to adopt multiscale techniques when modeling polymeric materials in order to account for all important mechanisms. Over the past two decades, a number of different multiscale computational techniques have been developed that can be divided into three categories: (i) coarse-graining methods for generic polymers; (ii) systematic coarse-graining methods and (iii) multiple-scale-bridging methods. In this work, we discuss and compare eleven different multiscale computational techniques falling under these categories and assess them critically according to their ability to provide a rigorous link between polymer chemistry and rheological material properties. For each technique, the fundamental ideas and equations are introduced, and the most important results or predictions are shown and discussed. On the one hand, this review provides a comprehensive tutorial on multiscale computational techniques, which will be of interest to readers newly entering this field; on the other, it presents a critical discussion of the future opportunities and key challenges in the multiscale geometric mapping matrix between all-atomistic and coarse-grained models N number of monomers per chain N e entanglement length, which is the number of monomers between two entanglements n v number of polymer chains per unit volume n ij (n 0 (r ij )) entanglement number (at equilibrium) between particle pairs i and j p r , P R configurational probability distributions in all-atomistic and coarse-grained models, respectively R ee end-to-end distance of polymer chain R G radius of gyration of polymer chain s segment index/contour length variable along primitive chain S(q) single chain coherent dynamic scattering function Z number of entanglements per chain, defined as Z = N/N e α exponent in standard Mittag-Leffler function σ

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Section: Polymer Dynamics At Interfaces and In Interphasesmentioning

confidence: 99%

Challenges in Multiscale Modeling of Polymer Dynamics

et al. 2013

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“…The inspection of the recent literature on the application of quasielastic neutron scattering (QENS) techniques on polymeric materials [1] reveals that this is indeed a very active field. The selectivity provided by the combination of neutron scattering and isotopic -in particular, proton/deuterium-labeling allows the isolated study of chosen molecular groups and/or components in a system.…”

Section: Introduction: Trends In Qens Investigations Of Polymer Systemsmentioning

confidence: 99%

Nanophase Separation and Exotic Dynamic Behavior in Comb-Like Polymers

Arbe

2013

J. Phys. Soc. Jpn.

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We show the potential of neutron scattering combined with isotopic labeling to unravel structural and dynamical properties of 'comb-like' polymers. Results on homopolymers with alkyl side groups of varying length, namely on the families of poly(n-alkyl methacrylates) (PnMAs) and poly(alkylene oxides) (PAOs) are summarized. Diffraction experiments and fully atomistic molecular dynamics simulations evidence the formation of self-assembled nanodomains of the side groups surrounded by the main chains, independently of the nature of the latter. Neutron spin echo, time of flight and backscattering techniques were employed to investigate the collective dynamics relating inter-and intra-nanodomain correlations as well as the incoherent scattering function of hydrogens. The results are combined with other experimental techniques -dielectric spectroscopy and differential scanning calorimetry-to put into a context the dynamical processes identified. Plasticization and confinement effects arise in PnMAs, but not in the PAOs counterparts. The results point to the dynamic asymmetry developed in systems with intrinsic dynamic heterogeneities between the constituent parts as the key ingredient leading to the main features observed in PnMAs. This scenario is supported by coarsegrained simulations on generic comb-like polymers.

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“…Nevertheless, these large scale dynamics are those which are mainly responsible for controlling the rheological properties of a glass-forming material. 49 These properties depend considerably on how larger or smaller is the working temperature from the T g , and therefore, we devoted a part of our research for the computation of the glass-transition temperature of the studied films.…”

Section: A Glass-transition Temperaturementioning

confidence: 99%

A coarse-grained molecular dynamics study of segmental structure and mobility in capped crosslinked copolymer films

Davris

Lyulin

2015

The Journal of Chemical Physics

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We present results from molecular-dynamics simulations of a generic bead-spring model of copolymer chains confined between solid walls and report on the glass-transition temperature and segmental dynamics as a function of film thickness and mesh size (the end-to-end distance of the subchains in the crosslinked polymer networks). Apparently, the glass-transition temperature displayed a steep increase for mesh-size values much smaller than the radius of gyration of the bulk chains, otherwise it remained invariant to mesh-size variations. The rise in the glass-transition temperature with decreasing mesh size and film thickness was accompanied by a monotonic slowing-down of segmental dynamics on all studied length scales. This observation is attributed to the correspondingly decreased width of the bulk density layer that was obtained in films whose thickness was larger than the end-to-end distance of the bulk polymer chains. To test this hypothesis, additional simulations were performed in which the crystalline walls were replaced with amorphous or rough walls. In the amorphous case, the high polymer density close to the walls vanished, but the dynamic response of the film was not affected. The rough walls, on the other hand, only slightly decreased the density close to the walls and led to a minor slowing-down in the dynamics at large length-scales.

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Recent progress on polymer dynamics by neutron scattering: From simple polymers to complex materials

Cited by 59 publications

References 153 publications

Challenges in Multiscale Modeling of Polymer Dynamics

Challenges in Multiscale Modeling of Polymer Dynamics

Nanophase Separation and Exotic Dynamic Behavior in Comb-Like Polymers

A coarse-grained molecular dynamics study of segmental structure and mobility in capped crosslinked copolymer films

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