How Long are Polymer Chains in Poly(3,4-ethylenedioxythiophene):Tosylate Films? An Insight from Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Donghyun Kim ◽  
Juan Felipe Franco-Gonzalez ◽  
Igor Zozoulenko
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Polymer Chains ◽  
Dynamics Simulations

scholarly journals Interface Characteristics of Neat Melts and Binary Mixtures of Polyethylenes from Atomistic Molecular Dynamics Simulations

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1059
Author(s):  
Sanghun Lee ◽  
Curtis W. Frank ◽  
Do Y. Yoon
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Molecular Dynamics Simulations ◽  
Binary Mixtures ◽  
Surface Segregation ◽  
Surface Region ◽  
Polymer Chains ◽  
Methyl Groups ◽  
Free Standing ◽  
Dynamics Simulations

Molecular dynamics simulations of free-standing thin films of neat melts of polyethylene (PE) chains up to C150H302 and their binary mixtures with n-C13H28 are performed employing a united atom model. We estimate the surface tension values of PE melts from the atomic virial tensor over a range of temperatures, which are in good agreement with experimental results. Compared with short n-alkane systems, there is an enhanced surface segregation of methyl chain ends in longer PE chains. Moreover, the methyl groups become more segregated in the surface region with decreasing temperature, leading to the conclusion that the surface-segregation of methyl chain ends mainly arises from the enthalpic origin attributed to the lower cohesive energy density of terminal methyl groups. In the mixtures of two different chain lengths, the shorter chains are more likely to be found in the surface region, and this molecular segregation in moderately asymmetric mixtures in the chain length (C13H28 + C44H90) is dominated by the enthalpic effect of methyl chain ends. Such molecular segregation is further enhanced and dominated by the entropic effect of conformational constraints in the surface for the highly asymmetric mixtures containing long polymer chains (C13H28 + C150H3020). The estimated surface tension values of the mixtures are consistent with the observed molecular segregation characteristics. Despite this molecular segregation, the normalized density of methyl chain ends of the longer chain is more strongly enhanced, as compared with the all-segment density of the longer chain itself, in the surface region of melt mixtures. In addition, the molecular segregation results in higher order parameter of the shorter-chain segments at the surface and deeper persistence of surface-induced segmental order into the film for the longer chains, as compared with those in neat melt films.

Molecular insight into the Mullins effect: irreversible disentanglement of polymer chains revealed by molecular dynamics simulations

2017 ◽  
Vol 19 (29) ◽  
pp. 19468-19477 ◽  
Author(s):  
Chi Ma ◽  
Tuo Ji ◽  
Christopher G. Robertson ◽  
R. Rajeshbabu ◽  
Jiahua Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Molecular Model ◽  
Polymer Chains ◽  
Mullins Effect ◽  
Key Characteristics ◽  
Dynamics Simulations ◽  
First Time ◽  
Insight Into

For the first time, the key characteristics associated with the Mullins effect are captured by a molecular model.

Simulation study on the subdiffusion of polymer chains in crowded environments containing nanoparticles

2021 ◽  
Author(s):  
Rong-Xing Lu ◽  
Jian-Hua Huang ◽  
Meng-Bo Luo
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Simulation Study ◽  
Polymer Chains ◽  
Dynamics Simulations ◽  
Crowded Environments

Polymer chains in crowded environments often show subdiffusive behavior. We adopt molecular dynamics simulations to study the conditions for the subdiffusion of polymer chains in crowded environments containing randomly distributed,...

Molecular dynamics simulation of thermo-mechanical behaviour of elastomer cross-linked via multifunctional zwitterions

2019 ◽  
Vol 21 (38) ◽  
pp. 21615-21625 ◽  
Author(s):  
Naveed Athir ◽  
Ling Shi ◽  
Sayyed Asim Ali Shah ◽  
Zhiyu Zhang ◽  
Jue Cheng ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Dynamics Simulations

Coarse-grained (CG) molecular dynamics simulations have been employed to study the thermo-mechanical response of a physically cross-linked network composed of zwitterionic moieties and fully flexible elastomeric polymer chains.

Thermal Conductivity of Polyethylene Chains Using Molecular Dynamics Simulations

2008 ◽  
Author(s):  
Asegun Henry ◽  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Polymer Chains ◽  
High Thermal Conductivity ◽  
Polymer Materials ◽  
Single Chain ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Limiting Case

We used molecular dynamics simulations to calculate the thermal conductivity of polyethylene chains, by employing the widely used Green-Kubo formula. The simulations use the AIREBO potential and employ periodic boundary conditions to mimic the dynamics of an infinite chain. In this limiting case, we observed that when the simulation domain is large enough the thermal conductivity diverges. The results suggest that single polymer chains intrinsically have high thermal conductivity. Although polymers are generally known to have low thermal conductivity, our observation of divergent thermal conductivity in a single chain suggests that high thermal conductivity polymer materials can be engineered, which would be of interest to a wide range of applications.

scholarly journals Strong reduction of the chain rigidity of hyaluronan by selective binding of Ca2+ ions

2020 ◽  
Author(s):  
G. Giubertoni ◽  
A. Pérez de Alba Ortíz ◽  
F. Bano ◽  
X. Zhang ◽  
R.J. Linhardt ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Electrostatic Interactions ◽  
Structural Changes ◽  
Polymer Chains ◽  
Single Chain ◽  
Molecular Hydrogen Bond ◽  
Dynamics Simulations ◽  
Chain Force ◽  
Molecular Picture

ABSTRACTThe biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well-recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intra-molecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of ~10-15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation, and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain.TOC

Polymer Nanocomposites: Molecular Dynamics Simulations of Polystyrene and Polystyrene-Polyisoprene Block Copolymer Nanocomposites

2002 ◽  
Vol 733 ◽  
Author(s):  
D. Shah ◽  
I. A. Bitsanis ◽  
U. Natarajan ◽  
E. Hackett ◽  
E.P. Giannelis
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Electrostatic Interactions ◽  
Polymer Chains ◽  
Aromatic Rings ◽  
Mobile Species ◽  
Minimum Number ◽  
Silicate Surface ◽  
Dynamics Simulations ◽  
Silicate Layers

AbstractMolecular dynamics simulations were used to study the interlayer structure and dynamics of polystyrene (PS) and polystyrene-polyisoprene (PS-PI) block copolymers intercalated in organically modified layered silicates. In the case of PS the polymer chains displace the aliphatic surfactant chains and reside adjacent to the silicate layers. The electrostatic interactions between the aromatic rings on the PS chains and the silicate surface drive the intercalation of the polymer into the host galleries. PI, which lacks such electrostatic interactions, is immiscible (does not intercalate) with the host. There appears to be a minimum number of PS mers for intercalation of PS-PI copolymers to take place. The intercalated copolymer appears to structure inside the host galleries with the PS mers adjacent to the silicate layers and the corresponding PI away from the surface and towards the middle of the gallery. Using the mean square displacements we find that PS is the least mobile species in the galleries with the surfactant chains been the most mobile of all.

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