scholarly journals A Molecular Dynamics Simulation Scenario for Studying Solvent-mediated Interactions of Polymers and Application to Thermoresponse of Poly (N-isopropylacrylamide) in Water

2021 ◽  
Author(s):  
Edder García ◽  
Debdip Bhandary ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Computation Time ◽  
Umbrella Sampling ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Single Chain ◽  
Representative Sampling ◽  
Advanced Sampling ◽  
Adequate Sampling ◽  
Equilibrium Data ◽  
Simulation Scenario

Studying equilibrium properties of polymers in solution by atomistic simulations is a challenging task as the available computation time is often not sufficient to ensure representative sampling of the phase space. One approach to tackle this problem is to create a simulation scenario which is simple enough to enable adequate sampling of equilibrium states while it retains the essential parts of the physics of the polymer in solution. In this work, we present and test such a scenario, which is designed for studying whether a given polymer will aggregate or dissolve in a given solvent. Two periodic polymer molecules are simulated in the explicit solvent. The distance d between the polymer chains lends itself as an order parameter so that advanced sampling techniques, such as umbrella sampling, can be applied easily. A state corresponding to dissolved polymers (large d) and a state corresponding to aggregated polymers (small d) can be defined. The scenario misses the intramolecular collapse of the single chain, but it retains full atomistic detail regarding the polymer-solvent and the intermolecular polymer-polymer interactions. Thethermoresponsive behavior of PNIPAM in water is studied with the new scenario, and it is shown that quantitative predictions of the experimental equilibrium data can be obtained after adjusting a single state-independent parameter in the force field.

scholarly journals Advances in the Multi-Orthogonal Folding of Single Polymer Chains into Single-Chain Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 293
Author(s):  
Agustín Blazquez-Martín ◽  
Ester Verde-Sesto ◽  
Angel J. Moreno ◽  
Arantxa Arbe ◽  
Juan Colmenero ◽  
...  
Keyword(s):  
Computer Simulations ◽  
Chemical Species ◽  
Synthetic Polymers ◽  
Review Article ◽  
Polymer Chains ◽  
Single Chain ◽  
High Dilution ◽  
Covalent Bonds ◽  
Covalent Interactions ◽  
Individual Polymer

The folding of certain proteins (e.g., enzymes) into perfectly defined 3D conformations via multi-orthogonal interactions is critical to their function. Concerning synthetic polymers chains, the “folding” of individual polymer chains at high dilution via intra-chain interactions leads to so-called single-chain nanoparticles (SCNPs). This review article describes the advances carried out in recent years in the folding of single polymer chains into discrete SCNPs via multi-orthogonal interactions using different reactive chemical species where intra-chain bonding only occurs between groups of the same species. First, we summarize results from computer simulations of multi-orthogonally folded SCNPs. Next, we comprehensively review multi-orthogonally folded SCNPs synthesized via either non-covalent bonds or covalent interactions. Finally, we conclude by summarizing recent research about multi-orthogonally folded SCNPs prepared through both reversible (dynamic) and permanent bonds.

Chemiluminescent self-reported unfolding of single-chain nanoparticles

2021 ◽  
Author(s):  
Fabian R. Bloesser ◽  
Sarah L. Walden ◽  
Ishrath M. Irshadeen ◽  
Lewis C. Chambers ◽  
Christopher Barner-Kowollik
Keyword(s):  
Polymer Chains ◽  
Linear Polymer ◽  
Single Chain

We demonstrate the light-induced, crosslinker mediated collapse of linear polymer chains into single-chain nanoparticles (SCNPs) capable of self-reporting their unfolding.

scholarly journals Investigation of Surfactant–Membrane Interaction Using Molecular Dynamics Simulation with Umbrella Sampling

2021 ◽  
Vol 1 (10) ◽  
pp. 1470-1480
Author(s):  
Yunqiao Ma ◽  
Sadiye Velioğlu ◽  
Thein An Trinh ◽  
Rong Wang ◽  
Jia Wei Chew
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Umbrella Sampling ◽  
Dynamics Simulation ◽  
Membrane Interaction

scholarly journals Contraction of Entangled Polymers After Large Step Shear Deformations in Slip-Link Simulations

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 370 ◽  
Author(s):  
Yuichi Masubuchi
Keyword(s):  
Dynamics Simulation ◽  
Uniaxial Deformation ◽  
Single Chain ◽  
Orientational Relaxation ◽  
Entangled Polymers ◽  
Constraint Release ◽  
Large Step ◽  
Entangled Polymer ◽  
Convective Constraint Release ◽  
Chain Contraction

Although the tube framework has achieved remarkable success to describe entangled polymer dynamics, the chain motion assumed in tube theories is still a matter of discussion. Recently, Xu et al. [ACS Macro Lett. 2018, 7, 190–195] performed a molecular dynamics simulation for entangled bead-spring chains under a step uniaxial deformation and reported that the relaxation of gyration radii cannot be reproduced by the elaborated single-chain tube model called GLaMM. On the basis of this result, they criticized the tube framework, in which it is assumed that the chain contraction occurs after the deformation before the orientational relaxation. In the present study, as a test of their argument, two different slip-link simulations developed by Doi and Takimoto and by Masubuchi et al. were performed and compared to the results of Xu et al. In spite of the modeling being based on the tube framework, the slip-link simulations excellently reproduced the bead-spring simulation result. Besides, the chain contraction was observed in the simulations as with the tube picture. The obtained results imply that the bead-spring results are within the scope of the tube framework whereas the failure of the GLaMM model is possibly due to the homogeneous assumption along the chain for the fluctuations induced by convective constraint release.

scholarly journals Direct observation of morphological transition for an adsorbed single polymer chain

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yukari Oda ◽  
Daisuke Kawaguchi ◽  
Yuma Morimitsu ◽  
Satoru Yamamoto ◽  
Keiji Tanaka
Keyword(s):  
Polymer Chain ◽  
Synthetic Polymer ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Morphological Transition ◽  
Nano Composite ◽  
Force Microscopy ◽  
Local Conformation ◽  
Atomic Force ◽  
Single Polymer Chain

AbstractA better understanding of the structure of polymers at solid interfaces is crucial for designing various polymer nano-composite materials from structural materials to nanomaterials for use in industry. To this end, the first step is to obtain information on how synthetic polymer chains adsorb onto a solid surface. We closely followed the trajectory of a single polymer chain on the surface as a function of temperature using atomic force microscopy. Combining the results with a full-atomistic molecular dynamics simulation revealed that the chain became more rigid on the way to reaching a pseudo-equilibrium state, accompanied by a change in its local conformation from mainly loops to trains. This information will be useful for regulating the physical properties of polymers at the interface.

Structure of Polymer Chains Confined in Vycor

1996 ◽  
Vol 464 ◽  
Author(s):  
Jyotsana Lal ◽  
Sunil K. Sinha ◽  
Loic Auvray
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Form Factor ◽  
Small Angle Neutron Scattering ◽  
Pore Diameter ◽  
Polymer Chains ◽  
Bulk Solution ◽  
Radius Of Gyration ◽  
Single Chain ◽  
Molecular Weights

ABSTRACTWe observe by Small Angle Neutron Scattering (SANS) the structure of polystyrene chains in semi-dilute solutions confined in model porous medium, Vycor. The size of the free polymer chains in solution is always larger than the pore diameter, 70 Å. The use of a suitable mixture of hydrogenated and deuterated solvents and polymers enables us to directly measure the form factor of one single chain among the others. The penetration of the chain in the porous media is almost complete for the concentration (Φ = 20%) and the range of molecular weights (35000 <M< 800000) used. The measured radius of gyration of confined chains is always smaller than the radius of gyration of free chains in the equivalent bulk solution.

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