Agglomeration Dynamics In Thermo-Sensitive Polymers Across The Lower Critical Solution Temperature: A Molecular Dynamics Simulation Study

2012 ◽  
Vol 1418 ◽  
Author(s):  
Sanket A. Deshmukh ◽  
Subramanian K.R.S. Sankaranarayanan ◽  
Derrick C. Mancini
Keyword(s):  
Molecular Dynamics ◽  
Lower Critical Solution Temperature ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Solution Temperature ◽  
Strongly Correlated ◽  
Critical Solution Temperature ◽  
Significant Difference ◽  
Fundamental Insight ◽  
Dynamics Simulations

ABSTRACTPoly(N-isopropylacrylamide) (PNIPAM), a classic thermo-sensitive polymer, has a lower critical solution temperature (LCST) at ∼32°C. In this work we have used molecular dynamics simulations to understand the origin of the LCST and agglomeration of PNIPAM chains of 5 and 30 monomer units (5-mer and 30-mer). Experimentally, when the concentration of PNIPAM is >1 ppm, polymer chains after undergoing coil-to-globule transition above the LCST aggregates to yield a stable colloidal dispersion.In our study two PNIPAM chains, consisting of 30 monomer units each, were placed in a cubic simulation cell and were subsequently solvated. Simulations were carried out below and above the LCST, namely at 278 and 310K for 10ns. Simulated trajectories were analyzed for structural and dynamical properties of both PNIPAM and water. We observe coil-to-globule transition in PNIPAM above the LCST. We also find that the PNIPAM chains agglomerate above the LCST. We also observe entanglement in PNIPAM chains below the LCST. We also study agglomeration of 5 PNIPAM chains each consisting of 5 monomer units. There was no significant difference in polymer agglomeration behavior across the LCST for these short chain oligomers. The agglomeration behavior is thus strongly correlated to the size of the polymer chains. These results provide fundamental insight into the atomistic scale mechanism of PNIPAM agglomeration across the LCST.

scholarly journals Atomistic simulation for coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate)

Soft Matter ◽  
2015 ◽  
Vol 11 (12) ◽  
pp. 2423-2433 ◽  
Author(s):  
Sa Hoon Min ◽  
Sang Kyu Kwak ◽  
Byeong-Su Kim
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Lower Critical Solution Temperature ◽  
Atomistic Simulation ◽  
Md Simulations ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Dimethylaminoethyl Methacrylate

We investigate the coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) in the aqueous solution through the lower critical solution temperature (LCST) by atomistic molecular dynamics (MD) simulations.

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.

Effect of Methanol/Water Mixtures on the Lower Critical Solution Temperature of Poly(N-isopropylacrylamide)

2014 ◽  
Vol 1622 ◽  
pp. 25-30 ◽  
Author(s):  
Sanket A. Deshmukh ◽  
Ganesh Kamath ◽  
Derrick C. Mancini ◽  
Subramanian K.R.S. Sankaranarayanan
Keyword(s):  
Mole Fraction ◽  
Lower Critical Solution Temperature ◽  
Md Simulations ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Radius Of Gyration ◽  
Solvation Dynamics ◽  
Water Mixture ◽  
Critical Solution Temperature ◽  
Lcst Behavior

ABSTRACTPoly(N-isopropylacrylamide) (PNIPAM) is a thermo-sensitive polymer that exhibits a lower critical solution temperature (LCST) around 305 K. Below the LCST, PNIPAM is soluble in water and above this temperature polymer chains collapse prior to aggregation. In the presence of methanol, electron paramagnetic resonance (EPR) spectroscopy suggests that, LCST of PNIPAM is depressed up to certain mole fraction of methanol (0.35 mole fraction) and it is speculated that addition of methanol affects the PNIPAM-water interactions. Above 0.35 mole fraction of methanol, LCST gets elevated to temperatures above ∼305 K (32°C) and cannot be detected up to 373 K (100 °C). The atomistic origin of this co-solvency effect on the LCST behavior is not completely understood. In the present study, we have used molecular dynamics (MD) simulations to investigate the effect of methanol-water mixtures on conformational transitions and the LCST of PNIPAM. We employ two different force fields i.e. polymer consistent force-field (PCFF) and CHARMM to study solvation dynamics and the PNIPAM LCST phase transition in various methanol-water mixture compositions (0.018, 0.09, 0.27, 0.5, and 0.98 mole fractions). Simulations are conducted at fully atomistic level for three different temperatures (260, 278, and 310 K) and radius of gyration (Rg) of PNIPAM chains was computed for determination of LCST behavior of PNIPAM.

Multicanonical Molecular Dynamics Simulation Study of the Liquid-Solid and Solid-Solid Transitions in Lennard-Jones Clusters

2011 ◽  
Author(s):  
Toshihiro Kaneko ◽  
Kenji Yasuoka ◽  
Ayori Mitsutake ◽  
Xiao Cheng Zeng
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Transition Temperature ◽  
Peak Position ◽  
Temperature Curve ◽  
Dynamics Simulation ◽  
Lennard Jones ◽  
Dynamics Simulations ◽  
First Time ◽  
Good Agreement

Multicanonical molecular dynamics simulations are applied, for the first time, to study the liquid-solid and solid-solid transitions in Lennard-Jones (LJ) clusters. The transition temperatures are estimated based on the peak position in the heat capacity versus temperature curve. For LJ31, LJ58 and LJ98, our results on the solid-solid transition temperature are in good agreement with previous ones. For LJ309, the predicted liquid-solid transition temperature is also in agreement with previous result.

scholarly journals Reactive molecular dynamics simulation of the high-temperature pyrolysis of 2,2′,2′′,4,4′,4′′,6,6′,6′′-nonanitro-1,1′:3′,1′′-terphenyl (NONA)

RSC Advances ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 5507-5515
Author(s):  
Liang Song ◽  
Feng-Qi Zhao ◽  
Si-Yu Xu ◽  
Xue-Hai Ju
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Dynamics Simulation ◽  
Reactive Molecular Dynamics ◽  
Ring Compounds ◽  
Fused Ring ◽  
Dynamics Simulations

The bimolecular and fused ring compounds are found in the high-temperature pyrolysis of NONA using ReaxFF molecular dynamics simulations.

A polyelectrolyte-containing copolymer with a gas-switchable lower critical solution temperature-type phase transition

2019 ◽  
Vol 10 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Jin-Jin Li ◽  
Yin-Ning Zhou ◽  
Zheng-Hong Luo ◽  
Shiping Zhu
Keyword(s):  
Phase Transition ◽  
Cloud Point ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Type Phase

A polyelectrolyte-containing copolymer with a CO2/N2-switchable cloud point, resulting from the gas-induced alternation of hydrophilicity, was prepared.

Molecular Dynamics Simulation Study of Lecithin Inhibiting Hydrate-Dissociation

2017 ◽  
Vol 890 ◽  
pp. 252-259
Author(s):  
Le Wang ◽  
Guan Cheng Jiang ◽  
Xin Lin ◽  
Xian Min Zhang ◽  
Qi Hui Jiang
Keyword(s):  
Molecular Dynamics ◽  
Water Movement ◽  
Simulation Analysis ◽  
Mass Density ◽  
Dynamics Simulation ◽  
Dissociation Process ◽  
Hydrate Dissociation ◽  
Hydrocarbon Chains ◽  
Dynamics Simulations ◽  
Mass Density Profile

Molecular dynamics simulations are used to study the dissociation inhibiting mechanism of lecithin for structure I hydrates. Adsorption characteristics of lecithin and PVP (poly (N-vinylpyrrolidine)) on the hydrate surfaces were performed in the NVT ensemble at temperatures of 277K and the hydrate dissociation process were simulated in the NPT ensemble at same temperature. The results show that hydrate surfaces with lecithin is more stable than the ones with PVP for the lower potential energy. The conformation of lecithin changes constantly after the balanced state is reached while the PVP molecular dose not. Lecithin molecule has interaction with lecithin nearby and hydrocarbon-chains of lecithin molecules will form a network to prevent the diffusion of water and methane molecules, which will narrow the available space for hydrate methane and water movement. Compared with PVP-hydrate simulation, analysis results (snapshots and mass density profile) of the dissociation simulations show that lecithin-hydrate dissociates more slowly.

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