Workflow for Investigating Thermodynamic, Structural, and Energy Properties of Condensed Polymer Systems

Andrews, James; Blaisten‐Barojas, Estela

doi:10.1007/978-3-030-69984-0_75

Cited by 3 publications

(4 citation statements)

References 12 publications

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“…A similar process was used for establishing the topology file of the glycerol (C 3 H 8 O 3 ) liquid. The simulation strategy is an adaptation of our more general MD modeling process for macromolecular systems (Andrews and Blaisten-Barojas, 2022).…”

Section: Model and Methodsmentioning

confidence: 99%

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Hopkins,

Blaisten-Barojas

2023

Front. Nanotechnol.

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Polymers exhibiting thermoresponsive behavior above a lower critical solution temperature (LCST) undergo a coil-to-globule phase transition that has many biomedical applications, including biosensing, the control of release devices, and gene or drug delivery systems. In addition, there has been sustained scientific interest in these polymers for their use in industrial applications, including water treatment and desalination. Since the coil-to-globule phase transition is greatly affected by the hydrophilic/hydrophobic balance of the polymer-solvent interactions, the LCST of a particular thermoresponsive polymer depends on the solvent environment and can be tuned through the modification of solution parameters such as co-solvent molar concentrations. While there have been numerous experimental and computational studies focused on the properties of these polymers in aqueous solutions, study of their behavior in more viscous solvents has been limited. In this article, the thermoresponsive behavior of poly (N-isopropylacrylamide) (PNIPAM) and poly (N,N-diethylacrylamide) (PDEA) has been evaluated when in solution with water, the highly viscous liquid glycerol, and both 50:50 and 90:10 glycerol:water mixtures. The adopted methodology includes molecular dynamics techniques and a modified OPLS all-atom force field, which is particularly challenging when the monomers of the targeted polymers have side-chains consisting of a hydrophobic isopropyl group and a hydrophilic amide group along the carbon backbone chain. Hence, our approach entailed simulations at the microsecond scale. The structural and energetic properties of the polymers were characterized, including radius of gyration, solvent accessible surface area, polymer-solvent hydrogen bonding, and interaction energies. Our predictions indicate that these polymers sustain a coil-to-globule phase transition in glycerol solvents at significantly higher LCSTs when compared to the LCST in less viscous aqueous solutions. These predictions highlight valuable insights that will prove advantageous for industrial and nano-scale applications requiring polymer phase behavior with elevated LCST well above ambient temperature.

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Section: Model and Methodsmentioning

confidence: 99%

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Hopkins,

Blaisten-Barojas

2023

Front. Nanotechnol.

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“…One of these structures was selected and positioned with random orientations at the sites of a 6 × 6 × 6 cubic lattice to build a condensed system with 216 PEG 2000 , which sums up to 68688 atoms. A simulation workflow we implemented recently was followed. , First, a steepest decent minimization was performed followed by an NPT MD equilibration run of 50 ns at 400 K and 101.325 kPa. Constraints on the hydrogen atoms were applied with the LINCS algorithm (lincs-order = 4).…”

Section: Methods and Modelsmentioning

confidence: 99%

“…A simulation workflow we implemented recently was followed. 28,49 First, a steepest decent minimization was performed followed by an NPT MD equilibration run of 50 ns at 400 K and 101.325 kPa. Constraints on the hydrogen atoms were applied with the LINCS algorithm (lincs-order = 4).…”

Section: Methods and Modelsmentioning

confidence: 99%

Solutions and Condensed Phases of PEG₂₀₀₀ from All-Atom Molecular Dynamics

Sponseller

Blaisten‐Barojas

2021

J. Phys. Chem. B

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Extensive all-atom molecular dynamics studies of polyethylene glycol (PEG 2000 ) when solvated and in the polymer bulk condensed phases were performed across a wide temperature range. We proposed two modified all-atom force field and observed the fate of the PEG 2000 macromolecule when solvated in water, water with 4% ethanol, and ethyl acetate. In aqueous solutions, the macromolecule collapsed into a prolate spheroidal ball-like structure while adopting a rather elongated coiled structure in ethyl acetate. Inspection of the polymer-condensed phases across the 150−340 K temperature range enabled the atomistic view of the solid glass below the glass transition temperature of 230 K < T g < 250 K and the rubber behavior above T g . Predicted properties include the enthalpy, density, and cohesive energy temperature behavior, the specific heat, thermal expansivity, thermal compressibility, bulk modulus, and Hildebrand solubility parameter both below and above T g . Within the polymer matrix, the PEG 2000 macromolecules were entangled displaying a wide distribution of sizes that persisted when transitioning from the glass to the rubbery phases. Calculated properties agree very well with experiments when available or stand as crucial predictions while awaiting experimental measurement. Understanding the thermodynamics and structure of this useful polymer enables the efficient prediction of its behavior when building novel composite materials for nanomedicine and nanotherapeutics.

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“…The generation of the heterogeneous system of a PLGA surface interfacing with different solvents entailed the preparation of the PLGA solid surface, which was based on our previous work on both PLGA in the condensed phase and the associated computational workflow . The Molecular Dynamics simulations were done with the GROMACS 2018–2020 − package using a 1 fs time step, 1.4 nm cutoff, periodic boundary conditions (PBC), and PME long-range electrostatic corrections.…”

Section: Models and Methodsmentioning

confidence: 99%

Distinctive Formation of PEG-Lipid Nanopatches onto Solid Polymer Surfaces Interfacing Solvents from Atomistic Simulation

Andrews

Blaisten‐Barojas

2021

J. Phys. Chem. B

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The interface between solid poly(lactic acid-co-glycolic acid), PLGA, and solvents is described by large-scale atomistic simulations for water, ethyl acetate, and the mixture of them at ambient conditions. Interactions at the interface are dominated by Coulomb forces for water and become overwhelmingly dispersive for the other two solvents. This effect drives a neat liquid-phase separation of the mixed solvent, with ethyl acetate covering the PLGA surface and water being segregated away from it. We explore with all-atom Molecular Dynamics the formation of macromolecular assemblies on the surface of the PLGA-solvent interface when DSPE-PEG, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(polyethylene glycol) n amine, is added to the solvent. By following in time the deposition of the DSPE-PEG macromolecules onto the PLGA surface, the mechanism of how nanopatches remain adsorbed to the surface despite the presence of the solvent is probed. These patches have a droplet-like aspect when formed at the PLGA-water interface that flatten in the PLGA-ethyl acetate interface case. Dispersive forces are dominant for the nanopatch adhesion to the surface, while electrostatic forces are dominant for keeping the solvent around the new formations. Considering the droplet-like patches as wetting the PLGA surface, we predict an effective wetting behavior at the water interface that fades significantly at the ethyl acetate interface. The predicted mechanism of PEG-lipid nanopatch formation may be generally applicable for tailoring the synthesis of asymmetric PLGA nanoparticles for specific drug delivery conditions.

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Workflow for Investigating Thermodynamic, Structural, and Energy Properties of Condensed Polymer Systems

Cited by 3 publications

References 12 publications

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Solutions and Condensed Phases of PEG₂₀₀₀ from All-Atom Molecular Dynamics

Distinctive Formation of PEG-Lipid Nanopatches onto Solid Polymer Surfaces Interfacing Solvents from Atomistic Simulation

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Workflow for Investigating Thermodynamic, Structural, and Energy Properties of Condensed Polymer Systems

Cited by 3 publications

References 12 publications

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Molecular dynamics simulations evidence the thermoresponsive behavior of PNIPAM and PDEA in glycerol solutions

Solutions and Condensed Phases of PEG2000 from All-Atom Molecular Dynamics

Distinctive Formation of PEG-Lipid Nanopatches onto Solid Polymer Surfaces Interfacing Solvents from Atomistic Simulation

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Product

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About

Solutions and Condensed Phases of PEG₂₀₀₀ from All-Atom Molecular Dynamics