Fully Atomistic Molecular Dynamics Simulations of Hydroxyl-Terminated Polybutadiene with Insights into Hydroxyl Aggregation

Tow, Garrett M.; Maginn, Edward J.

doi:10.1021/acs.macromol.9b02632

Cited by 19 publications

(63 citation statements)

References 83 publications

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“…PE acts as a building block for the synthesis and production of alkyd resins, varnishes, polyvinyl chloride stabilizers, tall oil esters, olefin antioxidants, and many other commercial products. Furthermore, PE has a tetra-functional –OH group, which can be passed in copolyesters to drive crosslinking networking to improve the mechanical property [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Amarasekara et al synthesized poly(levulinic acid–pentaerythritol), exhibiting a crosslinked structure and can be applied in producing household items, machine parts, medical equipment, packaging, and storage containers [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Bio-Based Poly(Butylene Adipate-co-Butylene Itaconate) Copolyesters with Pentaerythritol: A Thermal, Mechanical, Rheological, and Molecular Dynamics Simulation Study

et al. 2020

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Bio-based unsaturated poly(butylene adipate-co-butylene itaconate) (PBABI) aliphatic copolyesters were synthesized with pentaerythritol (PE) as a modifier, observing the melting point, crystallization, and glass transition temperatures were decreased from 59.5 to 19.5 °C and 28.2 to −9.1 °C as an increase of itaconate concentration, and Tg ranged from −54.6 to −48.1 °C. PBABI copolyesters tend to the amorphous state by the existence of the BI unit above 40 mol%. The yield strength, elongation, and Young’s modulus at different BA/BI ratios were valued in a range of 13.2–13.8 MPa, 575.2–838.5%, and 65.1–83.8 MPa, respectively. Shear-thinning behavior was obtained in all BA/BI ratios of PBABI copolyesters around an angular frequency range of 20–30 rad s−1. Furthermore, the thermal and mechanical properties of PBABI copolyesters can be well regulated via controlling the itaconic acid contents and adding the modifier. PBABI copolyesters can be coated on a 3D air mesh polyester fabric to reinforce the mechanical property for replacing traditional plaster applications.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Bio-Based Poly(Butylene Adipate-co-Butylene Itaconate) Copolyesters with Pentaerythritol: A Thermal, Mechanical, Rheological, and Molecular Dynamics Simulation Study

et al. 2020

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Section: Simulation Details and Cross-linking Methodologymentioning

confidence: 99%

“…The model and quantity of HTPB employed in this work is that from our previous work, with additional parameters for IPDI based on the all-atom optimized potentials for liquid simulation (OPLS-AA) force field; the atom typing is depicted in Figures S1–S4 and the force field parameters are given in Tables S1–S5. Five configurationally independent systems of 1 microsecond equilibrated HTPB melts at 333 K and 1 atm were taken from previous work . Full details of the polymer model are provided in the previous work, but a few quantities are reproduced here: 51450 total HTPB atoms, 50 difunctional chains, 50 branched trifunctional chains, 250 total hydroxyl groups, an average molecular weight of 2800.69 g/mol, and the equilibrated density of 0.8750 ± 0.0002 g/mol.…”

Section: Simulation Details and Cross-linking Methodologymentioning

confidence: 99%

“…To relax the system, the Fast Inertial Relaxation Engine (FIRE) minimization algorithm was employed in addition to the temporary use of dummy atoms at the center of the IPDI rings, as shown in Figure S4, to prevent the formation of unrealistic configurations of interlocked IPDI rings or polybutadiene segments within the IPDI cycle. Additionally, the stereochemistry of polybutadiene monomers was maintained during minimization using the same procedure utilized by Tow and Maginn during the initialization of their HTPB melt …”

Section: Simulation Details and Cross-linking Methodologymentioning

confidence: 99%

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Cross-Linking Methodology for Fully Atomistic Models of Hydroxyl-Terminated Polybutadiene and Determination of Mechanical Properties

Tow

Maginn

2021

Macromolecules

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A computational method for preserving the equilibrated structure of a fully atomistic model of a prepolymer melt while introducing cross-links is introduced. An atomistic model of hydroxyl-terminated polybutadiene (HTPB) is cured using isophorone diisocyanate (IPDI) to form an HTPB-IPDI elastomer. After cross-linking, the elastomer is quenched to several different temperatures and subsequently stressed via both compressive and tensile deformations to assess mechanical properties as a function of temperature. This study establishes the framework for investigating the degradation and embrittlement of HTPB-IPDI binders by molecular simulation.

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“…The cross terms couple internal coordinates in an effort to better reproduce the molecular energetics as well as the dynamics of a system by accounting for anharmonic and coupling interactions. However, it is of interest to develop a Class I force field for AP to use in conjunction with existing Class I force fields for the other components of conventional solid propellant, aluminum oxide [56] and the polymeric binder [57]. Here, we parameterize an AP force field with our force field optimization workflow; we previously had utilized hand-tuning methods to develop a Class I AP force field.…”

Section: Case Study: Hydrofluorocarbon Force Fieldsmentioning

confidence: 99%

Machine Learning Directed Optimization of Classical Molecular Modeling Force Fields

Befort,

DeFever,

Tow

et al. 2021

Preprint

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Quantitatively accurate molecular models, called force fields, are necessary for predictive molecular simulations. However, optimizing force fields to accurately reproduce experimental properties is a challenging endeavor. Here we present a machine learning directed workflow for force field optimization. Surrogate-assisted optimization is used to evaluate millions of prospective force field parameters while requiring only a small fraction of those to be evaluated with molecular simulations. The generality of the approach is demonstrated with two distinct test cases: optimizing force fields for simulations of hydrofluorocarbon (HFC) vapor-liquid equilibrium (VLE) and an ammonium perchlorate (AP) crystal phase. Our workflow identifies parameter sets for HFC-32 and HFC-125 which reproduce six experimental VLE properties to within 1.5% and 2.5% error, respectively, which are remarkably better than existing conventional all-atom force fields. When applied to AP, our workflow identifies parameter sets that better reproduce the AP structure than the best available force field in the literature and our own hand-tuned AP force field. The force field optimization workflow is general and can be used to improve the accuracy of existing force fields and develop new force fields for specific systems.

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Fully Atomistic Molecular Dynamics Simulations of Hydroxyl-Terminated Polybutadiene with Insights into Hydroxyl Aggregation

Cited by 19 publications

References 83 publications

Synthesis of Bio-Based Poly(Butylene Adipate-co-Butylene Itaconate) Copolyesters with Pentaerythritol: A Thermal, Mechanical, Rheological, and Molecular Dynamics Simulation Study

Synthesis of Bio-Based Poly(Butylene Adipate-co-Butylene Itaconate) Copolyesters with Pentaerythritol: A Thermal, Mechanical, Rheological, and Molecular Dynamics Simulation Study

Cross-Linking Methodology for Fully Atomistic Models of Hydroxyl-Terminated Polybutadiene and Determination of Mechanical Properties

Machine Learning Directed Optimization of Classical Molecular Modeling Force Fields

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