Elucidation of conformational characteristics and configurational properties of poly((R)-3-hydroxybutyrate) by ab initio statistical mechanics

Sasanuma, Yuji; Katsumata, Shiori

doi:10.1038/pj.2012.203

Cited by 14 publications

(17 citation statements)

References 37 publications

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“…In blends, the values of C ∞ PLA and C ∞ PHB were almost identical to those in the pure systems, indicating that the inherent stiffness of the chains does not change upon blending. The characteristic ratios are qualitatively comparable with the results of 11.8 for PLA and 6.1–6.3 for PHB obtained using light scattering experiments. , The observed small quantitative differences may stem from the short length of the chains in our simulations. Nevertheless, this confirms that our systems are well-equilibrated.…”

Section: Resultssupporting

confidence: 89%

“…Using the characteristic ratios, we calculated the persistence lengths l p PLA = 0.8 ± 0.1 nm and l p PHB = 0.5 ± 0.1 nm for PLA and PHB, respectively. At the same time, data from refs and give l p PLA = 0.9 nm and l p PHB = 0.5 nm; i.e., our simulations reproduce the difference in stiffness between PLA and PHB well. This validates the force field and the model.…”

Section: Resultssupporting

confidence: 76%

“…The characteristic ratios are qualitatively comparable with the results of 11.8 for PLA and 6.1−6.3 for PHB obtained using light scattering experiments. 75,76 The observed small quantitative differences may stem from the short length of the chains in our simulations. Nevertheless, this confirms that our systems are wellequilibrated.…”

Section: Resultsmentioning

confidence: 87%

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Scale-Dependent Miscibility of Polylactide and Polyhydroxybutyrate: Molecular Dynamics Simulations

et al. 2017

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Miscibility of polylactide (PLA) and polyhydroxybutyrate (PHB) is studied by the microsecond atomistic molecular-dynamics (MD) simulations for the first time. The model and the simulation protocol were confirmed through comparison of the glass transition temperature (T g ) with experimental data. It was established that PLA and PHB are miscible on the basis of the 2 Flory-Huggins theory. Analysis of the mobilities of PLA and PHB subchains revealed that the blends have two transitions to a glassy state at the length scale of a few Kuhn segments, which is in line with the predictions of the self-concentration model. At the same time at the larger length scale, a single transition to a glassy state was observed suggesting scale-dependence of PLA and PHB miscibility. This scale-dependence was confirmed through the evaluation of the interchain pair correlation functions.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 76%

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Scale-Dependent Miscibility of Polylactide and Polyhydroxybutyrate: Molecular Dynamics Simulations

et al. 2017

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“…Materials. MAA-13 C. 87,88 Acetyl-1-13 C chloride (1.0 g, 12.6 mmol) was added to methyl 2-hydroxyacetate (1.14 g, 12.6 mmol) under nitrogen atmosphere. The solution was stirred at room temperature for 1 h, heated gradually up to 120 °C, and kept there for 2 h. The reaction mixture was thrice washed with saturated saline solution, and the separated organic layer was identified by 1 H and 13 C NMR as MAA-13 C (yield, 0.40 g, 24%).…”

Section: ■ Methodsmentioning

confidence: 99%

Structure–Property Relationships of Poly(glycolic acid) and Poly(2-hydroxybutyrate)

2019

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Conformational analysis of poly(glycolic acid) (PGA) and poly(2-hydroxybutyrate) (P2HB) has been carried out via molecular orbital (MO) calculations and NMR experiments on model compounds. The MO energies validated through comparison with the NMR data were introduced into the rotational isomeric state (RIS) scheme to yield the configurational properties of the two polymers. The spatial configuration of the P2HB chain with chiral centers was calculated by the RIS scheme combined with stochastic processes and expressed as a function of (S)/(R) or meso/ racemo ratio. The above results are compared with those obtained previously for poly(lactic acid) and discussed. The density functional theory calculations with a dispersion force correction were performed for PGA crystal under periodic boundary conditions and revealed the origin of its superior thermostability and mechanical strengths.

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“…As such, the distance between the polar ester groups producing dipoles in grafted hydroxybutyrate (HB) chains is greater than in lactide chains. Furthermore, the persistence lengths of PHB and PLA are 0.5 ± 0.1 and 0.8 ± 0.1 nm, respectively, that is, the PHB chains have a slightly higher flexibility than the PLA ones. − There is, however, a more significant difference in the characteristic ratios, which are 10.2 and 5.8 for PLA and PHB in the long-chain limit, respectively . The characteristic ratio gives a dimensionless measure for the chain size and can be defined as C N = ⟨ R 2 ( N )/ N l b 2 ⟩, where R 2 ( N ) is the square of the intramolecular distance between two monomers separated by N monomers along a chain, l b stands for the mean length of the backbone chemical bond, and the angular brackets denote averaging over the chains .…”

Section: Introductionmentioning

confidence: 99%

Grafted Dipolar Chains: Dipoles and Restricted Freedom Lead to Unexpected Hairpins

et al. 2020

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We use atomistic molecular dynamics simulations to investigate the structure of oligohydroxybutyrate (OHB) and oligolactide (OLA) chains grafted onto cellulose nanocrystals (CNCs) in melts of polyhydroxybutyrate and polylactide chains, respectively. We observed that, contrary to the established theory for neutral chains, the more flexible OHB grafts extend further from the CNC surface, whereas the stiffer OLA ones tend to fold back toward the surface by forming hairpin-like structures. Both OHB and OLA grafts have dipoles but are charge-neutral. To resolve this apparent contradiction, interactions between the grafts' monomers as well as their flexibilities were evaluated. The interaction analysis, however, showed insignificant differences. We examined this further by systematically switching off the dipolar interactions and dihedrals from the OLA grafts. The observed counterintuitive behavior is due to a subtle combination of the dipole−dipole interactions and the additional methylene group in OHB that is critical in allowing the OHB grafts to sample more conformations than the more restricted OLA chains: the steric restrictions are critical and lead to hairpin-like structures and enable dipole−dipole interactions to effectively form a zipper that maintains the hairpin-like conformations.

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Elucidation of conformational characteristics and configurational properties of poly((R)-3-hydroxybutyrate) by ab initio statistical mechanics

Cited by 14 publications

References 37 publications

Scale-Dependent Miscibility of Polylactide and Polyhydroxybutyrate: Molecular Dynamics Simulations

Scale-Dependent Miscibility of Polylactide and Polyhydroxybutyrate: Molecular Dynamics Simulations

Structure–Property Relationships of Poly(glycolic acid) and Poly(2-hydroxybutyrate)

Grafted Dipolar Chains: Dipoles and Restricted Freedom Lead to Unexpected Hairpins

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