Structures of Mixed-Tacticity Polyhydroxybutyrates

Haslböck, Maria; Klotz, Moritz; Steiner, Lisa Maria; Sperl, Josef; Sieber, Volker; Zollfrank, Cordt; Opdenbosch, Daniel Van

doi:10.1021/acs.macromol.8b01047

Cited by 9 publications

(64 citation statements)

References 41 publications

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“…As also reported earlier (Haslbö ck et al, 2018), the lattice parameters a and b remained roughly the same, whereas c increased slightly with decreasing f meso [ Fig. 5(a)].…”

Section: Figuresupporting

confidence: 88%

“…The values of total non-amorphous phase are within the measure of uncertainty of the values we previously reported as the fractions of the crystalline phase (Haslbö ck et al, 2018). It is convenient that we earlier selected an integration cutoff at 35 2 (Haslbö ck et al, 2018) (then based on the first halo of the amorphous pattern), since it marks the approximate point of convergence via equation 3.…”

Section: Development Of Fractional Composition With F Mesosupporting

confidence: 54%

“…In the classic crystal model, c is the direction longitudinal along the polymer chains (Marchessault & Kawada, 2004;Birley et al, 1995). As a consequence, we determined small crystallite sizes L c for all f meso in earlier work (Haslbö ck et al, 2018). In the aforementioned model, a and b are the directions perpendicular to the chain orientations.…”

Section: Interpretation Of Directional Disorder Considering the A-phmentioning

confidence: 99%

“…In nature, exclusively isotactic PHB is produced from R-3hydroxybutanoic acid and crystallizes in the -PHB structure (Okamura & Marchessault, 1967;Barham et al, 1984;Wang & Tashiro, 2016). On the basis of earlier work (Bloembergen et al, 1989;Abe et al, 1994;Kemnitzer et al, 1995), we recently prepared synthetic variants in which defined amounts of S monomers were included randomly into the polymer chains (Haslbö ck et al, 2018). By nuclear magnetic resonance spectroscopy, we determined the respective compositions' fractions of meso diads f meso to be quadratically correlated to the fractions of R monomers f R .…”

Section: An Open Question With Regard To Mixed-tacticity Polyhydroxybmentioning

confidence: 99%

“…The function x(f R , f S ) recreates an empirical relation with the fractions of R and S monomers for each f meso (Haslbö ck et al, 2018). For the atactic segments x = (f R + 0.5)(f S + 0.5) and for the isotactic segments x = f R + 0.5f R f S were found to provide suitable progressions of with f meso (Haslbö ck et al, 2019).…”

Section: Figurementioning

confidence: 99%

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Determining paracrystallinity in mixed-tacticity polyhydroxybutyrates

Opdenbosch¹,

Haslböck²,

Zollfrank³

2021

J Appl Cryst

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Recently, the authors reported on the development of crystallinity in mixed-tacticity polyhydroxybutyrates. Comparable values reported in the literature vary depending on the manner of determination, the discrepancies being partially attributable to scattering from paracrystalline portions of the material. These portions can be qualified by peak profile fitting or quantified by allocation of scattered X-ray intensities. However, the latter requires a good quality of the former, which in turn must additionally account for peak broadening inherent in the measurement setup, and due to limited crystallite sizes and the possible presence of microstrain. Since broadening due to microstrain and paracrystalline order both scale with scattering vector, they are easily confounded. In this work, a method to directionally discern these two influences on the peak shape in a Rietveld refinement is presented. Allocating intensities to amorphous, bulk and paracrystalline portions with changing tactic disturbance provided internal validations of the obtained directional numbers. In addition, the correlation between obtained thermal factors and Young's moduli, determined in earlier work, is discussed.

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“…As also reported earlier (Haslbö ck et al, 2018), the lattice parameters a and b remained roughly the same, whereas c increased slightly with decreasing f meso [ Fig. 5(a)].…”

Section: Figuresupporting

confidence: 88%

Section: Development Of Fractional Composition With F Mesosupporting

confidence: 54%

Section: Interpretation Of Directional Disorder Considering the A-phmentioning

confidence: 99%

Section: An Open Question With Regard To Mixed-tacticity Polyhydroxybmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

See 3 more Smart Citations

Determining paracrystallinity in mixed-tacticity polyhydroxybutyrates

Opdenbosch¹,

Haslböck²,

Zollfrank³

2021

J Appl Cryst

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Free Volumes and Grüneisen Parameters in Mixed‐Tacticity Polyhydroxybutyrates

Opdenbosch

Klotz

Haslböck

et al. 2021

Macro Chemistry & Physics

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Recently, nonlinear progressions of mechanical and thermal properties of mixed‐tacticity polyhydroxybutyrates have been discovered with their fraction of meso diads fmeso. Characteristic fmeso is traced by a measure trueλ̂ of polymer chain segment length disturbance, due to the inclusion of S enantiomers in chains consisting otherwise of R monomers. In this article, the material compositions' thermal expansion coefficients are reported on as determined by X‐ray diffraction and connect the qualitative trueλ̂ to their free volume fractions. Further, it is demonstrate that the previously determined Einstein oscillator modes correlate to Grüneisen parameters determined for a range of mixed‐tacticity polyhydroxybutyrates.

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Poly(lactic acid) synthesized from non‐food biomass feedstocks with tin‐loaded ZA molecular sieve catalysts by direct melt polycondensation

Gao,

Wang,

Yang

et al. 2023

Polymer International

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The design and synthesis of catalysts loaded with active components has attracted considerable attention in current research owing to their exceptional catalytic performance. In this study, the focus was on the utilization of tin‐loaded ZA molecular sieves, possessing remarkable adsorption properties, alongside the catalytic activity of tin. These catalysts were successfully prepared and employed for the synthesis of poly(lactic acid) (PLA) from lactic acid derived from non‐food biomass. By modifying the treatment of ZA molecular sieves, the properties of tin‐loaded ZA molecular sieves were adjusted. The resulting catalysts exhibited a high tin capacity ranging from 2.29% to 2.81% and featured abundant mesoporous structures, providing a surface area of up to 341.2 m2 g−1. Regarding the preparation of PLA, our findings demonstrated that ZA‐III‐Sn2+ as a catalyst yielded PLA with a higher weight‐average molecular weight (Mw) up to 2.57 × 104 g mol−1 and a higher yield of 65.3% compared to other catalysts. Moreover, the most optimal catalytic effect was achieved by adding the catalyst in three separate stages. Moreover, the amount of catalyst, reaction temperature and reaction time were found to influence both the molecular weight and yield of PLA. This study not only provides a valuable strategy for the preparation of loaded catalysts for PLA production but also offers new insights into the overall preparation process of PLA. © 2023 Society of Industrial Chemistry.

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Structures of Mixed-Tacticity Polyhydroxybutyrates

Cited by 9 publications

References 41 publications

Determining paracrystallinity in mixed-tacticity polyhydroxybutyrates

Determining paracrystallinity in mixed-tacticity polyhydroxybutyrates

Free Volumes and Grüneisen Parameters in Mixed‐Tacticity Polyhydroxybutyrates

Poly(lactic acid) synthesized from non‐food biomass feedstocks with tin‐loaded ZA molecular sieve catalysts by direct melt polycondensation

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