Publications by authors named "Yeong-Hyun Seo"

Poly(1,4-butylene succinate) (PBS) is a promising sustainable and biodegradable synthetic polyester. In this study, we synthesized PBS-based copolyesters by incorporating 5-20 mol% of -OCCHCO- and -OCHCHO- units through the polycondensation of succinic acid (SA) with 1,4-butanediol (BD) and bis(2-hydroxyethyl) terephthalate (BHET). Two different catalysts, HPO and the conventional catalyst (nBuO)Ti, were used comparatively in the synthesis process.

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Article Synopsis
  • Polylactic acid (PLA), a biodegradable material made from renewable sources, faces challenges due to its brittleness, which limits its applications.
  • Researchers synthesized a range of biodegradable organic carbonates as plasticizers to enhance PLA's ductility, particularly noting the effectiveness of compound 1, which improved compatibility with PLA without losing morphological stability over time.
  • Despite the promising enhancements in flexibility and compatibility with PLA, blending these organic carbonate plasticizers did not significantly increase PLA's biodegradability under ambient conditions.
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Reevaluating the composition of the double metal cyanide catalyst (DMC) as a salt of (NC)Co anions with 1:1 Zn/(X)Zn cations (X = Cl, RO, AcO), we prepared a series of well-defined DMCs, [ClZn][Zn][(NC)Co][ROH], [(RO)Zn][Zn][(NC)Co], [(AcO)Zn][Zn][(NC)Co], [(RO)Zn][ClZn][Zn][(NC)Co], [(AcO)Zn][(tBuO)Zn][Zn][(NC)Co], and [(AcO)Zn][(tBuO)Zn][ClZn][Zn][(NC)Co]. The structure of [(MeOCHO)Zn][Zn][(NC)Co] was precisely determined at the atomic level through Rietveld refinement of the synchrotron X-ray powder diffraction data. By evaluating the catalyst's performance in both propylene oxide (PO) polymerization and PO/CO copolymerization, a correlation between structure and performance was established on various aspects including activity, dispersity, unsaturation level, and carbonate fraction in the resulting polyols.

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Zinc-glutarate (ZnGA) is a promising catalyst that can form polymers from CO and epoxides, thereby contributing to the development of CO utilization technologies and future sustainability. One of the obstacles to commercializing ZnGA in polymer industries is its low catalytic activity. In this study, we introduced activated two-dimensional (2D) ZnGA to improve its catalytic activity in polymerization.

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Synthetic biodegradable polyesters tend to undergo slow biodegradation under ambient natural conditions and, hence, have been rejected or even banned recently in ecofriendly applications. Here, we demonstrate the preparation of polyesters exhibiting enhanced biodegradability, which were generated through a combination of old controversial macromolecules and aggregate theories. HPO-catalyzed diacid/diol polycondensation afforded polyester chains bearing chain-end -CHOP(O)(OH) and inner-chain (-CHO)P(O)(OH) groups, which were subsequently treated with M(2-ethylhexanoate) (M = Zn, Mg, Mn, and Ca) to form ionic aggregates of polyesters.

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Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)-H][B(CF)] or [PhC][B(CF)]) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq.).

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CrCl(thf) is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl ([CrCl(μ-Cl)(thf)]), a crystalline solid, that enables structure determination by X-ray crystallography.

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