ACS Omega
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2021
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IF 3.512
Huichao Zhu,Jianjun Yang,Mingyuan Wu,Qingyun Wu,Jiuyi Liu,Jianan Zhang
A series of tartaric acid (TA) esters with different side chain lengths [dibutyl TA esters (DBTAE)-Cn], as plasticizers for poly(vinyl chloride) (PVC), is herein reported. Their structures have been fully characterized using proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Their compatibility and plasticizing effect for soft PVC were evaluated using thermogravimetric analysis, dynamic mechanical analysis, tensile testing, and migration testing. The results showed that all these TA esters exhibit good plasticizing performance. At a concentration of 30 phr in PVC, the best results for the plasticizing effect, in terms of glass transition temperature reduction and elongation at break, were achieved when the ester DBTAE-C4 was used. However, the longer side chains of these esters improved the thermal stability of soft PVC blends yet exacerbated the migration behavior of these esters from PVC films in n-hexane. The properties of the plasticized PVC blends depended on the structural features of DBTAE-Cn. The plasticizing performances of the esters DBTAE-C1 and DBTAE-C4 rivaled that of dioctyl phthalate (DOP), suggesting that they have the potential to replace DOP in soft PVC materials.
研究领域:
材料科学
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化学工程
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DOI
PubMed
高影响因子
MACROMOLECULES
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2021
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IF 5.985
Yujian Liu,Yanping Li,Yougen Chen
The current work presents the organocatalyzed group transfer polymerization (GTP) of alkyl sorbate, the postpolymerization modification at the double bond of the poly(alkyl sorbate) (PAS) backbone, and its thermal properties. The selected alkyl sorbate includes ethyl, n-hexyl, and n-octadecyl sorbate with the carbon number of the n-alkyl side chain being three times between every two neighboring monomers. The polymerization kinetics and mechanisms are briefly discussed for both the t-Bu-P4- and Me3SiNTf2-catalyzed GTPs of ethyl sorbate. Both of the two GTPs only undergo 1,4-addition to produce trans-rich PASs in which the former affords 81.9–85.4% trans content and the latter a much higher value as trans > 96%. The hydrogenation and epoxidation of the internal double bond turn out to be quantitative to provide the hydrogenated and epoxidized polymers, PAS-H2 and PAS-epoxy. The hydrogenation process makes the diastereochemistry and stereoregular structures of the two chiral carbons in the monomeric unit distinguishable by 13C NMR spectra, from which we know that the t-Bu-P4-catalyzed GTP produces erythro-rich PASs (erythro content = ca. 64%), while the Me3SiNTf2-catalyzed GTP gives relatively threo-rich PASs (threo content = 56–58%). However, the diisotactic/disyndiotactic ratios determined by 13C NMR spectra do not show an obvious difference between each other. Thermogravimetric analyses suggest that PAS-H2 shows the highest thermal stability and PAS-epoxy the lowest, due to the different polarity of the newly formed C–C bond in the main chain before and after the chemical modification of the internal double bond. For the amorphous poly(ethyl sorbate) (PES) and poly(n-hexyl sorbate) (PHS), change of the ethyl side group to n-hexyl greatly decreases the glass transition temperature (Tg). As for the same PES/PHS series polymers, either the hydrogenation or the epoxidation of the internal double bond drastically changes the Tg value of the final polymer product. In addition, the ca. 10% difference in the trans-cis composition for unmodified PES or PHS almost has no effect on Tg values, while the erythro/threo content shows a prominent influence for the chemically modified polymers as the Tg value can be changed from several to tens of Celsius degree when the same polymer changes from erythro-rich to threo-rich. On the contrary, crystallizable poly(n-octadecyl sorbate) (PODS) and its modified polymers possess melting points (Tm) in a pretty narrow temperature range of 34.7–41.4 °C, which is almost the same as the Tm of n-octadecyl sorbate. It is likely that the Tm values of PODS and its derivative polymers are only determined by the crystallization of the long n-octadecyl side chain, almost irrespective of the chain length, the trans-cis isomerization, the diastereochemistry, and the stereochemistry of the main chain.
研究领域:
高分子化学
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材料科学
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DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
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2022
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IF 6.449
Shumei Zhang,Jiali Zhou,Xin Gao,Heng Zhang
Application of polyethylene (PE) mulch in agriculture and horticulture is challenging due to scarce fossil-oil resources and serious environmental pollution. Therefore, bio-based mulches represent a promising alternative for petroleum-derived ones. From the lignocellulose from the whole corn stalk, the eco-benign cryogel absorbent and paper mulch has been modified by tartaric acid (TA) esterification and polyvinyl alcohol (PVA)/cationic starch (CSt) coating, respectively. This work reports a hybrid mulch of these two products via cellulosic partial-dissolution and regeneration processes and its excellent performance of water preservation for cultivation soil. The modification of TA molecules onto cellulose chains were confirmed by FTIR and X-ray diffraction, which showed the formation of ester bonds and crystallinity transition from cellulose I to the coexistence of cellulose II. SEM analyses proved a successful composite of TA-esterified cellulose absorbent and PVA/CSt-coated paper by ZnCl 2 -dissolved cellulose gel. The abundant H-bonding between interfaces of the coated paper and cellulose-derivative cryogel contributed to the favorable connection and thus mechanical properties, which both dry tensile strength (41.5 MPa) and wet tensile strength (35.6 MPa). The composites showed the reduction of water vapor transmission rate (WVTR) and oxygen transmission rate (OTR), which were 755.43 g/m 2 day and 10.6 mL/m 2 /day, respectively, and enhancement of water absorbency for 210.3 g/g as increasing the cryogel thickness. The green and biodegradable strategy proposed in this study will broaden the application range of composite mulches in agriculture and forestry .
研究领域:
农业科学
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材料科学
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环境科学
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DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2020
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IF 5.065
Shaoping Ma,Fenfang Li,Liangliang Liu,Liping Liao,Li Chang,Zhijian Tan
Two-phase system was widely used for the enantioselective liquid-liquid extraction (ELLE) of various enantiomers . The organic solvents are generally used as the extractants, moreover, the additional chiral selectors should be added to the extraction system. In this study, a biphasic recognition chiral extraction (BRCE) system based on hydrophilic and hydrophobic DESs was developed for the ELLE of tryptophan enantiomers. DESs can be simultaneously used as the phase-forming components and chiral selectors. The hydrophobic/hydrophilic methyl trioctyl ammonium chloride- L(+)-Diethyl L-tartrate/HP-β-CD-L-(−)-Malic Acid (MTAC-DE/HC-MA) system was screened as the optimal extraction system. The molar ratios of hydrogen-bond acceptor (HBA) and hydrogen-bond donor (HBD) in DESs were optimized for the enantioseparation. The other factors of phase volume ratio, initial tryptophan concentration, pH value, and extraction temperature were studied. The maximum enantiomeric excess ( e.e. ) value of 38.46% was obtained under the optimal conditions by one-step extraction. This BRCE system used for the chiral separation of tryptophan enantiomers has the advantages of environmental friendliness , simple operation, and high efficiency, which has the practical application potentiality in the continuous enantioseparation process.
研究领域:
化学
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分析化学
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手性分离
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环境科学
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DOI
高影响因子
危险品化学品经营许可证（带存储）