MACROMOLECULES
·
2019
·
IF 5.997
Na Zhao,Chuanli Ren,Yong Shen,Shaofeng Liu,Zhibo Li
Degradable long-chain aliphatic polyesters are promising alternatives to polyolefins. The ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) enables the synthesis of aliphatic polyesters with melting temperature close to low-density polyethylene (LDPE). However, this ROP reaction is of great challenge because of low ring strain of the PDL monomer. The occurrence of intra- and intermolecular transesterification reactions during ROP made it difficult to prepare well-defined block copolyesters for advanced properties. In this context, cyclic trimeric phosphazene base (CTPB) in combination with benzyl alcohol (BnOH) was proved to be an efficient initiator system for ROP of PDL, showing an excellent polymerization rate (TOF up to 600 h–1) at 80 °C. Well-defined diblock copolyesters, i.e., PPDL-b-PLLA, can be easily synthesized by sequential addition of PDL and l-lactide (L-LA). In contrast, sequential addition of PDL and ε-caprolactone (CL) or δ-valerolactone (VL) only led to the random copolyesters under the same conditions. On the other hand, CTPB is an inherent tribasic superbase and can be partially neutralized to decrease its basicity for better control over active lactones such as CL and VL. Hence, we introduced 0.33–1.0 equiv of benzoic acid (PhCOOH) relative to CTPB and demonstrated that it can diminish the transesterification during ROP of CL or VL. Based on this strategy, PPDL-b-PCL or PPDL-b-PVL diblock copolyesters were successfully prepared by sequential addition of monomers of CL or VL after ROP of PDL. The block copolyester structures were confirmed by the 13C NMR spectroscopy and DSC characterizations.
研究领域:
高分子化学
·
材料科学
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产品关联
DOI
高影响因子
Polymer Chemistry
·
2019
·Vol. 10
·期 43
·5905-5912
·
IF 4.76
Chuanzhi Wei,Xinhui Kou,Shaofeng Liu,Zhibo Li
Ring-opening polymerization (ROP) is a powerful method used for converting cyclic monomers to polymers, but ethylene carbonate (EC), which has a five-membered ring, is an exception owing to the unfavorable thermodynamics of its ring-opening reaction unless the release of CO2. This behavior stems from the faster cyclization to form a stable five-membered ring in comparison to the direct ring-opening reaction. Hence, many attempts have been made to copolymerize EC with other cyclic monomers such as cyclic esters to overcome the thermodynamic barrier. In this context, the copolymerization of EC with various cyclic esters, including ε-caprolactone (CL), δ-valerolactone (VL) and L-lactide (LLA), has been successfully achieved using an organocatalytic phosphazene superbase, such as a cyclic trimeric phosphazene base (CTPB). The random copolymerizations proceeded fast with a turnover frequency (TOF) of 19 800 h−1 under mild polymerization conditions and afforded the corresponding copolymers without formation of the ether unit. Under all kinds of experimental conditions, no homopolymerization of EC occurred. The molecular structures of the obtained P(EC-co-CL) copolymers were characterized using 1H NMR and 13C NMR, which demonstrated that ca. 38 mol% EC can be incorporated within the copolymer chain depending on the different ratios of the EC and CL monomers. With the same catalytic system and under similar conditions, the amounts of EC incorporated into EC/VL (up to 26 mol%) and EC/LLA (ca. 4.8 mol%) copolymerizations were lower than that for the EC/CL copolymerization. 2D NMR (1H–1H correlated spectroscopy (COSY), 1H–13C heteronuclear single quantum coherence (HSQC) and 1H–13C heteronuclear multiple bond correlation (HMBC)) were performed to confirm the assignments in the 1H NMR and 13C NMR spectra of the copolymers and to better understand the chain structures of the copolymers. Therefore, polycarbonate/polyester copolymers with greater incorporation of EC were realized using a fast, selective and metal-free process.
研究领域:
高分子化学
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有机催化
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材料科学
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产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2019
·
IF 2.29
Xiaojie Wang,Shanshan Zhu,Xiaopo Wang
The experimental measurements for liquid viscosities of four fatty acid methyl esters, including methyl hexanoate, methyl heptanoate, methyl caprylate, and methyl nonanoate, were carried out with a falling-cylinder viscometer. For the present measurement, the temperature ranges were from 292 K to 362 K and the pressure was reached to 30 MPa. The combined expanded relative uncertainty of the viscosity measurements was within 0.03 with 0.95 confidence level. The viscosity data for each studied esters were correlated by Andrade-Tait equation, and the average absolute relative deviation between the experimental data and calculated values is 0.31%, 0.44%, 0.38%, and 0.25% for methyl hexanoate, methyl heptanoate, methyl caprylate, and methyl nonanoate, respectively. The maximum absolute relative deviation is 1.09%, 1.28%, 1.28%, and 0.75%.
研究领域:
化学工程
·
物理化学
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产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2023
·
IF 8.8
Xinmiao Wang,Qian Wang,Dong Cai,Jinghan Yu,Xiaoyang Liu,Fawen Yin,Dayong Zhou
Phenolic esters are considered as promising functional food ingredients. However, their digestion, absorption and metabolism are still unclear. Tyrosol acyl esters (TYr-Es), hydroxytyrosol acyl esters (HTy-Es) and alkyl gallates (A-GAs) were hydrolyzed by carboxylesterase in plasma and exhibited slow release of polyphenols (phenolic acids). In vitro hydrolysis degrees initially increased and then decreased with the increasing carbon chain length (C2-C16). TYr-Es exhibited higher hydrolysis degrees compared to HTy-Es, and hydrolysis degrees of TYr-Es and HTy-Es were markedly higher than those of A-GAs. Due to the fast hydrolysis rates of TYr-Es and HTy-Es, they were undetectable in all rat plasma samples collected at several times within 24 h after administration. Whereas, A-GAs could be detected in rat plasmas and three absorption peaks were found in the pharmacokinetic profiles. Importantly, the T 1/2 , MRT, AUC 0-∞ , AUC 0-t in octyl gallate group were longer (or stronger) than those in propyl gallate and dodecyl gallate groups.
研究领域:
食品科学
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营养学
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生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
IRANIAN POLYMER JOURNAL
·
2017
·Vol. 26
·期 11
·821-831
·
IF 1.422
Cheng Chuanjie,Li Yupeng,Zhang Xu,Li Jin
Global resource crisis and severe environmental problems have compelled world scientists to develop sustainable and green chemical materials. In this work, eugenol, a cheap and renewable phenol derivative found in cloves, is successfully utilized to prepare hydroxyl non-isocyanate polyurethanes (HNIPU), with number-average molecular weights ( M
n ) from several to dozens of kilodaltons. First, a diepoxide intermediate is synthesized through three steps in 43.9% total yield. Second, this diepoxide reacts with CO 2 at atmospheric pressure to form an intermediate possessing two cyclic carbonate groups in moderate yield. Third, the cyclic carbonate-containing intermediate further reacts, with compounds such as 4,4′-diaminodiphenyl methane, 1,6-hexanediamine and p -xylene diamine by nucleophilic ring-opening to obtain the desired HNIPUs. Furthermore, the diepoxide intermediate and CS 2 undergo addition reaction to form cyclic dithiocarbonate intermediate that further reacts with 4,4′-diaminodiphenyl methane to afford polythiourethane (PTU). The resulting PTU contains mercapto groups in its each unit. Number-average molecular weight of PTU is Mn 2800 Da. Finally, crosslinking reactions occur between the mercapto groups of PTU and crosslinkers (1,6-hexanediol acrylate and/or cardanol) by thiol-ene reactions under UV ( λ = 365 nm) irradiation conditions, leading to their corresponding crosslinked polymers. The optimized conditions for preparing crosslinked polymers include: PTU/cardanol/1,6-hexanediol acrylate = 1:1:0.05 (mass ratio), and UV irradiation time for 30 min. This work is expected to expand applications of eugenol and to provide a new route to NIPUs and PTUs using various diamines.
研究领域:
材料科学
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绿色化学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2018
·Vol. 10
·期 2
·219
·
IF 2.935
Xin Chen,Chi Zhang,Weidong Li,Lei Chen,Wusheng Wang
A key for the preparation of polyacrylate-based polyurethane is the synthesis of hydroxyl-terminated polyacrylate. To our knowledge, exactly one hydroxyl group of every polyacrylate chain has not been reported. The hydroxyl-terminated poly(butyl acrylate) (PBA) has been successfully synthesized by degenerative iodine transfer polymerization (DITP) of then-butyl acrylate (n-BA) using 4,4′-azobis(4-cyano-1-pentanol) (ACPO) and diiodoxylene (DIX) as initiator and chain transfer agent, respectively, and subsequently substituted reaction of the iodine-terminated PBA with β-mercaptoethanol in alkaline condition. The latter reaction was highly efficient, and the terminal iodine at the end of polymer chains were almost quantitatively transformed to a hydroxyl group. 2,2′-Azobis(isobutyronitrile) (AIBN) and ACPO were used as initiators in the DITPs ofn-BA. The results demonstrated that they had a significant influence on the terminal groups of the formed polymer chains. The structure, molecular weight, and molecular weight distribution of the hydroxyl-terminated PBA have been studied by1H,13C NMR, and GPC results. The components of hydroxyl-terminated PBA were determined by MALDI-TOF MS spectra, and their formation is discussed. The broad molecular weight distribution of the PBA and the difference in the polymerization behaviors from typical living radical polymerization are explained based on the results of1H NMR and MALDI-TOF MS spectra. The hydroxyl-terminated PBA has been successfully used in the preparation of PBA-based polyurethane dispersions (PUDs). The aqueous PUDs were stable, and based on the DSC results it can be said that the miscibility of hard segments with PBA chains was improved.Keywords:poly(n-butyl acrylate);degenerative iodine transfer;free-radical polymerization;waterborne polyurethane
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Science & Engineering C-Materials for Biological Applications
·
2016
·
IF 3.42
Xuepeng Feng,Guirong Wang,Kevin Neumann,Wei Yao,Lin Ding,Songyan Li,Yang Sheng,Yan Jiang,Mark Bradley,Rong Zhang
Three polyether-ester triblock diols, with various molecular weights, were synthesized from ε-caprolactone and polyethylene glycol and used, with diisocyanates, as soft segments for the preparation of polyurethane acrylate oligomers. The polyurethane acrylates were used to generate cross-linked polyurethane films via UV initiated polymerization with and without cargo incorporation. Degradation experiment indicated that in PBS/H 2 O 2 /CoCl 2 the films degraded rapidly compared to PBS alone or with lipase. The polyurethane membrane loaded with the antibiotic tetracycline, demonstrated prolonged release over 200 h, suggesting that the polymers could be used as an implant coating for controlled drug release.
研究领域:
材料科学
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药学
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生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Polymer Materials
·
2025
·
IF 4.7
Xiaobo Xu,Minghui Cui,Mengqiu Quan,Yuqing Wang,Genzheng Sha,Jin Zhu,Ning Yan,Jing Chen
The use of renewable raw materials to construct environmentally friendly, nontoxic, nonisocyanate polymer materials has been gaining attention. Here, we prepared ferulic acid epoxy (FAE) by directly reacting the lignin derivative ferulic acid with epichlorohydrin. It was used as a precursor to construct five-membered cyclic carbonate (CC) and five-membered cyclic dithiocarbonate (DTC) with CO2 and CS2, respectively. These cyclic carbonates are then cured with different amines to produce nonisocyanate polyurethanes (NIPUs) and nonisocyanate polythiourethanes (NIPTUs) with excellent properties. Ferulic acid contains a rigid aromatic ring structure, so the prepared nonisocyanate polymer materials have excellent mechanical properties, and the maximum tensile strength can reach 34.2 MPa. We compared NIPUs and NIPTUs in terms of their chemical structure, cross-link density, mechanical properties, and processing for remodeling. In addition, Due to the autoxidation of pendant sulfhydryl groups, disulfide bonds are present in the network structure of NIPTUs in addition to thionourethane. This endows NIPTUs with higher cross-link density, lower relaxation activation energy (Ea), and lower remodeling temperature (<140 °C). After thermocompression remodeling, the tensile strength of NIPTUs significantly increased due to the enhanced thermally induced formation of disulfide bonds. This study evaluates the potential for the direct synthesis of biobased aromatic NIPUs and NIPTUs based on ferulic acid, providing a simple route for the preparation of nonisocyanate polyurethanes and polythiourethanes using cyclic carbonates.
研究领域:
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2025
·
IF 5.2
Junhao Shen,Jinbo Zhang,Wenhui Kong,Yuanchi Ma,Shaofeng Liu,Zhibo Li
3-Ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP), derived from the telomerization of carbon dioxide (CO2) with 1,3-butadiene, emerges as a promising intermediate for the production of high-value added materials from CO2. However, the current impediment lies in the challenge of accessing selective ring-opening (co)polymerization of EVP because of unfavorable thermodynamics under mild conditions and the competitive polymerization of highly reactive C═C double bonds. In this study, we report the chemoselective ring-opening copolymerization of EVP (selective ring-opening rather than vinyl polymerization) with ε-caprolactone (CL), even at room temperature, by using a phosphazene/urea binary catalyst. This process exclusively yields the ring-opening product of copolyester poly(CL-co-EVP). The resultant poly(CL-co-EVP)s exhibit predictable molar masses (Mns), narrow distributions (D̵ < 1.2 for most cases), wide range of EVP-contents (0–60 mol %), and thus tunable thermal properties. The kinetic and reactivity ratio (rCL = 3.67 and rEVP = 0.17) studies indicate a gradient structure for poly(CL-co-EVP). Moreover, these poly(CL-co-EVP)s possess two distinct pendant alkene groups, an internal one and a terminal one, which are ready to undergo sequential functionalization to prepare bifunctional polyesters or form cross-linked polyesters. Poly(CL-co-EVP) copolyester with only a 2 mol % EVP incorporation shows a significant improvement in both tensile strength (σb) and elongation at break (εb) in comparison to PCL homopolymer with a similar Mn, while cross-linking further facilitates the transformation of PCL from thermoplastics to elastomers. This study opens avenues to utilize EVP and synthesize sustainable and functional polyesters.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Xiaobing Chen,Zhenhua Li,Yuan Chun,Fan Yang,Haocheng Xu,Xingcai Wu
Many researchers reported that a sigmoid kinetic curve was obtained in oil transesterification with methanol catalyzed by CaO and gave different explanations for this formation. In this paper, heterogeneously catalyzed transesterification of soybean oil with methanol using CaO has been investigated. The solid catalyst and the liquid reaction mixture under different reaction time periods were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and high-performance liquid chromatography (HPLC) to reveal the formation of an S-shape kinetic curve. The appearance of calcium hydroxide, calcium methoxide, calcium glyceroxide, fatty acid calcium, diglycerides, and monoglycerides and their contributions to the kinetic curve have been discussed. The low reaction rate in the induction period can be attributed to mass transfer in this three-phase system. However, the formation of surfactants, diglycerides and monoglycerides, promotes the emulsification of the reaction mixture and numerous emulsion reactors are generated. These emulsion reactors can improve the contact of the solid catalyst with the reactants and thus accelerate the reaction.
研究领域:
化学工程
·
催化反应
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产品关联
DOI
PubMed
高影响因子
Energies
·
2024
·Vol. 17
·期 23
·5811
·
IF 3
Qing Zou,Zhenhui Chen,Siwen Ding,Jimin Xu,Maogang He,Xiangyang Liu
As a renewable energy source and potential substitute for fossil fuels, biodiesel plays an increasingly important role in both energy security and environmental protection. Accurate thermal conductivity data of biodiesels and their mixture with diesel are critical to engine design to achieve high combustion efficiency. This study measured the thermal conductivity of binary mixtures of heptane and biodiesel components, specifically methyl myristate, methyl laurate, and methyl caprate, over a temperature range of 298.15–328.15 K, using the two-wire 3ω method. Based on the experimental data, the effect of mass fraction, temperature, and carbon chain length of the fatty acid ester on the thermal conductivity was analyzed. The second-order Scheffé polynomial model, Flippov equation, Jamieson equation, and Chen equation were used to correlate the experimental data and compare to find a better one. The Flippov equation shows the lowest absolute average relative deviation of 0.80% for the binary mixtures of heptane with methyl myristate, methyl laurate, and methyl caprate.
研究领域:
能源科学
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环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2023
·
IF 13.6
Yan Liu,Shukun Tang,Xu Wang,Xiaoliang Wang,Xianghua Tang,Qian Wu,Zunxi Huang,Junmei Ding
The long-term and excessive use of pyrethroid pesticides poses substantial health risks and ecosystem concerns. Several bacteria and fungi have been reported that could degrade pyrethroids . The ester-bond hydrolysis using hydrolases is the initial regulatory metabolic reaction of pyrethroids. However, the thoroughly biochemical characterization of hydrolases involved in this process is limited. Here, a novel carboxylesterase, designated as EstGS1 that could hydrolyze pyrethroid pesticides was characterized. EstGS1 showed low sequence identity (<27.03%) compared to other reported pyrethroid hydrolases and belonged to the hydroxynitrile lyase family that preferred short short-chain acyl esters (C2 to C8). EstGS1 displayed the maximal activity of 213.38 U/mg at 60 °C and pH 8.5 using p NPC2 as substrate, with K m and V max were 2.21 ± 0.72 mM and 212.90 ± 41.78 µM/min, respectively. EstGS1 is a halotolerant esterase and remains stable in 5.1 M NaCl. Based on molecular docking and mutational analysis, the catalytic triad of S 74 -D 181 -H 212 and three other substrate-binding residues I 108 , S 159 , and G 75 are critical for the enzymatic activity of EstGS1. Additionally, 61 and 40 mg/L of deltamethrin and λ-cyhalothrin were hydrolyzed by 20 U of EstGS1 in 4 h. This work presents the first report on a pyrethroid pesticide hydrolase characterized from a halophilic actinobacteria.
研究领域:
环境微生物学
·
生物技术
·
酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）