APPLIED CATALYSIS A-GENERAL
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2017
·
IF 4.339
Zhixiong Luo,Somboon Chaemchuen,Kui Zhou,Andres Alvarado Gonzalez,Francis Verpoort
A series of metal organic frameworks (MOFs) MDABCO (M = Co, Ni, Cu, Zn; DABCO = 1,4-diazabicyclo[2.2.2]octane) are utilized as catalysts for the bulk ring-opening polymerization of l -lactide. The catalytic activity varies in the order CuDABCO, NiDABCO < ZnDABCO, CoDABCO. By adding lactic acid, we unexpectedly observed enhanced catalytic activity. The combined use of lactic acid and ZnDABCO during polymerization results in a highly active polymerization system, along with the gradual change of MOFs structure caused by an increased acid concentration. Compared to related homogeneous fragments, such as zinc nitrate and 1,4-diazabicyclo[2.2.2]octane, ZnDABCO is found to afford highly isotactic polylactide, which would be ascribed to the unique structural properties of MOFs.
研究领域:
材料科学
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高分子化学
✓ 已验证
DOI
高影响因子
Crystals
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2020
·Vol. 10
·期 9
·781
·
IF 2.404
Qintong Huang,Rui Li,Guangying Fu,Jiuxing Jiang
ZSM-5 zeolites are commonly used as a heterogeneous catalyst for reactions. Four ZSM-5 catalysts (with various crystallite sizes and a similar ratio of Si/Al) and their ball-milling/surface-poisoning derivates were used to convert L-lactic acid to L, L-lactide. The reaction products were analyzed by three independent analytical methods (i.e., Proton nuclear magnetic resonance (1H NMR), high-pressure liquid chromatography (HPLC), and chiral gas chromatography (GC)) for determining the L, L-lactide yield and L-lactic acid conversion. A clear size effect, i.e., smaller catalysts providing better performance, was observed. Further ball-milling/surface-poisoning experiments suggested that the size effect of the ZSM-5 catalysts originated from the diffusion-controlled nature of the reaction under the investigated conditions.Keywords:ZSM-5 zeolites;L,L-lactide;size effect;diffusion control
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
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2020
·Vol. 27
·期 6
·1-11
·
IF 2.426
Qiu Xibo,Zhai Hong,Li Longfei,Dong Peng,Bai Ying,Peng Ai-Yun,Quan Daping
The intention of this work was to study the polymerization of a cyclic carbonate monomer bearing one azido group, i.e. 2-(azidemethyl)-2-methyltrimethylene carbonate (AMTC), to disclose the characteristics of the resulted polymers and to explore the feasibility of their post-functionalization with alkynyl compounds via Click reaction. Homopolymerization of AMTC was first studied using stannous octoate (Sn(Oct) 2 ) as the catalyst and dodecanol as the initiator, which had the characteristic of active polymerization. Copolymerization of AMTC with L -lactide ( L -LA) was then investigated under the same reaction condition, in which L- LA exhibited higher reactivity than AMTC. The reactivity of AMTC was low not only in its homopolymerization but also in its copolymerization with L -LA, while the conversion of AMTC increased by extending the reaction time. The copolymer P(AMTC-co- L LA) (PLAC) had the semicrystalline characteristic due to the relative long block-like segments of P L LA ( \( {\overline{L}}_{\mathrm{L}}=35.5 \) ). Based on these results, copolymerization of AMTC with L -LA using PEG 4K as macroinitiator was further studied to afford PLAC-PEG-PLAC copolymers. The copolymerization could be well controlled at low ratio of [M] 0 /[I] 0 (from 10 to 50) and molar fraction of AMTC in feed ( f AMTC = 0.1, 0.2). The pendent azido groups of PLAC-PEG-PLAC could undergo post-functionalization through azide-alkyne click reaction easily and efficiently.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2019
·
IF 3.621
Hao Zhang,Yilin Dong,Keke Huang,Jingsheng Liu,Bo Dong,Feng Wang
This report describes the synthesis of a series of magnesium complexes bearing sterically congested phenoxide ligands and their catalytic performances in initiating immortal Ring Opening Polymerization of ε -caprolactone and rac -lactide. The magnesium complexes Mg1 - Mg3 were obtained in high yields, by treating bulky phenoxide ligands with half equivalents of Mg( n- Bu) 2 in THF ( Mg1 : Mg(O-2,6-Ph 2 CH-C 6 H 2 -4-Me) 2 (THF) 2 ; Mg2 : Mg(O-2,6-Ph 2 CH-C 6 H 2 -4-OMe) 2 (THF) 2 ; Mg3 : Mg(O-2-Ph 2 CH-C 6 H 2 -4,6- t Bu 2 ) 2 (THF) 2 ), and well-characterized by NMR spectrum analysis. The molecular structures of Mg2 , Mg3 were further determined by single crystal X-ray diffractions. In combination with excess of benzhydrol, these complexes could catalyze immortal Ring Opening Polymerization (ROP) of ε -caprolactone and rac -lactide, and benzhydrol served as co-initiator and chain transfer agents simultaneously, which afforded polymer esters with well-controlled molecular weights and narrow molecular weight distributions. End-functionalized polyester could be also accessed if functionalized benzhydrols were employed as chain transfer agents.
研究领域:
高分子化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
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2017
·Vol. 56
·期 2
·203-212
·
IF 2.952
Hai-Chao Huang,Zong-Jun Li,Bin Wang,Xiaolu Chen,Yue-Sheng Li
A series of novel aluminum complexes containing bulky aryl-β - ketiminato ligands [ArNCH C 10 H 7 C 6 H 5 O]Al(CH 3 ) 2 ( 3a , Ar = C 6 F 5 ; 3b , Ar = C 6 H 5 ; 3c , Ar = 2,6- i Pr 2 C 6 H 3 ) have been synthesized in high yields. These complexes were identified by 1 H and 13 C NMR spectroscopy, elemental analysis, and X - ray structural analysis. All the aluminum complexes could efficiently catalyze the ROP of ɛ- caprolactone ( ɛ -CL) and Lactide (LA) in a controlled manner. It was found that the steric effect of the ligand has less effect on the ROP of CL, while the polymerization rate of L -LA was suppressed significantly. More interestingly, this kind of catalysts can promote the random copolymerization of ɛ -CL and L -LA. The transesterification side reaction and the polymer composition could be adjusted by modulating the electronic and steric effects of the ligand. In paticular, compound 3c could produce quasi-random copolymers without transesterification side reactions, as indicated by both the values of the reactivity ratios of the two monomers ( r LA = 1.31; r CL = 0.99) and the similar average lengths of the caproyl and lactidyl sequences ( L CL = 2.34; L LA = 2.44). Finally, a drug-random copolymer conjugates could be easily prepared by using 3c , indicating a potential application of 3c in pharmacutical and biomedical field. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 203–212
研究领域:
高分子化学
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有机化学
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产品关联
DOI
高影响因子
ChemCatChem
·
2025
·
IF 3.9
Long Zhang,Linjie Guan,Jiashu Liu,Song Song,Ye Tian,Xingang Li
Graphical N-ZSM-5–40 nanosheet zeolites prepared by seed-induced growth coupled with mineralization agent assisted method exhibited remarkable activity and stability in conversion of lactic acid to lactide. Enhanced diffusion and accessible Brønsted acid sites amount benefit the production of lactide. Lactide (LD) is the key building block of high-quality polylactic acid (PLA), a biodegradable polymer with broad industrial applications. Developing an efficient catalyst for one-step conversion of lactic acid to LD is critical for the PLA industry. Herein, N-ZSM-5–40 nanosheets with a thickness of about 20 nm were successfully synthesized and first applied to this esterification reaction. The yield of LD over N-ZSM-5–40 reaches 60.5% after reaction at an oil bath temperature of 140 °C for 5 h. Systematic characterization revealed that reducing the b-axis thickness of MFI-type nanosheet zeolites improves Brønsted acid sites (BASs) accessibility, which was identified as a critical factor governing the yield of LD. Time-dependent product distribution experiments demonstrate that the nanosheet structure of N-ZSM-5–40 facilitates faster cyclization of L 2 A to LD, compared to commercial C-ZSM-5–40. In-situ FTIR results reveal that N-ZSM-5–40 nanosheets have a strong ability to adsorb and activate carbonyl groups, which promotes the rapid conversion of lactic acid to LD. Given the aforementioned advantages, ZSM-5 nanosheets hold great potential for guiding the development of industrial catalysts for sustainable LD synthesis.
研究领域:
催化化学
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材料科学
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绿色化学
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产品关联
DOI
高影响因子
Chemistry Africa-A Journal of the Tunisian Chemical Society
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2021
·Vol. 5
·期 1
·79-87
·
IF 0
Naz Farah,Ciprian Matteo,Luo Zhixiong,Yan Shilin,Iqbal Shahzad Zafar,Zhu Meifang,Chaemchuen Somboon,Verpoort Francis
The synthesis and use of MOF-derived Co/NCF (N-doped carbon framework) material as a heterogeneous catalyst for copolymers synthesis via ring-opening polymerization (ROP) are reported for the first time. The Co/NCF material is applied for the copolymerization of L -lactides (LA) and ε-caprolactone (ε-CL) as monomers via ROP in bulk without any solvent or co-catalyst. The as-prepared catalyst is characterized using XRD, TPD, XPS, SEM, and TEM analytical techniques. At the same time, 1 H and 13 C-NMR spectroscopy were used to analyze the microstructure of the copolymer confirming the random copolymer structure. The average r values calculated from the heterodiad analysis of the 1 H NMR, data were r LA = 0.96 and r CL = 0.93 and L value calculated from the triads analysis of 13 C NMR, data were L LA = 3.17 and L CL = 2.79, respectively. It has been observed that the melting temperature and glass transition temperature of the copolymer increases with higher LA content. The XRD and DSC analyses also confirmed that the as-synthesized copolymer possesses two phases corresponding to the polylactide and polycaprolactone, respectively. Additionally, the activity of Co/NCF is also compared with other Co-based heterogeneous catalysts to demonstrate its ability. Graphic Abstract
研究领域:
材料科学
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催化化学
✓ 已验证
DOI
ANALYTICAL SCIENCES
·
2017
·Vol. 33
·期 2
·235-238
·
IF 1.228
Xinchao BIAN,Zhiming CHEN,Lidong FENG,Bin SUN,Sheng XIANG,Yanlong LIU,Gao LI,Xuesi CHEN
An analytical method to determine the residual lactide in polylactide (PLA) was proposed using an internal standard method of gas chromatography (GC). PLA samples and diphenyl ether (DPE) as an internal standard were dissolved in dichloromethane, then PLA was precipitated in anhydrous alcohol. The residual lactide and DPE were extracted to alcohol for GC analysis. At room temperature, lactide could react with alcohol and change into ethyl lactoyl lactate (ELL), but the relative response factor of lactide versus DPE could be obtained through a numerical analysis method. Therefore, the residual lactide content could be quantitatively calculated in PLA. The relative standard deviation (RSD) of the measurements is not more than 7.0%, indicating that the method is suitably precise.
研究领域:
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Jiashu Liu,Shengnan Zhao,Song Song,Haifeng Cong,Wei Luo,Tong Ding,Ye Tian,Xingang Li
One-step lactide (LD) synthesis from lactic acid (LA) is a promising method for an economically viable polylactic acid (PLA) industry. However, this synthesis is based on a highly water-sensitive esterification reaction, and few studies focus on developing an efficient method to improve its activity by water removal from the reaction environment. Herein, we report a new strategy coupling salt-promoted toluene–water phase separation with heteroazeotropic distillation to enhance water removal to realize highly efficient LD synthesis. Different kinds of chloride salts (LiCl, NaCl, CsCl, MgCl2, and CaCl2) were selected to study their influence on the reaction. The highest yield of LD (84.7%) was obtained when CaCl2 was added, much higher than that of the salt-free reaction (72.3%). Hydrated Ca2+ cations with relatively large charge number and small radius can efficiently reduce the solubility of water in toluene due to their strong electrostatic force to attract more water molecules. Mechanism studies demonstrate that the increased yield of LD after adding CaCl2 was attributed to its significant inhibition of LD hydrolysis resulting from the deep water removal from the toluene solvent.
研究领域:
化学工程
·
高分子化学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2022
·Vol. 14
·期 12
·2317
·
IF 4.967
Juliene Oliveira Campos de França,Deborah da Silva Valadares,Mateus Freitas Paiva,Sílvia Cláudia Loureiro Dias,José Alves Dias
Poly(lactic acid) (PLA) is an important polymer that is based on renewable biomass resources. Because of environmental issues, more renewable sources for polymers synthesis have been sought for industrial purposes. In this sense, cheaper monomers should be used to facilitate better utilization of less valuable chemicals and therefore granting more sustainable processes. Some points are raised about the need to study the total degradability of any PLA, which may require specific composting conditions (e.g., temperature, type of microorganism, adequate humidity and aerobic environment). Polymerization processes to produce PLA are presented with an emphasis on D,L-lactic acid (or rac-lactide) as the reactant monomer. The syntheses involving homogeneous and heterogeneous catalytic processes to produce poly(D,L-Lactic acid) (PDLLA) are also addressed. Additionally, the production of blends, copolymers, and composites with PDLLA are also presented exemplifying different preparation methods. Some general applications of these materials mostly dedicated to the biomedical area over the last 10–15 years will be pointed out.Keywords:poly(lactic acid)-PLA;polymerization based on D,L-lactic acid;D,L-lactide;stereo polymerization of D,L-lactic acid;blends of PLA;poly(DL-lactide-co-polymer);composites of PDLLA
研究领域:
高分子化学
·
生物材料学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
International Journal of Polymeric Materials and Polymeric Biomaterials
·
2016
·
IF 1.667
Zhaosheng Hou,Hao Zhang,Wenqiang Qu,Zhen Xu,Zheng Han
In the study, a new approach for synthesizing biomedical segmented polyurethanes (SPUs) based on polyethylene glycol (PEG, Mn = 800), poly(ε-caprolactone-co-D,L-lactide) (PCLA) and aliphatic diurethane diisocyanates with a long uniform hard segment was developed. By the chain extension of a mixture of PEG diol and PCLA diol with diurethane diisocyanates based on inexpensive 1,6-hexanediisocyanate, three SPUs (SPU-I, SPU-II, and SPU-III) with different contents of hydrophilic segments (PEG) and hard segments were obtained. The chemical structures of diurethane diisocyanates, PCLA and SPUs were confirmed by 1H NMR, 13C NMR, FT-IR, HR-TOF-MS, and GPC. The SPU films exhibited similar thermostability, indicating that the hard segment content marginally affects on the thermostability. From the results of differential scanning calorimetry, two glass transition temperatures were observed, suggesting the microphase separation of soft and hard segments. The SPU films exhibited satisfactory mechanical properties with ultimate stress of 17.4–22.3 MPa and strain at break of 890–1060%, and the initial modulus increased with the increasing content of hard segments. In vitro degradation studies indicated that the time of SPU films to become fragments was 22–33 days, and the degradation rate increased with the increasing content of hydrophilic segments in SPU. Hence, the degradation time of SPU films could be controlled by adjusting the PEG content in SPU, which made them good candidates for further biomedical applications. Studies of in vitro drug release were conducted using vitamin B1 as model drugs. Drug-loaded films exhibited a high initial release rate and matrix-controlled release for more than two weeks, thereby demonstrating a promising material for a long-acting controlled release system. Cytotoxicity test of film extracts and cell attachment on the film surface were conducted using L929 mouse fibroblasts, and the results indicated that the SPU films possess excellent cytocompatibility and cell adhesive ability.
研究领域:
生物医学材料
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高分子化学
·
药物释放系统
✓ 已验证
产品关联
DOI
高影响因子
Journal of Macromolecular Science Part A-Pure and Applied Chemistry
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2013
·
IF 0.807
Shi-Ping Zhan,Xing Huang,Qi-Cheng Zhao,Li Chen,Wei-Min Hou,Song Zhang,Jin-Jun Deng
Dispersion polymerization of lactides and lactones has been studied and has received a great deal of attention used to prepare biodegradable polymers in supercritical carbon dioxide (ScCO2). The triblock copolymers of poly(ϵ-caprolactone) PCL-polydimethylsiloxane (PDMS)-poly(ϵ-caprolactone) PCL by the feed ratio of 1:2:1 and 1:3:1, respectively were synthesized to be used as the stabilizers in the dispersion polymerization of L-lactide. The fine poly(L-lactide) (PLLA) powders were obtained at the concentrations of 3% to 5%w/w (stabilizer/monomer). The results demonstrated that the triblock copolymers were the effective stabilizers for the dispersion polymerization of L-lactide. It was also found that the cooling process had a significant effect on the particle size of the fine powders. In order to obtain the best PLLA powders, it would be necessary to use the cooling process with stirring.
研究领域:
高分子科学
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化学工程
·
材料科学
·
绿色化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）