ChemistrySelect
·
2023
·Vol. 8
·期 34
·e202301948
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IF 2.1
Hai-Bo Wu,Xian-Tai Zhou,Xiao-Wu Zhou,Yan-Xiong Fang
Graphical Benzoic acid has been proved to be an efficient catalyst for the ring-opening polymerization of ϵ-caprolactone under mild conditions. A monomer-activated ring-opening polymerization mechanism mediated by benzoic acid was proposed. It is expected to realize the one-step preparing of poly (ϵ-caprolactone) through the direct aerobic oxidation of cyclohexanone. The development of a feasible industrial method for poly(ϵ-caprolactone) (PCL) preparation is great of significant and challenging. The bulk ring-opening polymerization of ϵ-caprolactone (ϵ-CL) using various organic acid catalysts and benzyl alcohol (BnOH) as the initiator was developed. Benzoic acid (BA) has been proved to be an efficient catalyst for the ROP of ϵ-CL under mild conditions. The conversion of ϵ-CL to PCL was 84.7 % under the optimized reaction conditions, with number-average molecular weight ( M n ) and dispersity (PDI) of 7700 g/mol and 1.25, respectively. Moreover, a monomer-activated ring-opening polymerization mechanism mediated by benzoic acid was proposed. Overall, this work is expected to provide a feasible industrial method for the preparation of PCL using benzoic acid as organocatalyst.
研究领域:
高分子化学
·
有机催化
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产品关联
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Yingying Ren,Zhiyong Wei,Xuefei Leng,Yurong Wang,Yang Li
Boric acid ( 1 , B(OH) 3 ) was investigated as metal-free biocatalyst for its activity towards the bulk ring-opening polymerization (ROP) of ε -caprolactone (CL) initiated by benzyl alcohol (BnOH). Moreover, other boric acid derivates such as phenylboronic acid ( 2 ), 2-thienylboronic acid ( 3 ), 2-furanylboronic acid ( 4 ) and 5-pyrimidinylboronic acid ( 5 ) were also used as acidic catalysts to synthesize poly( ε -caprolactone) (PCL), poly( δ -valerolactone) (PVL) and poly(trimethylene carbonate) (PTMC). The studies on the polymerization kinetics for all catalysts confirm that the reaction rates are first-order with respect to monomer and their catalytic activities follow the order 1 > 3 > 2 ≈ 4 > 5 . Furthermore, the block copolymerization of ε -caprolactone (CL) with δ -valerolactone (VL) and trimethylene carbonate (TMC) successfully proceeded by the sequential monomer addition to give PCL- b -PVL and PTMC- b -PCL copolymers , indicating the living nature of the present polymerization system. The end group analysis by 1 H NMR and MALDI-TOF MS measurements suggested that the benzyl moiety of initiator inserted into the synthesized polymeric chain. The existence of the interaction between the catalyst B(OH) 3 and the monomer CL supports that B(OH) 3 catalyzed ROP of CL preferred an activated monomer mechanism. A possible model for the initiation and propagation procedures of ROP of cyclic esters catalyzed by boric acid in the presence of benzyl alcohol was proposed.
研究领域:
材料科学
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催化化学
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高分子化学
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
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2023
·Vol. 31
·期 1
·1-9
·
IF 2.8
Wu Hai-Bo,Zhou Xian-Tai,Zhou Xiao-Wu,Fang Yan-Xiong
As a biodegradable polyester, the commercialized synthesis protocol of poly(ε-caprolactone) (PCL) under mild conditions is of great significance and attractive. Herein, the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) using FeCl 3 catalyst and benzyl alcohol (BnOH) as the initiator was developed. FeCl 3 has been proved to be an efficient catalyst for the ROP of ε-CL under mild conditions. The conversion of ε-CL to PCL was 98.8% at 60 °C within 4 h, with number-average molecular weight ( M n) and dispersity (PDI) of 1.65 × 10 4 g/mol and 1.28, respectively. Moreover, a coordination-insertion ring-opening polymerization mechanism mediated by FeCl 3 was proposed. Overall, this work is expected to provide a feasible industrial method for the preparation of PCL from the direct aerobic oxidation of cyclohexanone.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
POLYMER
·
2016
·
IF 3.586
Qilei Song,Yening Xia,Shuangyan Hu,Junpeng Zhao,Guangzhao Zhang
The copolymerization of ε -caprolactone (CL) with its structural isomer , δ -hexalactone (HL), or trimethylene carbonate (TMC) catalysed by diphenyl phosphate was investigated. Copolymers with molar fraction of CL units ranging from 54% to 95% were obtained. Molecular characterization exhibited random distribution of the two monomeric units (CL/HL or CL/TMC), owing to the extensive occurrence of transesterification scrambling reactions at high temperature. Compared with poly( ε -caprolactone) (PCL), the copolymers showed reduced crystallinity and enhanced enzymatic degradability as revealed by the analysis with differential scanning calorimetry and quartz crystal microbalance with dissipation, respectively. Interestingly, the incorporation of HL units showed a more profound impact than TMC. It is therefore considered that organocatalytic copolymerization with HL, a bio-renewable lactone, can serve as an effective method to regulate the properties of PCL.
研究领域:
材料科学
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生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2014
·Vol. 52
·期 8
·1185-1192
·
IF 3.245
Jinbao Xu,Junzhe Song,Stergios Pispas,Guangzhao Zhang
Ring-opening polymerization (ROP) of ε -caprolactone (CL) using salicylic acid (SAA) as the organocatalyst and benzyl alcohol as the initiator in bulk at 80 °C successfully proceeded to give a narrowly distributed poly( ε -caprolactone) (PCL). In addition, 2-hydroxyethyl methacrylate, propargyl alcohol, 6-azido-1-hexanol, and methoxy poly(ethylene glycol) were also used as functional initiators. The 1 H NMR, SEC, and MALDI-TOF MS measurements of the PCL clearly indicate the presence of the initiator residue at the chain end, implying that the SAA-catalyzed ROP of CL was through the activated monomer mechanism. The kinetic experiments confirmed the controlled/living nature of the SAA-catalyzed ROP of CL. Furthermore, the block copolymerization of CL and δ -valerolactone successfully proceeded to give poly( ε -caprolactone)- block -poly( δ -valerolactone). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 1185–1192
研究领域:
高分子化学
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材料科学
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
·
IF 5.518
Nehala Shahnawaz,Tauqir A. Sherazi,Rongqiang Li,Fengting Hao,Fengmei Yan,Youwei Liu
Using the potential of compartmenting free enzyme in dispersion phase of Pickering emulsion , a simple continuous flow system for free enzyme catalytic cycle-opening polymerization of ε-caprolactone has been studied. In order to generate suitable and stable Pickering emulsions, silica nanoparticles(SiNPs) modified with octyltrimethoxysilane (OTMS) and aminopropyltrimethoxysilane (APTMS) are synthesized, and the modification is confirmed by Fourier transformed infrared (FTIR) spectroscopy and water contact angle (CA). It is found that CA values of modified SiNPs increased from 107° to 168° with the increase of ratio of OTMS to APTMS from 1:1 to 8:1, which indicates that wettability of SiNPs has been changed from original hydrophilic to hydrophobic and consequent has an effect on the properties of Pickering emulsions. Among the modified SiNPs, the silica modified with OTMS: APTM (2:1) can construct stable W(water)/O(toluene) Pickering emulsion , confirmed by images from confocal laser microscope. The stable Pickering emulsion comprising of Candida Antarctica lipase B dispersed in water droplets is selected as a model for investigation of conditions for ring-opening polymerization of ε-caprolactone. The high monomer conversion is achieved with amount of emulsifier and enzyme being used 5 wt% and 3 wt%, respectively, and flow rate 3 mL h −1 in continuous flow process , which is higher than that in batch reaction system although the formula of Pickering emulsion is identical. Specially, the polycaprolactone (PCL) with an average molecular weight of 210151 g/mol, as per gel permeation chromatography (GPC) analysis, is achieved. The catalytic efficiency of enzyme for polymerization is not changed even after several cycles of use. The present enzyme immobilization within Pickering emulsion offers a green and prospective approach for synthesis of high molecular weight polymer in continuous flow process .
研究领域:
生物化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 22
·6687-6703
·
IF 6.177
Furong Cao,Yun Wang,Xing Wang,Wenjuan Zhang,Gregory A. Solan,Rui Wang,Yanping Ma,Xiang Hao,Wen-Hua Sun
Five types of N-(2-(diphenylphosphino)ethyl)-2-R-5,6,7,8-tetrahydroquinolin-8-amines (R = H L1, Me L2, iPr L3, Cl L4, Ph L5) along with one example of an N-isopropyl-5,6,7,8-tetrahydroquinolin-8-amine (L6) have been prepared and employed as neutral ligand supports for zinc(II) chloride complexes, LZnCl2 (Zn1–Zn6). All zinc compounds were characterized by multinuclear NMR spectroscopy (1H/13C/31P) and elemental analysis, while the structures of Zn2 and Zn5 were further studied by single crystal X-ray diffraction: distorted tetrahedral geometries with the diphenylphosphine moieties non-coordinated were a feature. Pre-treatment of Zn1–Zn5 with two equivalents of either LiCH2SiMe3 or LiN(SiMe3)2 led to catalysts displaying good to exceptionally high activity for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) at 50 °C. For example, Zn4/2LiCH2SiMe3 displayed a TOF of 2.1 × 104 h−1 with 71% conversion seen within 10 minutes with the ε-CL : Zn molar ratio at 5000 : 1; the resulting polycaprolactone (PCL) comprised predominately cyclic structures along with lower levels of trimethylsilylmethyl-capped linear PCL. By comparison, Zn1–Zn5 on treatment with two equivalents of LiN(SiMe3)2 at the same high monomer to zinc ratio, led to catalysts exhibiting an order of magnitude higher activity. Zn1/2LiN(SiMe3)2 in the presence of BnOH exhibited a remarkable TOF of 1.35 × 105 h−1 with 90% monomer conversion within two minutes. In these cases, a distinct selectivity towards linear polymers capped with CH3O end-groups (derived from the quenching solvent) was observed with cyclic polyesters only observable with larger amounts of ε-CL. As a general observation, the 2-R substituent on the chelating ligand showed noticeable effects on the efficiency and on the molecular weight of the PCLs, with 2-Cl-containing Zn4 in combination with LiCH2SiMe3 and BnOH affording the highest molecular weight PCL of the study (9.57 × 104 g mol−1). Based on the microstructural properties of the PCL, distinct mechanisms (viz., coordination–insertion and ring expansion) have been proposed to account for the mode of propagation mediated by Zn/2LiCH2SiMe3 and Zn/2LiN(SiMe3)2. In addition, a zinc silylamido L1−HZn[N(SiMe3)2] (Zn7) species has been tentatively assigned (obtained via deprotonation of L1 with Zn[N(SiMe3)2]2), that proved inactive for the ROP of ε-CL but displayed good activity for ROP of rac-LA.
研究领域:
有机化学
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高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMER TESTING
·
2020
·
IF 3.275
Lidong Feng,Sheng Xiang,Yanlong Liu,Xinchao Bian,Gao Li,Xuesi Chen
An analytical method was developed to quantitatively determine residual monomers, namely, lactide (LA) and ε -caprolactone (CL), in poly(lactide- co - ε -caprolactone) (PLCL) using an internal-standard method of gas chromatography (GC). PLCL and diphenyl ether (DPE) as an internal standard were initially dissolved in dichloromethane (DCM), and then PLCL was precipitated in cyclohexane. The residual LA and CL monomers in PLCL, as well as DPE, were extracted into cyclohexane from the polymer solution. The resulting solution was directly injected into a GC system. This method was practical for measuring the residual LA and CL contents in PLCL. The relative standard deviation ( RSD ) ( n = 5) denoting the repeatability of this method was less than 5.6% and 4.3% for the LA and CL measurements, respectively, indicating that the method was sufficiently precise. The recovery rate of standard addition was 96.5%–101.5% and 98.4%–104.2% for the determination of LA and CL in PLCL, respectively. The RSD of the recovery of standard addition ( n = 5) was not more than 2.0%, indicating that the method was sufficiently accurate.
研究领域:
分析化学
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高分子材料科学
·
医学材料
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产品关联
DOI
高影响因子
Polymer Chemistry
·
2014
·Vol. 5
·期 16
·4726-4733
·
IF 5.368
Jinbao Xu,Junzhe Song,Stergios Pispas,Guangzhao Zhang
Narrowly distributed poly(ε-caprolactone) (PCL) was synthesized by the ring-opening polymerization (ROP) of ε-caprolactone (CL) using tris(pentafluorophenyl)borane (B(C6F5)3) as an acidic catalyst and benzyl alcohol (BnOH) as the initiator in bulk at 80 °C. The use of functional initiators such as 2-hydroxyethyl methacrylate (HEMA), propargyl alcohol (PGA), 6-azido-1-hexanol (AHA) and methoxy poly(ethylene glycol) (mPEG) leads to end-functionalized PCLs. 1H NMR, SEC and MALDI-TOF MS measurements clearly indicate the presence of an initiator residue at the chain end of the obtained PCL homopolymers. The study on polymerization kinetics confirms the controlled/living nature of the B(C6F5)3-catalyzed ROP of CL. Accordingly, the block copolymerization of CL with δ-valerolactone (VL) and trimethylene carbonate (TMC) successfully proceeded to give PCL-b-PVL and PCL-b-PTMC copolymers. Macrocyclic PCL was also prepared by the intramolecular click reaction of the heterotelechelic α-azido,ω-ethynyl-PCL.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF PHARMACY AND PHARMACOLOGY
·
2013
·Vol. 66
·期 4
·557-563
·
IF 2.033
Zhang Zhaoliang,Xu Lu,Chen Hao,Li Xingyi
ObjectivesAllograft rejection is the major cause of corneal graft failure. To inhibit corneal allograft rejection, rapamycin as a novel immunosuppressive agent has been discovered. However, the high water insolubility and low bioavailability of rapamycin has strongly hindered its application in the clinical setting. In this paper, we attempted to develop a novel rapamycin nano-formulation using poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC) nanoparticles as carrier by an emulsion evaporation method for potential application in corneal transplantation.MethodsThe solubility of rapamycin in the nano-formulation was determined and in-vitro release studies were performed. The developed rapamycin-loaded PCEC nanoparticles were further characterized by dynamic light scattering, transmission electron microscopy, X-ray diffraction and differential scanning calorimetery. Toxicity studies were performed in eye-related cell lines.Key findingsThe rapamycin in nano-formulation exhibited ∼103-fold increased solubility as compared with native rapamycin. According to the results of the in-vitro cytotoxicity assay, the developed PCEC nanoparticles did not exhibit any apparent cytotoxicity against various eye-related cell lines with PCEC nanoparticle concentrations in the range of 0.05–10 mg/ml. In-vitro release study showed that the release of rapamycin was sustained from PCEC nanoparticles over a period of 48 h.ConclusionsAll the results suggested that the developed rapamycin-loaded PCEC nanoparticles might be suitable for immunosuppression in corneal transplantation by instillation administration.
研究领域:
药剂学
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眼科医学
·
生物材料学
✓ 已验证
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Chengdong Lv,Rulin Yang,Guangqiang Xu,Li Zhou,Qinggang Wang
An asymmetric kinetic resolution polymerization (AKRP) of 2-benzyl-ε-caprolactone (2-BnCL) and 6-benzyl-ε-caprolactone (6-BnCL) has been developed. Phosphoric acids catalyze the ring-opening polymerizations smoothly, delivering stereogradient polycaprolactones with controlled molecular weights and narrow molecular weight distributions. At 50% conversions, the selectivity factors of this AKRP process are in a range of 1.9–2.5, which indicates clear dynamic differentiations of two enantiomers. Regarding the AKRP of 6-BnCL, a high selectivity factor of 7.2 is obtained at the early stage, and an interesting chiral reduction phenomenon is observed as reaction proceeding. Kinetic studies illustrate the enantiomorphic site control plays dominate role in this AKRP process, and a mismatch of chiral induction and chain steric hindrance is proposed to be responsible for the chiral reduction issue.
研究领域:
高分子化学
·
有机化学
✓ 已验证
DOI
高影响因子
MACROMOLECULAR RESEARCH
·
2017
·Vol. 25
·期 11
·1070-1075
·
IF 1.405
Wu Dan,Lv Yin,Guo Rui,Li Jiahui,Habadati Aerman,Lu Bowen,Wang Heyun,Wei Zhong
To evaluate the effects of different alcohols (primary, secondary, and two different tertiary alcohols) as initiators on the structure of polycaprolactone (PCL) in ring-opening polymerization (ROP), four experiments were conducted in toluene with tin(II) 2-ethylhexanoate (Sn(Oct) 2 ) as the catalyst. The kinetics of ε -caprolactone ( ε -CL) ROP at different temperatures and monomer concentrations were studied with n -butanol as the initiator and Sn(Oct) 2 as the catalyst. The kinetic plot of ln(M 0 /M t ) vs. time ( t ) seems a linear, which indicates that the propagation rate is in the first order with respect to monomer concentration. When the reaction temperature increased, the reaction rate and the final relative maximum monomer conversions also increased. The molecular weight of PCL initially increased and then decreased as monomer conversion increased. This behavior can be attributed to the high viscosity of the system, which affected monomer diffusion and polymer chain propagation. In addition, prolonging reaction time caused inter-/intramolecular transesterification. However, when monomer concentration decreased, the reaction rate decreased. The actual activation energy of Sn(Oct) 2 -catalyzed ROP of ε -CL in toluene was -75 kJ/mol.
研究领域:
高分子化学
·
材料科学
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有机催化
·
化学反应工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）