CHEMICAL PAPERS
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2022
·Vol. 76
·期 4
·2145-2152
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IF 2.146
Zhu Xingji,Kou Xinhui
We disclose a metal-free catalyst system of organic bases/protic acids for effective fully alternating copolymerization of cyclohexene oxide and phthalic anhydride. A series of commercial organic bases and protic acids were employed as binary catalysts, and the effects of different kinds and ratios of organic bases and protic acids were performed to find optimal conditions for achieving the highest catalytic performance. And our results indicated that DMAP/DPP showed higher activity (TOF = 574 h −1 at 140 °C) and perfectly alternating selectivity (ester > 99%), producing polymers with narrow polydispersity (Ð = 1.08 ~ 1.22). Moreover, analysis of the resultant polymers was confirmed by GPC, NMR spectra and MALDI-TOF MS techniques which revealed that P(PA- alt -CHO) polyester with well-defined alternating structure without formation of polyether and DMAP can act as an initiator in DMAP/DPP catalyst system, resulting more effective ring-opening alternating copolymerization. However, trace amount of phthalic acid as an impurity in the system also acted as a bifunctional initiator influencing the molecular weight of the polymer. In addition, the DMAP/DPP catalytic system remained stable at high temperature and the development of this simple catalytic process provided a new chance to exploit in organocatalyzed polymerization.
研究领域:
高分子化学
·
有机催化
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DOI
高影响因子
Polymer Chemistry
·
2014
·Vol. 5
·期 12
·3838-3846
·
IF 5.368
Yonghang Xu,Min Xiao,Shuanjin Wang,Mei Pan,Yuezhong Meng
A series of salicylaldiminato-zinc and -tri-zinc complexes containing various Schiff base ligands were prepared using quick methods and then well identified by full characterization. All zinc complexes were examined as catalysts for the copolymerization of CO2 and cyclohexene oxide. Many factors such as electron-donating or -withdrawing substituents on the benzene rings of the ligands, as well as chloride anions or acetate groups bound to the zinc centers, are found to greatly influence on the insertion of CO2 and ring-opening of epoxides. Tri-metallic complexes 2a and 2b exhibited excellent catalytic activities, and thus the copolymerization conditions such as temperature, pressure and reaction time were optimized. The molecular weights of the resulting copolymers determined by gel permeation chromatography display a bimodal distribution with relatively wide polydispersities. The results of the investigation indicate that the catalytic activities of zinc complexes are highly dependent on the electronic density and steric environment around the Zn metal centers.
研究领域:
化学
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材料科学
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催化反应
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DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2023
·
IF 5.9
Gu Guo,Yuanlong Guo,Hailiang Sheng,Pengcheng Liu,Lei Dai,Michael North,Lei Deng,Xiaofeng Luo,Haibo Xie
A series of cellulose grafted alternating cyclic anhydride (CA) and epoxide (EPO) copolyesters (cell- g -P(CA-alt-EPO)) have been prepared in the novel DBU/DMSO/CO 2 cellulose solvent system. The DBU acted both as a reagent for cellulose dissolution and as a catalyst for ring-opening copolymerization (ROCOP) of cellulose with EPO and CA. The structural features and thermal performances of cell- g -P(CA-alt-EPO) were characterized via MALDI-TOF, FT-IR NMR, TGA, DSC and XPS. Perfectly alternating sequence distributions and controlled molecular weights of a series of cell- g -P(CA-alt-EPO) were easily achieved by a variation of the CA or EPO. The cell- g -P(CA-alt-EPO) also had satisfactory UV-absorbing properties and cellulose grafted phthalic anhydride and glycidyltrimethylammonium chloride exhibited outstanding antibacterial behavior. Antibacterial activity against Escherichia coli and Staphylococcus aureus were 96.7% and 99.4% respectively. Thus, cell- g -P(CA-alt-EPO) with good solubility, melt processability, UV absorption and antibacterial properties have potential applications in UV-shielding and antibacterial agent fields.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 28
·21580-21587
·
IF 3.84
Zhenghe Zhang,Lizhi Hong,Jinxia Li,Feng Liu,Haibo Cai,Yun Gao,Weian Zhang
Poly(maleimide isobutyl polyhedral oligomeric silsesquioxane-alt-vinylbenzyl polyethylene glycol) (P(MIPOSS-alt-VBPEG)) amphiphilic copolymer brushes with a sequence of alternating MIPOSS and polyethylene glycol (PEG) side chains were synthesized via ordinary radical polymerization and reversible addition–fragmentation transfer (RAFT) polymerization. A series of alternating copolymer brushes prepared by RAFT polymerization had a low polydispersity index (PDI) of less than 1.25. The thermal properties of these copolymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results displayed that the MIPOSS units could effectively enhance the thermal properties of the hybrid copolymers. The self-assembly behavior of the P(MIPOSS-alt-VBPEG) amphiphilic copolymer brushes in aqueous media was also studied by fluorescence spectrophotometry (FS), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results showed that these alternating copolymer brushes could form spherical aggregates in water.
研究领域:
高分子化学
·
纳米材料科学
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胶体与界面化学
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生物材料
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药物传递系统
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2014
·Vol. 6
·期 7
·1127-1136
·
IF 5.368
Shangfeng Wang,Bin Wu,Feng Liu,Yun Gao,Weian Zhang
We herein report a new strategy to fabricate novel well-defined alternating copolymers of poly(VBCDEG-alt-SaAEMI)s which were synthesized via alternating RAFT copolymerization of para-methoxydiethylene glycol-substituted styrenes (VBCDEG) and N-(2-salicylaldehyde-aminoethyl)maleimides (SaAEMI). 1H NMR, 13C NMR, FTIR and GPC results indicate that poly(VBCDEG-alt-SaAEMI) copolymers have well-defined alternating structures and narrow polydispersity (Mw/Mn < 1.35). It is interesting that poly(VBCDEG-alt-SaAEMI) alternating copolymers exhibit an excellent selective fluorescence “OFF–ON” response to Zn2+ by inhibiting the photoinduced electron transfer (PET) effect through copolymerization, while the monomer SaAEMI almost has no fluorescence response to Zn2+ due to the PET process. The sensors based on poly(VBCDEG-alt-SaAEMI) alternating copolymers have very fast response (30 s) to Zn2+, 62-fold fluorescence enhancement in aqueous solution and a detection limit of about 0.25 μM. Additionally, the poly(VBCDEG-alt-SaAEMI) alternating copolymers also show a remarkable green fluorescence “OFF–ON” switch (230∼fold) when the pH turns from 11 to 12, thus these copolymers have potential application in dual-color detection.
研究领域:
材料化学
·
分析化学
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DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2018
·
IF 1.047
Yongjun Liu,Ming Zhong,Chen Song,Shouri Sheng,Xiaoling Liu,Haoqing Hou
Novel alternating poly(aryl ether ketone)s (PAEKs) were prepared from a multiple aromatic difluoroketone monomer, that is, containing six aromatic rings via nucleophilic substitution polycondensation with various bisphenols. Each chain segment of the synthesized poly aryl ether ketone alternating copolymer was regularly separated by bisphenol units, which resulted in improvements in their thermal stability and solubility in common organic solvents. All glass transition temperatures of the alternating PAEKs were above 179°C, and the temperatures at 5% weight loss were above 446°C under nitrogen atmosphere. Wide-angle X-ray diffraction patterns confirmed that the resulting PAEKs were amorphous. PAEKs can form strong, transparent, and flexible films by solution casting, with a tensile strength of 72–79 MPa, Young’s modulus of 1.5–2.0 GPa, and elongation at break of 7–17%.
研究领域:
高分子化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2020
·Vol. 58
·期 6
·803-810
·
IF 0
Jinbo Zhang,Lebin Wang,Shaofeng Liu,Zhibo Li
The synthesis of high-molecular-weight polyesters via the ring-opening alternating copolymerization (ROAC) of cyclic anhydrides and epoxides using organocatalysts remains a major challenge. In this context, the organic cyclic trimeric phosphazene base ( CTPB ) was used as an efficient catalyst for the ROAC of phthalic anhydride (PA) with epoxides. It was found that the activity and PA conversion dramatically increased with the addition of triethyl borane (TEB) as a cocatalyst, even a small amount of TEB, for example, 5 mol % relative to CTPB . The molecular structures of obtained polyesters were characterized by nuclear magnetic resonance ( 1 H NMR, 13 C NMR) and matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF), which demonstrated the formation of perfectly alternating polyesters with unimodal and narrow molecular weight distributions. Different molecular weight polyesters (up to 118.5 kg mol −1 ) were facilely prepared by reducing the loading of CTPB and TEB, while the polymerizations were fast (turnover frequency, TOF up to 500 h −1 ). Thermal analysis of the resulting polymers indicated that the alternating polyesters were amorphous, and their T g s increased with the increment of molecular weights. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58 , 803–810 Graphical Organic cyclic trimeric phosphazene base ( CTPB ) with triethyl borane (TEB) as a co-catalyst (even 5 mol% relative to CTPB ) is highly active toward ring-opening alternating copolymerization (ROAC) of phthalic anhydride (PA) with various epoxides. The polymerizations are fast (TOF up to 500 h −1 ), and the resulting polymers have high molecular weights (up to 118.5 kg mol -1 ) and perfect alternating sequences (ester > 99%).
研究领域:
高分子化学
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材料科学
✓ 已验证
DOI
MACROMOLECULAR BIOSCIENCE
·
2021
·Vol. 21
·期 8
·2100077
·
IF 4.979
Yu Zhang,Xinming Liu,Xueping Wang,Pan He,Chunsheng Xiao,Haiyang Yu,Xuesi Chen
Chemotherapy using vascular targeting agents is an emerging new approach for cancer therapy. Combretastatin A4 (CA4) is a leading vascular-disrupting agent that targets the tumor blood vasculature for clinical tumor elimination. However, the extremely poor water solubility of CA4 hinders its biomedical applications. In this study, nanoparticles composed of novel PEGylated alternating copolymer-CA4 conjugates are designed to improve the therapeutic efficiency of CA4. First, an alternating copolymer with an alkene-pendant is synthesized by mPEG-OH-initiated ring-opening copolymerization. Then, side carboxyl groups are introduced by a thio-ene “click” chemical reaction, followed with CA4 conjugation through the Yamaguchi-reaction, resulting in the target copolymer, mPEG- b -P(PA- alt -GCA4). Interestingly, the polymer-drug conjugates can self-assemble into nanoparticles with an average diameter of 55.6 nm. The in vitro drug release and cytotoxicity of the obtained CA4-NPs toward 4T1 cells are investigated. Finally, the antitumor efficiency is evaluated in a 4T1-tumor bearing murine model. The in vivo test results demonstrate that CA4-NPs inhibited tumor growth much more efficiently at doses of 30 and 60 mg kg −1 , compared with the control group.
研究领域:
药学
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肿瘤学
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生物材料学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS COMMUNICATIONS
·
2014
·
IF 3.32
Jin Wang,Xiaofen Shan,Shaoyun Shan,Hongying Su,Shuisheng Wu,Qingming Jia
A novel heterogeneous catalyst was prepared by immobilizing salenCr III Cl on a modified poly (aniline-co-o-aminophenol) (MPOAP). The FT-IR, TEM, XRD, XPS and ICP results indicated that salenCr III Cl was successfully supported on MPOAP. The resulted catalyst (MPOAP-salenCr III Cl) exhibited excellent catalytic performance for alternating copolymerization of cyclohexene oxide (CHO) with carbon dioxide (CO 2 ). Moreover, the supported catalyst had an obvious effect on the microstructures of the copolymerization and the obtained polymer was found to be a linear alternating copolymer with narrower molecular weight distribution. The TG and DTG results indicated that the product prepared by the supported catalyst possessed higher decomposition temperature.
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2023
·
IF 4.3
Zhang Hao-Tian,Niu Ming-Xin,Zhang Qi,Hu Chen-Yang,Pang Xuan
Isothiourea is an important class of sulfur-containing molecules showing unique catalytic and biological activities. As such, polyisothiourea is envisioned to be an interesting type of polymer that potentially exhibits a number of interesting properties. However, there is no access to synthesizing well-defined polyisothiourea, and currently isothiourea-containing polymers are mainly prepared by immobilizing onto other polymer’s side chain. Herein, we report the first facile synthesis of polyisothioureas via alternating copolymerization of aziridines and isothiocayanates. Mediated by the catalytic system of phosphazene superbases/alcohol, a broad scope of aziridines and isothiocayanates could be transformed into polyisothioureas with adjustable substitutions (11 examples). The structures of obtained polyisothioureas were fully characterized with 1 H-NMR, 13 C-NMR, and 1 H- 13 C HMBC NMR. Moreover, the polyisothioureas show tunable thermal properties depending on substitutions on the isothiourea linkages. The novel structure of these polyisothioureas will enable a powerful platform for the discovery of next-generation functional plastics.
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 BULLETIN
·
2013
·Vol. 70
·期 6
·1795-1803
·
IF 1.332
Liu Jingcheng,Xiong Xiaomei,Liu Ren,Jiang Jinqiang,Liu Xiaoya
Novel branched alternating copolymers poly(styrene- alt -maleic anhydride) (BPSMA) were synthesized through free radical polymerization with styrene, maleic anhydride, and chain transfer monomer, 4-vinyl benzyl thiol. The successful synthesis of BPSMA was confirmed by a triple detection system including gel permeation chromatography, multiangle laser light scattering, and differential viscosity detectors, as well as thermal analysis (differential scanning calorimetry). This methodology proposes good prospects for scaling-up and thereby offers a wide range of branched alternating copolymers at low cost.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Boru Zhang,Heng Li,Huitong Luo,Junpeng Zhao
Epichlorohydrin (ECH), a chloromethyl-carrying epoxide, is subject to alcohol-initiated ring-opening copolymerization with cyclic anhydrides using a mild phosphazene base ( t -BuP 1 ) or a Lewis pair comprising t -BuP 1 and triethylborane as an organic/metal-free catalyst. The products exhibit controlled molar mass and strictly alternating sequence distribution without ether linkages though ECH is added in excess. The single-component organobase catalyst favors elevated reaction temperature (60 °C) and leads to broad molar mass distribution, especially at a relatively high catalyst loading, due to the nucleophilic substitution (NS) of the ECH chloromethyl groups by the chain-end carboxylate. This side reaction suspends the propagation of some chains and generates chloride anions that can reinitiate the copolymerization, thus leads to low-molar-mass byproducts. Meanwhile, the epoxy-ended copolymers may undergo chain-end ring opening to form high-molar-mass byproducts. On the other hand, the two-component catalyst allows for a wider range of reaction temperature (25–60 °C) and higher copolymerization rate. NS can be significantly delayed at room temperature with optimized catalyst loading and composition, resulting in narrowly distributed molar mass, ranging from 2 to 30 kg mol −1 , at high or complete anhydride conversion. Interestingly, NS still occurs at the end of the copolymerization so that pendent- and end-group bifunctionalized polyester can be achieved in one synthetic step.
研究领域:
有机化学
·
高分子科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）