EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Yuquan Cai,Jieyuan Zheng,Hong Fan
A facile and controllable way to prepared silane-crosslinked polyethylene by coordination polymerization was proposed in this article. Four alkene-derived chlorosilanes, trichloro(oct-7-en-1-yl)silane (Oct-TriSi), dichloro(methyl)(oct-7-en-1-yl)silane (Oct-DiSi), chlorodimethyl(oct-7-en-1-yl)silane (Oct-MoSi) and (2-(bicyclo[2.2.1]hept-5-en-2-yl)ethyl)dichloro(methyl)silane (Nor-DiSi) were first synthesized by hydrosilylation and copolymerized with ethylene to prepare cross-linkable polyethylene. The copolymerization results of ethylene/octenyl-silanes indicated monochloro-substituted silane showed lowest crosslinking ability while trichloro-substituted silane showed the lowest copolymerization ability, therefore, their ability to prepare cross-linkable polyethylene was: Oct-DiSi > Oct-TriSi > Oct-MoSi, moreover, Nor-DiSi outcompeted Oct-DiSi as comonomer to obtain higher copolymerization activity, comonomer proportion in copolymer, comonomer conversion and gel content. The crosslinking process was simply finished via alcoholysis with methanol and subsequent hydrolysis catalyzed with DBTDL. Even with a slight addition of Nor-DiSi, the polyethylene was able to be crosslinked, with the gel content ranging from 42.0 to 98.0%. The TGA and DMA tests demonstrated the crosslinked copolymers showed better thermal stability and heat deformation resistance than polyethylene. After crosslinking, the copolymers with an appropriate gel content would have higher yield stress, tensile modulus and tensile stress.
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
JOURNAL OF ORGANOMETALLIC CHEMISTRY
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2019
·
IF 2.066
Yi Zhou,Xuelian He,Ting Fu,Ning Zhao,Boping Liu
A series of novel Cr/Ti bimetallic polyethylene catalysts were successfully synthesized for the first time through introduction of chromium species into the (SiO 2 /MgR 2 /MgCl 2 )·TiCl x Ziegler-Natta catalysts. The bimetallic catalysts , which showed high activity, were simply prepared by refluxing titanium choloride with chromium modified silica gel/alkyl Mg adducts. Moreover, the effects of chromium content and calcination temperature were investigated in detail. The results obtained in the study were used to systematically discuss a clear relationship between the catalyst preparation condition and the relative performance of different metal active centers. Factors including surface hydroxyl content, catalyst performance in homo-polymerization, ethylene/1-hexene copolymerization were systematic investigated. Comparably, the chromium modified catalyst shows catalytic performance with 89% higher activity, 41.5% higher hydrogen response and 46.3% higher 1-hexene incorporation than the original (SiO 2 /MgR 2 /MgCl 2 )·TiCl x Ziegler-Natta catalyst. A new schematic model was proposed to explain the accelerated activation process of the bimetallic catalysts with kinetic and SEM results: chromium active sites on the outer surface of support react 10 times quicker than Ti active sites initially and help to crack the catalyst particle in the first stage; then the released inner surface active sites start to accelerate the polymerization reaction in the second stage.
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Zhang-Na Qin,Qiong-Wei Yu,Ren-Qi Wang,Yu-Qi Feng
A mixed-mode polymer monolithic column functionalized by arsonic acid groups was prepared by single-step in situ copolymerization of monomers p -methacryloylaminophenylarsonic acid ( p -MAPHA) and pentaerythritol triacrylate (PETA). The prepared poly( p -MAPHA- co -PETA) monolithic column has a homogeneous monolithic structure with good permeability and mechanical stability. Zeta potential measurements reveal that the monolithic stationary phase holds a negative surface charge when the mobile phase resides in the pH range of 3.0–8.0. The retention mechanisms of prepared monolithic column are explored by the separation of selected polycyclic aromatic hydrocarbons (PAHs), nucleosides, and three basic compounds. The results indicate that the column functions in three different separation modes associated with reversed-phase chromatography based on hydrophobic interaction, hydrophilic interaction chromatography, and cation-exchange chromatography. The column efficiency of prepared monolithic column is estimated to be 70,000 and 76,000 theoretical plates/m for thiourea and naphthalene, respectively, at a linear flow velocity of 0.85 mm/s using acetonitrile/H 2 O (85/15, v/v) as the mobile phase. Furthermore, an analysis of the retention factors obtained for the PAHs indicates that the prepared monolithic column exhibits good reproducibility with relative standard deviations of 2.9%, 4.0%, and 4.7% based on run-to-run injections, column-to-column preparation, and batch-to-batch preparation, respectively. Finally, we investigate the separation performance of the proposed monolithic column for select phenols, sulfonamides, nucleobases and nucleosides.
研究领域:
分析化学
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色谱技术
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产品关联
DOI
PubMed
高影响因子
CHINESE CHEMICAL LETTERS
·
2017
·
IF 1.932
Lan-Lan Li,Ru-Yi Jiang,Jin-Xing Chen,Mo-Zhen Wang,Xue-Wu Ge
Self-healable polyacrylamide-based hydrogels were prepared at room temperature via a one-step emulsion copolymerization of acrylamide (AM), dodecyl 2-methacrylate (DM), and 5-acetylaminopentyl acrylate (AAPA) using sodium dodecyl sulfonate (SDS) as the emulsifier and ammonium persulfate (APS) as the initiator. The produced linear multi-block copolymer chains are composed of randomly-linked hydrophilic polyacrylamide segments (PAM) and hydrophobic segments constituted by DM and AAPA units (P(DM- co -AAPA)). The P(DM- co -AAPA) segments will self-aggregate into hydrophobic microdomains during the polymerization process driven by the hydrophobic interactions, and finally separate from water phase, acting as the crosslinks and leading to the formation of strong hydrogels with a storage modulus as high as 400 Pa. These hydrophobic microdomains will be dissolved in water when the temperature increases to 70 °C, resulting in a temperature-responsive reversible sol-gel transition of the prepared hydrogels. Furthermore, the prepared hydrogels have excellent self-healing ability. The broken hydrogels can be automatically healed into a body with a same strength within 2-min’s contact. This work provides a new simple way to prepare reversible physical crosslinked hydrogel with high strength and self-healing efficiency.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
MACROMOLECULES
·
2019
·
IF 5.997
Cheng-Jian Zhang,Xiao-Han Cao,Xing-Hong Zhang
The placement of selenium (Se) atoms into polymers to achieve functional materials for diverse applications in adaptive and biomedical materials has attracted broad interest. However, the difficulty in creating well-defined Se-rich polymers is a critical limitation. In this work, we report the successful alternating and regioselective copolymerization of nonstrained γ-selenobutyrolactone with epoxides. Poly(selenide-alt-ester)s containing selenide and ester groups in each repeating unit are achieved under mild reaction conditions. The process mediated by the phosphazene base (P2)/alcohol at 25 °C exhibits high activity and living behavior, as evidenced by narrow molecular weight distributions (1.05–1.29) and switch on–off chain extension experiments. The nucleophilic attack of epoxides by selenol anions is the rate-determining step according to kinetic studies. The resultant Se-containing polyesters possess >99% alternating degree, >99% regioregularity, and programmable hydroxyl terminals. More importantly, these poly(selenide-alt-ester)s exhibit the initial thermal decomposition temperatures of up to 275 °C, low glass-transition temperatures of down to −59 °C, excellent solvability in common organic solvents, high refractive indexes (1.61–1.62), and good ionic conductivity (when doped with Li salt, 1.09 × 10–6 S/cm at 30 °C, 1.73 × 10–4 S/cm at 100 °C), indicating potential broad application prospects of these Se-rich polyesters.
研究领域:
高分子化学
·
功能材料科学
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产品关联
DOI
高影响因子
MACROMOLECULAR RAPID COMMUNICATIONS
·
2021
·Vol. 42
·期 7
·2000661
·
IF 5.734
Jianlei Lu,Mengdi Xu,Yi Lei,Lihao Gong,Chuanzhuang Zhao
The synthesis of thermo-responsive polymers from non-responsive and water-soluble monomers has great practical advantages but significant challenges. Herein, the authors report a novel aqueous copolymerization strategy to prepare polymers with tunable upper critical solution temperature (UCST) or lower critical solution temperature (LCST) from non-responsive monomers. Acrylic acid (AAc), N -vinylpyrrolidone (NVP), and acrylamide (AAm) are copolymerized in water, yielding copolymers with UCST behavior. Interestingly, by simply replacing AAm with its methylated homologue, dimethyl acrylamide (DMA), the thermo-responsiveness of the copolymers is converted into LCST-type. The cloud points of the copolymers can be tuned rationally with their monomer ratios and the condition of the solvent. The UCST property of the poly(AAc–NVP–AAm) comes from the AAc–AAm and AAc–NVP hydrogen-bonds, while the LCST property of poly(AAc–NVP–DMA) originates from the hydrophobic aggregation of AAc–NVP complex and DMA, as indicated by temperature-dependent 1 H NMR and dynamic light scattering.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 59
·31249-31260
·
IF 3.708
Yang Meng,Junfeng Chu,Jiajia Xue,Chaohao Liu,Zhen Wang,Liqun Zhang
Although polysiloxane elastomers have many merits, their fast crystallization at low temperature is problematic in some fields. In this study, a novel non-crystallizable, low-Tg epoxidized polysiloxane (ESR) with functional epoxy groups in side chains was designed and synthesized though two steps: (i) the preparation of poly(methylvinylsiloxane) (SR) by anionic ring-opening copolymerization of 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl cyclotetrasiloxane and octamethylcyclotetrasiloxane, and (ii) the subsequent epoxidation of the SR. Reaction kinetic studies demonstrated that the epoxidation of SR was a second-order reaction and more than 90% of the double bonds were converted into epoxy groups during the epoxidation. Despite a slight increase in the Tg of ESRs as the content of epoxy groups increased, the low-temperature performances of ESRs were greatly improved because of the inhibition of the crystallization of polysiloxane chains. Surprisingly, the ESRs also showed higher thermal degradation temperatures than the traditional poly(dimethylsiloxane) did. The excellent low-temperature performance and high degradation temperatures endowed the ESR with great potential as an elastic material in the aerospace industry where materials have to undergo very high and low temperature.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2015
·Vol. 145
·期 10
·1913-1921
·
IF 2.307
Wu Jing,Zhi Yunfei,Shan Shaoyun,Su Hongying,Wu Shuisheng,Jia Qingming
Abstract Polypyrrole(PPy) supported Cr(III)(salen)Cl catalyst was prepared for alternating copolymerization of cyclohexene oxide and carbon dioxide. The supported catalyst and the copolymerization products were characterized by FTIR, XRD, XPS, ICP-MS, SEM, TEM, NMR, gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. After the study, we concluded that the homogeneous Cr(III)(salen)Cl is successfully supported on the PPy, and its catalytic performance is much better than the homogeneous one. Moreover, the copolymerization product catalyzed by PPy-Cr(III)(salen)Cl exhibits higher molecular weight, narrower molecular weight distribution, superior thermal stability and selectivity. Graphical Abstract
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
Polymers
·
2017
·Vol. 9
·期 3
·89
·
IF 3.364
Fangjun Yao,Qingqing Liu,Zhengbiao Zhang,Xiulin Zhu
The impacts of hydrogen bonding on polymerization behavior has been of interest for a long time; however, universality and in-depth understanding are still lacking. For the first time, the effect of hydrogen bonding on the classical alternating-type copolymerization of styrene and maleimide was explored.N-phenylmaleimide (N-PMI)/styrene was chosen as a model monomer pair in the presence of hydrogen bonding donor solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), which interacted with N-PMI via hydrogen bonding. Reversible addition-fragmentation chain transfer polymerization (RAFT) technique was used to guarantee the “living” polymerization and thus the homogeneity of chain compositions. In comparison with the polymerization in non-hydrogen bonding donor solvent (toluene), the copolymerization in HFIP exhibited a high rate and a slight deviation from alternating copolymerization tendency. The reactivity ratios of N-PMI and St were revealed to be 0.078 and 0.068, respectively, while the reactivity ratios in toluene were 0.026 and 0.050. These interesting results were reasonably explained by using computer simulations, wherein the steric repulsion and electron induction by the hydrogen bonding between HFIP and N-PMI were revealed. This work first elucidated the hydrogen bonding interaction in the classical alternating-type copolymerization, which will enrich the research on hydrogen bonding-induced polymerizations.Keywords:alternating copolymerization;hydrogen bonding;N-phenylmaleimide;fluoroalcohol;reversible addition-fragmentation chain transfer (RAFT) copolymerization
研究领域:
高分子化学
·
物理化学
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产品关联
DOI
PubMed
高影响因子
ELECTROPHORESIS
·
2017
·
IF 2.744
Meng Ruan,Qiqin Wang,Huihui Wu,Yuqiang Wang,Hai Han,Zhengjin Jiang
In this study, a novel functional monomer N -[1-( α -naphthyl)ethylaminocarbonyl]-D- tert -leucine-[2-(methacryloyloxy)ethyl] amide (NA-D- tert -Leu-MA) was synthesized, and then employed to prepare polymeric monoliths (240 mm × 100 μm id) functionalized with tert -leucine derivative through a single step thermo-initiated co-polymerization approach or a multi-step post-modification approach. The multi-step approach involves the post-modification of a thiol-containing monolith with NA-D- tert -Leu-MA via “thiol-ene”click reaction. The physicochemical properties of the resulting monoliths were characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry and micro-liquid chromatography. Good column stability, permeability, efficiency and reproducibility were obtained for the optimized monoliths. The poly (NA-D- tert -Leu-MA- co -ethylene dimethacrylate) monolith prepared through the single step co-polymerization approach exhibited satisfactory achiral separation performance for various analytes, including phenols, aniline derivatives and intact proteins, while its enantioseparation ability is rather poor. In contrast to that, the monolith prepared through the multi-step post-modification approach showed much higher enantioselectivity for 7-nitro-2,1,3-benzoxadiazole (NBD)-derivatized amino acids. Three NBD-derivatized amino acids (theanine, proline and norleucine) could be baseline enantioseparated.
研究领域:
分析化学
·
材料科学
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产品关联
DOI
PubMed
高影响因子
IRANIAN POLYMER JOURNAL
·
2016
·Vol. 25
·期 6
·549-557
·
IF 1.684
Zhang Zhaosheng,Wang Ziwei,Ren Jianguo,Pei Jikai
Acrylic acid–isobutylene polyethylene glycol (AA-TPEG) copolymers are typical of polycarboxylate superplasticizers (PCEs). AA-TPEG copolymers are prepared via free-radical polymerization with potassium persulfate as the initiator. The obtained copolymers were characterized by gel permeation chromatography (GPC) and infrared spectra (FTIR). The GPC method can break through the former limitations of the instruments and receive instantaneous unreacted and instantaneous monomer concentrations and not the initial monomer feeds. Since TPEG monomer is highly bulky, the common calculation methods for determining monomer reactivity ratios in copolymerization based on terminal copolymerization equation are not suitable. However, this study created non-linear least squares curve fitting of terminal copolymerization equation (NLLSQ-T) and penultimate copolymerization equation (NLLSQ-P) methods, which used Python’s NumPy, SciPy, and SymPy libraries to generate code and did numerical computations, bringing greater accuracy of monomer reactivity ratios. The monomer reactivity ratios were calculated with Fineman–Ross, Kelen–Tüdös, YBR, NLLSQ-T, and NLLSQ-P methods and found to be r
AA = 10.888, r′
AA = 1.131, r
TPEG = 0.012, and r′
TPEG = 0.042 for AA-TPEG copolymers. Moreover, this study also explored specific copolymerization behavior of similar structure of copolymers with steric hindrance under penultimate copolymerization equation, such as dependence of the mole fractions in the copolymer on the mole fractions of unreacted monomers in solution, variation of copolymer compositions with conversion and sequence length distribution. The fluidity and flow loss of pastes containing PCEs were investigated, and the appropriate PCEs dosages resulted in a better workability of cement pastes.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 27
·22908-22916
·
IF 3.289
Jianwen Tian,Xiaohui He,Jingyin Liu,Xiaodan Deng,Defu Chen
Palladium(II) and copper(II) chloride complexes bearing bulky 9,10-dihydro-9,10-ethanoanthracene-11,12-diimine ligands were synthesized and sufficiently characterized by elemental and spectroscopic analysis along with X-ray diffraction analysis. The X-ray diffraction demonstrated that palladium(II) complexes (C1–C2) and copper(II) complexes (C3–C4) were four-coordinated. All these complexes displayed catalytic activities up to 105 gpolymer molMt−1 h−1 for norbornene vinyl-addition polymerization on treatment with excess methylaluminoxane (MAO). The parameters of the reaction conditions, the type of metals and steric effects of coordinative ligands had influences on the catalytic properties. C2 was selected as a catalyst precursor for the copolymerization of norbornene (NB) with 2-butyloxymethylene norbornene (BN), which exhibited catalytic activities up to 1.1 × 105 gpolymer molPd−1 h−1 and produced copolymers with relatively high molecular weights. The fraction of BN in the copolymer could reach up to 9.8–62.1% by controlling the monomer feed ratio range from 10–80%. The achieved vinyl-addition type poly(NB-co-BN) displayed high thermal stability and was soluble in common organic solvents, such as CHCl3 and THF.
研究领域:
高分子化学
·
配位化学
·
催化化学
·
有机金属化学
·
功能高分子材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）