FUEL
·
2018
·
IF 4.908
Dan Luo,Wang Yin,Shengnan Liu,Ning Yang,Shuqian Xia,Peisheng Ma
Pyrolysis oil is a promising material for renewable energy through a hydrogenation process. However, the polymerization, initiated especially by pyrolysis oil water-soluble fraction (PS), is a big hurdle to hydrogenation. The types and structures of the polymerization chemicals, their polymerization mechanisms are very important for upgrading pyrolysis oil. This study firstly compared the polymerization rates of water-soluble fraction (PS) and water-insoluble fraction (PL) by accelerating aging fresh PS and PL at different temperatures (80 °C, 90 °C, 100 °C and 110 °C) for 24 h and at 110 °C for different durations (12 h, 24 h, 36 h, 48 h and 60 h), respectively. The thermogravimetric and differential thermogravimetry analysis results showed that PS polymerized much more rapidly than PL. Then, PS polymerization was further investigated by evaluating the changes in its physical properties (water content, viscosity and element content) and chemical compositions (gas chromatography and liquid chromatogram) before and after aging. The results showed that hydroxy aldehydes and ketones (especially glycoaldehyde, hydroxyacetone and levoglucosan), dicarbonyl compounds (especially succindialdehyde) and α, β-unsaturated carbonyl compounds (especially 3-methyl-2-cyclopenten-1-one and dehydrate resultants of some aldol condensation products) were mainly responsible for PS polymerization.
研究领域:
能源科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS LETTERS
·
2021
·
IF 3.423
Lijian Song,Xiahua Zuo,Ying An,Jin Zhan,Youchen Zhang,Weimin Yang,Jing Tan,Lisheng Cheng
Dopamine (DA) has been applied in surface chemistry because of its green and simple polymerization process. However, the polymerization kinetics is slow for mass production. Herein, we proposed a novel method to increase the polymerization rate of DA significantly. The DA solution was treated by a two-step method using microwave irradiation and oxygen oxidation . As a result, the DA solution turned dark only in 6 min. The UV–vis spectra and molecular dynamics showed that microwave irradiation promotes the generation of reactive oxygen species, and the oxygen is used as a supplement to compensate for the overflow of oxygen during the microwave heating process. This study provides a new promising choice to polymerize DA quickly and will inspire related applications in various fields.
研究领域:
材料科学
·
化学工程
·
生物医学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2021
·Vol. 13
·期 11
·1754
·
IF 4.329
Huishi Pi,Weiping Li,Zhiwei Shi,Haining Chen,Xiaoyu Jiang
N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10−3, and the photosensitive sensitivity is 7.91 × 10−4cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.Keywords:transmission holography;photopolymer;polymerization rate;diffusion rate;diffraction efficiency
研究领域:
光学材料
·
全息技术
✓ 已验证
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Tianfeng Zhou,Haotian Duan,Zhenzhong Li,Yuxia Pang,Hongming Lou,Dongjie Yang,Xueqing Qiu
Polycarboxylate superplasticizers (PCEs) are primarily liquid products (40 wt%) with narrow application range, which incur high transportation and storage costs. However, the high reaction viscosity makes it challenging to produce high concentration PCEs. In our study, high concentration PCEs are successfully synthesized by a photoinitiated one-pot method at room temperature. The results show that the reaction viscosity of photoinitiation is slightly higher than that of traditional initiation systems, but the photoinitiated reaction remains stable and controllable, with no occurrence of violent polymerization. The impact of varying reaction concentrations on the polymerization rate, molecular structure, and properties of PCEs has been studied under the photoinitiated one-pot method. The results indicate that an increase in reaction concentration leads to a rise in polymerization rate, molecular weight, and molecular gyration radius of the polymers. The conversion rate of the macromonomer exceeds 80%, while the polydispersion index (PDI) for molecular weight is below 2 with a narrow distribution. Furthermore, the monomer polymerization ratio of the product remains close to the feeding ratio at different reaction concentrations. Finally, it is observed that PCEs with a high concentration of 80 wt% exhibit favorable dispersion, rheology and adsorption properties. This study presents a new method for synthesizing high concentration PCEs using photoinitiation.
研究领域:
材料科学
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化学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2022
·
IF 5.546
Yuhang He,Yangcheng Lu
An initiating system composed by ethylaluminum sesquichloride (Et 3 Al 2 Cl 3 )//2,6-dimethylpyridine (DMP) is established for fast living cationic polymerization of isobutylene. The polymerization can be accelerated at utmost to finish in only 4 s with extremely narrow molecular weight distribution in microflow system. Investigations on influence factors reveal that mixing intensity that dependent on Re affects the molecular weight distribution significantly. DMP has two-stage effect, corresponding to its interactions with protonic impurity and Lewis acid respectively. Polymerization rate can be facilely adjusted by changing the volume ratio of mixed solvent of n-hexane and CH 2 Cl 2 from 8:2 to 7:3 with the assurance of livingness. This polymerization system can even operate at elevated temperature as high as −55 °C without the loss of livingness, which is of great beneficial to the commercialization of polyisobutylene-based functional polymer materials.
研究领域:
高分子化学
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化学工程
·
材料科学
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有机化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Yuhang He,Hua Ke,Yangcheng Lu
The copolymerization of ethylene vinyl acetate (VAc) at 4.0 MPa and 75 °C has been studied experimentally and computationally in four organic solvents, namely, methanol (MeOH), tert-butyl alcohol (TBA), methyl acetate (MA), and dimethyl carbonate (DMC), to reveal the effect of the solvents on copolymerization. The results show a significant dependence of the copolymerization rate and reactivity ratio on the nature of the solvent. Polymerization rate constants decrease in the order of TBA > MeOH > DMC > MA. The results from FTIR spectra and complexation energy calculation suggest that the variance of the copolymerization rate is closely related to the interaction between the monomer and the solvent. A stronger interaction between the monomer and the solvent might decrease the average effective monomer concentration. Various reactivity ratios are interpreted in terms of the stabilization effect of the solvent on electron-deficient species that changes the selectivity of macroradicals. Density functional theory (DFT) calculation performs well in predicting the change in the reactivity ratio in different solvents. The molecular weight of the ethylene vinyl acetate copolymer is remarkably affected by the solvents due to the chain transfer reaction, while the unit sequence is little affected.
研究领域:
高分子科学
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化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
WOOD SCIENCE AND TECHNOLOGY
·
2021
·Vol. 56
·期 1
·205-218
·
IF 2.506
Zhou Yihang,Wang Kai,Hu Dongbo
Recent studies have discovered that surface-initiated activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) is an effective tool to maintain the dimensions of waterlogged archaeological wood (WAW). However, the polymer distribution behaviors in the WAW and the possible anti-shrinkage mechanism are still unclear and barely discussed. Therefore, experiments with varied conditions were conducted. On the basis of the results, the polymer distribution behaviors in the WAW are deduced to have a close connection to the propagation rate of polymerization. Additionally, the expansion phenomenon when the samples were overtreated and the nearly linear correlation between the weight percentage gains and volume changes suggest expansion stress can be generated during the surface-initiated ARGET ATRP. The residual stress can help counteract the shrinkage stress during the drying process of WAW, which partially accounts for the anti-shrinkage property.
研究领域:
考古学
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材料科学
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高分子化学
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文物保护科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
·
2021
·
IF 4.291
Junjie Li,Yuanyuan Peng,Jhair Peña,Jinfeng Xing
Nanogels based Polyethylene glycol diacrylate (PEGDA) attracted much attention due to their promising application in drug delivery and tissue engineering. Here, PEGDA photopolymerization at 532 nm with different initiating systems was investigated. Nanogels can be obtained using single 2′,4′,5′,7′-tetrabromofluorescein disodium salt (EY) as the photoinitiator. To increase the polymerization rate, EY, triethanolamine (TEOA), and diphenyl iodonium hexafluorophosphate (DPI) were investigated as a three-component initiating system. With that initiating system, the conversion of PEGDA double bond was higher than 90 % in 1 min at extremely low irradiation energy density (P= 0.95 mW/cm 2 ). However, the conversion of PEGDA double bond was only 51.5 % in 1 min at the same irradiation energy density when using EY and TEOA as two-component initiating system. Subsequently, the corresponding mechanism of the three-component (EY-TEOA-DPI) initiating system was illustrated. DPI might participate in two ways of photooxidation and reduction, which dramatically improved the polymerization rate. The EY-TEOA-DPI initiating system is promising to be applied in the preparation of multifunctional hydrogels.
研究领域:
材料科学
·
高分子化学
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生物医学工程
·
药学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 16
·2439-2446
·
IF 5.582
Junle Zhang,Mengya Li,Yanjie He,Xiaomeng Zhang,Zhe Cui,Peng Fu,Minying Liu,Xiaoguang Qiao,Qingxiang Zhao,Xinchang Pang
Gold (Au) nanocrystals were recognized to be a remarkable photocatalyst because of their strong localized surface plasmon resonance (LSPR). Here Au nanocrystals were exploited as plasmonic photocatalysts for photo-regulated reversible addition–fragmentation chain-transfer (RAFT) polymerization. In addition to the well-controlled RAFT polymerization process under a broadband of light (from visible to the near-infrared region), the dimension (0-D nanospheres and 1-D nanorods) and aspect ratio (length/width) of the nanocrystals exhibited a remarkable effect on the polymerization rate under different light sources. The reduction of plasmon damping leads to a relatively long-lived region of high electron density on the surface of the Au nanorods, which can accelerate charge transfer and induce a higher polymerization rate. Moreover, the aspect ratio related to the longitudinal absorption band of the Au nanorods may provide more flexible choices for advanced macromolecular photosynthesis for potential in biomedical and industrial applications.
研究领域:
材料科学
·
纳米技术
·
光催化
·
聚合物化学
✓ 已验证
DOI
高影响因子
MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2021
·Vol. 223
·期 3
·2100340
·
IF 2.527
Jianxiong Zhang,Junjin Duan,Dong Chen,Yuhong Ma,Wantai Yang
A direct photolysis reversible addition-fragmentation chain transfer (RAFT) polymerization of (meth)acrylates is developed with 2-cyano-2-propyldodecyl trithiocarbonate (TTP), which plays the dual role as photoinitiator and chain transfer agent. The polymerizations can be efficiently activated by blue light while maintaining a linear increase in M n versus conversion. With poly(methyl methacrylate)-TTP (PMMA-TTP, M n = 6700 g mol –1 , Ð = 1.29) as precursor, a higher molecular weight PMMA ( M n = 14 600 g mol –1 , Ð = 1.67) by chain extension, and a series of block copolymers, including poly(methyl methacryalte)- b -poly(glycidyl methacrylate), poly(methyl methacrylate)- b -poly(tert-butyl methacrylate), and poly(methyl methacrylate)- b -poly(benzyl meacrylate)(PMMA- b -PBnMA), are prepared. The M n,NMR = 14 900 g mol –1 of PMMA- b -PBnMA measured by NMR is very close to M n,GPC = 14 200 g mol –1 determined by gel permeation chromatography. Furthermore, the polymerization of acrylates exhibits higher controllability in regarding to dispersity ( Ð < 1.20) compared to those of polymethacrylates ( Ð = 1.10–1.80). With poly(methyl acrylate) (PMA-TTP, M n = 11 900 g mol –1 , Ð = 1.09) as macro-RAFT agent, a higher molecular weight PMA ( M n = 23 500 g mol –1 , Ð = 1.28) by chain extension, and PMA- b -PBnA ( M n = 26 500 g mol –1 , Ð = 1.19) are also prepared. A positive synergic effect is demonstrated by enhanced apparent polymerization rates at elevated temperature. For example, the apparent polymerization rates of MA increases from 0.0860 to 0.115 h –1 with temperature rising from 32 to 50 °C.
研究领域:
高分子化学
·
材料科学
·
光化学
✓ 已验证
产品关联
DOI
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2024
·
IF 6.5
Yuhan Zhang,Nan Xiao,Yanjing Gao,Fang Sun
This study introduces a novel p -diethylene glycol monomethyl ether cinnamyl formamide-based disulfide monomer , N,N′ -(disulfanediylbis(2,1-phenylene)) bis(4-(4-(2-(2-methoxyethoxy)ethoxy) phenyl)-2-oxobut-3-enamide) (Mp-BSCF), designed to reduce the volume shrinkage of photosensitive resins and initiate monomer polymerization under 455 nm LED light irradiation. The photochemical properties and photoinitiation efficiency of Mp-BSCF are systematically investigated using UV–vis absorption spectroscopy , electron paramagnetic resonance (EPR) and real-time infrared spectroscopy . Although its weak absorption around 455 nm, Mp-BSCF can generate arylthiyl radicals under 455 nm LED irradiation, and then effectively initiate the polymerization of triethylene glycol dimethacrylate (TEGDMA)/A glycerolate dimethacrylate (Bis-GMA) system. Increasing Mp-BSCF addition enhances the final double bond conversion and maximum polymerization rate of the TEGDMA/Bis-GMA system, reaching up to 82.0 % and 2.02 % s −1 , respectively. Notably, Mp-BSCF significantly reduces the volume shrinkage of the photopolymerization system, with the addition of 10 % Mp-BSCF resulting in a 50 % reduction compared to the control system. This reduction is attributed to the dynamic reversible nature of the S S bond “breaking-recovery” and the intermolecular hydrogen bond interaction. Additionally, Mp-BSCF improves the thermal stability, friction resistance, and hardness of the TEGDMA/Bis-GMA photopolymerization system.
研究领域:
材料科学
·
高分子化学
·
光化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）