Food Chemistry-X
·
2022
·
IF 6.443
Shihao Hu,Junqiao Wang,Shaoping Nie,Qiang Wang,Xiaojuan Xu
In this study, apple pectin (AP) and tomato pectin (TP) were demonstrated to be a high-ester (74.8%) polysaccharide with the weight-average molecular weight ( M w ) of ∼ 243 kDa and a low-ester (45.9%) polysaccharide with the M w of ∼ 19 kDa, respectively. The semi-rigid chain conformations of pectic polysaccharides in NaNO 3 aqueous solution were deduced according to the Smidsrød “ B values” of AP (0.025) and TP (0.029), while AP and TP exhibited higher stiffness in water due to the electric repulsion of carboxyl groups, which was visually observed by AFM images. Under steady shear, the shear-thickening behaviors of AP and TP in NaNO 3 aqueous solutions were observed in the shear rate range of < 1 s −1 , which were attributed to the disruption of the ordered arrangement induced by semi-rigid pectin chains into randomly entangled structure by weak shear force. AP exhibited stronger shear-thickening behavior due to the formation of more entanglements resulted from the higher M w and longer side chains highly branched at rhamngalacturonan region. This study provides the scientific basis for the construction of the relationship of steady-shear property with chain conformation and molecular weight of pectin.
研究领域:
食品科学
·
高分子化学
·
植物学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2023
·
IF 5.5
Gang Liu,Ronald G. Larson,Lei Li,Huan Luo,Xi He,Yanhua Niu,Guangxian Li
Polymerized ionic liquids (PILs) poly[1-(4-vinylbenzyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide] (P[VBMIM][TFSI]) covering a wide range of molecular weights are synthesized using reversible addition–fragmentation chain-transfer (RAFT) polymerization. The dependence of zero-shear viscosity on weight-average molecular weight (η0 ∼ Mwα) shows two power-law regimes corresponding to disentangled and entangled regimes with α = 1.1 ± 0.1 and 3.6 ± 0.4, as is typical for neutral entangled polymers. The entanglement molecular weight (Me,calc = 1.8 × 105 g/mol) of P[VBMIM][TFSI] estimated from the packing length p = 8.6 Å and Kuhn length b = 20 Å is consistent with the experimental result (Me,rheo = 1.6 × 105 g/mol) and is much higher than the most conventional uncharged polymers due to the bulkiness of the monomers. For entangled PIL samples, reversible strain-induced disentanglement is observed under large-amplitude oscillatory shear (LAOS) and strong strain hardening in extensional flow. The chain entanglement in high-molecular-weight P[VBMIM][TFSI] brings significant improvement in the mechanical strength and robust recoverability under cyclic stretch over that of the lower-molecular-weight, unentangled PILs, making high-molecular-weight P[VBMIM][TFSI] processable for high-performance electrolytes.
研究领域:
材料科学
·
高分子化学
·
流变学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Zhengrong Lin,Zutian Bi,Hongye Li,Xiaomei Pei,Zhao Chen,Zhenggang Cui,Binglei Song
Herein, a quaternary ammonium surfactant with dual heads and tails, N1,N1,N1,N3,N3-pentamethyl-N3-(3-(2-tetradecylhexadecanamido)propyl)propane-1,3-diaminium dibromide, abbreviated as Di-C14-N2, was synthesized. For the first time, clear observation of aggregate structures formed by surfactants in pure glycerol systems was achieved using cryogenic transmission electron microscopy (cryo-TEM). The system’s rheological properties were analyzed using both steady-state shear and oscillatory rheological measurements. The lubricating efficiency of the Di-C14-N2 glycerol solution was assessed for its tribological properties using a tribological wear tester, white light interferometer, and scanning electron microscope. In glycerol, Di-C14-N2 formed long wormlike micelles, which resulted in a glycerol solution with the zero-shear viscosity of 1013 Pa·s at 90 mM, which is the most viscous glycerol system up to now. The system displayed distinct rheological properties from the aqueous system, as evidenced by two intersections in the loss and storage moduli. The formed wormlike micelles in glycerol lead to a significant alteration in the viscoelasticity of the system, thus endowing the Di-C14-N2 glycerol solution with potential as an eco-friendly lubricant. The friction coefficient of the system was found to be 23% lower and the wear rate was 83% lower than that of pure glycerol after the addition of Di-C14-N2. This demonstrates that the addition of Di-C14-N2 greatly improves the frictional properties of pure glycerol. This study offers the possibility of directly observing the aggregate structures formed by surfactants in pure glycerol systems. It contributes to the exploration of the self-assembly behavior of surfactants in nonaqueous polar media, thereby aiding in a deeper understanding of the correlation between molecular structure, mesoscale structure, and macroscopic properties.
研究领域:
胶体化学
·
材料科学
·
表面化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TRIBOLOGY INTERNATIONAL
·
2023
·
IF 6.2
Peng Yue,Yujuan Zhang,Shengmao Zhang,Jiajia Jia,Kun Han,Ningning Song
The feasibility of using nanoparticles (NPs) as lubricant viscosity modifiers has attracted considerable attention as they can increase/decrease the lubricant viscosity. However, due to the lack of theoretical guidance for interface design, the practical application of NP viscosity modifiers is limited. In this study, molecular dynamics simulations are performed to analyze the non-bonding interactions of four typical lubricating oil/NP solid–liquid interfaces with different interface polarities. A model of the mechanism through which the NPs regulate the shear viscosity of the lubricating oil is proposed based on the solid–liquid interface slip behavior, which is verified experimentally. It is found that the shear resistance of the interface is determined by the "liquid all-atomic Coulomb potential energy" (LACPE) and is positively correlated with the “potential well” values of the LACPE distributed in the tangent plane parallel to the wall. Adjusting the characteristics of the solid surface and the "polar units", which are inside the lubricant molecules, as well as the linking modes between the polar units, is proposed as a means to regulate the interfacial shear resistance. This work could provide guidance for interface design and the R&D of nanoscale viscosity modifiers.
研究领域:
材料科学
·
机械工程
·
表面科学
✓ 已验证
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2020
·
IF 6.984
Xuejiao Li,Na Li,Weihua Liu,Zhongfeng Tang,Jianqiang Wang
The first principle molecular dynamics (FPMD) simulations in combination with experimental measurements are applied to investigate the thermophysical properties and structural evolution of MgCl 2 –NaCl–KCl (MNK) eutectic . The densities, melting point, and enthalpy of fusion simulated by FPMD within NPT ensemble are consistent with experimental results. Besides, the thermal conductivity of molten MNK eutectic evaluated from FPMD simulations with NVT ensemble gives satisfactory result. Furthermore, the shear viscosities of MNK eutectic are deduced based on ion self-diffusion coefficients and solvodynamic radius, similar to the data estimated by additive contribution method. Eventually, the change rules of radial and angular distribution functions and structural factor of MNK eutectic during melting are revealed, and the melting mechanism is proposed from the evolution of polyhedral coordination structures. These results are heuristic in structure-activity relationship of MNK eutectic, which sheds insight for further development of efficient heat transfer and storage media through microstructure engineering.
研究领域:
材料科学
·
热物理
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 76
·48120-48126
·
IF 3.108
Danhua Xie,Donghong You,Shaoming Ying,Binglei Song,Jinnian Tian
Exploration of novel wormlike micelle systems is important for both the theory and applications of surfactant self-assembly. A new anionic surfactant, sodium 2-phenoxyhexadecanoate (sodium Ph-C16), was synthesized in this work. This surfactant can self-assemble in solution to form wormlike micelles with the help of a bolaform salt, ethane-1,2-bis(trimethyl ammonium bromide) (N-2-N bromide), by removing inorganic salts. The resultant aqueous system was investigated using rheological measurements, freeze-fractured-TEM and 2D NOESY 1H NMR experiments. A supramolecular gemini-like structure constructed from electrostatic interactions was a prerequisite for the wormlike micelle formation. The zero shear viscosity (η0) of the system had a very strong dependence on the surfactant concentration with a scaling exponent of 16.8 in the semi-dilute region, which is attributed to the extremely strong electrostatic attraction between the surface-active anions and bolaform cations. These results are beneficial for understanding anionic wormlike micelles in the absence of inorganic salts.
研究领域:
化学
·
材料科学
·
界面科学
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2017
·
IF 4.811
Dandan Li,Na Yang,Yao Zhang,Lunan Guo,Shangyuan Sang,Zhengyu Jin,Xueming Xu
The aim of this study was to evaluate the effects of alcohol-acid degradation on the structural and physicochemical characteristics of guar gum. Guar gum (50 wt.%) was treated with methanol, ethanol, 2-propanol, or 1-butanol containing 1 or 2 mL 36% hydrochloric acid at 75 °C for 30–240 min. The linear relationship between 1/Mw and time suggested that alcohol-acid degradation followed first-order kinetics with rate constants varying directly with the number of alcohol carbon atoms and acid concentration. Alcohol-acid treatment exerted no effect on the chemical and crystal structure of guar but significantly decreased shear viscosity, slightly increased solubility, mildly reduced thermostability, and dramatically darkened colour. This study extended the knowledge of the effect of alcohol on the acid hydrolysis of guar and will contribute to the development of a large-scale procedure for guar gum degradation.
研究领域:
化学工程
·
材料科学
·
食品科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Jinbo Hu,Wenbo Wang,Xinyan Liu,Yeqi Du,Hao Zhang,Ranlong Duan,Xinchao Bian,Yanlong Liu,Xuesi Chen
The lower melt strength of poly(lactide) (PLA) limits its broader applications. Here, a strategy combining copolymerization with multi-arm branching was propose to enhance the melt strength of PLA. Initially, stereoisomeric cyclic ester monomers (CEM) synthesized via zeolite catalysis were copolymerized into PLA chains. Subsequently, rheological testing revealed that the zero-shear viscosity ( η 0 ) of linear PLA increased by 467 % with only 1 mol% of CEM units. Our study further systematically explored the relationship between the side group structure and chirality of the comonomers and the rheological properties of the copolymers. CEMs with long-chain branched structures and opposite chirality had the best enhancement effect. In order to further enhance the melt strength, we successfully achieved alterations in polymer topology by employing trimethylolpropane as an initiator, corresponding three-arm copolymers achieve up to a 67-fold increase in η 0 (1.0 kPa∙s to 68.1 kPa∙s). Tensile tests indicated that the mechanical properties of the copolymers were comparable to those of PLA, with a tensile strength of approximately 65 MPa. Additionally, due to the high melt strength, we successfully produced closed-cell PLA-based foam materials with uniform pore sizes. In summary, this study furnishes a feasible method for designing polymer materials possessing the desired melt strength.
研究领域:
高分子科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 36
·30320-30329
·
IF 3.289
Xuefei Leng,Zhiyong Wei,Yufei Bian,Yingying Ren,Yurong Wang,Qinyi Wang,Yang Li
Three series of narrowly dispersed comb-like graft poly(L-lactide) (PLLA) with controlled graft length and graft density have been facilely synthesized and characterized. The structural information was determined by means of 1H NMR, GPC, and viscometry, demonstrating the well-defined grafted structure. The effects of grafting parameters on rheological properties, thermal and crystallization behaviors were investigated systematically to illustrate the structure–property relationships. By the analysis of the rheological behavior, the increase of graft length and graft density can both lead to an elevated value of zero-viscosity (η0), enhanced complex modulus (G*) and increased complex viscosity (η*). Comparatively, graft density contributes more to the improvement of rheological properties than graft length does. For thermal properties, DSC results show that the glass transition temperature (Tg), the melting temperature (Tm) and the crystallization enthalpy (ΔHm) of graft PLLA increase with the chain length and decrease with the graft density. Furthermore, spherulite morphologies and growth rates were studied by polarized microscopy (POM), and the observation revealed a remarkable improvement of radius growth rate of the spherulites (G) when graft density increased. The results indicate that G depends more on the molecular weight of each arm (Mn,arm) than the total Mn.
研究领域:
高分子科学
·
材料科学
·
化学工程
✓ 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）