JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
·
2017
·Vol. 55
·期 18
·1373-1379
·
IF 2.838
Jiao Chen,Ye Sha,Siyang Gao,Chao Teng,Xiaoliang Wang,Dongshan Zhou,Linling Li,Wei Chen,Gi Xue
Understanding the conformational changes of polymeric chains in solutions is an essential and integral part of polymer physics. By increasing the concentration of polymer solutions from dilute to semidilute regime, the critical chain overlapping has been reported at the concentration termed as C *. In this study, the associated inter- and intrachain conformational transitions in polystyrene (PS) solutions are reported. By comparing the spectroscopic intensity ratio versus concentration for an intrachain PS system, a break point was observed in good solvent which coincided with the theoretically predicted C *. Moreover, the intrachain conformation showed no obvious change below C *, while significant collapse started to occur above C *. This result reveals a new insight in polymer physics, since traditionally the size of polymer chains is considered to decrease weakly regarding the concentration change in the semidilute regime. It is important to find such an abrupt intrachain conformational transition between the dilute and semidilute solutions and provide the first experimental observation that inter- and intrachain conformational transitions are correlated to one the other. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1373–1379
研究领域:
聚合物物理
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2018
·
IF 3.909
Peilin Chen,Qingxiang You,Xin Li,Qing Chang,Yi Zhang,Baodong Zheng,Xiaoke Hu,Hongliang Zeng
In this study, the relationships between the proliferation effect of polysaccharide fractions from the citrus shrub Fortunella margarita on Bifidobacterium adolescentis ATCC 15703 and their resulting structural changes were investigated. Four polysaccharide fractions, FP20, FP40, FP60, and FP80, were obtained by graded precipitation at ethanol concentrations of 20%, 40%, 60% and 80%, respectively. The results showed that polysaccharide fractions, especially FP20, FP40, and FP60, enhanced the proliferation of B. adolescentis ATCC 15703 and their effects were better than those of FP80, inulin or glucose. Moreover, acetic acid was mainly produced during fermentation. After fermentation, the molecular weight of polysaccharide fractions decreased and the tightly structural chain conformations of FP20, FP40, and FP60 changed to highly branched structures. The prebiotic effect of these polysaccharide fractions might be related to their molecular weight and chain conformation. Thus, these polysaccharides could be used as potential prebiotics.
研究领域:
食品科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CARBOHYDRATE POLYMERS
·
2021
·
IF 9.381
Zhixiang Cai,Hongbin Zhang
The chain conformational change in curdlan during carboxymethylation was investigated using nuclear magnetic resonance (NMR), circular dichroism (CD) spectroscopy, and atomic force microscopy (AFM). The distributions of carboxymethyl substituents within anhydroglucose unit (AGU) of CMCD were found to follow the order of OH (6) > OH (4) > OH (2) for CMCD with a low DS and OH (6) > OH (2) > OH (4) for CMCD with relatively high DS. The increased carboxymethylation level induced the chain conformation transition of curdlan from triple helix to random coil in water. The DS of 0.25 was the critical value of chain conformation transition, below which CMCD chains were triple helices. For DS larger than 0.25, CMCD existed in the state of random coils. The intermolecular hydrogen bonding between C2 hydroxyls in AGU sustained the triple helical conformation and stiffness of the polymer chain, which weakened with the increase in DS.
研究领域:
生物化学
·
高分子科学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Jingsi Zhang,Xin Chen,Qiping Zhan,Yifan Wang,Keke Meng,Qiuhui Hu,Liyan Zhao
Flammulina velutipes ( F. velutipes ) polysaccharides have been shown to play a crucial role in preventing inflammatory diseases. However, further exploration is needed to understand the specific relationship between their structure and anti-inflammatory activity. In this study, four structurally distinct F. velutipes polysaccharides (FVP2, FVP2U1, FVP2U2, and FVP2U3) were isolated via a previously established ultrasonic degradation model, and the exploration on the impact of chain conformation on their anti-inflammatory activities was focused. The results indicated that FVP2 exhibited a spherical conformation, while FVP2U1 and FVP2U2 displayed flexible chains, and FVP2U3 showed a semi-rigid chain. The study on the impact of four kinds of F. velutipes polysaccharides on inflammatory response in LPS-stimulated RAW264.7 cells revealed that ultrasonic degradation enhanced the anti-inflammatory activity of FVP2. The primary anti-inflammatory mechanism involved the inhibition of NO, TNF-α, IL-1β, and IL-6 release, and reduced transcriptional levels of TLR4, MyD88, NF-κB, and NLRP3. Among the ultrasonically degraded polysaccharides with compliant chain conformations and lower molecular weight demonstrated superior anti-inflammatory activity. These results provide insights into the relationship between molecular weight, chain conformation, and anti-inflammatory activity of F. velutipes polysaccharides, contributing to the potential application of ultrasound in developing highly active anti-inflammatory polysaccharides and related nutritional products.
研究领域:
生物化学
·
免疫学
·
食品科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Luyan Li,Hao Li,Mingzhang Lin,Jun Wen,Sheng Hu
The amidoxime group has received widespread attention owing to its high affinity for uranium. Since this property was discovered, various amidoxime-based adsorbents have been developed for uranium adsorption. However, the effect of chain conformation on the uranium adsorption performance (in terms of adsorption capacity, stability, selectivity, etc.) of amidoxime adsorbents has rarely been studied. Herein, three amidoxime-based adsorbents with different chain conformations (linear, multi-armed, and rigid) were constructed via tert -butyl hydroperoxide-initiated surface graft polymerization by incorporating different monomer structures. Adsorption experiments revealed that the linear structure of P-E-PAO exhibited the highest adsorption capacity owing to the highest monomer-grafting ratio; the multi-arm structure of P-E-PMGO was affected by pH and ionic strength because of the most cyclic imide dioxime structure; and the rigid structure of P-E-PEBO showed the highest selectivity owing to the most open-chain amidoxime structure. These findings are expected to have strong implications in the optimization of adsorption material designs.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
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
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Hao Peng,Xiaoyu Li,Lina Lv,Tingting Deng,He Chen,Lu Wang,Qiang He,Caiping Dang,Lianggui Bao,Yihao You,Fangting Chi
Amidoxime-based polymers have been widely regarded as ideal adsorbents for uranium extraction from seawater. However, significant challenges remain in the efficient utilization of amidoxime groups on the polymers which is closely related to the conformation of molecular chains in complex marine environments. Herein, by integrating multi-scale computational simulation with chain conformation regulation, three representative auxiliary group were designedly introduced to polyamidoxime (PAO) by grafting glycine, aminomethylsulfonic acid and aminomethylphosphonic acid. Firstly, the hydrophilicity of adsorbents was directly observed to increase significantly after modification by contact angle test and swelling test. Furthermore, the chain conformation was investigated by combined SAXS and MD simulation under real factors from seawater. Finally, uranium adsorption performance and mechanism were investigated by XPS and DFT calculation. The minimum contact angle reaches 26.9° and the maximum swelling rate is above 153.4 %. The conformation of the modified PAO was much more stretched than the raw one, with a radius of gyration up to 161.5 nm for PAO-AMP. The uranium adsorption capacity of PAO was only 165.5 mg/g, while that of the modified adsorbents PAO-AMP went up to 375.0 mg/g. The above results indicate that auxiliary groups played a role not only in optimizing the chain conformation of adsorbents but also in enhancing coordination capacity with uranium, which is beneficial for uranium extraction from seawater. This study offers a new point of view to assess adsorption phenomena of polymers, bridging chain conformations in different environment at the mesoscopic level with metal–ligand interactions at the molecular level.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2014
·
IF 3.766
Hai-Mu Ye,Yi-Ren Tang,Yun-Yang Song,Jun Xu,Bao-Hua Guo,Qiong Zhou
A series of random poly(hexamethylene succinate- co -hexamethylene fumarate) (PHSF) samples was synthesized through a two-step reaction process, and their properties were systematically studied using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The crystal modification of polyester changes from monoclinic to orthorhombic after substituting hexamethylene succinate (HS) units by hexamethylene fumarate (HF) units, and the chain conformation changes from all-trans to gauche. The copolyesters were found to be in a particular case as strict isomorphism in a limited composition range, adopting the same crystal modification when HF content ranged from 19 to 100 mol%. The melting point of the copolyester increases almost linearly with increasing molar content of HF, and the melting enthalpy hardly changes. Interestingly, FTIR results suggest that a special hydrogen-bonding interaction, in “C C–H···O C–C C” form, forms in the crystalline phase of PHSF and poly(hexamethylene fumarate) (PHF). The strong hydrogen-bonding interaction might be responsible for the transformation of conformation from all-trans to gauche in hexamethylene segments, and triggers the variation of crystal modification.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2013
·Vol. 29
·期 5
·1022-1028
·
IF 0.735
Liu Gui-hua,Qiu Xue-peng,Siddiq Mohammad,Bo Shu-qin,Ji Xiang-ling
Temperature dependence of chain conformation and local rigidity of two soluble isomerized polyimides (PIs), poly(hexafluorodianhydride/3,3′-dimethylbenzidine)[poly(6FDA/3,3′-DMB)] and poly(hexafluorodianhy-dride/2,2′-dimethylbenzidine)[poly(6FDA/2,2′-DMB)] were investigated by dilute solution viscosity, size exclusion chromatography(SEC) coupled with multi-angle laser light scattering, viscometer, and refractive index detector in dimethylformamide(DMF) with either 0.1 mol/L LiBr or 3.1 mmol/L tetrabutylammonium bromide(TBAB) in the temperature range of 30 to 50 °C. The scaling relationships of [ η ]= K
η
M
α and R
g = K
g
M
ν obtained are employed to investigate the temperature dependence of chain conformation for the two polyimides. The values of α and ν are in the range of 0.66–0.69 and 0.53–0.56, respectively, for poly(6FDA/3,3′-DMB), meanwhile they are in the range of 0.64–0.68 and 0.53–0.56, respectively, for poly(6FDA/2,2′-DMB). These results reveal that random coil conformations for both PIs are not affected visibly with increasing temperature from 30 °C to 50 °C. However, values of more exact intrinsic viscosity from dilute solution measurement indicate there is only tiny coil extension or shrinkage for both PIs with temperature rising. Parameters related to chain flexibility of polymer, including persistence length l
p , shift factor M
L
(relative molecular weight per unit contour length) and backbone diameter d are estimated from the relationship between intrinsic viscosity and molecular weight for the continuous wormlike cylinder model, which indicates that two samples are flexible chains, only the chain of poly(6FDA/3,3′-DMB) is stiffer than that of poly(6FDA/2,2′-DMB) slightly.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2023
·Vol. 14
·期 9
·1043-1053
·
IF 4.6
Xuejun Pan,Weiling Wu,Mo Zhu,Jixian Yang,Zhi-Chao Yan,Lianwei Li
This work reports the conformational, crystalline and rheological properties of poly(octadecyl-stat-methyl acrylate) (P(ODAx-stat-MAy)Nb) random copolymers, where Nb is the overall degree of polymerization, and x and y represent the molar fraction of ODA and MA, respectively, with x + y = 1.0. By a combination of ATRP, esterification and graft-onto strategies, a library of P(ODAx-stat-MAy)Nb samples with statistically random distribution features have been prepared. The average molar mass (M), viscometric radius (Rη) and intrinsic viscosity ([η]) are determined in solution, and a scaling-law of Rη ∼ M0.28 is established. For the conformation of P(ODAx-stat-MAy)Nb, it is found that [η] increases with x first due to chain expansion but decreases with x when x > 0.25, because the increase in segmental density dominates at high x. The rheological measurement indicates that the viscous flow activation energy remains constant first and then increases with decreasing x, reflecting the reduction of internal plasticization. In addition, the entanglement plateau modulus for the sample with x = 0.99 is one decade lower than that of the backbone, which is consistent with the prediction for the densely grafted bottlebrush polymers. This work provides a new strategy to synthesize model PODA-based random copolymers, and clarifies the change of the chain conformation, crystalline properties, and rheological behavior with the grafting density x, and this knowledge could be used to regulate the conformation and processing properties of comb/bottlebrush polymers by precisely designing the alkyl side chain's grafting density and length.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Zihao Meng,Ying Wang,Yanlong Luo,Zhenyang Luo,Linling Li,Ye Sha
Using a “core-first” approach with atom transfer radical polymerization, fluorescent center-functional star polymers of equivalent molecular weight but with varying numbers of arms (di-, tri-, and tetra-arm) were prepared. The sensitivity of fluorescence, combined with a dye-labeling technique introducing a fluorescent donor (carbazole) and an acceptor (anthracene) at the center of poly(methyl methacrylate) (PMMA) chains, enabled the application of time-resolved fluorescence resonance energy transfer to obtain quantitative insights into the conformation of the star polymer chains in the film state. When the results of star-branched polymers were compared with those of linear polymers of identical type and molecular weight, the impact of branching on polymer behavior was isolated for examination. Although the star topology does not alter the average intercoil distance, it affects the distance dispersity. Star polymers with higher arm numbers display decreased dispersity from distance due to reduced intermolecular aggregation at their geometric centers. This study presents the first spectroscopic evidence regarding the distribution of geometric centers in star polymers, offering a physical understanding of chain interpenetration and entanglement within star polymers.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
FOOD CHEMISTRY
·
2025
·
IF 9.8
Binghong Gao,Chuanyan Rao,Xingmeng Lei,Siqi Li,Xiaochuan Huang,Yanlin Liu,Dongqing Ye
Modification of wine bitterness is subtle and complex. To investigate the mechanism underlying the differences in the initial bitter inhibition of grape seed extract (MOPC) by mannoproteins (MPs), the molecular interactions between MPs from different chain conformations and MOPC at different concentrations were analyzed using methylation, laser light scattering, rheological behavior analysis, and spectral techniques. The results indicated that MPs with linear hyperbranched structures at low concentrations (0.25 mg/mL) exhibit strong initial bitter inhibition, primarily due to the structural characteristics of the MPs-MOPC binary complexes. This included binding protein components to MOPC through electrostatic and hydrophobic interactions and encapsulating protein components and MOPC within a dense, strongly hydrophilic polysaccharide shell. These findings provide a theoretical basis for producing more efficient MPs by clarifying the key conformation and mechanism by which MPs inhibit wine bitterness.
研究领域:
食品科学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）