共查询到20条相似文献,搜索用时 31 毫秒
1.
《Physics and Chemistry of Liquids》2012,50(3):428-435
The mixture of polyisoprene with sodium-2-diethylhexyl sulfosuccinate (AOT)/H2O/cyclohexane microemulsion is studied with the photon correlation spectroscopy (PCS) and small angel X-ray scattering (SAXS). The water with AOT induces nano-droplets inside the cyclohexane and addition of concentration and length scale of polyisoprene (PI) can change diffusion of nano-droplets. The collective diffusion coefficient (Dc) of nano-droplets decreased with increase in concentration of PI. From SAXS experiment, a spherical–cylindrical transition of nano-droplets by increase in polyisoprene concentrations observed that it can describe behaviour of diffusion. 相似文献
2.
《Physics and Chemistry of Liquids》2012,50(5):660-670
The effect of length scale of triblock oil-soluble polymer (poly (ε-caprolactone)–poly butadiene-poly (ε-caprolactone)) (PCL-PB-PCL) on the properties of a water-in-oil (W/O) droplet microemulsion (R ~ 5.5 nm) has been studied as a function of the amount of added telechelic polymer. Small-angle X-ray scattering (SAXS) measurements show that the size of the droplets is not affected by the polymer addition but it induces attractive interactions at low concentration and repulsive ones at high polymer content. Measurements of the diffusion coefficient by dynamic light scattering (DLS) show different relaxations in mixed systems. The fast diffusion coefficient increases with increase in polymer concentration. At higher polymer content, the network formation leads to an additional slow relaxation mode in DLS that can be related to the formation of clusters of microemulsion droplets interconnected by the polymer. The collective diffusion of slow relaxations decreases with increase of polymer concentrations. 相似文献
3.
《Physics and Chemistry of Liquids》2012,50(5):586-594
We study the effect of polyethylene glycol (PEG) on the dynamic and structure of water droplets at the reverse sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) microemulsion. The mixture of water and oil with anionic surfactant AOT can form microemulsion. The dynamic of microemulsion in the presence of PEG is investigated by photon correlation spectroscopy technique. We mainly focus on the variation of the translational diffusion behaviour as a function of the polymer concentration and polymer length scale. By increasing the content of the lowest PEG length scale (Mn = 285), the dynamic of microemulsion slows down. In addition, one relaxation process is distinguished for all polymer concentration. However, for the two higher polymer length scale (Mn = 2200 and 6000), two relaxations are observed and the dynamic of microemulsion speeds up. We used the small angle X-ray scattering technique to monitor the size and the polydispersity of the mixture system (AOT microemulsion/PEG). 相似文献
4.
Chaoqing Yin Jie Dong Zixin Zhang Qinghua Zhang Jinyou Lin 《Journal of Polymer Science.Polymer Physics》2015,53(3):183-191
Co‐polyimide (co‐PI) fibers with outstanding mechanical properties were fabricated via thermal imidization of polyamic acids, derived from a new design of combining the amide and benzimidazole diamine monomers, 4‐amino‐N‐(4‐aminophenyl)benzamide (DABA) and 2‐(4‐aminophenyl)‐5‐aminobenzimidazole (BIA), with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA). The crystalline structure and micromorphology of the prepared co‐PI fibers were investigated by synchrotron wide‐angle X‐ray diffraction (WAXD) and small‐angle X‐ray scattering (SAXS). The two‐dimensional WAXD spectra imply that the co‐PI fibers possess a structure between smectic‐like and three‐dimensionally ordered crystalline phase, and all the obtained fibers are highly oriented along the fiber axis. SAXS patterns exhibit a pair of meridional scattering streaks for the homo‐PI (BPDA/BIA) fiber, suggesting the presence of periodic lamellar structure. The incorporation of DABA into the polymer chains destroyed the lamellar structure but led to smaller size of microvoids upon increasing DABA moiety, based on SAXS analysis. The co‐PI fibers, with the molar ratio of BIA/DABA being 7/3, exhibited the optimum tensile strength and modulus of 1.96 and 108.3 GPa, respectively, attributed to the well‐defined ordered and dense structure. The chemical structure and molecular packing significantly affected the thermal stability of fibers, resulting in the different glass transition temperatures (Tg) from 350 to 380 °C. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 183–191 相似文献
5.
Bilge Gurun David G. Bucknall Yonathan S. Thio Chin Ching Teoh Eileen Harkin‐Jones 《Journal of Polymer Science.Polymer Physics》2011,49(9):669-677
A unique in situ multiaxial deformation device has been designed and built specifically for simultaneous synchrotron small angle X‐ray scattering (SAXS) and wide angle X‐ray scattering (WAXS) measurements. SAXS and WAXS patterns of high‐density polyethylene (HDPE) and HDPE/clay nanocomposites were measured in real time during in situ multiaxial deformation at room temperature and at 55 °C. It was observed that the morphological evolution of polyethylene is affected by the existence of clay platelets as well as the deformation temperature and strain rate. Martensitic transformation of orthorhombic into monoclinic crystal phases was observed under strain in HDPE, which is delayed and hindered in the presence of clay nanoplatelets. From the SAXS measurements, it was observed that the thickness of the interlamellar amorphous region increased with increasing strain, which is due to elongation of the amorphous chains. The increase in amorphous layer thickness is slightly higher for the nanocomposites compared to the neat polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
6.
Random copolymers of polystyrene-co-polyvinyl triethoxysilane (PS-co-PVTES) were prepared via semi-batch emulsion polymerization with different feed monomer compositions and evaluated as precursors of polystyrene (PS)/silica nanocomposites. Small-angle X-ray scattering (SAXS) profiles acquired from 20 °C to 180 °C showed that, at temperatures higher than glass transition temperature (T g) of PS, the latex particles aggregate. On thermal annealing at 180 °C, silica-rich domains are formed, as corroborated by scanning electron microscopy. Infrared spectroscopy and differential scanning calorimetry analyses showed a reduction of the silanol concentration and an increase in the T g value, respectively. The silica long domain spacing, measured by SAXS, depends on the concentration of vinyl triethoxysilane (VTES) in the feed; this value varied from 35 to 57 nm when the weight ratio of the monomers (styrene/VTES) was 50:50 and 90:10, respectively. 相似文献
7.
As a solution theory, Raoult’s law is commonly used to estimate the activities of solutes and solvents of comparable molecular sizes while the Flory–Huggins (F–H) model is used for the activities of small liquids in high polymers. For a great many systems where the solute and solvent differ only moderately in molecular size (e.g., by 4–10 times), there has been no confirmed choice of a preferred model; examples of such systems are those of ordinary organic compounds in liquid triolein (MW = 885.4 g·mol?1) and poly(propylene glycol) (PPG) (MW = ~1,000 g·mol?1). The observed nearly athermal solubilities of many nonpolar organic solids in these solvents provide unique experimental data to examine the merit of a solution model. As found, Raoult’s law underestimates widely, and the F–H model underestimates slightly, the solid solubilities in triolein and PPG because these models underestimate the solution entropy for these solute–solvent pairs. To rectify this problem, the molecular segments of a large sized liquid solvent (e.g., triolein) are assumed to act as independent mixing units to increase the solute–solvent mixing entropy. This adjustment leads to a modified F–H model in which the “ideal” or “athermal” solubility of a solid in volume fraction, at a particular temperature, is equal to the solid’s activity at that temperature. Results from other studies give further support for the modified F–H model to interpret the partition data of compounds with organic solvents. 相似文献
8.
Eloi Feitosa Vanessa R.O. Cavalcante Lia Q. Amaral 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):82-86
The ternary phase diagram for the orange essential oil (OEO)/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water system was constructed at 25 °C. It indicates a large single phase region, comprising an isotropic water-in-oil (W/O) microemulsion (ME) phase (L2), a liquid crystal (LC) (lamellar or hexagonal) and a large unstable emulsion phase that separates in two phases of normal and reverse micelles (L1 and L2). In this communication the properties of the ME are investigated by viscosity, electric conductivity and small angle X-ray scattering (SAXS) indicating that the isotropic ME phase exhibits different behaviors depending on composition. At low water content low viscous “dry” surfactant structures are formed, whereas at higher water content higher viscous water droplets are formed. The experimental data allow the determination of the transition from “dry” to the water droplet structures within the L2 phase. SAXS analyses have also been performed for selected LC samples. 相似文献
9.
A small-angle x-ray scattering (SAXS) investigation of two linear segmented polyurethanes was carried out to learn about the respective domain structure (morphology). Both urethanes had a hard segment of methylene-bis(4)phenyl isocyanate (MDI) and butanediol. These two components comprised 28% by weight of each system. The soft segments differed in that one was a polyether (tetramethylene oxide, molecular weight 1000), while the other was a polyester (polytetramethylene adipate, molecular weight 1000). Both of these segmented urethanes were stored at room temperature for over 6 months prior to investigation. Using an automated Kratky camera, SAXS scans were made. By detailed analysis (using the computer program of Vonk) the average interfacial thickness E of the domains was determined by two approaches. The value of E for the polyester was 10–12 Å, while it was 5–7 Å for the polyether. Within the limits of the assumptions used for analysis, these data directly support the conjecture that polyether urethanes generally lead to better phase separation. Other aspects of the analysis provided further information on the morphological structure. Some cautionary comments are provided on the use of quantitative SAXS data obtained from these or similar systems. 相似文献
10.
Ziauddin Ahmed Carsten Müller Jaya J. Johnston Kevin Nguyen Christopher P. J. Schubert Karina Abitaev 《Liquid crystals》2019,46(6):896-904
We investigate the origins of ‘de Vries-like’ liquid crystalline behaviour by introducing an ethynyl spacer in the core of the tricarbosilane-terminated 5-phenylpyrimidine mesogens QL16-6 and QL17-6. The rationale for this structural change is based on the assumption that an ethynyl spacer would create more free volume in the core sub-layer and therefore decrease the orientational order parameter S2 in the SmA phase. The tricarbosilane-terminated mesogens WL41-5 and WL42-6 with a 5-(phenylethynyl)pyrimidine core in either a normal or inverted orientation were synthesised, and their mesomorphic and ‘de Vries-like’ properties characterised using polarised optical microscopy, differential scanning calorimetry, birefringence measurements, small–angle (SAXS) and 2D X-ray scattering. Reduction factors R derived from SAXS and optical tilt angle measurements suggest that neither WL41-5 (R = 0.49) nor WL42-6 (R = 0.80) exhibit ‘de Vries-like’ properties. The S2(T) profiles show an increase in orientational order with decreasing temperature and a sharp discontinuity at the SmA-SmC transition, which is consistent with ‘de Vries-like’ behaviour. However, the Leff(T) profiles suggest an increase in interdigitation that reduces the positive effect of increasing S2 in compensating for the molecular tilt. 相似文献
11.
Simultaneous determination of the novel tyrosine kinase inhibitor meditinib and its active metabolite demethylation meditinib in monkey plasma by liquid chromatography–tandem mass spectrometry and its application to pharmacokinetic studies
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Yongqi Guo Yu Wang Dejie Sun Shi Liu Jinling Cai Yongbiao Guan Rigao Ding 《Biomedical chromatography : BMC》2015,29(8):1259-1266
Meditinib (ME) is a novel tyrosine kinase inhibitor used as an antichronic myeloid leukemia drug. A simple, sensitive and specific LC/MS/MS method was developed and validated for the analysis of ME and its metabolite demethylation meditinib (PI) in monkey plasma using naltrexone as the internal standard. Sample preparation involved protein precipitation with methanol. The analysis was carried out on an Agilent C8 column (3.5 µm, 2.1 × 50 mm). Elution was achieved with a mobile phase gradient varying the proportion of a water solution containing 0.1% formic acid (solvent A) and a 0.1% formic acid in methanol solution (solvent B) at a flow rate of 300 μL/min. The method had a linear calibration curve over the concentration range of 2–1000 ng/mL for ME and 2–1000 ng/mL for PI. The lower limits of quantification of ME and PI were 2 and 2 ng/mL, respectively. The intra‐ and inter‐day precision values were <15% and accuracy values were within ±10.0%. The mean recoveries of ME and PI from plasma were >85%. The assay has been successfully used for pharmacokinetic evaluation of ME and PI using the monkey as an animal model, and those data are reported for the first time. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
12.
J. A. Forrest A. C. Rowat K. Dalnoki-Veress J. R. Stevens J. R. Dutcher 《Journal of Polymer Science.Polymer Physics》1996,34(17):3009-3016
We have used Brillouin light scattering (BLS) to investigate the mechanical properties of thin polystyrene (PS) and polyisoprene (PI) films incorporated in a multilayer geometry consisting of alternating layers of the two polymers. All samples had a total thickness h ∼ 1600 Å, and consisted of between 2 and 10 individual polymer films; individual layer thicknesses were as small as 160 Å. Ellipsometry was used to determine the thickness of the PS and PI layers. The velocities of several high-frequency film-guided mechanical waves were measured using BLS and the results are compared with values calculated using an effective medium approach. The effective elastic constants of the multilayered films were obtained from those determined for thick films of PS and PI. Remarkable agreement was obtained between the measured and calculated velocities even for samples in which the individual layer thicknesses were much less than the unperturbed size of the polymer molecules. These results suggest that the mechanical properties of polymers change very little even when the molecules are forced into highly confined geometries. © 1996 John Wiley & Sons, Inc. 相似文献
13.
Bruce X. Fu Ling Yang Rajesh H. Somani Steven X. Zong Benjamin S. Hsiao Shawn Phillips Rusty Blanski Patrick Ruth 《Journal of Polymer Science.Polymer Physics》2001,39(22):2727-2739
Crystallization studies at quiescent and shear states in isotactic polypropylene (iPP) containing nanostructured polyhedral oligomeric silsesquioxane (POSS) molecules were performed with in situ small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry (DSC). DSC was used to characterize the quiescent crystallization behavior. It was observed that the addition of POSS molecules increased the crystallization rate of iPP under both isothermal and nonisothermal conditions, which suggests that POSS crystals act as nucleating agents. Furthermore, the crystallization rate was significantly reduced at a POSS concentration of 30 wt %, which suggests a retarded growth mechanism due to the molecular dispersion of POSS in the matrix. In situ SAXS was used to study the behavior of shear‐induced crystallization at temperatures of 140, 145, and 150 °C in samples with POSS concentrations of 10, 20, and 30 wt %. The SAXS patterns showed scattering maxima along the shear direction, which corresponded to a lamellar structure developed perpendicularly to the flow direction. The crystallization half‐time was calculated from the total scattered intensity of the SAXS image. The oriented fraction, defined as the fraction of scattered intensity from the oriented component to the total scattered intensity, was also calculated. The addition of POSS significantly increased the crystallization rate during shear compared with the rate for the neat polymer without POSS. We postulate that although POSS crystals have a limited role in shear‐induced crystallization, molecularly dispersed POSS molecules behave as weak crosslinkers in polymer melts and increase the relaxation time of iPP chains after shear. Therefore, the overall orientation of the polymer chains is improved and a faster crystallization rate is obtained with the addition of POSS. Moreover, higher POSS concentrations resulted in faster crystallization rates during shear. The addition of POSS decreased the average long‐period value of crystallized iPP after shear, which indicates that iPP nuclei are probably initiated in large numbers near molecularly dispersed POSS molecules. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2727–2739, 2001 相似文献
14.
《Physics and Chemistry of Liquids》2012,50(3):436-441
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and cholesterol are used to prepare liposome. Dynamic light scattering was used to study the dynamics of different concentration of the DSPC on liposomal structure. The results show that with increase of DSPC concentration the diffusion coefficient decreases. The small angle X-Ray scattering (SAXS) experiments show that an increase of the DSPC of 0.5–5% changes the size of liposomal structure from 35 to 112 nm, this is analysed in leaves of hard sphere core shell model. Moreover, the addition of NaCl at 0.001 molar can decrease the size of liposomal structure. 相似文献
15.
Lihong Geng Xiangfang Peng Chengbo Zhan Ali Naderi Priyanka R. Sharma Yimin Mao Benjamin S. Hsiao 《Cellulose (London, England)》2017,24(12):5417-5429
Carboxylated cellulose nanofibers (CNFs), having an average width of 7 nm and thickness of 1.5 nm, were produced by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation method. The fiber cross-sectional dimensions were determined using small-angle X-ray scattering (SAXS), transmission electron microscopy and atomic force microscopy techniques, where the rheological properties under different concentration and ionic strength were also investigated. The formation of hydrogel was evidenced by increasing the CNF concentration or ionic strength of the solvent (water), while the gel structure in ion-induced CNF hydrogels was found to be relatively inhomogeneous. The gelation behavior was closely related to the segmental aggregation of charged CNF, which could be quantitatively characterized by the correlation length (ξ) from the low-angle scattering profile and the scattering invariant (Q) in SAXS. 相似文献
16.
X. Lefbvre M. H. J. Koch H. Reynaers C. David 《Journal of Polymer Science.Polymer Physics》1999,37(1):1-18
The thermal behavior of poly(hexamethylene terephthalate) (PHT) oligomers containing variable amounts of isophthalic (IPA) monomer has been investigated. Poly(hexamethylene terephthalate‐co‐isophthalate) 3400 was first studied. This polymer has a M n of 3400, is constituted by heterodisperse PHT units (crystallizable units) with a M n of 2000, contains an average number of 2.6 IPA per chain, and has carboxylic chain ends. DSC results have shown that this polymer exhibits multiple melting endotherms. These are described in terms of (i) the existence of two melting zones located on both sides of Tc and associated with two polymer fractions differentiated by their crystallizable unit length, (ii) different crystalline populations growing at Tc, (iii) a reorganization process. A simultaneous small (SAXS) and wide (WAXS) angle time resolved X‐ray scattering study using synchrotron radiation has revealed that the different crystalline populations are characterized by different lamellar structures rather than by different crystalline lattices. Other PHTcoIs and PHTs differing from PHTcoI 3400 by their molecular weight and IPA content were also studied using DSC. IPA acts as a defect for crystallinity and causes Tm and ΔHm depression in the PHTcoIs. When the molecular weight of PHT increases, Tm increases and ΔHm decreases as usually reported in the literature. Finally, two crosslinked polymers (PHTcoI 3400 and PHTcoI 4700) were investigated. The insoluble fraction of crosslinked PHTcoI 3400 does not crystallize anymore while the one of PHTcoI 4700 does. This results from shorter crystallizable units and from the distance between the crosslinks of the former. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1–18, 1999 相似文献
17.
Joel Hagman Luigi Gentile Christian Moestrup Jessen Manja Behrens Karl-Erik Bergqvist Ulf Olsson 《Cellulose (London, England)》2017,24(5):2003-2015
We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0 M NaOH(aq)] solutions using a combination of small angle X-ray (SAXS) and static light scattering (SLS), \(^1\)H NMR, NMR self-diffusion, and rheology experiments. NMR and SAXS data demonstrate that the cellulose is fully molecularly dissolved. SLS, however, shows the presence of large concentration fluctuations in the solution, consistent with significant attractive cellulose-cellulose interactions. The scattering data are consistent with fractal cellulose aggregates of micrometre size having a mass fractal dimension \(D\sim 1.5\). At 25\(\,^{\circ }\mathrm {C}\) the solution structure remains unchanged on the time scale of weeks. However, upon heating the solutions above 35\(\,^{\circ }\mathrm {C}\) additional aggregation occurs on the time scale of minutes. Decreasing or increasing the NaOH concentration away from the “optimum” 2 M also leads to additional aggregation. This is seen as an increase of the SAXS intensity at lower q values. Addition of urea (1.8 and 3.6 M, respectively) does not significantly influence the solution structure. With these examples, we will discuss how scattering methods can be used to assess the quality of solvents for cellulose. 相似文献
18.
Mikhail Nikolaevich Krakhalev Oxana Olegovna Prishchepa Vitaly Sergeevich Sutormin Victor Yakovlevich Zyryanov 《Liquid crystals》2017,44(2):355-363
The polymer dispersed nematic liquid crystal (LC) with the tilted surface anchoring has been studied. The droplet orientational structures with two point surface defects – boojums and the surface ring defect – are formed within the films. The director tilt angle α = 40° ± 4° at the droplet interface and LC surface anchoring strength Ws ~ 10–6 (J m?2) have been estimated. The bipolar axes within the studied droplets of oblate ellipsoidal form can be randomly oriented are oriented randomly relatively to the ellipsoid axes as opposed to the droplets with homeotropic and tangential anchoring. 相似文献
19.
James B. Wittenberg 《Supramolecular chemistry》2014,26(3-4):157-167
Recently, we reported the synthesis of two new dimeric cucurbit[6]uril compounds (1 and 2). Herein, we describe the ability of compound 1 to undergo supramolecular polymerisation when combined with polyethylene glycol (PEG) derived divalent guests 3MW (MW = 300, 1000, 3350, 10,000). Interestingly, we find that the shorter PEG-derived guests 3300, 31000 and 33350 lead to low degrees of oligomerisation based on the diffusion coefficients obtained by diffusion-ordered spectroscopy measurements. In contrast, when 1 was combined with the longest PEG-derived guest 310,000, we observed the formation of a supramolecular polymer with a degree of oligomerisation of at least 36. We observe that the supramolecular polymer 1n·(310,000)n undergoes a slow decrease in its degree of oligomerisation to 22 over the course of 14 days controlled by the slow dissociation rate constant of the hexanediammonium unit of 310,000 from the CB[6]-sized cavity of 1. 相似文献
20.
Santosh K. Sar Rashmi Mandavi Nutan Rathore P. K. Pandey 《Journal of Dispersion Science and Technology》2013,34(9):1288-1290
The hydrolysis of the p-nitrophenyl acetate catalyzed by different hydroxamate ions (RCONHO?; R = C6H5, 2-OHC6H4, CH3) was investigated at 27°C in aqueous media containing polyethylene glycol(MW = 4000 and 8000) at various pH values. Hydroxamate ions are effective alpha effect nucleophile for acylation reactions. Addition of PEG accelerates the rate of hydrolysis. The rate-polymer profile has been explained by applying different models. A mechanism for the catalyzed reaction is proposed. The BHA-PEG combination is more effective. 相似文献