Characterization of Anadenanthera macrocarpa exudate polysaccharide

Exudate gum from Anadenanthera macrocarpa Benth. trees was purified and fractionated using 0·1M aq. NaCl/ethanol as a solvent/non-solvent system. The composition of the polysaccharide was determined as 67% arabinose, 24% galactose, 2% rhamnose and 7% glucuronic acid, by a combination of high performance liquid chromatography of fully hydrolysed gum and colorimetric analysis of uronic acid. Molecular characteristics of the polysaccharide and its fractions were investigated by light scattering intensity, dilute solution visco-metry and gel permeation chromatography (GPC). The whole gum was shown to possess a broad molar mass distribution with Mw = 3·7×10⁶ g mol^-1 and [η] = 11cm³ g^-1. Hydrodynamic properties indicated a highly branched structure. Fractions were obtained covering a range of molar masses. The intrinsic viscosity in 1·0 M aq. NaCl at 25°C was found to depend on molar mass according to: [η]/cm³ g^-1 =0 ·0145 M^0·44. The hydrodynamic volume parameter [η]M gave a common GPC calibration for branched polysaccharide fractions and linear poly(oxyethylene) standards. ©1997 SCI     

Ozonization of phenols from Anacardium occidentale (cashew)

The phenolic lipid components cardanol and cardol, obtained from heat-processed technical cashew nutshell liquid from Anacardium occidentale, and anacardic acid from the natural product, each containing monoene, diene, and triene constituents, were ozonized. The ozonides were reduced chemically and catalytically to give 8-(3-hydroxyphenyl)octanal, 8-(3,5-dihydroxyphenyl)octanal, and 8-(3-hydroxy-2-carboxyphenyl)octanal, respectively, together with formaldehyde, malondialdehyde, butanal, and heptanal in each case. Reduction of the 8-(3-hydroxyphenyl)octanal, which was synthesized from 3-benzyloxybenzaldehyde, gave 3-octylphenol. Oxidation of the aldehyde with potassium permanganate gave 8-(3-hydroxyphenyl)octanoic acid, and reduction with sodium borohydride yielded 8-(3-hydroxyphenyl)octanol. For comparison, the trans-diols of cardanol were prepared by treatment of cardanol with peroxyformic acid and cleaved by periodate oxidation to give an alternative route to 8-(3-hydroxyphenyl)octanal but in lower yield. Likewise, the cis-diols were obtained with potassium permanganate and cleaved without isolation to give the same product in lower yield compared with ozonization.     

Synthesis and characterization of carboxymethylated red angico (Anadenanthera macrocarpa) exudate polysaccharide

Red angico is a heteropolysaccharide (arabinogalactan) obtained from Anadenanthera macrocarpa trees. Carboxymethylation of angico gum (AG) with monochloroacetic acid (MCA) in alkaline aqueous medium resulted in samples which were characterized by ¹³C nuclear magnetic resonance spectroscopy and gel permeation chromatography. The effects of reaction parameters, such as alkali concentration, MCA/AG ratio and temperature on the reaction yield and degree of substitution (DS) were investigated. The DS and MCA total efficiency values increase up to 2 h reaction time and then decrease. The DS varied from 0.11 to 1.10 depending on NaOH/MCA/AG ratio and temperature. The highest MCA total efficiency (0.57) was obtained for NaOH/MCA/AG molar ratio equal to 3:1:1, at 70°C. (DS = 0.63, yield = 91.0%). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) analysis shows that polymer degradation was observed in all samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2985–2991, 2007     

Characterization of branched polymers by size exclusion chromatography coupled with multiangle light scattering detector. I. Size exclusion chromatography elution behavior of branched polymers

The elution behavior of branched macromolecules during their separation by size exclusion chromatography (SEC) was studied. The elution behavior of branched polymers was investigated using samples of randomly branched polystyrene and star branched poly(benzyl methacrylate) of different levels of branching by means of a SEC chromatograph coupled with a multiangle light scattering detector. Abnormal SEC elution behavior was found to be typical for highly branched polymers. After a normal elution at small elution volumes the molar mass and root mean square radius of the eluting molecules increased with increasing elution volume. Several SEC experiments were carried out to find explanation for this effect and SEC separation was compared with the separation by thermal field flow fractionation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1588–1594, 2001     

Molecular weight determinations of polyamides by N-trifluoroacetylation

By N-trifluoroacetylation (TFA) polyamides become soluble in ordinary organic solvents such as acetone, butanone, methylene chloride, chloroform and tetrahydrofuran. In these solvents light scattering and osmotic measurements (membrane and vapour-phase osmometry) were carried out to determine the weight and number average degrees of polymerization. Comparison with the results on non-TFA-polyamides in various solvents clearly shows that no polymer degradation takes place. The [η]-P relationships of Trogamid^R-TFA and nylon-6-TFA in tetrahydrofuran at 25°C were determined and corrected for polydispersity.     

Characterization of branched polymers by SEC coupled with a multiangle light scattering detector. II. Data processing and interpretation

This study deals with the characterization of branched polymers by means of size-exclusion chromatography coupled with a multiangle light scattering detector (SEC-MALS). The application of SEC-MALS is demonstrated on several randomly branched polystyrene and star-branched poly(benzyl methacrylate) samples. Various methods of the data processing are compared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 454–460, 2001     

Gelation of pectinic acids in the presence of calcium counterions

Pectins are polysaccharides which are able to gel in the presence of calcium ions if their degree of esterification is lower than 40%. From a purified pectin, a de-esterification was carried out by alkali and by enzymes in order to obtain samples with a different charge density and esterification pattern (random or blockwise distribution of carboxylic acid sites). The pectin-calcium interactions were studied in a dilute solution of calcium pectinates by conductimetry. If the concentration of highly charged polymer is increased, a multichain association can occur: the same process is observed with dilute solutions (c_p≤10-3 eq. 1^?1) but in the presence of an excess of calcium ions. This first step of the gelation was followed by light scattering and by viscometry. The gelling system can be described by a power law including a critical ratio (equivalent concentration of calcium ions/pectin carboxylic sites) and quasi-critical exponents. The values of these critical parameters have been discussed as a function of charge density of the pectins, their esterification pattern, their concentration, and the nature of the divalent counterion.     

Biophysical Characterization of Adeno-Associated Virus Vectors Using Ion-Exchange Chromatography Coupled to Light Scattering Detectors

Ion-exchange chromatography coupled to light scattering detectors represents a fast and simple analytical method for the assessment of multiple critical quality attributes (CQA) in one single measurement. The determination of CQAs play a crucial role in Adeno-Associated Virus (AAV)-based gene therapies and their applications in humans. Today, several different analytical techniques, including size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), qPCR or ELISA, are commonly used to characterize the gene therapy product regarding capsid titer, packaging efficiency, vector genome integrity, aggregation content and other process-related impurities. However, no universal method for the simultaneous determination of multiple CQAs is currently available. Here, we present a novel robust ion-exchange chromatography method coupled to multi-angle light scattering detectors (IEC-MALS) for the comprehensive characterization of empty and filled AAVs concerning capsid titer, full-to-total ratio, absolute molar mass of the protein and nucleic acid, and the size and polydispersity without baseline-separation of both species prior to data analysis. We demonstrate that the developed IEC-MALS assay is applicable to different serotypes and can be used as an orthogonal method to other established analytical techniques.     

Micellization of three-block copolymer poly[styrene-b-(ethene-co-butene)-b-styrene] in mixed solvents of tetrahydrofuran/ethanol

The behaviour of dilute solutions of a three-block copolymer poly[styrene-b-(ethene-co-butene)-b-styrene] in mixtures of tetrahydrofuran (THF)/ethanol was studied using viscometry, osmometry and light scattering. In solutions with a lower ethanol content the copolymer dissolved, but in solutions with a higher ethanol content it became associated, to form spherical micelles with cores composed of middle (aliphatic) blocks. Between the molecular and micellar solutions a region of the so-called anomalous micellization was described. Micelles in mixtures with a higher ethanol content were stabilized by means of fast electrons, isolated and characterized in THF solutions.     

Solution properties of xanthan. Light scattering and viscometry on dilute and moderately concentrated solutions

Elastic and quasi-elastic light-scattering, viscometric and rheological studies are given for solutions of the microbial polysaccharide Xanthomonas campestris (xanthan) in aqueous 0.62N NaCl for polymer concentrations from 0.03 to 2.2 g kg⁻¹. The observed negative ∂ln[η]/∂ln T is interpreted as a decrease of the persistence length with increasing T. The behaviour in moderately concentrated solutions (2<[η]c<25) reveals intermolecular association, leading to gel formation in the extreme case. The effect of the association on the viscometric and light-scattering data is discussed. It is concluded that the early stages of association involve structure with the chain axes nearly parallel, but that larger, particulate-like structures develop with increasing c, eventually leading to gel formation under certain conditions.     

Interaction parameters in ternary polystyrene solutions at high temperature

A combination of dilute solution viscometry and Rayleigh light scattering has been used to evaluate experimentally the interaction parameters χ_ij in solutions comprising tetralin (1), polystyrene (2) and 3-methyl cyclohexanol (3). The measurements were carried out at 371.5 K, where binary solutions of the polymer in 3-methyl cyclohexanol are under θ-conditions and tetralin is a thermodynamically good solvent for polystyrene. For polymer-solvent interaction, values of χ₁₂ = 0.40 ± 0.01 and χ₂₃ = 0.50 were obtained. The solvent-solvent interaction parameter χ₁₃ was composition dependent, having limiting values of 0.52 and 0.73 at X₁ = 0 and X₁ = 1, respectively, where X₁ is the mol fraction of liquid 1 in binary mixtures of liquids (1) and (3).     

Determination of molecular weight and molecular sizes of polymers by high temperature gel permeation chromatography with a static and dynamic laser light scattering detector

Flow-mode static and dynamic laser light scattering (SLS/DLS) studies of polymers, including polystyrene, polyethylene, polypropylene and poly(dimethylsiloxane) (PDMS), in 1,2,4-trichlorobenzene (TCB) at 150 °C were performed on a high temperature gel permeation chromatography (GPC) coupled with a SLS/DLS detector. Both absolute molecular weight (M) and molecular sizes (radius of gyration, R_g and hydrodynamic radius, R_h) of polymers eluting from the GPC columns were obtained simultaneously. The conformation of different polymers in TCB at 150 °C were discussed according to the scaling relationships between R_g, R_h and M and the ρ-ratio (ρ=R_g/R_h). Flow-mode DLS results of PDMS were verified by batch-mode DLS study of the same sample. The presented technique was proved to be a convenient and quick method to study the shape and conformation of polymers in solution at high temperature. However, the flow-mode DLS was only applicable for high molecular weight polymers with a higher refractive index increment such as PDMS.     

On the molecular weight determination of a poly(aryl-ether-ether-ketone) (PEEK)

Attempts have been made to determine the weight average molecular weight ($\text{M}\text{?}{}_{\mathrm{<mtext>W</mtext>}}$), the radius of gyration ($\text{R}\text{?}{}_{\mathrm{<mtext>G</mtext>}}$) and the second virial coefficient (A₂) of five samples of poly(ether-ether-ketone) (PEEK) by light scattering (LS) in concentrated sulphuric acid. Account has been taken of the sulphonation of the polymer. Correlations between LS-molecular weights, melt viscosities and intrinsic viscosities in sulphuric acid or in a $\text{50}\text{50}$ phenol-trichlorobenzene mixture have been established. Gel permeation chromatography (g.p.c.) analyses at 115°C have been performed in this latter solvent and two calibration methods were compared.     

Characterization of Polyglycerol Polyricinoleate Formulations Using NMR Spectroscopy, Mass Spectrometry and Dynamic Light Scattering

Three different analytical techniques, namely NMR spectroscopy, mass spectrometry and dynamic light scattering, were used to unravel the structure and morphology of polyglycerol polyricinoleate (PGPR). This material is used as an emulsifier in the preparation of chocolate and other confectionary products. The use of 1D and 2D NMR techniques led to the distinction of two separate entities in commercial ricinoleic acid (RA) and PGPR samples, namely the monomeric and oligomeric RA (estolides). ¹H and ¹³C spectra of PGPR confirmed the presence of polyglycerol moieties of various lengths being esterified by RA and estolides and to a lesser extent by oleic and linoleic acids. ¹³C-NMR DOSY experiments demonstrated the occurrence of several species in PGPR. Electrospray Ionization and tandem Mass Spectrometry succeeded in identifying the presence of over 30 glycerol/polyglycerol species containing n glycerol moieties with n = 1–6 esterified by monomeric and oligomeric RA molecules. Dynamic light scattering contributed to the characterization of PGPR morphology. The PGPR mixture contains relatively small-sized entities (monomers, dimmers, trimmers) and larger aggregates resulted from chain association. The percentage of larger aggregates is minimal compared to small-sized species.     

Characterization of poly(N-vinyl-2-pyrrolidone)s with broad size distributions

We report on the characterization of the solution structure of poly(N-vinyl-2-pyrrolidone)s (PVP) by small-angle X-ray scattering (SAXS) and by online coupling of asymmetrical flow field-flow fractionation (A4F), SAXS and dynamic light scattering (DLS). The commercial products PVP K30 and PVP K90 with nominal molar masses of 40 × 10³ and 360 × 10³ g mol⁻¹, respectively, were investigated separately and as binary mixture. Detailed information for all polymer fractions is available on the polymer contour lengths and the diffusion coefficients. Key areas of applications for the A4F-SAXS-DLS coupling are seen in comparison to static light scattering for polymers with radii of gyration smaller than 10 nm, for which only SAXS produces precise analytical results on the size of the polymers in solution.     

Miscibility of blends of Aeromonas gum or Erwinia gum with other polysaccharides

Aeromonas (A) gum and Erwinia (E) gum are acidic heteropolysaccharides, which exist in water as expanded chains caused by the electrostatic repulsion between the charged groups. A modified approach, which was suggested to estimate miscibility of stiff polymer in our previous study, was used to determine miscibility parameter μ for blends between A gum or E gum with other polysaccharides, by using viscometry in aqueous 0.1M NaCl solution. When weight ratios of E gum/pectin were in the range of 3 : 7 ∼ 7 : 3, the blends in aqueous solution are miscible. The blends of A gum/xanthan, A gum/pectin, and E gum/xanthan in aqueous solution are obviously immiscible. When the weight fraction (w₂) of A gum or E gum in the mixture solution is 0.7, the μ predicts that the miscibility of blend films was on the order of E gum/pectin > E gum/xanthan > A gum/pectin > A gum/xanthan. These results are in good agreement with those observed by scanning electron microscopy and Fourier transform IR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1387–1395, 1999     

Solution properties of poly(fluorostyrene-co-chlorostyrene) copolymers. I. Light scattering,differential refractometry and viscometry

The weight-average molecular weights (M?_w) of nominally random, unfractionated copolymers of ortho- and para-fluorostyrene and ortho- and para-chlorostyrene were determined by light scattering measurements in tetrahydro-furan, toluene, carbon tetrachloride and chloroform. It was shown that there is no significant variation in measured M?_w in the various solvents, a finding indicating that the copolymers are not compositionally heterogeneous. Intrinsic viscosity measurements in the same solvents established a consistent relationship between [n] and M?_w despite the differences in copolymer compositions. It was not possible to establish a similar relationship between the second virial coefficient A₂ and M?_w. It was concluded that measurements of the specific refractive index increment could be used for determining copolymer composition if the measurements were performed in thermodynamically poorer solvents. The results established for the Mark-Houwink constant α, intrinsic viscosity, and A₂ values indicated that these solvated copolymer molecules are in a less expanded conformation than are polystyrene molecules of similar molecular weights in a given solvent.     

Molecular size and aggregation behavior of Erwinia gum in aqueous solution

Erwinia (E) gum, a stabilizer and thickening agent of food, is composed of glucose, fucose, galactose, and glucuronic acid (1 : 0.1 : 0.05 : 0.3 by molar ratio). The apparent weight‐average molecular weight M_w and intrinsic viscosity [η] in 0.2 M NaCl aqueous solution were measured to be 7.83 × 10⁵ and 268 mL g⁻¹, respectively, by light scattering and viscometry. The aggregation behavior of E gum in aqueous solution was investigated by gel permeation chromatography (GPC) and dynamic light scattering. The results showed that 7.5% E gum exists as an aggregate, whose diameter is 12 times greater than single‐stranded chain, in aqueous solution at 25°C, and the aggregates' content decreased with increasing temperature or decreasing polymer concentration. The aggregates at higher temperature were more readily broken than in exceeding dilute solution. GPC analysis proved that a significant shoulder, corresponding to a fraction of higher molecular weight due to chain aggregation, appeared in the chromatogram of E gum in 0.05 M KH₂PO₄/5.7 × 10⁻³ M NaOH aqueous solution (pH 6.0) at 35°C, and decreased with increasing temperature, finally disappeared at 90°C. The disaggregation process of E gum in aqueous solution can be described as follows: with increasing temperature, large aggregates first were changed into the middle, then disrupted step by step into single‐stranded chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1083–1088, 2000     

聚合物流动行为的光散射表征

简要地介绍了光散射原理及目前光散射技术在聚合物流变学的中的应用，归纳并分析了前人的一些主要工作成果。对于一些至今难以解释的实验现象提出了自己的一些认识，并对仍未有人涉足的振动力场下聚合物复杂流动光散射表征提出了新的设想。     

Synthesis,Characterization, Evaluation of Interfacial Properties and Antibacterial Activities of Dicarboxylate Anacardic Acid Derivatives from Cashew Nut Shell Liquid of Anacardium occidentale L.

Anacardic acid, 2-hydroxy-6-[(8Z,11Z-pentadeca-8,11,14-trienyl]-benzoic acid, extracted from cashew nut shell liquid (CNSL), has been structurally modified to obtain the 2-(O-carboxymethyl)-6-[(8Z,11Z)-pentadeca-8,11,14-trienyl]-benzoic acid and its disodium carboxylate salt. Our separation method allows to easily obtain anacardic acid, which has been of interest for the fabrication of green products. These methods proposed for the first time to synthesize these derivatives are short and cheap, and with a high yield. The elucidation of its structure was carried out by means of infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques. Interfacial rheology properties of surfactant-air-water and surfactant-heptane-water systems were determined by using a new oscillating spinning drop rheometer apparatus. Physicochemical characterization was performed with a salinity scan in a surfactant-heptane-brine system, obtaining a value of the surfactant characteristic parameter σ = −4.3 for the disodium salt and a critical micellar concentration (cmc) of 0.08 wt%, showing high surface activity. The biological activity of both compounds was determined and measurements of their potential antimicrobial activity against Gram-positive and Gram-negative bacteria were performed, exhibiting high effectiveness, especially for the disodium salt against Gram-positive bacteria.