Xylan sulphate films

Aqueous-based particulates were investigated with respect to their use in fabrication of lithium-ion battery cathode as a function of degree of substitution (DS) on carboxymethyl cellulose (CMC). The dispersion properties of particulates were characterized using electroacoustic measurements, rheology, and microstructural observations at two different DS values on CMC. It was found that the suspensions with lower DS had better long-term dispersing efficiency and more compact microstructure than those with higher DS. Furthermore, the electrodes with lower DS exhibited a better electrochemical cycling performance than those with higher DS after the same number of cycles.

Effect of degree of substitution on the structural degradation and butyric acid production of butyrylated starch during in vitro fermentation.

Cationic polysaccharide polyelectrolytes are important synthetic targets for drug and gene delivery, especially by encapsulation of nucleic acids and proteins through electrostatic interactions. They also have potential as paracellular permeability enhancers that may increase transport across the gastrointestinal (GI) epithelium, especially for therapeutic hydrophilic macromolecules. Semisynthetic chitosan has been more heavily investigated as a cationic polysaccharide polyelectrolyte. This study explores the synthetic conditions needed to produce ammonio and phosphonio cellulose derivatives regioselectively by halogen displacement at C-6 while maximizing the degree of substitution (DS) of cationic substituent. Regioselective substitution was successful, however there were found to be some limitations to the DS and solubility of ammonium derivatives prepared in this way (highest DS 0.43); conversely, water-soluble 6-phosphonio-6-deoxycellulose derivatives were produced with DS > 0.5, with highest DS of 0.73. The repulsion between accumulating positive charges was confirmed as a likely source of DS limitation since high DS (0.9) of 6-triethylamino cellulose was synthesized under comparable conditions. Further reaction of 6-ammonio-co-6-bromo derivatives with a thiol produced 6-ammonio-co-6-thiolated products with improved aqueous solubility. The thiol DS of 0.68 determined by elemental analysis confirmed substitution of residual bromide from low DS (0.30) ammonium products to give essentially complete substitution at C-6.

This research investigated the optimized condition (i.e., esterifying agent, reaction time, reaction temperature) to modify lignin for utilization as a precursor in carbon fiber production. The lignin was successfully modified by esterification reaction in dimethylformamide solvent under different reaction temperatures and times using different types of fatty acid chloride including butyryl chloride, octanoyl chloride, and lauroyl chloride as an esterifying agent. The effects of fatty acid chloride chain length and degree of substitution on the chemical structure, functional groups, morphology, crystallinity, thermal properties, and solubility of esterified-lignin were studied. The chemical structure of the obtained product was characterized by FTIR and 1H- and 13C-NMR. The FTIR results showed that modified lignin from all esterifying agents exhibited the evidence of esterification by showing the increasing in the ester bands at 1701 cm-1 (carbonyl C=O stretching of ester) and the significant increasing intensity of the aliphatic carbon peaks at around 2800–2900 cm−1, and the decreasing in the intensity of O-H band at 3400 cm-1. The 1H-NMR spectra showed the peaks of alkyl groups of fatty acid chain between 1.1-1.2 ppm, the decreasing in the intensity of the hydroxyl group at 3.33 ppm. The 13C-NMR spectra of the modified lignin showed the strong increase of the aliphatic carbon signals at around 10-40 ppm along with the peak of ester group at 174 ppm. All modified lignin revealed a packing of small and large particles with a smooth surface depending on the types of esteritying agent. The optimum conditions for the modified lignin that yield low, medium, and high degree of substitution (DS) values with reasonable %weight increase were 2 hr 30 oC (DS 0.27),6 hr 50 oC (DS 0.87), and 4 hr 70 oC (DS 1.28) for lignin butyrate, 2 hr 30 oC (DS 0.62), 2 hr 70 oC (DS 0.96), and 6 hr 70 oC(DS 1.33) for lignin octanoate, and 2 hr 30 oC(DS 1.72), 2 hr 50 oC (DS 2.85), and 4 hr 50 oC (DS 3.68) for lignin laurate, respectively. The thermal stability of all esterified lignins decreased when lignin was modified by fatty acid chloride with different chain lengths. Lignin was insoluble in non-polar solvents (e.g. toluene and xylene); however, after esterification lignin laurate can be dissolved in toluene, chloroform, and xylene. Then, 75%lignin laurate powder (high DS) blended with 25% PLA was fabricated into film by casting method using chloroform as solvent. The results on mechanical properties showed that the tensile strength and elongation at break of PLA-lignin laurate film were 20.66 ± 0.17 MPa and 0.19 ± 0.02 %, respectively. The contact angle value of PLA-lignin laurate films was 71.0 ±1.6◦.

The use of starch, a natural polymeric material, and derivatives thereof is based on its adhesive, thickening, gelling, swelling, and film-forming properties, as well as its ready availability. The objective of this research work is to develop an effective propylated Dioscorea abyssinica starch (PDAS) as a hydrophobic excipient for pharmaceutical applications with a reasonable price. This paper reports on the synthesis, characterization, and in vivo safety evaluation of PDAS. Native Dioscorea abyssinica starch (NDAS) was modified to its propylated form with propionic anhydride and characterized. Crystallinity, morphological structure, thermal behavior, solubility, and safety of PDAS were evaluated using x-ray diffraction, SEM, thermogravimetric, gravimetric, and toxicity studies, respectively. Propionyl content and degree of substitution (DS) of starch increased significantly (p < 0.05) with an increase in reaction time and temperature. Propionyl content and DS of starch increased significantly (p < 0.05) with a decrease in the ratio of starch to pyridine and starch to propionic anhydride in the reaction medium. FTIR spectra of PDAS indicated that hydroxyl groups participated in the propylation reaction. X-ray diffraction results showed that the chemical modification destroyed the crystalline structure of the NDAS. SEM of NDAS showed a rounded shape which became irregular after propylation. Thermogravimetric curves revealed that all the PDAS samples decomposed at higher temperatures than their native counterparts. At higher DS, swelling power and solubility in an aqueous environment significantly (p < 0.05) decreased below that of the native starch. PDAS with high DS, were soluble in organic solvents at room temperature. But PDAS with lower DS didn't dissolve in all types of organic solvents used. PDAS (DS = 2.842) in distilled water did not produce adverse effects in rats. Based on the results obtained, it can be concluded that PDAS can be considered as a generally safe excipient and fulfills the physicochemical properties of a hydrophobic excipient.

Reported is the preparation of various condensed tannin stearates and the associated chemical characterization and thermal properties of these products. Stearate esters of condensed tannins from both quebracho and pine bark extracts were prepared in generally high, isolated yields from reaction with stearic acid chloride. Tannin esterification was confirmed by both Fourier transform infrared and nuclear magnetic resonance (NMR), and the average degree of stearate substitution was calculated from 1H‐NMR analysis. Product degree of substitution (DS) was observed to proportionately increase with higher stearic acid chloride ratio with maximum DS values of 4.0 and 5.1 achieved for quebracho and pine tannins, respectively. Thermal analysis revealed that tannin stearate products have increased thermal stability with a degradation onset at significantly higher temperature for those samples possessing relatively greater DS. Analysis using differential scanning calorimetry revealed isolated products to consist of multiple components which exhibit interesting melt behaviors, a likely result from their work up on isolation. However, multiple melt features of the individual components in products were lost on heating to give single, broad melt endotherms due to coalescence of sample components. Furthermore, tannin stearate samples with high DS show relatively greater endothermic melting at higher temperature than those samples with lower DS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used in the preparation of the hydrogel. MIP analysis showed that the overall networks were clearly macroporous with pore sizes ranging from 0.065 to 10 microm. As expected, the average pore size decreased as DS increased and as initial water content decreased. Moreover, the porosity values ranged from 75 up 90%, which shows that these hydrogels present an interconnected pore structure. Nitrogen adsorption analyses showed that the specific surface area of dexT70-VA hydrogels increased either by increasing the DS or by decreasing the initial water content of the hydrogel. SEM results revealed that the surface of hydrogels with lower DS presented either a porous structure or a polymeric "skin" covering the pores, whereas hydrogels with higher DS were totally porous. Furthermore, the interior morphology varied according to the DS and the initial water content of the hydrogels. Finally, the average pore size was also determined from the swelling of hydrogel using a theoretical model developed by Flory-Rehner. The comparison of the SEM and MIP results with the ones obtained by the equilibrium swelling theory of Flory-Rehner shows that this approach highly underestimates the average pore size.

Wheat starch carbamate: Production, molecular characterization, and film forming properties

Effect of degree of substitution of carboxymethyl starch on diaspore depression in reverse flotation

A novel cationic polymer was developed by conjugating imidazole and poly(ethylene glycol) (PEG) on poly(N-(8-aminooctyl)acrylamide) (P8Am) for complexing with pDNA to exhibit high gene expression with low cytotoxicity and the resistance against erythrocyte agglutination and serum inhibition. Cytotoxicity results indicated that these P8Am derivatives with varying substitutions were more biocompatible than unmodified P8Am and PEI control. Moreover, the particle size and zeta potential experiment demonstrated that they were capable of complexing pDNA into sub-micrometer (135–625 nm) and positively charged (+10 to +43 mV) particles, while the high degree of substitution might impede their pDNA complexation ability that formed less positive and larger polyplexes. Flow cytometry analysis demonstrated that the cellular uptake efficiency was dependent on the degree of substitution; low degree of substitution would mediate high uptake efficiency. The gene-transfection ability, evaluated by luciferase assay, revealed low substitution in P8Am-IM11 (substituted with 11 mol% imidazole moieties) and P8Am-PG7 (substituted with 7 mol% PEG moieties) in transfected cells more efficient than unmodified P8Am. Therefore, a multi-functional P8Am derivative, P8Am-IM11-PG7, containing both imidazole and PEG, was developed according to the optimized contents. In the presence of serum, P8Am-IM11-PG7 polyplexes significantly enhanced the gene-transfection efficiency relative to unmodified P8Am polyplexes. Moreover, they exhibited minimal cytotoxicity and the erythrocyte aggregation assay showed that P8Am-IM11-PG7 polyplexes had good blood compatibility as compared to P8Am and PEI polyplexes. This indicated that, by chemical modification, P8Am-IM11-PG7 could possess the required abilities to overcome the difficulties encountered in gene transfection and be a promising alternative of a gene carrier.

Adsorption of guar gum and CMC on pyrite

Effect of new hydrophobic modification of hyaluronan on its solution properties: evaluation of self-aggregation

New cellulose derivative CMC-Li was synthesized, and nanometer fiber composite material was applied to lithium-ion battery and coated with AQ by electrospinning. Under the protection of inert gas, modified AQ/ carbon nanofibers (CNF) /Li nanometer composite material was obtained by carbonization in 280OC as lithium battery anode materials for the first time. The morphologies and structure performance of materials were characterized by using IR, SEM, CV and EIS, respectively. Specific capacity was increased to226.4 mAh.g-1after modification for the first discharge at the rate of 2C. Performance of cell with CMC-Li with the high degree of substitution (DS) was superior to that with low DS. Cellulose materials were applied to lithium battery to improve battery performance by electrospinning.

Molar mass characterization of cellulose acetates over a wide range of high DS by size exclusion chromatography with multi-angle laser light scattering detection

This study considers a public firm that provides a profitable service and an unprofitable service. In our model, only the public firm supplies the unprofitable service, while both the public firm and multiple private firms supply the profitable service. The two services may be substitutes, complements, or independent in demand, and the public firm has inferior technology. We examine whether the public firm should privatize either the profitable service or the service that faces competition from private firms. We obtain the following results. When the two services are complementary, the critical cost of the public firm such that privatizing the profitable service is socially preferable increases with the degree of complementarity. When the two services are substitutes, the critical cost decreases (increases) with the degree of substitution for a low (high) degree of substitution. For a sufficiently high degree of substitution, the critical cost becomes small.