Synthesis and spectroscopic analysis of cellulose sulfates with regulable total degrees of substitution and sulfation patterns via C NMR and FT Raman spectroscopy

Synthesis and spectroscopic characterisation of cellulose sulfate (CS) were reported. Various CS exhibiting diverse degrees of sulfation (DS_S) were prepared through acetosulfation or direct sulfation of cellulose. During the acetosulfation, intermediate product - cellulose acetate sulfate (CAS) - was formed after the comparative esterification and subsequent deacetylation of CAS led to CS. The direct sulfation proceeded quasi-homogeneously and heterogeneously in N,N-dimethylformamide (DMF) or homogeneously in N,N-dimethylacetamide (DMAc)/LiCl mixture. The total DS_S between 0.21-2.59 and partial DS_S6 as well as DS_S2 of up to 1 were determined via elemental analysis and ¹³C NMR spectroscopy. Besides, solid-state CP/MAS ¹³C NMR could characterise CS regarding the sulfation. Subsequently, FT Raman investigation of obtained CS was conducted with the aim to establish analysis methods quantifying the total DS_S. The intensities of Raman bands ascribed to the vibrations of OSO and C-O-S groups were used as analysis parameters, yielding calibration curves with high correlation coefficients of more than 0.96.     

Nucleophilic displacement reactions on tosyl cellulose by chiral amines

Summary New 6-deoxy-6-amino cellulose derivatives with a degree of substitution (DS) in the range from 0.4 to 0.6 were synthesized by nucleophilic displacement (S_N) reactions of cellulose tosylates (DS_Tos 0.74 and 1.29) with R(+)-, S(−)- and racemic 1-phenylethylamine under homogeneous conditions in N,N-dimethylformamide and water. The structure of the polymers was characterized by elemental analysis, FTIR and ¹³C NMR spectroscopy. The DS values obtained as well as the optical rotation and circular dichroism measurements in dimethyl sulfoxide reveal that the initial chirality of the cellulose backbone does not have any significant influence on its reactivity with either of the two enantiomeric amines. Received: 21 September 2000/Accepted: 5 January 2001     

Semiquantitative analysis of thiophenic compounds in light cycle oil (LCO) using C NMR spectroscopy

S-methyltetrafluoroborate salts of the thiophenic compounds (CH₃-S⁺:BF₄⁻) present in LCO petroleum fractions were obtained and analyzed by ¹H and ¹³C NMR spectroscopy. The methylation of the samples was carried out using 99.5% ¹³C enriched methyl iodine, to improve the sensitivity of the technique. The amount of the methylated derivatives was determined by the internal standard method; using dioxane as a reference, 37 sulphur compounds were detected. Among them, benzo[b]thiophene, dibenzo[b,d]thiophene, and several isomers of methyl, dimethyl and trimethyl[b]benzothiophenes were the most abundant. With this research, it was demonstrated that NMR spectroscopy can be used to analyze thiophenic compounds from petroleum medium fractions.     

Synthesis and characterization of the new cellulose derivative films based on the hydroxyethyl cellulose prepared from esparto “stipa tenacissima” cellulose of Eastern Morocco. II. Esterification with acyl chlorides in a homogeneous medium

Esparto “Stipa tenacissima” cellulose esters derivatives: HECA‐COO? C₄H₈? COOC₂H₅, HECA‐COO? C₈H₁₆? COOC₂H₅, and HECA‐COO? C₆H₄? COOC₂H₅ were successfully prepared in Tetrahydrofuran (THF)/triethylamine system with a degree of substitution (DS), respectively, DS_AD‐Et=0.32, DS_SB‐Et=0.22, and DS_TRP‐Et=0.50 using hydroxyethyl cellulose acetate (HECA; DS_AC=0.50) as intermediate product, and we avoided the drawbacks of cellulose solubility. The structural modifications were investigated using Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (¹H‐NMR), Carbon‐13 nuclear magnetic resonance (¹³C‐NMR), and Distortionless Enhancement by Polarization Transfer 135° (DEPT‐135). The results from these analyses revealed the presence of the characteristic groups indicating that the grafting reaction was successful. The crystallinity and the structure order changes during the esterification reactions were recorded by X‐ray diffraction (XRD), it is found that the crystallinity degree decrease from 63.1% for Esparto “Stipa tenacissima” cellulose to 27.74% for HECA. The thermal stability of the esterified and unmodified cellulose samples was studied by thermogravimetric analysis (TGA)‐differential thermal analysis (DTA); the modified HECA exhibits a decrease in thermal stability relatively to the unmodified HECA, and this may be related to the groups grafted. The resulted cellulose esters HECA‐P_x (x = 1, 2, or 3) were soluble in THF and present an amorphous structure justified by XRD spectra. It was noted by TGA‐DTA analysis that the cellulose esters with low melting range were proved as thermoplastic polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Intermediate accumulation and efficiency of anaerobic digestion treatment of surfactant (alcohol sulfate)‐rich wastewater at increasing surfactant/biomass ratios

Textile (eg cotton) finishing industry wastewater is characterised by high concentrations of surfactants (up to 2 g dm^?3) and of readily biodegradable biopolymers (COD 5–15 g dm^?3). The anionic surfactant decyl sulfate (DS) was chosen as model surfactant and soluble starch (size) as model compound for the readily biodegradable fraction of the wastewater. Twenty‐two batch experiments with increasing DS/biomass ratio (and starch/biomass ratio) were started simultaneously. Biomass concentrations ranged from 50 to 15 000 mg dm^?3. Minor inhibition effects were found for the surfactant degradation itself at all DS/biomass ratios (maximum biodegradation rate 7.7 mg_DS g_biomass^?1 h^?1). The starch hydrolysis started without a lag‐phase at DS/biomass ratios of up to 0.15 g_DS g_biomass^?1. The lag‐phase was prolonged to about 100 h at a very high DS/biomass ratio (3 g_DS g_biomass^?1). The relative importance of the accumulated intermediates was dependent on the DS/biomass ratio. Above 0.3 g_DS g_biomass^?1 10% of the substrate organic carbon accumulated as ethanol, but no ethanol accumulation was observed at low DS/biomass ratios. Moderate DS/biomass ratios caused a considerable delay of the methanogenesis; high DS/biomass ratios prevented the methanogenesis almost completely. © 2002 Society of Chemical Industry     

Aluminated hierarchical silicalite-2 particles: Catalyst with remarkably increased lifetime for methanol to hydrocarbons

Aluminated hierarchical silicalite-2 with both large particle size and high external surface area was prepared by aluminating silicalite-2 under the protection of TBA⁺ cations in a mild alkaline solution. The textural and acidic properties of thus formed material (Z11-meso) were characterized by SEM, TEM, XRD, N₂ adsorption, FTIR, NH₃-TPD, and ²⁷Al NMR spectroscopy. The resulting hierarchical Z11-meso contained mainly tetrahedral coordinated aluminum species with low Brønsted/Lewis ratio (B/L) while preserved the zeolitic structure. Owning to the high external surface area (S_ext), hierarchical porous structures and low B/L ratio, Z11-meso outperformed the microporous ZSM-11 counterparts in methanol to hydrocarbons in terms of both activity and stability.     

Pecipamide,a New Sphingosine Derivative from the Cultures of <Emphasis Type="Italic">Polyporus picipes</Emphasis> (Basidiomycetes)

A new C₁₈-ceramide congener named pecipamide (1), together with the known ergosta-4,6,8(14),22-tetraen-3-one (2), was isolated from the solid fermentations of the basidiomycetous fungus Polyporus picipes. The structure of the new metabolite was established as (2′R,2S,3R)-N-2′-hydroxyheptadecanoyl-2-amino-octadecane-1,3-diol on the basis of spectroscopic data, including 1D- and 2D- nuclear magnetic resonance spectroscopy (NMR) experiments, as well as by means of mass spectrometric measurements (MS).     

Sorption of aqueous organic contaminants onto dodecyl sulfate intercalated magnesium iron layered double hydroxide

Dodecyl sulfate anion (DS⁻) intercalated magnesium iron layered double hydroxide (DS–Mg–Fe LDH) was firstly prepared by the co-precipitation method, and was characterized by the means of X-ray diffraction (XRD), Fourier infrared (FT-IR), Total Organic Carbon analysis (TOC), themogravimetric and differential thermal analysis (TG-DTA) and surface characteristics analysis (BET-N₂). The sorption characteristics and mechanisms of hydrophobic organic contaminants (naphthalene, nitrobenzene, acetophenone) and hydrophilic contaminant (aniline) on DS–Mg–Fe LDH were investigated, and were subsequently compared with that on the inorganic magnesium iron layered double hydroxides (CO₃–Mg–Fe LDH and NO₃–Mg–Fe LDH). The greater sorption amount of organic contaminants on DS–Mg–Fe LDH than on CO₃–Mg–Fe LDH and NO₃–Mg–Fe LDH indicated that organic modified LDHs were potential sorbents for the abatement of organic contaminants. Sorption mechanism on DS–Mg–Fe LDH varied with the types of organic contaminants. The uptake curves of naphthalene, nitrobenzene and acetophenone on DS–Mg–Fe LDH were linear, and sorption capacities for three hydrophobic compounds were in the sequence of their hydrophobicity (refers to water solubility or K_ow). These results suggested that the sorption mechanism was the partition between water and the organic interlayer phase composed of the alkyl chain of DS⁻. After eliminating the influence of the hydrophobicity, the polar compounds (nitrobenzene and acetophenone) exhibited higher affinity to DS–Mg–Fe LDH than nonpolar compound (naphthalene), which demonstrated that both the hydrophobicity and polarity benefited the sorption of hydrophobic compounds on organic LDHs. For hydrophilic compound, aniline, its uptake curve was nonlinear. The sorption process of aniline was the cooperation of the adsorption on hydroxide surface through forming the hydrogen bonding and the weak partition to the interlayer organic phase.     

Sintering behavior,structure, and microwave properties of novel Li2xCu1-xMoO4 ceramics

In this study, we prepared a novel series of Li_2xCu_1-xMoO₄ (x = 0.02, 0.04, 0.06, 0.08, and 0.10) microwave ceramics. The dynamic sintering behavior, crystal phases, micro-morphologies, and dielectric properties of the samples were studied. The substitution of Li⁺ contributed to refining the crystal grain size, promoting the densification of microstructure, and enhancing the quality factor. Due to different valence substitutions, Cu⁺ ions were created, which were verified by X-ray photoelectron spectroscopy (XPS) and Raman experiments. In addition, the Raman shift, full width at half maximum (FWHM) value of the A_1g peak, and crystal microstrains were analyzed to gain a mechanistic understanding of the influence of structure on the dielectric properties. When x = 0.08, the Li_2xCu_1-xMoO₄ ceramic sintered at 675 °C exhibited optimal comprehensive properties with ε_r = 8.17, Qf = 68 476 GHz, and τ_f = ?25 ppm/°C, and good chemical stability between the ceramic and Al electrode was also achieved. These promising properties make Li_2xCu_1-xMoO₄ (x = 0.08) more suitable for ultra-low temperature co-fired ceramic (ULTCC) applications.     

Wetchemical surface modification of plasticized PVC. Characterization by FTIR-ATR and Raman microscopy

The chemical modification of plasticized PVC films with amino thiophenol in mixtures of DMF/H₂0 has been studied. The degree of modification and the distribution of modified groups within the films were determined using Raman spectroscopy and FTIR-ATR. The amounts of plasticizer (bis-2-ethylhexyl phtalate, DOP) bleached out during the reaction and the amount of dimethylformamide (DMF) penetrated into the film were analysed in control reactions without the reactant using ¹H NMR spectroscopy and Raman spectroscopy.Reaction kinetics and surface selectivity of the modification reaction were compared with the corresponding reactions of PVC films without plasticizer.     

Modified polysulfones 5: synthesis and characterization of tetramethyl polysulfones containing trimethylsilyl groups and their gas transport properties

Polysulfones with rigid backbone structures and silyl-containing substituents were prepared as membrane materials with potentially enhanced gas transport properties. Tetramethylbisphenol-A polysulfone (TMPSf) and tetramethylbiphenol polysulfone (TMPPSf) were made by polycondensation then post-modified to introduce trimethylsilyl (TMS) groups by bromination and lithiation methodology. Substitution of high levels of TMS groups at the ortho-sulfone sites was achieved using direct lithiation followed by addition of a trimethylsilane electrophile. In an approach to increase the overall TMS substitution level as well as introduce these groups on the bisphenol segment, both TMPSf and TMPPSf were cleanly brominated to a degree of substitution (DS) of 2.0 for bromine. While the subsequent lithium-halogen exchange and reaction with TMS electrophile did not give high regioselectivity because of steric hindrance, the overall DS of TMS in the polymers was increased when excess n-butyllithium was used to activate both brominated and ortho-sulfone sites. The polymer structures were characterized by NMR spectroscopy. Their thermal properties as well as O₂, N₂, CO₂ and CH₄ gas transport properties were measured. Polymers with a high DS of TMS had very high CO₂ and O₂ permeabilities and good permselectivities from N₂. The permselectivities of CO₂/N₂ were at or close to the Robeson upper-bound performance line [J. Membr. Sci. 62 (1991) 165].     

Polymerization of maleic acid and itaconic acid studied by FT‐Raman spectroscopy

In this research, we used a new redox free radical initiation system consisting of potassium persulfate (K₂S₂O₈) and sodium hypophosphite (NaH₂PO₂). In the presence of NaH₂PO₂, the thermal decomposition of K₂S₂O₈ is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K₂S₂O₈/NaH₂PO₂ initiation system in an aqueous solution, and monitored the polymerization process with FT‐Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disappearance of the characteristic bands of MA as the thermal decomposition of K₂S₂O₈ progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001     

Spectroscopic investigations of the microstructure changes induced by substrate temperature in nitrogen-substituted amorphous carbon thin films

The effect of substrate temperature (T_S) on the microstructure of amorphous nitrogen-substituted carbon thin films (a-C_1−xN_x) has been studied. The a-C_1−xN_x films were deposited on Si(1 0 0) using reactive radio-frequency (RF) magnetron sputtering of a high-purity graphite target in a pure nitrogen plasma using different RF powers and different substrate temperatures T_S. Combined Fourier transform infrared (FTIR), Raman spectroscopy and residual stress measurements are used to fully characterise the films in the as-deposited state. FTIR spectra showed the existence of NCsp² and CN triple bonding, and suggested the presence of N-Csp³ bonding in the deposited films. The analysis of the spectra versus T_S reveals two rearrangement mechanisms of the microstructure. Up to 150 °C, the reversion of NCsp² to N-Csp³ and CCsp²respectively, and the increase the connectivity of the C-C network for higher T_S. The Raman features reveals that this progressive graphitisation of the material, with increasing T_S, is accompanied by a high disorder form of Csp² sites. These results are used to describe the stress variation that accompanies nitrogen evolution within the deposited films.     

Effect of Processing Variables on the Solution Characteristics of γ-Glycidoxypropyltrimethoxysilane (γ-GPS)

The effects of the hydrolysis and condensation processes on the molecular structure of γ-glycidoxypropyltrimethoxysilane (γ-GPS) in aqueous solutions were investigated using Fourier-transform nuclear magnetic resonance (FT-NMR) spectroscopy and FT-Raman spectroscopy. Hydrolysis was characterized by monitoring the production of methanol and the decrease in concentration of SiOCH₃ groups in 1% solutions of deuterium oxide using proton NMR. The production of methanol and loss of methoxy groups in 25% solutions of γ-GPS in water was characterized using Raman spectroscopy. Hydrolysis was found to be a very rapid process, whose rate could be increased or decreased by altering the pH of the solution. NMR spectroscopy showed that hydrolysis was complete in a 1% γ-GPS solution in deuterium oxide after 34 minutes. Raman spectroscopy also showed hydrolysis to be rapid and complete in a 25% solution of γ-GPS in water after 1 hour. Condensation, on the other hand, took a relatively long time to occur. In the NMR spectra, condensation was observed by the broadening of peaks due to the protons on the carbon atom adjacent to the silicon atom. In the Raman spectra, condensation was characterized by the disappearance of the SiOH band near 725 cm^?1 and the development of an SiOSi band near 600 cm^?1. In addition to the proton NMR, Si-29 NMR was used to characterize the silane in 10% solutions of γ-GPS in water. The Si-29 NMR showed oligomer growth with respect to time. The oligomer growth was correlated with mechanical test results.     

Sol-gel processing and nanoscale characterization of (Bi0.5Na0.5)TiO3-SrTiO3 lead-free piezoelectric thin films

(1-x)(Bi_0.5Na_0.5)TiO₃-xSrTiO₃ (BNT-xST) (0 ≤ x ≤ 0.4) thin films were fabricated using a sol-gel technique on Pt(111)/Ti/SiO₂/Si(100) substrates, which were investigated by piezoresponse force microscopy (PFM) and Raman spectroscopy. The composition-induced phase transition was analyzed by acquiring structural variations and the domain distribution on a local scale. Raman spectra showed phonon anomalies with peak broadening and shifting when increasing SrTiO₃ (ST) concentrations were used. Changes in the domain morphology with changes in the composition were observed, and grains smaller than 0.5 µm were observed at lower concentrations of x = 0–0.25, while larger grains appeared with increasing ST contents. The switching spectroscopy PFM (SS-PFM) results supported a ferroelectric (FE) to relaxor ferroelectric (RFE) phase transition at approximately x ≈ 0.3 by means of analyzing the parameters as a function of the composition including the piezoresponse parameters of hysteresis loops (D_max, D_rem) and amplitude butterfly loops (S_total, S_neg). Hence, these results demonstrated that the composition-driven FE to RFE phase transition behavior, which is consistent with the localized response behavior, is dependent on the ST content in bulk BNT-xST ceramics.     

Synthesis and characterization of alternating poly(amide urethane)s from ε-caprolactam, amino alcohols, and diphenyl carbonate

Alternating poly(amide urethane)s from ε-caprolactam, amino alcohols H₂N-(CH₂)_x-OH (x=2-6), and diphenyl carbonate were prepared by polycondensation of α-hydroxy-ω-O-phenylurethanes 4a-e. The degree of oligomerization was adjusted by the conversion. Oligomers with two or three O-phenylurethane end groups and predetermined molecular weight were prepared by polycondensation of the α-hydroxy-ω-O-phenylurethanes 4a-e in the presence of comonomers with O-phenylurethane end groups in a given concentration. In order to prepare oligomers with hydroxyl and carboxyl groups at both chain ends suitable for coupling reactions, chain analogous reactions were performed with amino acids and amino alcohols. The microstructure of the polymers and the nature of end groups was determined by means of ¹H NMR spectroscopy and the molecular weights were determined by means of gel permeation chromatography. The poly(amide urethane)s 5a-e prepared are semicrystalline materials with melting points between 150 and 200 °C.     

Effect of ZnO content change on the structure and properties of zinc borophosphate glasses

The glass system xZnO-10B₂O₃-(100 ? x)P₂O₅ was prepared by cooling using the melt-quenching technique in the composition series x from 30 to 60 mol %. The density, thermal expansion coefficient, glass transition temperature, and softening temperature of the glass system were determined. Structural characterization was performed by using a combination of IR and Raman spectroscopy and ¹¹B/³¹P solid state NMR spectroscopy data. In particular, variations in the phosphate network structure upon the addition of ZnO were investigated. Data analysis indicated that increasing the ZnO content and decreasing the P₂O₅ content increased the extent of cross-linking between the phosphate and borate units in the glass network; this was because incorporation of ZnO polyhedra into the structural network of ZnO increased the network dimensionality. These structural changes were confirmed by Raman and IR spectroscopy.     

Preparation,structural characterization,and flocculation ability of amphoteric cellulose

A series of amphoteric celluloses (QACMCs) were prepared from sodium carboxymethyl cellulose (CMC) and 2,3-epoxypropyltrimethylammonium chloride (EPTMAC) with a cationic degree of substitution (DS_cat) of 0.24–1.06 and a carboxymethyl degree of substitution (DS_ani) of 0.60. The structures of the samples were characterized by FTIR and NMR spectroscopy, which revealed that DS_cat depended on the ratio of EPTMAC to CMC in the reaction mixture and that the substituent distribution of the cationic group at the C2, C3, and C6 positions of the QACMCs ranked as follows: C2 > C6 > C3. The QACMCs dissolved over a wide range of pH levels and exhibited flocculation ability against kaolin suspensions. In particular, the samples with high DS_cat exhibited excellent flocculation performance. In addition, the flocculation characteristics of the QACMCs depended on the pH of the kaolin suspension.     

Adsorption of Congo Red from Aqueous Solutions Using Chitosan Hydrogel Beads Formed by Various Anionic Surfactants

The structural organization of chitosan hydrogel beads (CSBs) formed by various anionic surfactants, sodium dodecyl sulfate (SDS), sodium decyl sulfate (DS), dodecyl benzenesulfonic acid sodium salt (SDBS), and dioctyl sulfosuccinate sodium salt (DSS), and their applications as adsorbents for environmental purifications were investigated using Congo red (CR) as a model dye. The adsorption capacities of CSB as a function of surfactant concentration revealed that CSBs formed by 5 g/L anionic surfactant were the most effective for CR adsorption. The structure of CSBs and their adsorption capacities for CR depend on the nature of anionic surfactants. The maximum adsorption capacities of CSB_SDS, CSB_DS, CSB_SDBS, and CSB_DSS obtained from the Langmuir isotherm model were 186.02, 209.28, 207.25, and 113.83 mg/g, respectively, indicating that CSB_DS was the best adsorbent for CR.     

Synthesis of a gold(I) complex with a (thio)phosphine-modified β-cyclodextrin

A gold(I) complex with the bidentate ligand 6^A-S-[2-(diphenylphosphino)-ethyl]thio-β-cyclodextrin has been prepared. The complex has been studied by mass spectrometry as well as IR and NMR spectroscopy. The influence of the ligand:metal ratio on the coordination mode has also been examined.