Presence Of Diethylene Glycol Research Articles

Application of the polyurethane foam recycling product as an asphalt extender for sustainable road construction

Polyurethane foam (PUF) is widely used across industries owing to its excellent properties, but it has caused a solid waste stream in the environment. Alcoholysis has been found to be an effective and eco-friendly approach to address this issue. However, substantial by-products are generated in the alcoholysis process, presenting challenges to waste PUF recycling. The by-products of the PUF recycling process (BPF) exhibit similar physical properties to asphalt binder. Therefore, this study uses BPF as an asphalt extender to prepare BPF-asphalt, focusing on its influence on asphalt binder properties. The results show that BPF can greatly maintain or even improve the performance of asphalt binder with good compatibility and workability through physical mixing. The optimum amount is 10 % of the mass of the base asphalt binder. Differences in chemical composition lead to differences in BPF-asphalt properties. Thermal polymerization of polystyrene with small molecular weight in BPF plays an important role in improving the high-temperature performance and fatigue resistance. The presence of diethylene glycol has a negative effect on the performance of BPF-asphalt. This study demonstrates the feasibility of the solution of BPF as an asphalt extender to alleviate the disposal pressure of waste PUF and the consumption of asphalt resources.

Synthesis and Mechanical Performances of Polyurethane Bio-Based Adhesives Resulted from the Depolymerization of Lignocellulose Biomass.

The purpose of this study is to valorize biomass waste into products with added value for indoor applications. Thus, broadleaf sawdust was chemically processed by the solvolysis reaction in acid catalysis in the presence of diethylene glycol at 160 °C for 4 h. After filtration and removal of the unreacted biomass, the glycolysis product was used in 6 different polyurethane adhesive formulations for wood bonding. The adhesive films were characterized by FT-IR, TGA, and DMA, while the mechanical performances were investigated by tensile and three-point bending tests. An innovative method for the determination of the working time was proposed. After the displacement of the wood substrates by the tensile test, the bonded area was investigated by SEM analysis. To confirm a correlation between the mechanical performances of the adhesives and their structure/formulation, two-dimensional (2D) simulations were performed based on the tensile tests.

Design of polyurethane composites obtained from industrial plastic wastes, pyrite and red mud

The purpose of this study consisted in the synthesis and characterization of composite materials based on polyurethane (PUR) rigid foam reinforced with two industrial wastes such as pyrite and red mud for the retention of mercury ions, Hg2+, ions from contaminated water and applications as paving stones in construction area. The diol used to create the urethane bond resulted from the depolymerization of poly(ethylene terephthalate) (PET) wastes in the presence of diethylene glycol (DEG). The resulted diol was characterized by gel permeation chromatography (GPC), registering a molecular weight, Mn = 420 g/mol. The hydroxyl index of the diol, IOH = 256.731 mgKOH/g was determined based on ASTM D4274-99. In this study, 6 types of PUR foams were obtained by reacting the diol with the polycondensation agent, 4,4′-methylene diphenyl diisocyanate (MDI) in the presence of different concentrations of filling agents. All specimens were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), EDX mapping, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and compression tests. The formation of urethane group was confirmed by FT-IR for all specimens. The porous structure of the PUR foams was evidenced by SEM, while (EDX) and EDX mapping were used to analyze the elemental composition of the composite materials and the uniform distribution of the filling agents within the cellular structure. TGA proved that both types of PUR foams increased their thermal resistance compared with blank samples. However, the specimens loaded with red mud exhibited increased thermal resistance as the concentration of red mud was increased compared with pyrite-based samples. The final residual mass registered for red mud was 24%, compared with pyrite-based samples that registered 21%. Unexpectedly, the DSC analysis indicated that Tg values decreased up to 47 °C as the pyrite concentration was increased compared with blank sample (57 °C), while the Tg values for red mud-based samples increased as the concentration of the red mud was increased up to 60 °C. Similar results were confirmed by the compression tests, this behavior being attributed to pyrite aggregate formation in PUR matrix and confirmed also by the density values for which a correlation between the filling agent concentration and density was not possible. In the case of red mud-based PUR foams the mechanical resistance decreased as the concentration of the filling agent was increased as expected.

Дослідження екстракційного розділення бензинових фракцій, одержаних внаслідок піролізу вживаних шин.

In recent years, the high demand for energy resources and environmental degradation have been pressing issues faced by humanity due to the over-exploitation and use of fossil fuels. With the increasing environmental awareness of the population, technologies for the reuse of waste, including waste tires, deserve special attention, which in turn allows to reduce the negative impact on the environment, maximize resource utilization and reduce dependence on fossil fuels. In this work, we analyze the process of extraction separation of the fraction boiling above 200°C to remove aromatic and unsaturated compounds obtained as a result of the pyrolysis process of used tires at a small pilot plant. Two solvents, N-methylpyrrolidone and diethylene glycol (DEG), were used in the extraction separation of the fraction boiling above 200 °C. The volume ratios of raw materials to solvent were chosen as follows: 1:0.5, 1:1, 1:1.5, and 1:2 for N-methylpyrrolidone, and 1:5, 1:10, 1:15, and 1:20 for DEG, respectively. As a result of the studies, the influence of solvents on the physicochemical properties of the obtained products was determined. It has been proved that the best physicochemical properties are characterized by the raffinates and extracts obtained at a volume ratio of raw materials to solvent of 1:2.0 in the presence of N-methylpyrrolidone, and 1:20 in the presence of DEG. It was found that the use of N-methylpyrrolidone in a ratio of 1:2 resulted in a decrease in the density and bromine number of the refined product by 2.64 % and 10.79 % compared to the initial fraction, respectively, and the use of DEG in a ratio of 1:20 resulted in a decrease in the density and bromine number of the refined product by 1.44 % and 12.06 % compared to the initial fraction, respectively. Further ways of using the obtained products of the extraction separation process of the gasoline fraction at a boiling above 200 °C are proposed. Keywords: used tires, waste tires, tire pyrolysis, gasoline, fraction, extraction separation. Corresponding author: B.O. Korchak, e-mail: kor4ak93@gmail.com

Characteristics of hydroxyapatite-reduced graphene oxide composite powders synthesized via hydrothermal method in the absence and presence of diethylene glycol

The synthesis of nanocomposites containing hydroxyapatite and graphene sheets has received much attention recently. Therefore, strategies that improve their properties will be useful. The aim of this study was to investigate the effect of diethylene glycol on the characteristics of hydroxyapatite-reduced graphene oxide powders synthesized by a hydrothermal method (180 ​°C, 5 ​h) and the nanocomposites obtained by spark plasma sintering (950 ​°C, 50 ​MPa). Graphene oxide, calcium nitrate tetrahydrate and diammonium hydrogenphosphate were used as precursors. The characterization methods included electron microscopy, X-ray diffraction, Raman spectroscopy, and indentation technique. Obtained results have shown that the presence of diethylene glycol reduced the average size of hydroxyapatite crystallites from 27 to 16 nm, reduced the particle size distribution, and increased the graphene oxide reduction rate. The presence of diethylene glycol during the synthesis process increased the elastic modulus (from 116.4 ​± ​4.9 to 125 ​± ​3.8 ​GPa), hardness (from 4.08 ​± ​0.7 to 6.32 ​± ​0.4 ​GPa), and fracture toughness (from 1.66 ​± ​0.7 to 1.87 ​± ​0.9 ​MPa ​m0.5) of the composite.

Linear Tetranuclear Lanthanide Cymantrenecarboxylates with Diethylene Glycol Ligand: Synthesis, Magnetism, and Thermolysis

AbstractExchange reactions of LnCl3 and CymCO2K in aqueous‐organic medium in the presence of diethylene glycol (DEG) bring about isostructural tetranuclear cluster complexes with linear core, [Ln4(CymCO2)12(O(CH2CH2OH)2)2(H2O)4] ⋅ 2THF (Ln=Nd (1), Gd (2), Tb (3), Dy (4), Ho (5); Cym=(η5‐C5H4)Mn(CO)3). The complexes have centrosymmetric structure and contain two types of Ln3+ coordination centers. Thermal decomposition of the complexes under argon and air atmospheres was studied; in the latter case it brings about mixed oxides LnMn2O5 as one of the products. The complexes 1–5 were characterized by dc‐ and ac‐magnetic measurements. Complexes of Nd, Gd, and Dy exhibit the properties of single‐molecule magnets (SMMs) with remagnetization barriers Δeff/kB of 14 K for 1 under 2500 Oe dc‐field, 13 K for 2 under 1500 Oe dc‐field, and with two barriers, 18 and 19 K, for 4 in zero field. The presence of field‐induced slow relaxation of the magnetization detected for the complex 2 is a rare case for Gd complexes.

A promising preparation method for highly active cobalt based Fischer-Tropsch catalysts supported on stabilized Al2O3

The effectiveness of the addition of diethylene glycol (DEG) to the impregnating solution in synthesizing highly dispersed Co-based catalysts supported on stabilized alumina (Al2O3(s)) is investigated. Both the properties and catalytic performance in the Fischer-Tropsch synthesis (FTS) of the material obtained using DEG (CoDEG/Al2O3(s)) are compared with those of a catalyst with the same formulation but prepared without the addition of DEG in the impregnating solution (Co/Al2O3(s)). When using Co-nitrate as Co-precursor, the addition of DEG leads to a very fast and exothermic decomposition of Co-nitrate into Co oxides during the calcination step. This prevents the agglomeration of Co3O4 particles, thus generating highly dispersed Co3O4 crystallites on the support. In line with the decrease of the Co3O4 crystallites size, the CoDEG/Al2O3(s) catalyst is more difficult to reduce than the Co/Al2O3(s) catalyst. As a result, the metallic surface of the two catalysts is very similar. Nonetheless, when tested in the FTS, the CoDEG/Al2O3(s) catalyst shows CO conversion higher than the Co/Al2O3(s) sample. This is attributed to the high intrinsic activity (i.e. high Turnover Frequency, TOF) of the small Co0 crystallites of the CoDEG/Al2O3(s) catalyst. We explain this result assuming that the combustion phenomenon occurring during the fast calcination induced by the presence of DEG may generate structural defects on the catalyst surface that are beneficial for the FTS. Notably, the product distribution of CoDEG/Al2O3(s) catalyst is only slightly affected.

The effect of diethylene glycol on pollution from offshore gas platforms

Environmental contextMarine mining activities are potential sources of environmental pollution. Diethylene glycol used in offshore platforms has been suspected to facilitate the release of toxic substances into the sea. The results obtained elucidate that this release is not significant for the metals examined here, apart from iron, nor for polycyclic aromatic hydrocarbons, even at very high diethylene glycol concentrations. AbstractThe role of diethylene glycol (DEG) as a co-solvent for selected organic and inorganic pollutants adsorbed onto the particulate matter in produced formation water (PFW) from offshore gas platforms is thoroughly evaluated. Artificial seawater samples were spiked with certified sediments containing several polycyclic aromatic hydrocarbons (PAH) and metals. Aliquots (1 L) containing no DEG and DEG at 3500 and 5000 mg L−1 were kept in static and dynamic modes for 24 h before analysis to allow sufficient partitioning time between solid and liquid phases for the selected analytes. The Italian legislation on this matter sets 3500 mg L−1 as the highest concentration for DEG in PFW. In our experiments, concentrations equal to and above the set limit were chosen to enhance any possible co-solvent effect. Real PFW samples were also analysed, both with and without DEG. The analyses were conducted by using GC-MS for the PAH, and ICP-MS for the metals. A minor co-solvent effect was observed for low-molecular-weight PAH in the artificial seawater in static mode. Among metals, only iron showed an increase in solubility in the presence of DEG, demonstrating the co-solvent effect of DEG. The experiments in dynamic mode revealed no increase in the solubility of any other analytes in the liquid phase compared with static mode.

Self-aggregation of ionic liquid-cationic surfactant mixed micelles in water and in diethylene glycol–water mixtures: Conductometric, tensiometric, and spectroscopic studies

Interaction of imidazolium based surface-active ionic liquid (SAIL), 1-decyl-3-methylimidazolium chloride [C10mim][Cl], with cationic surfactant cetrimide (CET) has been studied by using conductometric, tensiometric, and spectroscopic methods in pure water and in presence of diethylene glycol (DEG)–water binary mixtures. Addition of DEG has marked effect on the thermodynamic and aggregation behavior of these studied systems. From conductometric approach various parameters have been calculated such as critical micelle concentration, (cmc), micellar mole fraction, X1, of component 1 (CET), micellar interaction parameter, β, activity coefficients ƒ1 and ƒ2 of component 1 and component 2 (SAIL), standard Gibbs energy of micellization (ΔGm0), and degree of counter ion dissociation (g). Rubingh's non-ideal solution theory confirms the attractive and non-ideal behavior among the surfactant molecules in the mixed micelles. From the tensiometric studies different parameters such as surface tension reduction efficiency (pC20), maximum surface excess concentration (Γmax), minimum area per surfactant molecule (Amin) and standard Gibbs free energy of adsorption ΔGad0 at the interface were evaluated. The packing parameters of amphiphiles in the micelles, P, volume contribution of the hydrophobic chain, v, and its effective length, lC have also been evaluated for the pure and mixed systems. The micelles/mixed micelles formed have spherical geometry. Cresol red, an anionic dye, was used as a probe for UV–visible spectra of pure and mixed systems, which supports the role of SAIL in the mixed micellization process.

Photocatalytic removal of hexavalent chromium by newly designed and highly reductive TiO2 nanocrystals

Hexavalent chromium Cr(VI), a highly toxic oxyanion, widely occurs in drinking water supplies. This study designed and synthesized a new type of highly reductive TiO2 nanocrystals for photochemical Cr(VI) removal, via the thermal hydrolysis of TiCl4 in the presence of diethylene glycol (DEG). Surface analyses and hydroxyl radical measurements suggested that DEG was chemically bonded on TiO2 surface that resulted in an internal hole-scavenging effect and a high electron-releasing capacity, making it advantageous to conventional TiO2 materials. Upon UV irradiation, the synthesized TiO2 photocatalyst exhibited fast Cr(VI) reduction kinetics in diverse water chemical conditions. Fast elimination of Cr(VI) was achieved on a time scale of seconds in drinking water matrices. The removal of Cr(VI) by reductive TiO2 exhibited a three-stage kinetic behavior: an initial fast-reaction phase, a lag phase resulting from surface precipitation of Cr(OH)3(s), and a final reaction phase due to surface regeneration from oxidation-reduction induced ripening process. The lag phase disappeared in acidic conditions that prevented the formation of Cr(OH)3(s). The catalyst exhibited extremely high electron-releasing capacity that can be reused for multiple cycles of Cr(VI) removal in drinking water treatment.

Synthesis and Preparation of Magnetic Fe-Doped CeO2 Nanoparticles Prepared by Simple Sol-Gel Method

Fe-doped ceria nanoparticles were synthesized by a simple co-precipitation method via iron nitrate (Fe( NO3)3⋅9 H2O) and cerium nitrate (Ce(NO3)3⋅6H2O) as a precursor in the presence of diethylene glycol and ammonia solution. The prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), vibration sampling magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR) in different temperatures. The XRD results showed a cubic structure of Fe-doped CeO2. The mean particle size of the as-prepared samples was around 30 nm, and that of samples annealed at 500 ∘C for 3 h was 35 nm. This analysis also indicated the change of particles to rod-like shape by increasing temperature. The TEM studies exhibited the square-like shaped nanoparticles. The sharp peaks in the FTIR spectrum determined the element of Fe–Ce nanoparticles. The magnetic measurements of the as-prepared samples showed a coercive field and saturation magnetism at about 1611 G and 0.06 emu/g, respectively.

OBSTRUCTION OF STORAGE HARDENING IN NR BY USING POLAR CHEMICALS

ABSTRACT The effect of the polar chemicals phenol, diethylene glycol, and hydroxylamine hydrochloride on obstruction of storage hardening in NR was examined. A decrease in gel content and molecular weight of NR was observed after addition of diethylene glycol and hydroxylamine hydrochloride, whereas no significant change was observed after addition of phenol. The storage hardening behavior of NR containing these polar chemicals was investigated by accelerated storage with phosphorus pentoxide. The gel content, Mooney viscosity, and Wallace plasticity values of NR containing phenol increased obviously during accelerated storage hardening, whereas these values increased gradually in the presence of diethylene glycol and were constant in the presence of hydroxylamine hydrochloride. The efficiency of these polar chemicals for inhibiting storage hardening in NR follow the order hydroxylamine hydrochloride, diethylene glycol, and phenol, respectively. The mechanism of network formation during accelerated storage hardening was proposed to involve phospholipids at the chain ends of the NR molecule. Molecular structure analysis by Fourier transform infrared spectroscopy suggested that hydroxylamine inhibits storage hardening in NR by chemical interaction with phospholipid, apart from its polarity.

Preparation of Uniform BiOI Nanoflowers with Visible Light-Induced Photocatalytic Activity

Novel 3D flower-like bismuth oxyiodide (BiOI) nanomaterials were obtained via a facile solvothermal method using bismuth nitrate (Bi(NO3)3) and potassium iodide (KI) as precursors and diethylene glycol as the capping reagent. The morphology of the BiOI nanoarchitecture strongly depends on the experimental conditions such as the presence of diethylene glycol and hydrothermal time. The photocatalytic property of the BiOI nanostructures by monitoring the degradation of rhodamine B (RhB) and methyl orange (MO) mixed dyes was studied under visible light illumination, which has not been reported previously. The degradation of single cationic RhB dye is faster when compared with that of anionic MO dye. This result is due to the surface negative charges on the BiOI nanoflowers that display good selectivity towards positive RhB dye organic groups owing to electrostatic attraction.

Tertiary recycling of poly(ethylene terephthalate) wastes for production of polyurethane–polyisocyanurate foams

The present work aims at tertiary recycling of poly(ethylene terephthalate) (PET) wastes to derive raw materials for production of polyurethane–polyisocyanurate foams. The first step involves glycolytic depolymerization of PET in the presence of diethylene glycol (DEG), under the influence of microwave irradiation with an aim to reduce the energy intensiveness of the process. Experimental conditions like PET:DEG ratio and reaction time were optimized to maximize the extent of PET conversion. Multiple extrusion of PET led to reduction in its molecular weight, which increased its reactivity towards glycolysis. The time required for glycolytic depolymerization of PET could be significantly reduced by employing microwave irradiation instead of conventional thermal process. The glycolysate was subsequently reacted with two different diacids: adipic acid (AA) and sebacic acid (SA) to obtain aromatic oligoesters. For the purpose of comparison, analogous aliphatic oligoesters were also prepared by reacting AA and SA with DEG under similar reaction conditions. The oligoesters were subsequently employed as a raw material for the preparation of polyurethane foams by reacting with diphenylmethane diisocyanate. The hydroxyl:isocyanate ratio in the formulation was decreased to introduce isocyanurate linkages, which resulted in the formation of polyisocyanurate foams with high compressive strength. Various characterization techniques were employed to determine the effect of the aromatic phenyl group and chain length of the diacid on the mechanical and structural properties of the resultant foams.

Fate of isotopically labeled zinc oxide nanoparticles in sediment and effects on two endobenthic species, the clam Scrobicularia plana and the ragworm Hediste diversicolor

Although it is reported that metal and metal oxide nanoparticles, which are among the most rapidly commercialized materials, can cause toxicity to organisms, their fate in the environment and toxicity to marine organisms are not well understood. In this study, we used a stable isotope labelling approach to trace the fate of nanoparticles (NPs) in sediments and also investigated bio-uptake in two estuarine intra-sedimentary invertebrates Scrobicularia plana and Nereis diversicolor. We selected exposure to 3mgkg−1 sediment ZnO NPs since this level is a realistic prediction of the environmental concentration in sediments. 67ZnO NPs (DLS: 21–34nm, positively charged: 31.3mV) suspensions were synthesised in diethylene glycol (DEG). We explored the fate of 67ZnO NPs in sediment, 67Zn bioaccumulation and the biochemical (biomarkers of defence and damage) and behavioural (burrowing kinetics and feeding rates) biomarkers in both species to 67ZnO NPs and DEG on its own during a 16d laboratory exposure. After exposure, 67Zn concentrations in sediment showed higher levels in the upper section (1cm: 2.59mgkg−1) decreasing progressively (2cm: 1.63mgkg−1, 3cm: 0.90mgkg−1, 4cm: 0.67mgkg−1) to a minimum value at the bottom (5cm: 0.31mgkg−1). 67Zn bioaccumulation was observed in both organisms exposed to 67ZnO NPs in DEG but no major inter-species differences were found. At the biochemical level, 67ZnO NPs exposure significantly induced increased glutathione-S-transferase activity in worms and catalase activity in clams whereas superoxide dismutase activity and thiobarbituric acid reactive substance levels were not affected in any species. Exposure to DEG on its own leads to a significant increase of metallothionein-like protein levels in clams compared with those exposed to 67ZnO NPs or controls. Burrowing behaviour as well as feeding rate were significantly impaired in both species exposed to 67ZnO NPs. Concerning exposure to DEG on its own, burrowing behaviour impairments were also shown in both species and feeding rate was impaired in bivalves. At environmentally realistic concentration of 67ZnO NPs in sediment, there is no strong evidence for a severe nanoparticle effect since most effects were also observed in the presence of DEG alone.

SYNTHESIS OF MAGNETITE NANO-PARTICLES BY REVERSE CO-PRECIPITATION

Magnetite nano-particles have been synthesized by reverse co -precipitation method using iron salts in alkaline medium in the presence of diethylene glycol (DEG). Effect of DEG on the nano-particle characteristics was investigated by XRD, FE-SEM, FTIR and VSM techniques. From XRD results it was concluded that in the presence of DEG the composition of magnetite did not change, however the mean crystallite size reduced from 10 to 5 nm. SEM micrograph showed that DEG decreased the size of spherical magnetite nano-particles from 50 to 20 nm. Fourier transform infrared spectra (FTIR) indicated that the DEG molecules chemisorbed on the magnetite nano-particles. Under the given experimental conditions, the rate of crystallization and growth reduced, which is probably due to the capping of DEG to the magnetite nano-particles. The agglomeration was also decreased which is attributed to the coating of magnetite nano-particles by DEG which prevents the formation of hydrogen bonding between magnetite and water molecules.

Craze initiation in glassy polymers: Quantifying the influence of molecular orientation

A study has been made of crazing stress in oriented glassy polystyrene. The aim was to develop a methodology for prediction of crazing stress in glassy polymers with frozen-in molecular orientation. Oriented specimens of two grades of monodisperse polystyrene (PS) and one grade of polydisperse PS were produced by uniaxial melt-drawing and subsequent quenching of compression-moulded bars. Birefringence and crazing stress parallel to the draw direction (in the presence of diethylene glycol) were measured on miniature beam specimens cut from them. The crazing stress increased substantially with orientation, and the magnitude of the increase relaxed approximately on a timescale associated with the longest Rouse time. Specifically, a linear correlation was found, to within experimental scatter, between the increase in crazing stress and the orientation expressed in terms of frozen-in conformational stress, as predicted by the theory of Maestrini and Kramer [13]. The inverse gradient (constant β in the theory) was found to be 0.059 ± 0.002, when inferring the conformational stress from the measured birefringence. Crazing was found to be suppressed in favour of yielding in the most highly oriented specimens, and this could be explained in terms of the differing sensitivities of crazing and yield to molecular orientation.

Synthesis of pH‐responsive crosslinked poly[styrene‐co‐(maleic sodium anhydride)] and cellulose composite hydrogel nanofibers by electrospinning

AbstractBACKGROUND: Stimuli‐sensitive materials show enormous potential in the development of drug delivery systems. But the low response rate of most stimuli‐sensitive materials limits their wider application. We propose that electrospinning, a technique for the preparation of ultrafine fibrous materials with ultrafine diameters, may be used to prepare materials with a fast response to stimuli.RESULTS: Poly[styrene‐co‐(maleic sodium anhydride)] and cellulose (SMA‐Na/cellulose) hydrogel nanofibers were prepared through hydrolysis of precursor electrospun poly[styrene‐co‐(maleic anhydride)]/cellulose acetate (SMA/CA) nanofibers. In the presence of diethylene glycol, the SMA/CA composite nanofibers were crosslinked by esterification at 145 °C, and then hydrolyzed to yield crosslinked SMA‐Na/cellulose hydrogel nanofibers. These nanofibers showed better mechanical strengths and were pH responsive. Their water swelling ratio showed a characteristic two‐step increase at pH = 5.0 and 8.2, with the water swelling ratio reaching a maximum of 27.6 g g−1 at pH = 9.1.CONCLUSION: The crosslinked SMA‐Na hydrogel nanofibers supported on cellulose showed improved dimensional stability upon immersion in aqueous solutions. They were pH responsive. This new type of hydrogel nanofiber is a potential material for biomedical applications. Copyright © 2009 Society of Chemical Industry

Influence of Mn Doping on Structural and Vibrational Properties of Self-Assembled Mn Doped ZnO Nanocrystals

Nanocrystallites (15-25 nm) of Mn doped ZnO prepared by refluxing their acetate precursors in the presence of diethylene glycol, self-assemble into polydisperse spheres of broad size distributation (100-400 nm). The center of X-ray diffraction peaks shifts towards lower angle and the line gets broadened on increasing Mn concentration. Compared to the vibration modes of wurtzite ZnO, one additional vibration mode is observed in the range of 522-518 cm(-1) in Raman spectra of Mn doped ZnO whose intensity increases on increasing the Mn concentration. The origin of this peak could be related to the incorporation of Mn2+ in Zn2+ lattice site. Further, on increasing Mn concentration, infrared band red shifted and surface phonon mode absorption get pronounced due to the incorporation of Mn2+ in Zn2+ lattice site resulting changes in the local structure parameters (effective mass, force constant, bond length).

Renewable-Resource Thermoplastic Elastomers Based on Polylactide and Polymenthide

An alpha,omega-functionalized polymenthide was synthesized by the ring-opening polymerization of menthide in the presence of diethylene glycol with diethyl zinc as the catalyst. Termination with water afforded the dihydroxy polymenthide. The reaction of this telechelic polymer with triethylaluminum formed the corresponding aluminum alkoxide macroinitiator that was used for the controlled polymerization of lactide to yield biorenewable polylactide-b-polymenthide-b-polylactide triblock copolymers. The molecular weight and chemical composition were easily adjusted by the monomer-to-initiator ratios. Microphase separation in these triblock copolymers was confirmed by small-angle X-ray scattering and differential scanning calorimetry. A representative triblock was prepared with a hexagonally packed cylindrical morphology as determined by small-angle X-ray scattering, and tensile testing was employed to assess the mechanical behavior. On the basis of the ultimate elongations and elastic recovery, these triblock copolymers behaved as thermoplastic elastomers.