Mole Proportions Research Articles

Study on water vapor corrosion resistance of rare earth monosilicates RE2SiO5 (RE = Lu, Yb, Tm, Er, Ho, Dy, Y, and Sc) from first-principles calculations

Corrosion resistance of rare earth monosilicates (RE2SiO5, RE = Lu, Yb, Tm, Er, Ho, Dy, Y, and Sc) in water vapor has been studied using the first-principles calculations. The results show that the water vapor corrosion resistance of RE2SiO5 demonstrates the following order: Sc2SiO5 > Dy2SiO5 > Y2SiO5 > Ho2SiO5 > Er2SiO5 > Yb2SiO5 > Tm2SiO5 > Lu2SiO5. To further improve their water vapor resistance, a doping strategy has been employed for the first time. Two scenarios have been investigated: one is a half mole proportion of substitution of various rare earth elements for Yb in the Yb2SiO5 lattice; the other is a half mole fraction substitution of rare earth elements in RE2SiO5 (RE = Lu, Yb, Er and Y) by scandium. It is unveiled that the water vapor resistance of YbScSiO5 and YScSiO5 has been greatly improved in contrast to other rare earth monosilicates. The current study provides guidelines for the selection of environmental barrier coatings with a better water vapor corrosion resistance.

Preliminary study on TRUs utilization in a small modular Th-based molten salt reactor (smTMSR)

Abstract Small modular reactors (SMRs) can provide an energy option with low carbon emission, enhanced safety conviction, convenient construction and operation. Meanwhile, molten salt reactors (MSRs) have been recognized as one of the reference reactors of the Generation IV International Forum (GIF) with the unique potential (inherent safety, no fuel fabrication, online fuel reprocessing, etc). Combining advantages of SMRs and MSRs, the small modular Th-based molten salt reactor (smTMSR) has excellent performances such as inherent safety, economics, sustainability, and proliferation resistance. Moreover, thorium is still an attractive fuel in a smTMSR with characteristics of online refueling and reprocessing. In this paper, we attempt to study the capability of the transition to thorium fuel cycle in a thermal smTMSR by analyzing the neutronic characteristics using TRUs as starting fuel. Optimizations are conducted to produce the required amount of U-233 for starting a new smTMSR based on various fuel fractions in thermal energy region. It is concluded that the U-233 production is superior with higher fuel fraction in the core, which indicates that a thermal smTMSR with a proper fuel fraction can achieve the transition to thorium fuel cycle. The HM and Pu mole proportions which may have a negative influence on the molten salt stability are analyzed. Moreover, the temperature feedback coefficient as a key safety parameter is also discussed. With a suitable fuel fraction in thermal region, the smTMSR can well satisfy the restrictions of HM and Pu mole proportions and safety demands.

Improving flame retardancy and mechanical properties of halogen-free unsaturated polyester resin with diethylene glycol as comonomer

Unsaturated polyester resin (UPR) is a widely applied engineering material with drawbacks of high fire risks and brittleness. In this paper, low-cost diethylene glycol (DEG) was used as one of diols to react with saturated and unsaturated anhydrides for unsaturated polyester pre-polymers. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatograph were used for studying their structures and differential scanning calorimetry, thermogravimetric analysis (TG) for studying their thermal properties. Incorporated DEG comonomer improves limited oxygen index values of cross-linked UPR from 20 to 26% as the mole proportion of DEG increases from 0 to 50 mol% in diols. Combustion test indicates that the UPR sample with 70 mol% DEG in diols is self-extinguishing with none drop, referring to nonflammable burning grade. What is more, mechanical properties are also increased greatly by comparing with typical UPR base. Pyrolysis behaviors of UPR in nitrogen atmosphere suggest that the polyesters incorporated with DEG will produce more char and residues during the degradation process. By comparing the pyrolysis behaviors of UPR having DEG with those of UPR adding ammonium polyphosphate in TG curves, the flame-retarding mechanism of DEG incorporation is probably due to residual char forming in temperature range of 500–800 °C, which is close to the burning temperature. This study suggests that DEG element increases effectively and environmental friendly the fire safety of UPR materials.

Challenges in constraining theP–Tconditions of mafic granulites: An example from the northern Trans‐North China Orogen

AbstractSome mafic granulites in the Sanggan area of the northern Trans‐North China Orogen (TNCO) have a relatively simple mineralogy with low energy grain shapes that are compatible with an assumption of equilibrium, but the rock‐forming minerals show variations in composition that create challenges for thermobarometry. The mafic granulites, which occur as apparently disrupted dyke‐like bodies in tonalite–trondhjemite–granodiorite gneisses, are divided into two types based on petrography and chemical composition. Type 1 mafic granulites are fine‐ to medium‐grained with an equilibrated texture and an assemblage of plagioclase+clinopyroxene+garnet+magnetite+ilmenite and sometimes minor hornblende±orthopyroxene. Type 2 mafic granulites are coarse‐grained and hornblende bearing with a peak assemblage of garnet+clinopyroxene+plagioclase+hornblende and variably developed coronae and symplectites of plagioclase+hornblende+orthopyroxene partially replacing porphyroblastic garnet±clinopyroxene.SIMSU–Pb dating of metamorphic zircon from two type 1 mafic granulites yields metamorphic ages ofc. 1.84 and 1.83 Ga, consistent with published ages of the type 2 mafic granulites. Based on phase equilibrium modelling, we use the common overlap ofP–Tfields defined by the mineral assemblage limits, and the mole proportion and composition isopleths of different minerals in each sample to quantify the metamorphic conditions. For type 1 granulites, overlap of the mineral proportion and composition fields for each of three samples yields similarP–Tconditions of 710–880°C at 0.57–0.79 GPa, 820–850°C at 0.59–0.63 GPa and 800–860°C at 0.59–0.68 GPa. For the type 2 granulites, overlaying the peak assemblage fields for three samples yields commonP–Tconditions of 870–890°C at 1.1–1.2 GPa. For the retrograde assemblage, overlap of the mineral proportion and composition fields for each sample yields similarP–Tconditions of 820–840°C at 0.85–0.88 GPa, 860–880°C at 0.83–0.86 GPa and 880–930°C at 0.89–0.95 GPa. TheP–Tconditions appear distinct between the two types of mafic granulite, with the mineralogically simple type 1 mafic granulites recording the lowest pressures. However, there are significant uncertainties associated with these results. For the granulites, there are uncertainties related to the determination of modes and composition of the equilibration volume, particularly estimation of O and H2O contents, and in the phase equilibrium modelling there are uncertainties that propagate through the calculation of mole proportions and mineral compositions. The compound uncertainties on pressure and temperature for high‐Tgranulites are large and the results of our study show that it may be unwise to rely onP–Tconditions determined from the simple intersection of calculated mineral composition isopleths alone. Since the samples in this study are from a limited area—a few hundred square metres—we infer that they record a singleP–Tpath involving both decompression and cooling. However, there is no evidence of the high‐Pgranulite facies event at 1.93–1.90 Ga that is recorded elsewhere in theTNCO, which suggests that the precursor basic dykes were emplaced late during the assembly of the North China Craton.

Processable heat resistant polyamides containing tetraphenyl thiophene having pendant phenyl moiety with heterocyclic quinoxaline unit: Synthesis and characterization

ABSTRACTA series of new polyamides containing tetraphenyl thiophene having pendant phenyl moiety with heterocyclic quinoxaline unit were synthesized by using the solution polycondensation method of novel diamine monomer V with isopthaloyl chloride (IPC) and terpthaloyl chloride (TPC) in various mole proportions. These novel polymers were characterized by FT-IR, solubility, inherent viscosity, thermal analysis and X-ray diffraction studies. Inherent viscosities of these polymers were in the range 0.66 to 1.44 dL/g indicating moderate to high molecular weight built-up. These polymers exhibited solubility in various solvents such as DMAc, NMP, pyridine, m-cresol etc. X-ray diffraction pattern of polymers showed that introduction of pendant phenyl moiety would disturb the chain regularity and packing, leading to amorphous nature. Thermal analysis by TGA and DSC showed excellent thermal stability of polymers. The structure -property correlation among these polyamides were studied, in view of these polymer's potential applications as processable high temperature resistance materials.

YSZ-based mixed potential H2S sensor using La2NiO4 sensing electrode

Abstract In this paper, mixed potential electrochemical sensors based on YSZ and La2NiO4 sensing electrode were fabricated for the sub-ppm H2S detection. The sensing materials La2NiO4 was prepared by a sol-gel method. The different moles citric acid (CA) were used as complex agent to change the micro-structure of the La2NiO4. In comparison with other mole proportions, the sensor based on La2NiO4-SE with n(CA):n(La3+ + Ni2+) = 1:1 performed the highest response of −55 mV to 500 ppb H2S at 500 °C. Moreover, a short temperature pulse of 700 °C was used to decrease the recovery time and the result shows a significance decrease for the sensor to 500 ppb H2S, which is changed from 20 min to about 150s. In addition, the sensor displayed good stability for H2S during the testing period and excellent selectivity toward H2S in comparison to the other interference gases, such as SO2, NO2, NO, CO, CH4 and NH3. The sensing mechanism related to the mixed potential ws proposed for the sensor based on YSZ and oxide electrodes.

Preparation of hydrophobic carboxymethyl starches and analysis of their properties as fluid loss additives in drilling fluids

Hydrophobic carboxymethyl starch (HCMS) was successfully synthesized, and major factors affecting esterification were systematically investigated. The physicochemical properties of HCMS were determined through FTIR spectroscopy, scanning electron microscopy (SEM), and viscosity analysis. The results indicated that the suitable parameters for the preparation of HCMS from carboxymethyl corn starch (CMS) were as follows: temperature, 35°C; reaction time, 60 min; benzoyl chloride (BC), 2.5 (in mole proportion to CMS); and sodium hydroxide (NaOH), 1.0 (in mole proportion to BC). Under these conditions, the degree of substitution (DSBz) was approximately 0.85 and the reaction efficiency (REBz) was approximately 43%. FTIR analysis revealed that benzoyl groups were grafted onto the CMS chain units. SEM images showed that HCMS granules exhibited slightly rough surfaces and their edges lost some definition; their sides were porous. The HCMS displayed good solubility and hydrophobicity. The selected HCMS (DSBz, 0.31) drilling fluids provided a remarkably effective reservoir protection in the cores, and its permeability recovery value reached 90%.

Synthesis and characterization of processable heat resistant co-poly(ester-amide)s containing cyclopentylidene moiety

ABSTRACTNew cyclopentylidene ring-containing diamino-diesters, 1,1-bis(3-aminobenzoyloxy phenyl) cyclopentane, was prepared through reaction of cyclopentanone with two moles of phenol to yield 1,1-bis (4-hydroxy phenyl) cyclopentane (BHPP) (I), the resulting diol (I) on reaction with 3-nitrobenzoyl chloride in N,N-dimethyl acetamide (DMAc) and triethyl amine yield 1,1-bis(3-nitrobenzoyloxy phenyl) cyclopentane (II) which on finally reduced by catalytic hydrogenation in presence of 10% Pd/C in DMAc and stirred at room temperature under a 4 kg/cm2 hydrogen pressure yields 1,1-bis(3-aminobenzoyloxy phenyl) cyclopentane (III) (m-BABPP). The structure of novel m-diester-diamine was confirmed by FT-IR, 1H-NMR and 13C-NMR. A series of new m-poly (ester-amide)s and co-poly(ester-amide)s were synthesized by using the solution polycondensation method of novel diamine (III) with IPC and TPC in various mole proportion. These novel polymers were characterized by FTIR spectroscopy, solubility, inherent viscosity and thermal analysis and XRD studies. Inherent viscosities of these polymers were in the range 0.30 to 0.46 dL/g indicating moderate molecular weight built-up. These polymers exhibited excellent solubility in various polar aprotic solvents such as NMP, Pyridine. These polymers were partially soluble in DMSO, DMAc, DMF etc.X-Ray diffraction pattern of polymers showed that introduction of cardo moiety containing ester linkage would disturb the chain regularity and packing, leading to amorphous nature. Thermal analysis by TGA showed excellent thermal stability of polymers. The structure -property correlation among these poly(ester-amide)s were studied, in view of these polymer's potential applications as processable high temperature resistance materials.

Poly(aspartic acid) (PAA) hydrolases and PAA biodegradation: current knowledge and impact on applications.

Thermally synthesized poly(aspartic acid) (tPAA) is a bio-based, biocompatible, biodegradable, and water-soluble polymer that has a high proportion of β-Asp units and equivalent moles of D- and L-Asp units. Poly(aspartic acid) (PAA) hydrolase-1 and hydrolase-2 are tPAA biodegradation enzymes purified from Gram-negative bacteria. PAA hydrolase-1 selectively cleaves amide bonds between β-Asp units via an endo-type process, whereas PAA hydrolase-2 catalyzes the exo-type hydrolysis of the products of tPAA hydrolysis by PAA hydrolase-1. The novel reactivity of PAA hydrolase-1 makes it a good candidate for a biocatalyst in β-peptide synthesis. This mini-review gives an overview of PAA hydrolases with emphasis on their biochemical and functional properties, in particular, PAA hydrolase-1. Functionally related enzymes, such as poly(R-3-hydroxybutyrate) depolymerases and β-aminopeptidases, are compared to PAA hydrolases. This mini-review also provides findings that offer an insight into the catalytic mechanisms of PAA hydrolase-1 from Pedobacter sp. KP-2.

Synthesis, characterization and thermal decomposition of novel soluble copoly(aryl ether nitrile) containing phthalazinone and biphenyl moieties

A series of novel soluble phthalazinone-based copoly(aryl ether nitrile)s (PPBENs) were successfully synthesized by the nucleophilic substitution reaction of 2,6-difluorobenzonitrile (DFBN) with varying mole proportions of 4-(4-hydroxylphenyl)-2,3-phthalazin-1(2H)-one (DHPZ) and 4,4′-dihydroxybiphenyl (BP). These obtained copolymers had inherent viscosities between 0.88 and 1.26 dL/g in N-methyl-2-pyrrolidone (NMP) at a concentration of 0.5 g dL−1 at 25 °C. Most of the obtained copolymers were soluble in common polar aprotic solvents, involving NMP, DMF, DMAc and chloroform, etc., at room temperature. The glass transition temperature was found to increase with increasing the DHPZ unit concentration in the copolymer main chain, ranging from 222 to 286 °C. Thermal gravimetric analysis showed that all the copolymers had 5 % weight loss temperature up to 521 °C and the high char yield above 65 % at 800 °C in nitrogen atmosphere. PPBEN2 exhibited the best mechanical properties which were measured using film samples. Its tensile strength and elongation at break were up to 137 MPa and 15 %, respectively. The thermal degradation process of PPBENs was discussed using thermogravimetric analysis (TGA) and FTIR. The apparent activation energy values were 273.5 and 274.1 kJ/mol which were calculated by Kissinger–Akahira–Sunose method and Flynn–Wall–Ozawa method, respectively. The results showed that the obtained copolymers possess excellent thermooxidation.

Performance Investigation of Nanoscale Strained Ge pMOSFETs with a GeSn Alloy Stressor.

A germanium (Ge)-based substrate combined with germanium-tin (GeSn) alloy embedded in source/drain (S/D) regions has attracted significant attention because of its ability to satisfy the requirements of a high-mobility channel. Devices are shrunk in their geometries to meet the target of superior density in layout arrangement. Thus, determining the influences of devices on mobility gain is important. Accordingly, several designed factors, including gate width, S/D length, and Sn concentration of the GeSn stressor, are systematically analyzed in this study. A second-order formula composed of piezoresistance coefficients is derived and adopted to achieve a precise mobility gain estimation. A peak of the carrier mobility gain appears when a nanoscale geometry combination of 20 nm gate length and -200 nm gate width is used in the Ge channel, and 10% of the Sn mole proportion of the GeSn alloy is applied.

Galactans of Gracilaria pudumadamensis (Gracilariales, Rhodophyta) of Indian Waters

Galactans from the Indian agarophyte Gracilaria pudumadamensis were extracted and characterized. The isolated native (GP(Native)) and alkali treated (GP(Alkali)) galactans were characterized by IR, 13C NMR, GC-MS and GPC. It was found that GP(Native) and GP(Alkali) were composed mainly of 3,6-anhydro L-galactose, 6-O-methylated D-galactose and galactose in various mole proportions (15.6:69.9:17.5 mole% for GP(Native) and 20.2:69.8:10.0 mole% for GP(Alkali)). The GP(Native) and GP(Alkali) exhibited low gel strengths (< 100 g/cm2) and high melting points (-76 degrees C), which may be due to the presence of high 6-O-Me-galactose contents. The latter, having low sulfate (2.1%), was by far the greatest 6-O-Me-galactose containing polysaccharide in a Gracilaria spp. reported in the literature. This methylated agar contained very low heavy metal ions estimated by inductively coupled plasma spectrophotometry (ICP). The results of this investigation would be useful in bioprospecting of agarophytes, especially those occurring in Indian waters and would be potentially useful in food, personal care and related domains.

Tailored bifunctional polymer for plutonium monitoring.

Monitoring of actinides with sophisticated conventional methods is affected by matrix interferences, spectral interferences, isobaric interferences, polyatomic interferences, and abundance sensitivity problems. To circumvent these limitations, a self-supported disk and membrane-supported bifunctional polymer were tailored in the present work for acidity-dependent selectivity toward Pu(IV). The bifunctional polymer was found to be better than the polymer containing either a phosphate group or a sulfonic acid group in terms of (i) higher Pu(IV) sorption efficiency at 3-4 mol L(-1) HNO3, (ii) selective preconcentration of Pu(IV) in the presence of a trivalent actinide such as Am(III), and (iii) preferential sorption of Pu(IV) in the presence of a large excess of U(VI). The bifunctional polymer was formed as a self-supported matrix by bulk polymerization and also as a 1-2 μm thin layer anchored on a microporous poly(ether sulfone) by surface grafting. The proportions of sulfonic acid and phosphate groups in both the self-supported disk and membrane-supported bifunctional polymer were found to be the same as expected from the mole proportions of monomers in polymerizing solutions used for syntheses. α radiography by a solid-state nuclear track detector indicated fairly homogeneous anchoring of the bifunctional polymer on the surface of the membrane. Pu(IV) preconcentrated on a single bifunctional bead was used for determination of the Pu isotopic composition by thermal ionization mass spectrometry. The membrane-supported bifunctional polymer was used for preconcentration and subsequent quantification of Pu(IV) by α spectrometry using the absolute efficiency at a fixed counting geometry. The analytical performance of the membrane-supported-bifunctional-polymer-based α spectrometry method was found to be highly reproducible for assay of Pu(IV) in a variety of complex samples.

Catalytic removal of benzene over CeO2–MnO x composite oxides with rod-like morphology supporting PdO

CeO2-MnO (x) composites possessing rod-like morphology (fixed mole proportion of Ce/Mn) were synthesized through hydrothermal method and chosen as supporters to load PdO nanoparticles (PdO/Ce (x) Mn1-x ). The size of loaded PdO nanoparticles is about 2 nm. The catalytic behaviors of supported catalysts were examined through the complete catalytic oxidation of benzene. The results illustrated that the activities of supported catalysts were enhanced greatly as compared to unsupported, and the completely conversion temperature of benzene was reduced to ca. 250 A degrees C. The effect of noble metal species (PdO) addition on the catalytic property and crystal structure of composites was researched in detail. The data revealed that the interaction between PdO and supporter, and intrinsic properties of supporter resulted in the enhancement of catalytic abilities.

Soluble copoly(aryl ether ether ketone ketone)s containing xanthene and hexafluoroisopropylidene moieties

Several new copoly(aryl ether ether ketone ketone)s (PEEKKs) containing xanthene and hexafluoroisopropylidene moieties were prepared via nucleophilic substitution polycondensation of 1,4-bis(4-fluorobenzoyl)benzene with 9,9-bis(4-hydroxyphenyl)xanthene (BHPX) and 4,4′-hexafluoroisopropylidenediphenol (6F-BPA) by varying mole proportions of BHPX to 6F-BPA (5/95–75/25) in tetramethylene sulfone in the presence of anhydrous potassium carbonate. These polymers with weight-average molecular weights of 78,900–81,500 and number-average molecular weights of 38,500–40,800 were all amorphous and soluble in organic solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF), and even in THF and chloroform at room temperature. The copolymers showed glass transition temperatures (Tg's) between 180 and 216°C, and the Tg values increased with increase in concentration of the BHPX units in the polymer. Besides, all the polymers were stable up to 470°C with 5% weight loss temperatures ranging from 525 to 544°C, and char yields of 58–64% at 800°C in nitrogen. These copolymers could be cast into transparent, strong, and flexible films with tensile strengths of 52.4–75.1MPa, elongations at break of 8–13%, and tensile moduli of 2.05–2.55GPa. Their films had low dielectric constants of 2.58–2.84 (1MHz) and low water absorptions in the range of 0.24–0.38%, and high transparency with an ultraviolet–visible absorption cut-off wavelengths in the 356–376nm range.

Sol–gel hydrothermal synthesis of strontium hexaferrite nanoparticles and the relation between their crystal structure and high coercivity properties

Hard magnetic strontium hexaferrite SrFe 12 O 19 nanoparticles were synthesized by the sol–gel hydrothermal method. The factors affecting the synthesized process, such as the mole proportion of the reactants, pH, temperature, the hydrothermal conditions and the calcination process, have been investigated. The crystal structures of these materials were refined by Rietveld method. The obtained materials have single crystal phase, equal nano-size, plate shape and high anisotropy. The high magnetic coercivity of 6.3 kOe with the magnetization at 11.1 kOe of 66 emu g −1 at room temperature was observed for the strontium hexaferrite nanoparticles. For other nanoparticles (SrLn x Fe 12-x O 19 and SrFe 12 O 19/CoFe 2 O 4) synthesized on the basis of SrFe 12 O 19 the complex completion of the crystal structure distortion and the interaction between magnetic phases were observed.

Synthesis, structural, magnetic, DFT calculations and CShM studies of three new pentanuclear Mn(ii) clusters

The ditopic ligand PyPzOAPz (N-[(Z)-amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid) was synthesized by in situ condensation of methyl imino pyrazine-2-carboxylate with 5-methyl-1-(2-pyridyl) pyrazole-3-carbohydrazide. In this work we have also used two of our earlier ligands PzCAP (5-methyl-N-[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazonic acid) (Dalton Trans., 2009, 8215) and PzOAP (N-[(Z)-amino(pyridin-2-yl)methylidene]-5-methyl-1H-pyrazole-3-carbohydrazonic acid) (Dalton Trans., 2007, 1229). These ligands PzCAP, PzOAP and PyPzOAPz were made to react with Mn(ClO(4))(2)·6H(2)O to produce three pentanuclear Mn(II) clusters [Mn(5)(PzCAP)(6)](ClO(4))(4) (1), [Mn(5)(PzOAP)(6)](ClO(4))(4) (2) and [Mn(5)(PyPzOAPz)(6)](ClO(4))(4) (3). These complexes have been characterized by X-ray structural analyses and variable temperature magnetic susceptibility measurements. All complexes have a pentanuclear core with trigonal bipyramidal arrangement of Mn(II) atoms, where, the axial metal centers have a N(3)O(3) chromophore and the equatorial centers have N(4)O(2) with an octahedral arrangement. These Mn(5)(II) clusters 1, 2 and 3 show the presence of antiferromagnetic coupling within the pentanuclear manganese(II) core (J = -2.95, -3.19 and -3.00 cm(-1) respectively). Density functional theory calculations and continuous shape measurement (CShM) studies have been performed on these complexes to provide a qualitative theoretical interpretation of the antiferromagnetic behaviour shown by them. The pentanuclear Mn(II) cluster (1) on reaction with Cu(NO(3))(2)·6H(2)O in 1:1 mole proportion in CH(3)OH:H(2)O (60 : 40) forms a homoleptic [2 × 2] tetranuclear Cu(4)(II) grid [Cu(4)(PzCAP)(4)(NO(3))(2)](NO(3))(2)·8H(2)O (4). The same Cu(4)(II) grid is also obtained from a direct reaction between the ditopic ligand PzCAP with Cu(NO(3))(2)·6H(2)O in 1:1 mole proportion. This conversion of a cluster to a grid is a novel observation.

Kinetics of thermal decomposition and antimicrobial screening of terpolymer resins

Polycondensation technique was employed to synthesize terpolymer resins of anthranilic acid, urea, and formaldehyde (AUF-I, II, and III) in dimethyl formamide medium with varying mole proportions. The terpolymer was characterized by infra-red, nuclear magnetic resonance (1H and 13C) spectroscopy, gel permeation chromatography (GPC), and scanning electron microscopy (SEM). The thermal decomposition pattern and the kinetics of thermal decomposition of the terpolymers were investigated by thermogravimetric analysis (TGA) in a static nitrogen atmosphere at a heating rate of 20 °C/min. Freeman–Carroll and Sharp–Wentworth methods have been adopted to evaluate the kinetic and thermodynamic parameters such as thermal activation energies (Ea), order of the reaction (n), entropy change (ΔS), free energy change (ΔF), apparent entropy (S*), and frequency factor (Z). The thermal decomposition model for the terpolymers was also proposed using Phadnis–Deshpande method. The synthesized terpolymer resins were screened for antimicrobial activity against pathogenic bacteria and fungi. The resins show potent inhibition against bacteria such as Escherichia coli, Klebsiella, Staphylococcus aureus, and Pseudomonas aeruginosa and fungi viz.Aspergillus flavus, Aspergillus niger, Penicillium species, Candida albicans, Cryptococcus neoformans, and Mucor species.

A novel class of organosoluble poly(arylene ether nitrile) copolymers containing methyl substituent and cardo xanthene moiety

9,9-Bis(3-methyl-4-hydroxyphenyl)xanthene (BMHPX) was synthesized in 72% yield by a HCl/ZnCl2-catalyzed condensation reaction of xanthenone with excess o-cresol. Based on this new bisphenol monomer, a series of poly(arylene ether nitrile) (PAEN) and PAEN copolymers containing methyl substituent and cardo xanthene moiety were prepared by the nucleophilic substitution reaction of 2,6-difluorobenzonitrile (DFBN) with BMHPX and with varying mole proportions of BMHPX to hydroquinone (HQ) (100/0–40/60) using N-methyl-2-pyrrolidone (NMP) as solvent in the presence of anhydrous potassium carbonate. These polymers had inherent viscosities between 0.54 and 0.72 dl/g, and their weight-average molecular weights and number-average molecular weights were in the range of 32,600–36,400 and 17,300–18,300, respectively. All PAENs were amorphous and were soluble in dipolar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc), and even in THF and chloroform at room temperature. The resulting polymers showed glass transition temperatures (Tg's) between 213–226°C, and the Tg values of the copolymers were found to increase with increase of the BMHPX units content in the polymer. Thermogravimetric studies showed that all the polymers were stable up to 404°C, with 10% weight loss temperatures ranging from 444 to 455°C, and char yields of 52–58% at 700°C in nitrogen. All new PAENs could be cast into transparent, strong, and flexible films with tensile strengths of 102–120 MPa, elongations at break of 14–18%, and tensile moduli of 3.3–3.7 GPa. Copyright © 2011 John Wiley & Sons, Ltd.

The investigation of structural and thermosensitive properties of new phosphazene derivatives bearing glycol and amino acid

In this study, hexachlorocyclotriphosphazene, N(3)P(3)Cl(6) (cylotriphosphazene), was reacted with hydrophilic and hydrophobic groups to synthesize amphiphilic phosphazene derivatives (4-12). Cylotriphosphazene was reacted triethylene glycol monomethyl ether (TEGME), dipropylene glycol monomethyl ether (DPGME), diethylene glycol monobutyl ether (DEGBE), (1 : 3 mole proportion) in the presence of sodium hydride and using tetrahydrofuran (THF) as solvent at -60 °C. Three isomers (nongeminal cis-2,4,6 (1a-3a); nongeminal trans-2,4,6 (1b-3b); geminal 2,2,4 (1c-3c)) were isolated from the reaction of hexachlorocyclotriphosphazatriene (trimer) (1) with TEGME, DPGME and DEGBE. The substitution reactions of cis-tris isomers (1a-3a) with 4-amino butyric acid, 5-amino valeric acid and 6-amino hexanoic acid were separately done to provide amphiphilic phosphazenes (4-12). All compounds were characterized by using elemental analysis, (31)P NMR and mass spectroscopy. Thermosensitive properties of compounds were studied. The compounds (4-12) were soluble in both water and organic media that shows they are amphiphilic molecules. Concentration-dependent LCST (Lower Critical Solution Temperature) behaviours of new compounds (4-12) were measured in water. Compounds 7, 9, 11 and 12 exhibited a reversible and thermosensitive phase transition in aqueous medium, from soluble to insoluble states.