Transparent acryl–clay nanohybrid films with low thermal expansion coefficient

The aim of this study was to prepare transparent nanohybrid films with low coefficient of thermal expansion (low CTE), which consist of acryl resin and nanosized clay. The hybrid films with different clay contents were prepared by UV curing of tricyclodecane dimethanol diacrylate (TCDDMDA) including nanosized clay. All obtained films were transparent similar to pure poly(TCDDMDA). In addition, the film containing 40 wt.% of clay showed a low CTE of 10 ppm/K in 150–200 °C, which is similar to that of inorganic materials such as glass. The significant property improvement is related to shape effect and orientation of clay in polymer matrix. Wide-angle X-ray diffraction measurement was carried out to investigate orientation of nanosized clay in polymer matrix. From this measurement, it was confirmed that the clay platelets were oriented parallel with film surface with increasing clay content, and orientation coefficient of the clay in polymer matrix reached to f?=?0.65 for the hybrid film containing 40 wt.% of clay. Though, in comparison with the matrix, the flexibility of the hybrid film evaluated by the wind roll test with steel bar was lowered by increase of clay content, the hybrid film containing 40 wt.% of clay could be rewound with steel bar 10 mm across, and its flexibility was retained.     

Effects of solid acidity of clay minerals on the thermal decomposition of 12-aminolauric acid

In this study, the effects of four types of clay minerals on the thermal decomposition of 12-aminolauric acid (ALA) were investigated. The decomposition temperature of ALA in ALA–clay complexes was in the range of 200–500 °C. The derivative thermogravimetry results indicated that all clay minerals exhibited catalytic activity on the decomposition of ALA. Pure ALA decomposed at approximately 464 °C, a temperature higher than the decomposition temperature of ALA in the presence of clay minerals. The decomposition temperature of ALA in different ALA–clay complexes follows the order illite (452 °C) > kaolinite (419 °C) > rectorite (417 °C) > montmorillonite (400 °C). This order is negatively correlated with the amounts of solid acid sites in the clay minerals, indicating that ALA is catalyzed by the solid acid sites in these minerals.     

Thermal stability of ionene polymers

Two different cationic polymers of the same chemical type and with very similar chemical structures were reacted with a natural bentonite over a wide range of polymer/clay ratios. This study involved the synthesis of cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene. Ionenes are ion-containing polymers that contain quaternary nitrogen atoms in the main macromolecular chain as opposed to a pendant chain. The CHN content, basal spacing, and elemental composition of each of the polymer–clay complexes were analyzed by X-ray diffraction, X-ray fluorescence, and thermogravimetry. All the polycations reacted to form interlayer complexes with clay, which displaced more Na⁺ and little Ca²⁺. Sodium and calcium were both present as interlayer cations in the clay and its complexes. The TG/DTG curves show that both polymers underwent thermal degradation in more than one stage. Specifically, 3,6-ionene was found to undergo two stages of decomposition and 3,6-dodecylionene undergo three stages. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174,85 kJ mol^?1) complexes have greater thermal stability than 3,6-ionene (E = 115,52 kJ mol^?1) complexes. The mechanism of degradation suggests a direct interaction with the dodecyl chain containing 12 carbons, which are present in 3,6-dodecylionene but not in 3,6-ionene.     

三氟化硼乙醚/乙酸混合电解质中芴的电化学聚合

在三氟化硼V(乙醚):V(乙酸)=4:5的混合电解质体系中直接氧化芴,获得芴聚合物膜,其电导率为0.5 S cm-1,高于在纯三氟化硼乙醚中制得的聚芴的电导率0.25 S cm-1.在三氟化硼乙醚:乙酸=4:5的混合电解质体系中获得的聚芴膜具有良好的电化学性质和化学稳定性.FTIR,1H-NMR和量化计算表明反应发生在...     

Thermal and mechanical analysis of injection moulded poly(lactic acid) filled with poly(ethylene glycol) and talc

In our research, the effect of talc particle size was analysed on the thermal and mechanical properties of renewable resource-based, biodegradable polymer poly(lactic acid) (PLA). Various talc particles with an average particle size of 24, 1.9, and 0.7 μm were blend mixed with PLA in 10 and 20 mass% containing no or an additional 10 mass% of poly(ethylene glycol) (PEG) to increase molecular chain mobility. It was demonstrated that with decreasing talc particle size, its nucleation ability increased as well as all of the investigated mechanical properties of the compounds, however, in case of compounds containing PEG, this tendency was the opposite according to Charpy impact strength results. The talc with the best nucleating ability was selected and a full factorial design of experiment was made to optimise the talc and PEG content and to investigate their cross-effect in the 1-3-5-10-15 mass% additive content range. Finally, the effect of mould temperature and cooling time was analysed on the crystallinity and heat deflection temperature of the final injection-moulded parts.     

One-pot synthesis of nylon 6–clay hybrid

Nylon 6–clay hybrid is a molecular composite of nylon 6 and uniformly dispersed silicate layers of montmorillonite. One-pot synthesis of the hybrid was carried out by the following procedures. Montmorillonite was dispersed in water, and then ε-caprolactam, acid (phosphoric acid, hydrochloric acid, benzenesulfonic acid, isophthalic acid, trichloroacetic acid, or acetic acid), and 6-aminocaproic acid were added to the dispersion. The mixtures were reacted at 260°C for 6 h, yielding the nylon 6–clay hybrids (1potNCHs). X-ray diffraction revealed that the silicate layers of 1potNCH by phosphoric acid were uniformly dispersed in the nylon 6 matrix. The 1potNCH had excellent mechanical properties. The strength and the modulus of the hybrid increased compared with previously reported nylon 6–clay hybrid (NCH) synthesized by montmorillonite intercalated with 12-aminolauric acid. The heat distortion temperature (HDT) of the 1potNCH was 160°C, which was 8°C higher than that of NCH. In other 1potNCHs, montmorillonite had a smaller effect on the increase of those properties, and interlayer spacing of montmorillonite was observed at ca. 20 Å. © 1993 John Wiley & Sons, Inc.     

Synthesis of Poly(Adipic Anhydride) by Use of Ketene

Polyadipic anhydrides were prepared (a) from the mixed anhydride of adipic acid and acetic acid, (b) from the mixed anhydride of adipic acid and ketene in tetrahydrofurane solution (0°C), (c) by melt polycondensation of adipic acid with ketene, and (d) from the seven-membered ring adipic anhydride. The polymers were characterized by means of NMR, IR, DSC, and GPC. The polymer with the highest melting temperature was obtained by melt polycondensation of adipic acid with ketene (T _peak 76°C). The heat of fusion was approximately 40 J/g in all four methods. The number-average and weight-average molecular weights of the polyanhydrides were 2000 and 3000, respectively.     

Electrical Characterization and Ionic Transport Properties of Carboxyl Methylcellulose-Oleic Acid Solid Polymer Electrolytes

Electrical impedance spectroscopy was used to measure the conductivity of solid polymer electrolytes. From the impedance study, the highest ionic conductivity of solid polymer electrolytes based on carboxyl methylcellulose as polymer host and oleic acid as the doping salt, prepared by the solution casting method at room temperature, σ_r.t, is 2.11 × 10^?5 S cm^?1 for the sample containing 20 wt.% of oleic acid. Transference number measurement was performed to correlate the diffusion phenomena to the conductivity behavior of carboxyl methylcellulose-oleic acid solid polymer electrolytes. From the transference number measurement study, the conduction species carrier of the cation (+) is higher than that of the anion (?). Thus, the results proved that the samples are proton-conducting solid polymer electrolytes.     

Rapid identification, by use of the LTQ Orbitrap hybrid FT mass spectrometer, of antifungal compounds produced by lactic acid bacteria

Fungal contamination of food causes health and economic concerns. Several species of lactic acid bacteria (LAB) have antifungal activity which may inhibit food spoilage fungi. LAB have GRAS (generally recognised as safe) status, allowing them to be safely integrated into food systems as natural food preservatives. A method is described herein that enables rapid screening of LAB cultures for 25 known antifungal compounds associated with LAB. This is the first chromatographic method developed which enables the rapid identification of a wide range of antifungal compounds by a single method with a short analysis time (23 min). Chromatographic separation was achieved on a Phenomenex Gemini C18 100A column (150 mm?×?2.0 mm; 5 μm) by use of a mobile-phase gradient prepared from (A) water containing acetic acid (0.1%) and (B) acetonitrile containing acetic acid (0.1%), at a flow rate of 0.3 µL min^?1. The gradient involved a progressive ramp from 10–95% acetonitrile over 13 min. The LC was coupled to a hybrid LTQ Orbitrap XL fourier-transform mass spectrometer (FTMS) operated in negative ionisation mode. High mass accuracy data (<3 ppm) obtained by use of high resolution (30,000 K) enabled unequivocal identification of the target compounds. This method allows comprehensive profiling and comparison of different LAB strains and is also capable of the identification of additional compounds produced by these bacteria.     

Polyethylene glycol/clay nanotubes composites

Nanocomposites of poly(ethylene) glycol (PEG) 20000 filled with clay nanotubes (HNTs) were prepared. The thermal properties obtained from thermogravimetry and differential scanning calorimetry were correlated to the morphology imaged by scanning electron microscopy. Low amounts of HNTs generate compact structure while large amounts of HNTs create craters and voids. The decrease of polymer degradation temperature in the presence of large amount of nanoclay (ca. 80 wt%) is a consequence of the morphology at the mesoscale range. The thermal opposite effect observed in the HNTs low regime (up to ca. 20 wt%) is due to the gas entrapment into the nanoparticles lumen. The quantitative analysis of the PEG 20000 enthalpy of melting in the presence of HNTs allowed us to characterize the polymer adsorption onto the nanoclay surface.     

Production of acetic acid from liquid crystal display waste by use of a hydrothermal method

Because of the large quantity of liquid crystal displays (LCDs) in use, the volume of waste LCDs is ever-increasing, causing growing concern about their effective treatment. Polarizers are among the most important functional films used in LCDs and are mainly treated by incineration after being discarded. In this study, they were used to produce acetic acid under the hydrothermal conditions; this could aid development of a new environmentally sustainable process for treatment of waste polarizers. The experiment was performed in a 5.7-ml bath reactor heated by use of a salt-bath. The liquid product was analyzed by high-performance liquid chromatography. The effect of reaction temperature, reaction time, and oxidant on acetic acid production was investigated. Results showed that the yield and selectivity for acetic acid initially increased with increasing reaction temperature, reaction time, and H₂O₂ supply but then decreased within the ranges of the experiments performed. The highest acetic acid yield of 33.4 %, with selectivity of 26.7 % based on carbon, was obtained by hydrothermal treatment of waste polarizer at 350 °C for 5 min with 0.6 ml H₂O₂.     

Morphology and properties of polypropylene/ethylene–octene copolymer/clay nanocomposites with double compatibilizers

The influence of nanoclay on the morphology and properties of the polypropylene (PP)/ethylene–octene block copolymer (EOC) blend with double compatibilizers of maleated PP (PP‐g‐MA) and maleated EOC (EOC‐g‐MA) was investigated and compared with the nanocomposites containing either PP‐g‐MA or EOC‐g‐MA as a compatibilizer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy were utilized for morphological characterization in conjunction with dynamic mechanical thermal analysis, mechanical testing, and rheological evaluation of these nanocomposites. The results suggested that in the nanocomposite including both compatibilizers of PP‐g‐MA and EOC‐g‐MA, clay was dispersed as a mixed structure of intercalation and exfoliation in both phases of the polymer blend. Comparing the mechanical properties of the studied nanocomposite with nanocomposites of PP/EOC/PP‐g‐MA/clay and PP/EOC/EOC‐g‐MA/clay also indicated that the nanocomposite containing mixed compatibilizers displayed higher tensile modulus, tensile strength, and complex viscosity because of the better dispersion of clay in both phases. The results also confirmed the increased structural stability and reduced dispersed phase size of PP/EOC/PP‐g‐MA/EOC‐g‐MA blend in the presence of clay that proposed the compatibilization role of clay in this nanocomposite. Copyright © 2014 John Wiley & Sons, Ltd.     

前沿分析法研究对-羟基苯甲酸印迹整体柱的热力学行为

采用矩形前沿分析法对原位聚合的对-羟基苯甲酸印迹整体柱的热力学吸附等温线进行了测定. 印迹整体柱的吸附等温线是分别以乙腈、甲醇、 四氢呋喃和含有体积分数分别为1%, 3%, 5%和7%乙酸的乙腈为流动相以及在以甲醇为流动相时柱温分别为20, 40和50 ℃的条件下测定的. 吸附等温线表明, 印迹整体柱对模板分子的吸附能力比其结构类似物(邻-羟基苯甲酸)的吸附能力强. 用双Langmuir方程对不同条件下得到的实验数据进行拟合, 得到模板分子和邻-羟基苯甲酸在印迹整体柱各种吸附位点上的饱和吸附量和键合常数, 结果表明, 流动相中乙酸含量、有机溶剂的性质和柱温对模板分子容量因子的影响比对邻-羟基苯甲酸的大, 造成印迹聚合物的选择性随条件的变化而发生了明显的改变.     

一种液晶共聚酯/粘土纳米复合材料的制备及其相转变温度

一些无机微粒被广泛用做聚合物的增强材料,其中特别引起人们注意的是一种粘土,即蒙脱土（ｍｏｎｔｍｏｒｉｌｌｏｎｉｔｅ）．蒙脱土具有层状结构,其特点一是微粒尺寸小,二是可以和多种单体发生插层聚合反应,给出聚合物／蒙脱土纳米复合材料［１～３］．纳米复合材料指的是其基质中分散相的尺寸至少有一维小于１００ｎｍ数量级的复合材料．由于其纳米尺度效应、大的比表面积以及强的界面相互作用,纳米复合材料的物理力学性能优于相同组分常规复合材料．因此,无论从基本理论研究角度还是从应用角度上看,对聚合物纳米复合材料的研究都…     

Application of Dipotassium Glycoxides–Activated 18-Crown-6 for the Synthesis of Poly(propylene oxide) with Increased Molar Mass

Mono- and dipotassium salts of dipropylene glycol were applied for the polymerization of propylene oxide in mild conditions, i.e., tetrahydrofuran solution at ambient temperature. The structure of polymers was investigated by use of ¹³C NMR and MALDI-TOF techniques. The structure depends strongly on the kind of initiator and additives that are used such as coronand 18-crown-6 and dipropylene glycol. The lowest unsaturation, represented by allyloxy starting groups, has the polymer obtained by use of monopotassium salt without the ligand. The highest unsaturation degree is for the polymer synthesized in the presence of dipotassium salt–activated 18-crown-6. This polymer, obtained at high initial monomer concentration and low initial concentration of initiator, consists of two fractions, i.e., a low molar mass fraction (M_n = 9400) containing mainly macromolecules with alkoxide starting and end groups and a much higher molar mass fraction (M_n = 29500 g/mol) containing macromolecules with allyloxy starting groups and alkoxide or hydroxyl end groups. Addition of free glycol to this system decreases the molar mass of polymers. Similar results were obtained by use of dipotassium salts of other glycols. The mechanisms of the studied processes are discussed.     

Synthesis and characterization of Poly(N-isopropylacrylamide)/Poly(acrylic acid) semi-IPN nanocomposite microgels

A novel pH- and temperature-sensitive nanocomposite microgel based on linear Poly(acrylic acid) (PAAc) and Poly(N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was synthesized by a two-step method. First, PNIPA microgel was prepared via surfactant-free emulsion polymerization by using inorganic clay as a crosslinker, and then AAc monomer was polymerized within the PNIPA microgel. The structure and morphology of the microgel were confirmed by FTIR, WXRD and TEM. The results indicated that the exfoliated clay platelets were dispersed homogeneously in the PNIPA microgels and acted as a multifunctional crosslinker, while the linear PAAc polymer chains incorporated in the PNIPA microgel network to form a semi-interpenetrating polymer network (semi-IPN) structure. The hydrodynamic diameters of the semi-IPN microgels ranged from 360 to 400 nm, which was much smaller than that of the conventional microgel prepared by using N,N′-methylenebis(acrylamide) (MBA) as a chemical crosslinker, the later was about 740 nm. The semi-IPN microgels exhibited good pH- and temperature-sensitivity, which could respond independently to both pH and temperature changes.     

Rapid and Efficient Microwave-Assisted Friedländer Quinoline Synthesis

A microwave-based methodology facilitates reaction of 2-aminophenylketones with cyclic ketones to form a quinoline scaffold. Syntheses of amido- and amino-linked 17β-hydroxysteroid dehydrogenase type 3 inhibitors with a benzophenone-linked motif were pursued using 2-aminobenzophenone as building block. Two amido-linked targets were achieved in modest yield, but when using microwave-assisted reductive amination for the amino-linked counterparts an unexpected product was observed. X-ray crystallography revealed it as a quinoline derivative, leading to optimisation of a simple and efficient modification of Friedländer methodology. Using reagents and acetic acid catalyst in organic solvent the unassisted reaction proceeds only over several days and in very poor yield. However, by employing neat acetic acid as both solvent and acid catalyst with microwave irradiation at 160 °C quinoline synthesis is achieved in 5 minutes in excellent yield. This has advantages over the previously reported high temperatures or strong acids required, not least given the green credentials of acetic acid, and examples using diverse ketones illustrate applicability. Additionally, the unassisted reaction proceeds effectively at room temperature, albeit much more slowly.     

Greffage radiochimique de l'acide methacrylique sur des films de polytetrafluoroethylene

Methacrylic acid was grafted into the bulk of PTFE films 50 μm thick by irradiating the films in aqueous solutions of monomer containing CuCl₂. The influences of radiation dose-rate and of temperature were investigated. The swelling of the grafted films was studied in the following solvents for the grafted branches: water, methanol, DMF and their mixtures. In each case the molar ratios corresponding to the limiting swelling were determined. It was further found that the grafted films swell in carboxylic acids such as methacrylic, acrylic and acetic acids, which are non-solvents for the grafted branches. This swelling is much slower than the swelling in good solvents. It is suggested that it results from a molecular association of the carboxyl groups of the solvent with those of the polymer.     

Evaluation of the Temperature Responsive Stationary Phase Poly(N-isopropylacrylamide) in Aqueous LC for the Analysis of Small Molecules

Liquid chromatography columns were packed with a temperature responsive stationary phase based on poly(N-isopropylacrylamide) (PNIPAAm) attached to aminopropyl silicagel. This polymer shows hydrophilic properties below 32 °C and becomes hydrophobic above that temperature. The temperature responsive properties of the coupled phase are demonstrated using only water as mobile phase, whereby an increase in retention is observed with raising temperature. Mixtures of compounds covering a wide polarity range and including phenones, alkylbenzenes, phenols, alkylated benzoic acids, anilines, sulfonamides and carbamates were analyzed and the retention, peak shapes and plate counts were compared under identical conditions. For retained solutes, an increase in retention as a function of the temperature between 25 and 55 °C could be noted, whereby this was higher for the analytes containing a longer hydrophobic chain. Compounds with similar hydrophobic chains, but containing additional polar functions showed increased retention and improved peak shapes, suggesting a mixed mode interaction mechanism also at temperatures well above the transition temperature of the polymer. Weak acids and bases could be analyzed by pH adjustment. This is demonstrated for mixtures of benzoic acid derivatives and sulfamide drugs. A carbamate pesticide mixture was analyzed at 55 °C with water (pH 5.5) as mobile phase and ESI-MS detection. Temperature responsive stationary phases open perspectives for green chromatography.     

Synthesis of high-performance superabsorbent glycerol acrylate-cross-linked poly (acrylic acid)

Glycerol acrylate (GA) is synthesised by an acryloylation reaction with acryloyl chloride. An ester was used as a cross-linking agent at varying proportions in the synthesis of poly acrylic acid (PAA). The amount of cross-linking density in the product (GA-PAA) and degree of neutralisation determine the absorbency of the polymer samples. A sample of GA-PAA containing 0.8 % GA was discovered to absorb 395 and 66 g/g of water and saline solution, respectively. Different solvent uptakes were tested with the sample showing varying capacity for different solvents. The temperature of the reaction was maintained at 60 °C and a reaction time of 2½ h. FTIR, TGA, SEM and XRD analyses were used to characterise the products.