Synthesis of multifunctional high strength,highly swellable,stretchable and self‐healable pH‐responsive ionic double network hydrogels

The multifunctional double network (DN) soft hydrogels reported here are highly swellable and stretchable pH‐responsive smart hydrogel materials with sufficient strength and self‐healing properties. Such multifunctional hydrogels are achieved using double crosslinking structures with multiple physical and chemical crosslinks. They consist of a copolymer network of acrylamide (AM) and sodium acrylate (Na‐AA) and other reversible network of poly(vinyl alcohol)–borax complex. They were characterized by Fourier transform IR analysis and studied for their hydrogen bonding and ionic interaction. The degree of equilibrium swelling was observed to be as high as 5959% (at pH 7.0) for a hydrogel with AM/Na‐AA = 25/75 wt% in the network (GS‐6 sample). The highest degree of swelling was observed to be 6494% at pH 8.5. The maximum tensile strength was measured to be 1670, 580 and 130 kPa for a DN hydrogel (GS‐2 sample: AM/Na‐AA =75/25 wt% with 20, 40 and 60 wt% water content, respectively). The self‐healing efficiency was estimated to be 69% for such a hydrogel. These multifunctional DN hydrogels with amalgamation of many functional properties are unique in hydrogel materials and such materials may find applications in sensors, actuators, smart windows and biomedical applications. © 2018 Society of Chemical Industry     

Ultramarine blue from Asturian “hard” kaolins

Ultramarine blue made with Asturian refined hard kaolin from deposits associated with Armorican quartzite, is compared with the pigment made with China kaolin, both produced in the same synthesis conditions. Properties after a deep characterization (XRD, IRFT and Ramman Spectroscopies, Light Reflectivity, Colorimetry and Micro-analysis) showed that the Asturian Teresa mine kaolin is good enough, once washed and classified, to produce a good blue pigment. The pigment is quite comparable in quality to the one produced with China kaolin. Moreover, it can be obtained from a cheap and abundant material which so far had only been used for calcined fire-clay raw materials, used in low alumina refractories and castables production.     

Interrogation of “surface,” “skin,” and “core” orientation in thermotropic liquid‐crystalline copolyester moldings by near‐edge X‐ray absorption fine structure and wide‐angle X‐ray scattering

Injection molding thermotropic liquid‐crystalline polymers (TLCPs) usually results in the fabrication of molded articles that possess complex states of orientation that vary greatly as a function of thickness. “Skin‐core” morphologies are often observed in TLCP moldings. Given that both “core” and “skin” orientation states may often differ both in magnitude and direction, deconvolution of these complex orientation states requires a method to separately characterize molecular orientation in the surface region. A combination of two‐dimensional wide‐angle X‐ray scattering (WAXS) in transmission and near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy is used to probe the molecular orientation in injection molded plaques fabricated from a 4,4′‐dihydroxy‐α‐methylstilbene (DHαMS)‐based thermotropic liquid crystalline copolyester. Partial electron yield (PEY) mode NEXAFS is a noninvasive ex situ characterization tool with exquisite surface sensitivity that samples to a depth of 2 nm. The effects of plaque geometry and injection molding processing conditions on surface orientation in the regions on‐ and off‐ axis to the centerline of injection molded plaques are presented and discussed. Quantitative comparisons are made between orientation parameters obtained by NEXAFS and those from 2D WAXS in transmission, which are dominated by the microstructure in the skin and core regions. Some qualitative comparisons are also made with 2D WAXS results from the literature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Electrically conductive and mechanically tough graphene nanocomposite hydrogels with self‐oscillating performance

Conventional hydrogels are extremely brittle, fragile and poorly conductive, which limits their applications in a variety of aspects. In this study, we fabricated a novel kind of nanocomposite self‐oscillating hydrogel poly(AA‐co‐Fe(phen)₃)/PVA/RGO with high conductivity and good mechanical strength by dispersing reduced graphene oxide (RGO). Due to the synergetic effect of RGO dispersed in the hydrogels or dry gels and Fe metal which is the reduction product of the Fe(phen)₃ moiety by RGO, the hydrogels have a high conductivity of 18.2 S m^?1 with 0.67 wt% RGO content. The dispersed RGO in the hydrogels combined with the network structure by means of hydrogen bonding, π–π stacking and electrostatic interaction and was demonstrated to enhance the mechanical properties of the hydrogels. The elastic modulus achieves 65.2 kPa (1020% of the tensile strength) and 236.4 kPa (with 70% compression), respectively. In addition, the prepared hydrogels exhibit a self‐oscillating behavior in a Belousov–Zhabotinsky solution free of catalyst. These results can be broadly applied in the future in the development of an autonomous on–off switching, flexible/stretchable, graphene‐based soft electronic device. © 2019 Society of Chemical Industry     

Salt‐Controlled Selectivity in “on Water” and “in Water” Passerini‐Type Multicomponent Reactions

We have demonstrated that simple sodium salts can completely reverse the product ratios of the Passerini reaction in aqueous media. Furthermore, the use of the “salting‐in” salt and a small excess of the nucleophile gives significantly higher yields than the use of the saturated solution of the nucleophile alone.     

“Coupled soft modes and double triple points in ferroelectrics”

P-T diagrams for ferroelectrica of the displacement type are constructed based on the coupling of two or more soft modes of the lattice. They are compared with experimental phase diagrams. Typical are in particular triple points and sequences of triple points. This one also finds in purely elastically instable systems, suggesting that the construction principle offered has actually a broader basis. Also, a generalisation of the method such as to include phase transitions of the first kind is possible.     

Phase Transformation and Rheological Behaviour of Highly Paraffinic “Waxy” Mixtures

An experimental investigation was undertaken for the rheology and phase transformation of prepared solutions comprising a paraffin wax dissolved in n‐dodecane or n‐hexadecane. The liquid‐solid phase transformation in wax‐solvent mixtures was investigated through the measurement of wax appearance/disappearance temperature (using cross polar microscopy, differential scanning calorimetry, viscometry and a visual method), pour point temperature and crystallization temperature. The results were utilized to prepare a temperature‐composition phase diagram for the wax+n‐C₁₆H₃₄ pseudo‐binary system. The effects of composition, temperature, cooling rate and shear rate were studied on the rheology of wax‐solvent mixtures. A correlation was developed for the apparent viscosity of wax‐solvent mixtures.     

Fatty acids characterization in “Alicante” and “Jijona” nougat bars,two Spanish sweets

In this work the fatty acids in two typical Spanish sweets have been characterized: Alicante and Jijona nougat bars, using gas chromatography with a flame-ionization detector. The majority of the fatty acids in these two sweets are unsaturated, and only a low proportion is saturated, which turns them into a type of food with low influence on cholesterol resulting in low atherogenic power, due to the low amount of saturated fatty acids, which is far from constituting 1/3 of the total sum of fatty acids granted by a diet, a limit that has been advised by a great number of International Scientific Committees.     

Synthesis and characterization of reversible and self‐healable networks based on acylhydrazone groups

A series of seven dynamic covalent networks based on pentaerythritol tetra(benzohydrazide) and 1,10‐decanediol dibenzaldehyde were prepared in N,N‐dimethylformamide (DMF). The equilibrium degree of swelling in DMF and the sol fraction displayed a minimum at or near the hydrazide–benzaldehyde stoichiometric ratio. The composition of the sol fraction changed according to the feed composition, with the dibenzaldehyde‐rich preparations exhibiting extractables composed of star oligomers based on tetra(benzohydrazide) cores. Finally, network reversibility and self‐healing were demonstrated in the presence of acid. © 2014 Society of Chemical Industry     

Crystallization behavior of “wet brush” and “dry brush” blends of PS‐b‐PEO‐b‐PS/h‐PEO

The crystallization behavior of the blending system consists of homopolymer poly(ethylene oxide) (h‐PEO) with different molecular weights, and polystyrene‐block‐poly (ethylene oxide)‐block‐polystyrene (PS‐b‐PEO‐b‐PS) triblock copolymer has been investigated by DSC measurements. The crystallization of PEO block (b‐PEO) in block copolymer occurs under much lower temperature than that of the h‐PEO in the bulk (ΔT > 65 °C), which is attributed to the homogeneous nucleation crystallization behavior of the b‐PEO microdomains. In both the “dry‐brush” and the “wet brush” blending systems, the homogeneous nucleation crystallization temperature of PS‐b‐PEO‐b‐PS/h‐PEO blends increases due to the increase of the domain size. The heterogeneous nucleation crystallization temperatures of h‐PEO in the wet brush blending systems are higher than that of the corresponding h‐PEO in the bulk. At the same time, the heterogeneous nucleation crystallization temperature of b‐PEO10000 decreases from 43°C to 30°C and 40°C in the h‐PEO600 and h‐PEO2000 blending systems, respectively, because of the stretching of the PEO chains in the wet brush. However, this kind of phenomenon does not happen in the dry brush blending systems. The self‐seeding procedure was used to further ascertain the nucleation mechanism in the crystallization process. As a result, the self‐seeding domains have been confirmed, and the difference between the dry brush and wet brush systems has been observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Let's call it “color‐gamut rendering”

The term “color gamut” historically has been associated with color output such as optimal color stimuli and additive and subtractive imaging systems. Recently, this term has been used with input devices such as scanners and digital cameras. It is proposed that the term “color‐gamut rendering” should be used instead of input devices. This clarifies the distinction between input (analysis) and output (synthesis) color systems in terms of the effect of an input system on defining the colorimetric properties of an output system. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 334–335, 2007     

Efficient, “one-pot” synthesis of suspension crosslinked sulfonated polystyrene via a Friedel–Crafts reaction

A suspension technique leading to macronet ionic resins is described based on a single reactor process. The procedures demonstrate sulfuric acid as a polar suspending medium that can act as a sulfonating agent, a Friedel–Crafts catalyst, and a crosslinking agent. The sulfonation reaction was finally completed using sulfuric acid excess, or oleum 65%. High yields were obtained for the crosslinking and the sulfonation reaction, while the final products were characterized by using ion-exchange capacity measurements, U.V. spectra, and determination of the degree of crosslinking. The number average molecular weight between crosslinks and the ion-exchange capacity H⁺→Na⁺ of the resins was decreasing by increasing the nominal crosslinking ratio. © 1992 John Wiley & Sons, Inc.     

“Binary salt” of hexane‐1,6‐diaminium adipate and “carbon nanotubate” as a synthetic precursor of carbon nanotube/Nylon‐6,6 hybrid materials

A novel chemical approach was established to produce carbon nanotube/Nylon‐6,6 hybrid materials from readily available substrates, that is, Nylon‐6,6 salt and oxidized multiwall carbon nanotubes (O‐MWCNTs). The key synthetic precursor hexane‐1,6‐diaminium adipate and “carbon nanotubate”—“Binary nanotube salt”—was obtained and isolated as stable and easy‐to‐handle solid in over 80% yield and with no nanotube losses. The final hybrid materials of various nanotube loadings were synthesized at 270°C and were easily purified from the homopolymer. Purified hybrids were comprehensively analyzed (yields and grafting ratios, SEM, TEM, FT‐IR) revealing a two‐phase characteristics—individually grafted nanotubes and cross‐linked nanotube material. Isothermal TGA kinetic studies showed that in the “binary salts” diamine and diacid molecules were anchored to the nanotube outer shells and then held electrostatically enabling growth of polymer immobilized on O‐MWCNTs (“grafting‐from” mechanism). Depending on the density and type of nanotube functionalities and filler concentration in the “binary salt,” the O‐MWCNT/Nylon‐6,6 hybrids can be treated as hybrid material of a proportion of aliphatic polyamide and polyaramide properties. POLYM. COMPOS., 35:523–529, 2014. © 2013 Society of Plastics Engineers