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Kazutoshi Haraguchi - One of the best experts on this subject based on the ideXlab platform.
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uniaxial and plane orientations of clay platelets in nanocomposite gels with different compositions during stretching and recovery
Polymer, 2017Co-Authors: Kazutoshi Haraguchi, Kazutaka Murata, Yuji KimuraAbstract:Abstract Changes in the birefringence (ΔnNC) of nanocomposite (NC) gels upon stretching and recovery were investigated for gels comprising a poly(N-isopropylacrylamide)−clay network structure. Irrespective of the composition of the NC gels, a change in the birefringence appeared upon stretching; ΔnNC varied greatly depending on the clay and water contents (Cclay and Cw, respectively) of the gels and the stretching ratio. The NC gels with low Cclay gave rise to unique ΔnNC vs. strain curves with a maximum ΔnNC. For samples with higher Cclay, the variation of ΔnNCs observed in the edge- and through-directions, which is attributed to plane-orientation of the clay platelets, increased with increasing Cclay. This was confirmed by scanning electron microscopy observation, and the percentage plane-orientation was evaluated from the ΔnNC data. On recovery of the strain, the plane-oriented clay platelets underwent minimal reversion to the original state, although most of the PNIPA chains reverted to the random conformation. The effects of Cw on the ΔnNC–strain curves were also clarified.
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swelling deswelling behavior of zwitterionic nanocomposite gels consisting of sulfobetaine polymer clay networks
European Polymer Journal, 2015Co-Authors: Kazutoshi Haraguchi, Jinyan NingAbstract:Abstract The swelling and thermosensitive behaviors of zwitterionic nanocomposite gels (Zw-NC gels) consisting of sulfobetaine polymer–exfoliated clay networks were investigated in water and aqueous NaCl solutions and compared with those of physically and chemically crosslinked zwitterionic gels and non-zwitterionic NC gels. Zw-NC gels showed different swelling behavior that was strongly dependent on the salt concentration (CNaCl), clay concentration (Cclay), and temperature. In water, characteristic swelling-to-deswelling behavior and an abnormal increase in the degree of swelling (DS) with increasing Cclay (∝ crosslink density) were observed. These behaviors were in stark contrast to those obtained with other types of zwitterionic gels. In NaCl solutions, spontaneous deswelling disappeared within small CNaCl, and above the critical point (0.01 M), the DS increased with CNaCl via an anti-polyelectrolyte effect of the zwitterions and decreased with increasing Cclay. The transparency also changed depending on the CNaCl, Cclay, swelling time, and thermosensitivity of the sulfobetaine polymer. These swelling behaviors and transparency changes of Zw-NC gels were explained by the combined effects of the zwitterionic polymers (anti-polyelectrolyte), ionic clay (polyelectrolyte), and clay as a crosslinker.
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characteristic swelling deswelling of polymer clay nanocomposite gels
Macromolecules, 2011Co-Authors: Huaiyin Ren, Meifang Zhu, Kazutoshi HaraguchiAbstract:Swelling behavior of nanocomposite hydrogels (NC gels) having organic polymer/inorganic clay network structures were systematically investigated, focusing on the role of exfoliated clay platelets with sodium counterions in the network and effects of various swelling conditions. NC gels in water exhibited characteristic swelling–deswelling behavior, i.e., initial large swelling, maximum swelling, and subsequent deswelling toward an equilibrium state, under conditions where the water was changed frequently. Effects of swelling conditions, such as the frequency of changing the water, amount of water per unit gram of gel, salt concentration, and pH of the swelling solvent, gel composition (e.g., kind of polymer, clay concentration (Cclay), and polymer concentration (Cp)), swelling temperature, and gel size, were clarified. NC gels with different polymers were all found to exhibit swelling–deswelling behavior except at very low Cclay and high Cp. Spontaneous deswelling of the gels was attributed to the combine...
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control of cell cultivation and cell sheet detachment on the surface of polymer clay nanocomposite hydrogels
Biomacromolecules, 2006Co-Authors: Kazutoshi Haraguchi, Toru Takehisa, Makiko EbatoAbstract:Cell cultivation on the surface of a novel poly(N-isopropylacrylamide) (PNIPA) hydrogel (N-NC gel), consisting of a specific type of organic (PNIPA)/inorganic (clay) network, was studied using three cell types; HepG2 human hepatoma cells, human dermal fibroblasts, and human umbilical vein endothelial cells. For the first time, it was found that cells could be cultured to be confluent on the surfaces of PNIPA hydrogels using N-NC gels, regardless of gel thickness. Cell adhesion and proliferation on N-NC gels exhibit strong dependencies on clay concentration (Cclay), and the numbers of cultured cells are maximum at about Cclay = 6 × 10-2 mol (45.72 g)/1 L of H2O. On the contrary, it was almost impossible to culture cells on conventional, chemically crosslinked PNIPA hydrogels, regardless of their cross-linker concentration. The reasons why cells cultured only on the surfaces of N-NC gels with their specific network structure and composition were discussed in terms of water content, protein adsorption, surfa...
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mechanical properties and structure of polymer clay nanocomposite gels with high clay content
Macromolecules, 2006Co-Authors: Kazutoshi HaraguchiAbstract:The mechanical properties and structures of nanocomposite gels (NC gels), consisting of poly(N-isopropylacrylamide) (PNIPA) and inorganic clay (hectorite), prepared using a wide range of clay concentration (∼25 mol % against water) were investigated. All NC gels were uniform and transparent, almost independent of the clay content, Cclay. The tensile modulus (E) and the strength (σ) were controlled without sacrificing extensibility by changing Cclay. The E, σ, and fracture energy observed for as-prepared NC gels attained 1.1 MPa, 453 kPa, and 3300 times that of a conventional chemically cross-linked gel, respectively, and σ increased to 3.0 MPa for a once-elongated NC25 gel. From the tensile and compression properties, in addition to optical transparency, it was concluded that a unique organic/inorganic network structure was retained regardless of Cclay. The effects of Cclay on the tensile mechanical properties on the first and second cycles, the time-dependent recovery from the first large elongation and ...
Amit Bhatnagar - One of the best experts on this subject based on the ideXlab platform.
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clay polymer nanocomposites progress and challenges for use in sustainable water treatment
Journal of Hazardous Materials, 2020Co-Authors: R Mukhopadhyay, Subhas Sarkar, Debarati Bhaduri, Binoy Sarkar, Ruhaida Rusmin, Deyi Hou, Rubina Khanam, Jayanta Kumar Biswas, Meththika Vithanage, Amit BhatnagarAbstract:Abstract Contaminant removal from water involves various technologies among which adsorption is considered to be simple, effective, economical, and sustainable. In recent years, nanocomposites prepared by combining clay minerals and polymers have emerged as a novel technology for cleaning contaminated water. Here, we provide an overview of various types of clay–polymer nanocomposites focusing on their synthesis processes, characteristics, and possible applications in water treatment. By evaluating various mechanisms and factors involved in the decontamination processes, we demonstrate that the nanocomposites can overcome the limitations of individual polymer and clay components such as poor specificity, pH dependence, particle size sensitivity, and low water wettability. We also discuss different regeneration and wastewater treatment options (e.g., membrane, coagulant, and barrier/columns) using clay–polymer nanocomposites. Finally, we provide an economic analysis of the use of these adsorbents and suggest future research directions.
R Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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clay polymer nanocomposites progress and challenges for use in sustainable water treatment
Journal of Hazardous Materials, 2020Co-Authors: R Mukhopadhyay, Subhas Sarkar, Debarati Bhaduri, Binoy Sarkar, Ruhaida Rusmin, Deyi Hou, Rubina Khanam, Jayanta Kumar Biswas, Meththika Vithanage, Amit BhatnagarAbstract:Abstract Contaminant removal from water involves various technologies among which adsorption is considered to be simple, effective, economical, and sustainable. In recent years, nanocomposites prepared by combining clay minerals and polymers have emerged as a novel technology for cleaning contaminated water. Here, we provide an overview of various types of clay–polymer nanocomposites focusing on their synthesis processes, characteristics, and possible applications in water treatment. By evaluating various mechanisms and factors involved in the decontamination processes, we demonstrate that the nanocomposites can overcome the limitations of individual polymer and clay components such as poor specificity, pH dependence, particle size sensitivity, and low water wettability. We also discuss different regeneration and wastewater treatment options (e.g., membrane, coagulant, and barrier/columns) using clay–polymer nanocomposites. Finally, we provide an economic analysis of the use of these adsorbents and suggest future research directions.
Huaiyin Ren - One of the best experts on this subject based on the ideXlab platform.
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characteristic swelling deswelling of polymer clay nanocomposite gels
Macromolecules, 2011Co-Authors: Huaiyin Ren, Meifang Zhu, Kazutoshi HaraguchiAbstract:Swelling behavior of nanocomposite hydrogels (NC gels) having organic polymer/inorganic clay network structures were systematically investigated, focusing on the role of exfoliated clay platelets with sodium counterions in the network and effects of various swelling conditions. NC gels in water exhibited characteristic swelling–deswelling behavior, i.e., initial large swelling, maximum swelling, and subsequent deswelling toward an equilibrium state, under conditions where the water was changed frequently. Effects of swelling conditions, such as the frequency of changing the water, amount of water per unit gram of gel, salt concentration, and pH of the swelling solvent, gel composition (e.g., kind of polymer, clay concentration (Cclay), and polymer concentration (Cp)), swelling temperature, and gel size, were clarified. NC gels with different polymers were all found to exhibit swelling–deswelling behavior except at very low Cclay and high Cp. Spontaneous deswelling of the gels was attributed to the combine...
Subhas Sarkar - One of the best experts on this subject based on the ideXlab platform.
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clay polymer nanocomposites progress and challenges for use in sustainable water treatment
Journal of Hazardous Materials, 2020Co-Authors: R Mukhopadhyay, Subhas Sarkar, Debarati Bhaduri, Binoy Sarkar, Ruhaida Rusmin, Deyi Hou, Rubina Khanam, Jayanta Kumar Biswas, Meththika Vithanage, Amit BhatnagarAbstract:Abstract Contaminant removal from water involves various technologies among which adsorption is considered to be simple, effective, economical, and sustainable. In recent years, nanocomposites prepared by combining clay minerals and polymers have emerged as a novel technology for cleaning contaminated water. Here, we provide an overview of various types of clay–polymer nanocomposites focusing on their synthesis processes, characteristics, and possible applications in water treatment. By evaluating various mechanisms and factors involved in the decontamination processes, we demonstrate that the nanocomposites can overcome the limitations of individual polymer and clay components such as poor specificity, pH dependence, particle size sensitivity, and low water wettability. We also discuss different regeneration and wastewater treatment options (e.g., membrane, coagulant, and barrier/columns) using clay–polymer nanocomposites. Finally, we provide an economic analysis of the use of these adsorbents and suggest future research directions.
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synthesis and characterization of nanoclay polymer composites from soil clay with respect to their water holding capacities and nutrient release behavior
Journal of Applied Polymer Science, 2014Co-Authors: Subhas Sarkar, S C Datta, D R BiswasAbstract:Water and nutrients are two important inputs to agriculture that need to be used judiciously with higher efficiency to save these limited resources. For these purposes, a series of nanoclay–polymer composite (NCPC) superabsorbent nutrient carriers were prepared. These NCPCs were based on the reactions of different types of nanoclays (10 wt %) with partially neutralized acrylic acid and acryl amide by a free-radical aqueous solution copolymerization reaction with N,N′-methylene bisacrylamide as a crosslinker and ammonium persulfate as an initiator. The nanoclays isolated from three different types of soils were dominant in kaolinite (clay I), mica (clay II), and montmorillonite (clay III), and a portion of each was freed from amorphous aluminosilicate. Thus, there were six different types of nanoclays used, namely, those dominated by kaolinite, mica, and smectite with and without amorphous aluminosilicate. Fourier transform infrared spectroscopy and X-ray diffraction (XRD) investigations showed evidence of interaction between the clays and polymer. XRD investigation also showed that the reaction between the polymer and clays I and II occurred on the surface of various clay particles without intercalating into the stacked silicate galleries, whereas in the case of clay III (the smectite-dominated clay), evidence indicated the intercalation of polymer into the stacked silicate galleries of the clay and the exfoliation of the clay. The water absorbency decreased in the NCPCs compared to that of the pure polymeric hydrogel. In case of the pure polymer, the entire amount of nutrient loading released within 15 h of incubation; this was higher than that of the NCPCs. In the initial stage (up to 15 h), no significant differences in nutrient release were observed among the different polymer/clay composites, but there were differences in later stages. Among the different NCPCs, the percentage release of nutrients at 48 h ranged from around 70% in the polymer/clay III composite to 90% in the polymer/clay I composite. The presence of amorphous aluminosilicates in clay did not make any difference in the nutrient-release rate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39951.