Poly(acrylamide/laponite) nanocomposite hydrogels: Swelling and cationic dye adsorption properties

Super adsorbent polyacrylamide (PAAm)/nanoclay (laponite, Lap) hydrogels were prepared by in situ free radical polymerization of AAm in an aqueous solution with clay as a crosslinker. The swelling properties and water‐soluble cationic dye adsorption behaviors of the PAAm/laponite (PAAm/Lap) nanocomposite (NC) hydrogels were investigated. The parameters of swelling and diffusion of water in dye solutions were evaluated for the PAAm/Lap NC hydrogels. The adsorption behavior of the monovalent cationic dyes such as Basic Blue 12 (BB 12), Basic Blue 9 (BB 9), and Basic Violet 1 (BV 1), were studied on the NC hydrogels. The effects of the clay content of the hydrogel on its cationic dye uptake behavior were studied. The adsorption studies indicated that the rates of dye uptake by the NC hydrogels increased in the following order: BB 9 > BB 12 > BV 1. This order is similar to the swelling results of the PAAm/Lap NC hydrogel in the dye solutions. The equilibrium uptakes of the different dyes by the PAAm/Lap NC hydrogel were nearly the same. In the dye absorption studies, S‐type adsorption in the Giles classification system was found for the BB 12 and BV 1 dyes, whereas L ‐type was observed for the BB 9 dye. After the heat treatment of PAAm/Lap, the rate of dye uptake and equilibrium dye uptake were increased. The NC hydrogels may be considered as a good candidate for environmental applications to retain more water and to remove dyes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Use of superswelling acrylamide/maleic acid hydrogels for monovalent cationic dye adsorption

Acrylamide/maleic acid (AAm/MA) superswelling hydrogels prepared by irradiation with γ radiation were used in experiments on swelling, diffusion, and adsorption of some water‐soluble monovalent cationic dyes such as basic red 5 (BR‐5), basic violet 3 (BV‐3), and brilliant cresyl blue (BCB). The AAm/MA hydrogel containing 60 mg MA and irradiated at 5.20 kGy was used for swelling and diffusion studies in water and aqueous solutions of the monovalent cationic dyes. For this superswelling hydrogel the swelling studies indicated that swelling increased in the following order: BR‐5 > water > BV‐3 ≥ BCB. The diffusion of water and the dyes within the hydrogels was found to have a non‐Fickian character. The uptake of the cationic dyes to the AAm/MA superswelling hydrogels was studied by the batch adsorption technique at 25°C. The uptake of dyes within the hydrogel increased in the following order: BR‐5 > BV‐3 > BCB. In the experiments of the adsorption equilibrium, S‐type adsorption in Giles' classification system was found. The binding ratio of the hydrogel/dye systems was gradually increased with the increase of the MA content in the AAm/MA hydrogel and the irradiation dose. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1809–1815, 2001     

Swelling behavior of poly(acrylamide)/clay nanocomposite hydrogels in acrylamide aqueous solution

The swelling behaviors of poly(acrylamide) (PAAm)/clay nanocomposite hydrogels (hereinafter abbreviated as NC gels) in acrylamide (AAm) aqueous solution have been investigated. As‐prepared PAAm/clay hydrogels (S‐M gels) were posttreated by immersing them in AAm aqueous solution. It was found that the swelling ratio of the NC gels increased greatly when the concentration of the solution is below a critical concentration (c*), whereas the gels were disintegrated in the solution when the concentration of the solution is above the c*. Some disc‐like particles were found in the AAm solution accompanying with the unusual swelling behaviors. This unusual swelling behavior is resulted from the change of network structure of the NC gels in AAm aqueous solution, which was further convinced by transmission electron microscopy and element analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Strengthening mechanism of poly(acrylamide)/graphene oxide/laponite dual nanocomposite hydrogels

Laponite or graphene oxide (GO) is usually used as a multifunctional crosslinker or a nanofiller to improve the nanocomposite gel strength. To explore the strengthening mechanism of GO/Laponite‐based dual nanocomposite hydrogels, we synthesized a dual nanocomposite hydrogel through in situ polymerization of acrylamide (AM) in the dispersion of GO and Laponite. The interactions between GO and Laponite were confirmed by rheological test. GO and Laponite nanosheets were exfoliated well and dispersed uniformly in the hydrogels at low concentration of GO. Crosslinking network and thermal behaviors were investigated with respect to the concentration of GO and Laponite. The gel exhibited a high mechanical strength of 391 kPa with extensibility of 1420% and a high toughness of 2.58 MJ/m³, which was expected to be applied in biological engineering field. GO is not a much more effective agent than Laponite due to formation of GO aggregates in high concentration of GO. This work provides a guidance for the synthesis of tough dual nanocomposite hydrogels. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44963.     

pH‐sensitive dimethylaminoethyl methacrylate (DMAEMA)/acrylamide (AAm) hydrogels: Synthesis and adsorption from uranyl acetate solutions

A random copolymer of dimethylaminoethyl methacrylate (DMAEMA) and acrylamide(AAm) [poly(DMAEMA/AAm)], with a pH‐sensitive character, was prepared by a redox polymerization method. Increasing the DMAEMA content of the gel, the pH, and the ionic strength of the solution decreased the swelling ratios of the hydrogels. The adsorption of poly(DMAEMA/AAm) hydrogels from uranyl acetate (UA) solutions was studied at different pHs. The adsorption capacity of hydrogels increased from 200 to 1200 mg of UA per gram of dry hydrogel with increasing pH of the adsorption solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2028–2031, 2003     

A study on the adsorption of some cationic dyes onto acrylamide/itaconic acid hydrogels

Summary Acrylamide/itaconic acid (AAm/IA) hydrogels prepared by irradiating with radiation were used in experiments on the adsorption of some cationic dyes such as basic red 9 (BR 9), basic green 4 (BG 4), cresyl violet (CV), and basic blue 20 (BB 20). Adsorption of the cationic dyes onto AAm/IA hydrogels is studied by batch adsorption technique. In the experiments of the adsorption, Langmiur type adsorption in the Giles classification system was found. Monolayer coverages for AAm/IA hydrogel-dye systems were calculated by using B point method. Adsorption studies indicated that monolayer coverages of AAm/IA hydrogel by these dyes were increased with following order; BB 20>CV>BR9>BG 4.     

Swelling kinetics of poly(acrylamide)/poly(mono-n-alkyl itaconates) hydrogels

Hydrogels of mono-n-alkyl itaconate/N-acrylamide have been synthesised. The swelling process at three different pH values (acid, neutral and basic) has been studied. The experimental data indicate that our hydrogels follow second-order swelling kinetics. According to this, the kinetic constant, K_∞, and the swelling capacity at equilibrium, W_∞, have been calculated. The influence of the solvent pH and the molar mass of the mono-n-alkyl itaconate monomeric unit has been analysed. It seems that the general balance between the hydrogen bonding and the hydrophobic interactions regulates the swelling process of these hydrogels.     

阳离子聚合物/膨润土纳米复合吸附材料的性能及对红色染料的脱色

利用阳离子聚合物-聚环氧氯丙烷二甲胺为插层剂,采用 “有机高聚物溶液直接插层复合法”制备了一系列阳离子聚合物聚环氧氯丙烷二甲胺/膨润土纳米复合吸附材料,经特性分析表明,经聚环氧氯丙烷二甲胺插层复合后的膨润土比表面积显著增加,表面电性由负值变为正值,颗粒的聚集程度增加,有较好的吸附和沉降性能.在此基础上,研究了还原大红R、分散大红S-R、活性艳红K-2BP等红色染料在复合膨润土上的吸附行为.结果表明,聚环氧氯丙烷二甲胺/膨润土对三种染料的吸附脱色能力明显大于钠基膨润土,平衡吸附量q_e与平衡浓度C_e之间的关系均符合Langmuir和Freundlich等温吸附模型,吸附动力学行为遵循Langmuir方程所述规律.     

温敏性聚(N-异丙基丙烯酰胺)/聚丙烯酰胺互穿网络水凝胶

采用紫外引发法制备了物理交联的聚(N-异丙基丙烯酰胺)和化学交联聚丙烯酰胺为组分的互穿网络水凝胶。利用FFIR对所得的凝胶进行了结构分析;测定了该水凝胶在20℃时的溶胀率和50℃时的水保持率;利用DMA和DSC分别研究了水凝胶的储能模量随温度的变化及相转变行为。结果表明:与聚(N-异丙基丙烯酰胺)水凝胶相比,该水凝胶有较好的溶胀率;且具有超快的响应速率,如10 min内失去90%的水;其储能模量增加;虽然其相转变行为变弱,但临界溶解温度(LCST)有所提高。     

Chitosan hydrogels for targeted dye and protein adsorption

There is an urgent requirement to devise and develop highly‐effective materials for the purification of industrial wastewater. Colored effluents are particularly problematic due to their toxicity in plants, aquatic organisms, and animals, dictating that polymeric adsorbents are highly sought for their capture. Chitosan hydrogels are a cost‐effective substrate for the adsorption of dye molecules as they contain a biopolymeric gelator that can form hydrogels with a polymer content as low as 3% by mass. Such materials are also highly suited for use within a biomedical context as carrier vehicles for the encapsulation and delivery of protein macromolecules, due to their hydrophilic nature. We disclose the capability chitosan‐based hydrogels to noncovalently adsorb both reactive and disperse dye molecules, and a model anionic protein from aqueous solution. The materials generated offer both a platform for dye removal from industrial wastewater, and for the encapsulation and pH‐mediated release of protein macromolecules. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44846.     

Synthesis and characterization of poly(propylene carbonate)/modified sepiolite nanocomposites

A series of poly(propylene carbonate) (PPC)/modified sepiolite (mSp) nanocomposites with different mSp contents were prepared via a solution‐based processing method. The modified sepiolite was obtained by fabricating sepiolite with methyl trimethoxysilanes (MTMS) gel. The effect of mSp amount, in the range 1–10 wt%, on the morphology, mechanical properties, and thermal degradation of PPC was investigated by means of scanning electron microscopy (SEM), X‐ray diffractometry (XRD), static strenching analysis, thermogravimetric analyses (TGA), differential scanning calorimetry (DSC). Morphological studies showed the homogeneous dispersion of mSp in the PPC matrix whose structure remains amorphous. The nanoscale dispersion of mSp significantly enhanced the mechanical properties and thermal stability. The thermal motion and degradation of the polymer occur at higher temperature in the presence of mSp because of the strong interfacial adhesion between the two components. POLYM. COMPOS., 21–27, 2016. © 2014 Society of Plastics Engineers     

Interaction of some cationic dyes with acrylamide/itaconic acid hydrogels

Acrylamide/itaconic acid (AAm/IA) hydrogels prepared by irradiating with γ radiation were used in experiments on uptake of some cationic dyes such as union green B (UG-B), basic blue 17 (BB-17), basic red 2 (BR-2), and lauths violet (LV). Adsorption of the cationic dyes onto AAm/IA hydrogels is studied by batch adsorption technique at 25°C. In the experiments of the adsorption, Langmiur type adsorption in the Giles classification system was found. Some binding and thermodynamic parameters for AAm/IA hydrogel-dye systems were calculated by using Klotz method. Adsorption studies indicated that monolayer coverages of AAm/IA hydrogel by these dyes were increased with following order BB-17 > UG-B > BR-2 > LV. © 1996 John Wiley & Sons, Inc.     

自交联阳离子丙烯酰胺共聚物合成及应用

以甲基丙烯酰氧乙基三甲基氯化铵（DMC）作为阳离子单体,甲基丙烯酸缩水甘油酯（GMA）为交联单体,与丙烯酰胺（AM）通过水溶液共聚法,并采用分子量调节剂和活性基团保护剂,本文制备得到自交联阳离子丙烯酰胺共聚物（G-CPAM）。通过傅里叶红外光谱（FTIR）及溶液稳定性测试对G-CPAM的结构和稳定性进行了表征,探讨了DMC及GMA单体用量对G-CPAM的性能及施胶后纸张的物理性能的影响,利用热失重分析仪（TGA）、X射线光电子谱（XPS）以及纸张施胶前后的FTIR测试对G-CPAM的自身交联与纸张性能增强机理进行了研究。结果表明：当DMC用量为质量分数20%,GMA用量为质量分数13%时,制备得可交联环氧阳离子聚丙烯酰胺,此时聚合物溶液平均粒径为176.9nm,黏度为143mPa·s,分子量为63204,且在150℃下稳定存在。 G-CPAM添加量为质量分数1.6%,进行浆内施胶,纸张干、湿抗张指数分别为58.29N·m/g和17.75N·m/g,环压强度指数为11.10N·m/g,撕裂指数为12.41mN·m²/g,纸张物理性能增强明显。     

Study of silane treatment on poly‐lactic acid(PLA)/sepiolite nanocomposite thin films

Poly‐lactic acid (PLA) nanocomposite film was prepared with untreated and silane treated sepiolite through solution casting method. Sepiolite is found to be promising nano inorganic filler used to prepare biodegradable PLA nanocomposite films. The effect of sepiolite loading on the thermal, mechanical, gas permeability, and water vapor permeability (WVP) properties of the films was investigated. X‐ray diffraction analysis revealed the crystallinity index and well dispersed sepiolite in PLA/sepiolite thin films. By modifying sepiolite, depending on the nanoclay content, the mechanical properties of films were enhanced. PLA/sepiolite films exhibited improved gas barrier and WVP properties compared to neat PLA. The scanning electron microscope results demonstrated that there is a good interface interaction between sepiolite and PLA. The surface treatment of sepiolite increased the adhesion of the PLA matrix to the sepiolite nanoclay which yielded better mechanical properties of the films as compared to pure PLA. It was observed after 1.5% wt sepiolite, nano‐filler tended to agglomerate, therefore mechanical and barrier properties of films decreased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41428.     

Poly (vinyl alcohol)/graphene oxide nanocomposite films and hydrogels prepared by gamma ray

ABSTRACT

Poly (vinyl alcohol)/graphene oxide (PVA/GO) gamma irradiated nanocomposite films and hydrogels were prepared. In composite films, GO was initially irradiated by gamma ray in order to improve interactions between GO and PVA. The film containing 1?wt-% GO was very strong where tensile modulus and tensile yield strength were 45 and 115% higher than those of pure PVA. In the second set of experiments PVA/GO hydrogels were made by irradiating PVA/GO suspensions by gamma ray at various doses. It was an interesting finding that GO increased the gel portion of hydrogels through contribution of H-bonds between PVA and GO. The hydrogels prepared at 20?kGy had remarkable water swelling ratio that reached as high as 20 at water temperature of 80°C. The hydrogel metal ion adsorption capability was tested on Cu²⁺ ions. It was shown that the GO contributed significantly to the adsorption capacity of PVA hydrogels.     

瓜尔胶-g-聚(丙烯酸钠-co-苯乙烯)/海泡石复合高吸水性树脂的制备及溶胀行为

以瓜尔胶(GG)、部分中和丙烯酸(NaA)、苯乙烯(St)和海泡石(ST)为原料, 过硫酸铵(APS)为引发剂, N,N′-亚甲基双丙烯酰胺(MBA)为交联剂, 在水溶液中通过接枝共聚反应合成了瓜尔胶-g-聚(丙烯酸钠-co-相似文献   

Synthesis and swelling behaviour of poly (sodium acrylate)/sepiolite superabsorbent composites and nanocomposites

A series of novel composites and nanocomposites xerogels based on acrylic acid, sepiolite and N,N′‐methylenebisacrylamide were prepared using a solution polymerization technique at 70 °C. The quality of dispersion of the micronized sepiolite in the monomer is the crucial point for obtaining nanocomposites. A good dispersion explains the improvement of the absorbent properties of the nanocomposites with respect to the composites. This work investigates not only the influence of the mixing procedure on the swelling behaviour, but also the effect of the amount of clay on the absorbency of these hydrogels in deionized water and saline solution (0.2 wt% NaCl_(aq)). A crosslinker concentration of 5 wt% sepiolite nanocomposite superabsorbent was shown to give the best results (1419 g g^?1). Moreover, experimental results indicate that the absorbency in saline solution is smaller than that in deionized water. Rates of swelling for these absorbents were found to fit the Voigt expression. Finally, the model approximates Case II sorption in the early stages of the swelling process and Case I in the later stages. Copyright © 2006 Society of Chemical Industry