Preparation and characterization of aluminum pillared K10 and KSF for adsorption of trimethoprim

Montmorillonite KSF and K10 were used as precursor materials for synthesis of aluminum pillared K10 and KSF (Al-K10 and Al-KSF) which characterized by TGA, XRD, SEM and FT-IR spectroscopic analysis. The sorption of trimethoprim (TMP) which is commonly employed as an antibiotic onto Al-K10 and Al-KSF was also investigated as a function of adsorbent dosage, solution pH, contact time and temperature. The adsorption kinetics was interpreted using pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model. The pseudo-second-order model provided the best correlation. Adsorption isotherm parameters were obtained from Freundlich, Langmuir and Dubinin–Radushkevich (DR) isotherm models. Adsorption of TMP onto Al-K10 and Al-KSF was physical in nature and ion-exchange mechanism for DR equation, respectively. Al-K10 exhibits higher removal capacity at lower adsorbent dosages in comparison with Al-KSF. The removal capacity was increased by increasing pH. ΔH⁰, ΔS⁰ and ΔG⁰ showed that adsorption of trimethoprim was endothermic, increasing randomness and not spontaneous in nature.     

Collagen-g-poly(Sodium Acrylate-co-Acrylamide)/sodium montmorillonite superabsorbent nanocomposites: synthesis and swelling behavior

Nanocomposite superabsorbents were synthesized by graft copolymerization of mixture of acrylamide (AAm) and acrylic acid (AA) onto collagen using potassium persulfate (KPS) as a free radical initiator and methylenebisacrylamide (MBA) as a crosslinker. Nanoclay sodium montmorillonite (MMt) was introduced as filler into superabsorbent. The chemical structure of the Collagen-g-poly(Sodium Acrylate-co-Acrylamide)/MMt nanocomposite was characterized by means of FTIR spectroscopy, XRD patterns, and TGA thermal methods. Morphology of the sample was examined by scanning electron microscopy (SEM). The effects of reaction variables were systematically optimized to achieve a superabsorbent with swelling capacity as high as possible. Under the optimized conditions concluded, the maximum swelling capacity in distilled water was 950 g/g. Dewatering of nanocomposite and clay-free superabsorbent revealed that inclusion of nanoclay into superabsorbents can improve water retention of superabsorbent under heating. The swelling ratio in various salt solution and kinetic of dewatering was also determined and additionally, the swelling of nanocomposite superabsorbent was measured in solution with pH ranged 1–13. The synthesized nanocomposite exhibited a pH-responsive characteristic.     

聚(丙烯酸-丙烯酰胺)/水滑石纳米复合高吸水性树脂的制备及表征

首先用尿素法合成了水滑石(HT),然后用甲基丙烯磺酸钠(SMAS)对水滑石进行插层,得到了插层的水滑石(SMAS-HT),最后通过反相悬浮聚合制备了一种新型的聚(丙烯酸-丙烯酰胺)/水滑石纳米复合高吸水性树脂,其中N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)为引发剂。通过傅里叶变换红外光谱(FTIR)、X-射线衍射(XRD)及扫描电镜(SEM)等手段表征其结构和形貌。考察了SMAS-HT的含量对其吸水(盐)性能的影响。结果表明,插入SMAS的水滑石片层在聚合后发生了剥离,添加少量的SMAS-HT可以明显提高树脂的吸水(盐)性能,当SMAS-HT含量为3.0%（质量）时,树脂的吸(盐)水性能达到最大。     

Effect of hydrophobic monomer on the synthesis and swelling behaviour of a collagen‐graft‐poly[(acrylic acid)‐co‐(sodium acrylate)] hydrogel

BACKGROUND: Graft polymerization of vinylic monomers onto natural backbones is an efficient approach for the synthesis of natural‐based superabsorbents. The nature of the monomers will affect the swelling behaviour of the superabsorbents. Here, a novel superabsorbent was synthesized through grafting of acrylic acid onto collagen in the presence of hydrophobic styrene as co‐monomer. Subsequently, the effect of styrene on the swelling behaviour of the superabsorbent was studied. RESULTS: The highly swelling superabsorbent was prepared by introducing styrene into a collagen‐graft‐poly(acrylic acid) hydrogel. By inclusion of styrene monomer, the swelling capacity of the hydrogel was increased; this is discussed according to the network composition. The effect of swelling media (salt solutions and various pH values) was investigated. The results of absorbency under load showed that hydrogels containing phenyl groups exhibit better behaviour; however, by introducing styrene, the rate of water uptake and resistance to water holding under heating was reduced. Scanning electron micrographs of hydrogels revealed a decrease in porosity on using styrene. CONCLUSION: Inclusion of styrene monomer in the ionic superabsorbent caused high swelling capacity with better absorbency under load. This can be used to prepare highly swelling superabsorbents with good mechanical properties. The pH reversibility of the synthesized superabsorbent makes it a candidate for use in the controlled release of drugs and in agrochemicals. Copyright © 2008 Society of Chemical Industry     

合成方法对高吸水性材料结构与性能的影响探讨

分别采用水溶液法和泡沫体系分散聚合法合成CMC—g—PAA高吸水性材料,对比了两种材料的结构及吸液性能。结果表明,泡沫体系分散聚合法合成的材料具有多孔结构,密度较小,吸液性能优于水溶液法合成的材料;泡沫体系分散聚合法合成的材料具有低温敏感性,两种方法合成的材料都具有良好的pH响应性。     

Study on superabsorbent composites. IX: Synthesis,characterization and swelling behaviors of polyacrylamide/clay composites based on various clays

A series of clay-based superabsorbent composite from acrylamide (AM) and various clays, such as attapulgite, kaolinite, mica, vermiculate and Na⁺-montmorillonite, was prepared by free-radical aqueous polymerization, using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator, and then saponified with sodium hydroxide solution. In this paper, the reaction mechanism and thermal stability of the superabsorbent composites incorporated with various clays were characterized by FTIR, XRD and TGA, respectively. The effects of clay kind and clay content on equilibrium water absorbency of these composites were also investigated and compared. In addition, the influences of clay kind on comprehensive swelling behaviors of the PAM/clay superabsorbent composites were studied. The results indicated that the introduced clays could influence physicochemical properties of obtained superabsorbent composites. Mica could improve thermal stability of corresponding superabsorbent composites to the highest degree comparing with the other clays. The PAM/clay superabsorbent composites incorporated with 10 wt% clay of various kinds were all endowed with equilibrium water absorbency of more than 1300 g g⁻¹. The equilibrium water absorbency decreases with increasing clay content and correlates with the kind of clay. Attapulgite-based superabsorbent composite was endowed with higher water absorbency in univalent cationic saline solution, however, the vermiculite- and the kaolinite-based ones acquired the highest water absorbency in CaCl₂ and FeCl₃ aqueous solution, respectively. Moreover, the superabsorbent composites incorporated with Na⁺-montmorillonite have higher swelling rate and that of doped with mica was endowed with higher reswelling capability.     

Saline solution absorbency and structure study of poly (AA-AM) water superabsorbent by inverse microemulsion polymerization

A series of novel copolymer superabsorbents based on acrylamide (AM), acrylic acid(AA) were prepared by inverse microemulsion copolymerization using ammonium persulfate (APS) as the initiator and N,N-methylenebisacrylamide (MBA) as the crosslinking agent and OP-10 and SDS as complex surfactants. The synthetic variables (amount of crosslinking agent and initiator, water/oil ratio, monomer/surfactant ratio and AA/ Am ratio) and their effects on the absorbencies of the synthesized superabsorbents were investigated. The experimental results of superabsorbent polymers (SAPs) showed the maximum saline solution absorbency of 130 g/g within 75 min, and the saline solution absorbency of 111 g/g within 30 min. FTIR indicated the structure of the acrylic acid and acrylamide copolymer. SEM indicated that the particles prepared with higher crosslinker content (0.03%) showed smaller pore sizes and less porous structures compared with those with less crosslinker content (0.01%) and the number of the micropores largely decreased with the water/oil ratio increasing from 8% to 14%.     

Preparation of chitosan‐g‐poly(acrylamide)/montmorillonite superabsorbent polymer composites: Studies on swelling,thermal, and antibacterial properties

Superabsorbent composites based on chitosan‐g‐poly(acrylamide) and montorillonite (CTS‐g‐PAAm/MMT) were synthesized through in situ radical polymerization by grafting of crosslinked acrylamide onto chitosan backbone in presence of MMT at different contents. The formation of the grafted network was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). The obtained porous structure was observed by scanning electron microscope (SEM). The presence of clay and its interaction with chitosan‐g‐poly(acrylamide) (CTS‐g‐PAAm) matrix was evidenced by ATR‐FTIR analysis. The morphology was investigated by both X‐ray diffraction (XRD) and SEM analyses. It was suggested the formation of mostly exfoliated structures with more porous structures. Besides, the thermal stability of these composites, observed by TGA analysis, was slightly affected by the clay loading as compared to the matrix. These hydrogel composites were also hydrolyzed to achieve anionic hydrogels with ampholytic properties. Swelling behaviors were examined in doubly distilled water, 0.9 wt % NaCl solution and buffer solutions. The water absorbency of all superabsorbent composites was enhanced by adding clay, where the maximum was reached at 5 wt % of MMT. Their hydrolysis has not only greatly optimized their absorption capacity but also improved their swelling rate and salt‐resistant ability. The hydrolyzed superabsorbent showed better pH‐sensitivity than the unhydrolyzed counterparts. The results of the antibacterial activity of these superabsorbents composites against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), assayed by the inhibitory zone tests, have showed moderate inhibition of the bacteria growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39747.     

Synthesis and water absorbency of the copolymer of acrylamide with anionic monomers

A series of novel copolymer superabsorbents based on acrylamide, sodium allylsulfonate, sodium acrylate, and N,N′-methylenebisacrylamide were prepared by copolymerization. The resulting superabsorbents have a fast swelling rate. The experimental results show that absorbency increases to a maximum as the cross-linking increases, but an excess of cross-linking leads to a swelling decrease. Their water retention was observed at pressures of 1–10 kg/cm² and temperatures of 60 and 100°C, respectively. The water retention of soil has been enhanced by using the poly(acrylamide–sodium allysulfonate–sodium acrylate) superabsorbent; its use for bean growth was also investigated. © 1994 John Wiley & Sons, Inc.     

不同产地坡缕石粘土对高吸水树脂吸水性能的影响

以玉米秸秆,丙烯酸,不同产地坡缕石粘土为原料合成复合高吸水树脂MS-g-PAA/PGS。通过红外光谱,X射线衍射,扫描电镜和热重分析来研究坡缕石粘土的结构和形态。通过红外光谱和扫描电镜对复合高吸水树脂形貌及结构进行了表征。研究了各地坡缕石粘土形态,结构及组成对高吸水树脂吸水保水性能的影响.结果显示添加靖远坡缕石粘土的复合高吸水树脂有着最佳吸水保水性能。     

紫外光引发聚(丙烯酸-丙烯酰胺)/膨润土高吸水性复合材料的制备研究

以N,N-亚甲基双丙烯酰胺(MBAM)为交联剂,Irgacure184为光引发剂,采用紫外光引发聚合的方法制备了聚(丙烯酸-丙烯酰胺)/膨润土高吸水性复合材料。研究了膨润土用量、光引发剂、交联剂、中和度等因素对吸水性能的影响,并用红外吸收光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)的方法表征了复合材料的结构和形态。     

海泡石接枝P(AMPS-co-AM)高吸水树脂的合成和性能

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酰胺(AM)和海泡石黏土(ST)为原料,采用微波辐射方法制备了ST接枝P(AMPS-co-AM)耐盐性高吸水性树脂,考察了海泡石用量、无机盐溶液金属离子价态和浓度对树脂吸水倍率的影响,研究了树脂的吸水速率和保水性能。用FTIR、XRD、SEM对吸水性树脂进行了表征。结果表明,树脂的吸水倍率随着无机盐溶液浓度的增加而减小,在不同价态金属离子盐溶液中,树脂的吸水倍率顺序为NaCl>CaCl2>FeCl3,在体系中适量地引入ST能显著提高树脂的吸水能力,树脂具有较快的吸水速率和良好的保水性能。FTIR和XRD表明,ST和有机单体之间发生了接枝共聚反应,部分单体插入到ST的层间形成插层型复合高吸水性树脂,SEM显示树脂具有多孔的层状结构。     

GG-g-PAA/LOESS复合高吸水性树脂的制备与性能

以瓜尔胶(GG)、丙烯酸(AA)和黄土(LOESS)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,采用水溶液聚合法制备了瓜尔胶接枝聚丙烯酸/黄土(GG-g-PAA/LOESS)复合高吸水性树脂。采用FTIR和SEM对其结构进行了表征,研究了LOESS的添加量对复合高吸水性树脂的溶胀能力和溶胀动力学的影响,考察了复合高吸水性树脂的保水性能、反复溶胀性以及在不同pH溶液中的吸水性能。结果表明,瓜尔胶、丙烯酸和LOESS发生了接枝共聚,体系中引入LOESS能够显著提高复合高吸水性树脂的吸水性能。当LOESS的质量分数为2%时,该树脂最高吸水倍率可达602 g/g,室温下6 d后,其保水率仍达28%,5次反复溶胀,吸水倍率仍能保持初始时的49%。此外,该复合高吸水性树脂还表现出优异的pH稳定性。     

Photo,thermal, and ultrasonic degradation of EGDMA-crosslinked poly(acrylic acid-co-sodium acrylate-co-acrylamide) superabsorbents

Superabsorbent polymers (SAPs) based on acrylic acid (AA), sodium acrylate (SA), and acrylamide (AM) were synthesized by inverse suspension polymerization using ethylene glycol dimethacrylate as the crosslinking agent. The equilibrium swelling capacities and the rates of swelling of SAPs varied with the AM content and followed first-order kinetics. The photodegradation of SAPs in their equilibrium swollen state was carried out by monitoring their swelling capacity and the residual weight fraction. The SAPs degraded in two stages, wherein the swelling capacity increased to a maximum and then subsequently decreased. Thermogravimetric analysis of the SAPs indicated that the copolymeric superabsorbents had intermediate thermal stability between the homopolymeric superabsorbents. The activation energies of SAPs with 0, 20, and 100 mol % AM content were determined by Kissinger method and were found to be 299, 248, and 147 kJ mol⁻¹, respectively. The ultrasonic degradation of the superabsorbents was carried out in their equilibrium swollen state, and the change in the viscosity with ultrasonication time was used to quantify the degradation. The ultrasonic degradation of AA/SA superabsorbent was also investigated at various ultrasound intensities. The degradation rate coefficients were found to increase with the intensity of ultrasound. The ultrasonic degradation of AA/SA/AM (20% AM) was also carried out, and degradation rate was found to be more than that of the AA/SA superabsorbent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and Swelling Behavior of Fast‐Swelling Superabsorbent Hydrogels Based On Starch‐g‐Poly(acrylic acid‐co‐sodium acrylate)

Summary: A novel fast‐swelling porous superabsorbent hydrogel was prepared by grafting acrylic acid onto corn starch through free‐radical polymerization in aqueous solution using N,N′‐methylenebisacrylamide as a crosslinker, ammonium persulfate as an initiator, sodium dodecyl sulfate and p‐octyl poly(ethylene glycol)phenyl ether as pore‐forming agents. The graft polymerization and surface morphology of the porous superabsorbents were characterized by FTIR and SEM. The results indicate that the porous superabsorbents were endowed with higher equilibrium water absorbency and faster swelling rate (they needed only 10 min to reach 90% of their equilibrium water absorbency) compared with the nonporous superabsorbents. The dewatering method employed had a significant influence on the swelling behavior of the superabsorbents and dewatering agents were useful to preserve the pores formed during the polymerization process.

The equilibrium water absorbency in distilled water, for the porous and non‐porous starch‐g‐poly(acrylic acid‐co‐sodium acrylate) superabsorbent hydrogels dried through different procedures.     

The synthesis and incorporation of a star-shaped bio-based modifier in the acrylic acid based superabsorbent: a strategy to enhance the absorbency under load

ABSTRACT

The mechanical strength of superabsorbents is an important practical factor that can be characterized by measuring the absorbency of the superabsorbent under load. In the last decades, many efforts have been devoted to enhancing the mechanical strength of superabsorbents. Herein, as an attempt to increase the superabsorbent mechanical strength, two types of star-shaped bio-based modifiers were designed and synthesized via condensation reaction between acids and alcohols. The chemical structures of the bio-based modifiers were characterized via FT-IR and ¹H NMR analysis. Glycerin, lactic acid, succinic acid, and itaconic acid used for the synthesis of the star-shaped modifier, which further used in different ratios in the bulk of the superabsorbent. Moreover, another modifier was synthesized from glycerin, lactic acid, and methacrylic anhydride, and successfully used as a surface modifier for superabsorbents in different ratios. The absorption analysis showed that the employment of the optimum amount of the bulk modifier (4.75 wt.%) increases the AUL almost 4 units, without significant impacts on the water and NaCl solution absorbencies. Also, the incorporation of the optimum amount of the surface modifier increases the AUL about 3 units. As a result, the AUL value of the acrylic acid- sodium acrylate superabsorbent enhanced ~7 units by the incorporation of these bio-based modifiers-from 17.3 for the pristine superabsorbent to 24.2.     

高吸水树脂结构与性能的关系及结构表征方法研究进展

首先系统综述了高吸水树脂的结构与吸水性能关系的研究进展和高吸水树脂结构表征手段的开发进展,指出了当前在结构与性能关系方面研究的不足和表征方法的局限性,并对其原因进行了分析.然后就深入研究高吸水树脂结构与性能关系提出了设想和思路。     

环境响应型吸水树脂研究进展

环境响应型吸水树脂面对外界刺激时能够快速产生响应,物理结构和溶胀性能迅速发生变化,有望应用于人造肌肉、药物控释载体、吸附分离、细粒煤脱水等领域。随着科学技术的进步,对其结构与性能提出了新的要求和用途,研究者在制备方法和改性研究方面也取得了新的成果。本文综述了近几年来环境响应型吸水树脂的研究进展,简述了环境响应型吸水树脂的结构与性质,重点介绍了4类不同响应类型(温度、pH、盐及磁响应)吸水树脂的响应机理、研究水平及应用现状,最后讨论了环境响应型吸水树脂在面向应用的研究过程中要解决的关键科学问题,提出制备具有多重响应机制并兼顾刺激响应特性与机械性能的吸水树脂可加快其由实验室基础研究向实际工业应用过渡和成果转化的进程。     

Design and synthesis of superabsorbent polymers

A series of novel copolymer superabsorbents based on the monomers acrylamide (AM), acrylic acid (AA), acrylonitrile, methacrylic acid, sodium acrylate (SA), and 2‐hydroxyethyl methacrylate (HEMA) were prepared by copolymerization using ammonium persulfate as an initiator and N,N‐methylenebisacrylamide as a crosslinking agent. The experimental results of superabsorbent polymers (SAPs) show that the absorbency in water and NaCl solutions is maximum for AM, SA, HEMA and AM, AA, SA combinations. The copolymers were characterized by IR spectroscopy. The water retention of soil was also enhanced using the above superabsorbents. Use of SAPs for the growth of the croton plant was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2635–2639, 2001     

Preparation and morphology of high‐performance exfoliated poly(sodium acrylate)/hydrotalcite nanocomposite superabsorbents

A poly‐matrix composite—poly(sodium acrylate) (PSA)/hydrotalcite (HT) (PSA/HT) nanocomposite superabsorbent—with obvious improvements in both the water absorbency and salt absorbency has been prepared by the intercalated HT, using sodium methyl allyl sulfonate as an intercalation agent. The superabsorbents acquired their highest water (salt) absorbency when the content of HT is 3 wt%. The highest absorbency for deionized water and 0.9 wt% NaCl _(aq) were 1100 g/g and 145 g/g, respectively. Microstructures were analyzed by X‐ray diffraction and scanning electron microscope. Chemical analysis was determined measurements. Results showed that HT incorporated into the superabsorbents was by Fourier infrared spectroscopy and energy dispersion spectroscopy. Results showed that the superabsorbent particles were in the form of spheres, and the hydrogels were in the form of regular network structures. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers