Showing papers on "Acrylic acid published in 2018"
TL;DR: In this article, a poly(acrylic acid) (PAA)-based super-adsorbent nanocomposite hydrogel (NC gel) acting as an effective dye adsorbent is prepared via free radical in situ polymerization of acrylic acid by employing nonaggregated calcium hydroxide (Ca(OH)2) nano-spherulites (CNSs) with a diameter less than 5 nm as cross-linkers.
Abstract: Adsorptive removal of dyes from industrial effluent has attracted intensive interest in the treatment of water pollution. Although we have witnessed great development in adsorbents for treating dyeing waste water, super-adsorbent hydrogels still cannot meet the high requirement for huge adsorption capacities towards various dyes. Traditional uncross-linked poly(acrylic acid) (PAA) adsorbents possess a low adsorption capacity towards dyes due to the poor three-dimensional structure in the bulk, which has a negative effect on the exposure of adsorptive sites and the penetration of water within the internal channels of the adsorbent. Thus, other monomers or chemical cross-linkers are introduced to design a well-cross-linked PAA-based super-adsorbent hydrogel with the intention of improving its adsorptive behavior. However, the above-mentioned additives may negatively affect the adsorptive properties of composite adsorbents based on the PAA hydrogel. To the best of our knowledge, adsorption capacities of PAA-based super-adsorbent hydrogels for organic dyes reaching more than 2000 mg g−1 have rarely been reported as yet. Therefore, it is urgent to explore super-adsorbent hydrogels with high adsorptive properties to alleviate dye-based water pollution. In this work, a novel poly(acrylic acid) (PAA)-based super-adsorbent nanocomposite hydrogel (NC gel) acting as an effective dye adsorbent is prepared via free radical in situ polymerization of acrylic acid by employing non-aggregated calcium hydroxide (Ca(OH)2) nano-spherulites (CNSs) with a diameter less than 5 nm as cross-linkers. The high water penetration of our super-adsorbent NC gel with a high swelling ratio (500 times) allows the internal adsorption sites to be fully exposed to methylene blue (MB). Thus, the adsorption capacity is as high as 2100 mg g−1 for MB under near neutral pH conditions due to the exposure of a large amount of active sites. This is the first time that it has been reported that a maximum adsorption of more than 2000 mg g−1 for MB has been obtained using a PAA-based super-adsorbent NC gel. In addition, the adsorption behavior of our NC gel matches well with the pseudo-second-order model and Langmuir adsorption isotherm model. This work confirms that CNSs can create a well-cross-linked structure of a PAA hydrogel without the aid of any other cross-linker and further confirms that the PAA-based super-adsorbent NC gel has a potential application in the removal of organic dyes from dyeing waste water.
226 citations
TL;DR: The XG-cl-PAA/o-MWCNTs hydrogel nanocomposite exhibited a very high adsorption potential, and its adsorptive capacities calculated based on the Langmuir isotherm for MB was 521.0 mg/g at 30 °C.
145 citations
TL;DR: In this article, a strategy to modulate the electrocatalytic activity of copper toward CO2 reduction involving adsorption of acrylamide, acrylic acid, and allylamine polymers is presented.
Abstract: A strategy to modulate the electrocatalytic activity of copper toward CO2 reduction involving adsorption of acrylamide, acrylic acid, and allylamine polymers is presented. Modification of electrodeposited copper foam with poly(acrylamide) leads to a significant enhancement in faradaic efficiency for ethylene from 13% (unmodified foam) to 26% at −0.96 V vs RHE, whereas methane yield is unaffected. Effects from crystalline phase distribution and copper oxide phases are ruled out as the source of enhancement through XPS and in situ XRD analysis. DFT calculations reveal that poly(acrylamide) adsorbs on the copper surface via the oxygen atom on the carbonyl groups and enhances ethylene formation by (i) charge donation to the copper surface that activates CO for dimerization, (ii) chemical stabilization of the CO dimer (a key intermediate for C2 products) by hydrogen-bond interactions with the −NH2 group, and (iii) facilitating the adsorption of CO molecules near the polymer, increasing local surface coverage. ...
141 citations
TL;DR: In this paper, a class of extremely stretchable and electrically conductive hydrogels with dually synergistic networks are fabricated for wearable resistive-type strain sensors, which have high tensile strength, controllable conductivity and large tensile deformation.
Abstract: Flexible strain sensors are highly used in soft robotics, human–machine interfaces and health monitoring devices. However, it is still a big challenge to construct strain sensors with excellent mechanical properties and broad sensing ranges. In this study, a class of extremely stretchable and electrically conductive hydrogels with dually synergistic networks are fabricated for wearable resistive-type strain sensors. Dually synergistic networks are composed of a soft poly(acrylic acid) (PAA) network and a rigid conductive polyaniline (PANI) network. The PAA network is crosslinked by amphiphilic block copolymers, and the PANI network is chemically doped and ionically crosslinked by phytic acid and these two networks are further interlocked by physical entanglements, hydrogen bonds and ionic interactions. The resulting hydrogels have high tensile strength, controllable conductivity and large tensile deformation (1160%). Moreover, these hydrogels are utilized for fabricating strain sensors with good sensitivity and a wide sensing range (0–1130%). The high performances of hydrogels make such strain sensors suitable for wearable devices monitoring both subtle and large strains induced by human motions, including moving of two hands, bending of joints, conducting of gestures and swallowing.
139 citations
TL;DR: This study provides a new strategy for preparing super-strong physically cross-linked hydrogels and other polymeric materials and this super- strong and tough hydrogel may find potential applications in biomedical and load-bearing fields.
Abstract: Synthetic hydrogels or water-containing polymeric materials are much inferior to biological tissues and solid plastics in many aspects of mechanical properties; it is a great challenge to develop hydrogels with mechanical properties comparable with or even superior to those of biological tissues and plastics. Here, we report a type of super-strong and tough hydrogen-bonded poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) hydrogel by immersing as-prepared PVA hydrogels in aqueous PAA solutions and then cold-drawing the hydrogels to different strains. The immersing process introduces PAA chains into the PVA hydrogels, which increases the cross-linking density by hydrogen bonding and hence, much improved mechanical properties and low water contents (35.9–40.2 wt%) are observed. The cold-drawing orients the polymer chains, which enables the formation of more and stronger hydrogen bonds. The mechanical properties of cold-drawn gels are dramatically enhanced, with tensile strength and elastic modulus up to 140 and 100 MPa, respectively; also, super-high toughness (117 MJ m−3) and fracture energy (101 kJ m−2) are obtained. Very impressively, the ultra-high tensile strengths of the cold-drawn hydrogels are superior to those of biological tissues and most solid engineered plastics. Characterizations and comparative studies prove that the enhancement of mechanical properties is mainly due to the formation of more hydrogen bonding rather than the loss of water or the change in crystallinity. This study provides a new strategy for preparing super-strong physically cross-linked hydrogels and other polymeric materials. This super-strong and tough hydrogel may find potential applications in biomedical and load-bearing fields.
136 citations
TL;DR: An environmentally friendly method for the generation of multifunctional poly(vinyl alcohol)/poly(acrylic acid) (PVA-PAA) composite membranes via green electrospinning and thermal crosslinking and bypassing any potential toxicity concerns caused by organic solvent residues is reported.
123 citations
TL;DR: In this article, an efficient removal of selected heavy metal ions using a low-cost superabsorbent polymer hydrogel (SPH) composed of acrylic acid and acrylamide in different compositions which were prepared by single step free radical polymerization technique using ammonium persulphate and N, N-methylene bis-acrylamides as an initiator and crosslinker respectively.
119 citations
TL;DR: XG-cl-pAA/rGO is recommended as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in dyes removal.
108 citations
TL;DR: The results showed that SA had good water retention and slow N-release properties, which are expected to have potential applications in sustainable modern agriculture.
Abstract: To reduce the preparation cost of superabsorbent and improve the N release rate at the same time, a novel low-cost superabsorbent (SA) with the function of N slow release was prepared by chemical synthesis with neutralized acrylic acid (AA), urea, potassium persulfate (KPS), and N,N’-methylenebis(acrylamide) (MBA). The order of influence factors on the water absorbency property was determined by an orthogonal L18(3)7 experiment. On the basis of the optimization results of the orthogonal experiment, the effects of a single factor on the water absorption were investigated, and the highest water absorbency (909 g/g) was achieved for the conditions of 1.0 mol urea/mol AA ratio, 100% of AA neutralized, K+, 1.5% KPS to AA mass fraction, 0.02% MBA to AA mass fraction, 45 °C reaction temperature, and 4.0 h reaction time. The optimal sample was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behaviors of the superabsorbent were investigated in distil...
104 citations
TL;DR: The results indicated that the new superabsorbent polymers have a good swelling ability, water evaporation rate, excellent salt tolerance and pH sensitivity, and have potential as a water-retaining agent.
103 citations
TL;DR: In this article, a ring-opening reaction of epoxidized soybean oil (ESO) with hydroxyethyl methacrylated maleate (HEMAMA) precursor, a synthesized unsaturated carboxylic acid having two active C═C groups and a side methyl group, was studied.
Abstract: Novel soybean-oil-based (SBO-based) epoxy acrylate (EA) resins were developed via ring-opening reaction of epoxidized soybean oil (ESO) with hydroxyethyl methacrylated maleate (HEMAMA) precursor, a synthesized unsaturated carboxylic acid having two active C═C groups and a side methyl group. Experimental conditions for the synthesis of the precursor and the SBO-based EA (ESO-HEMAMA) product were studied, and their chemical structures were confirmed by FT-IR, 1H NMR, 13C NMR, and gel permeation chromatography. Subsequently, the volatility of HEMAMA was studied and compared with acrylic acid (AA). Furthermore, gel contents and ultimate properties of the UV-cured ESO-HEMAMA resins were investigated and compared with a commercial acrylated ESO (AESO) resin. At last, UV-curing behaviors of the SBO-based EA resins were determined by real-time IR. It was found that the HEMAMA precursor showed much lower volatility than AA, and the optimal pure ESO-HEMAMA resin possessed a C═C functionality up to 6.02 per ESO and ...
TL;DR: In this study, hydrogel polymer was synthesized by incorporation of acrylic acid, vinylphosphonic acid and N-maleyl chitosan and the adsorbent was successfully employed for successive four cycles of adsorption-desorption.
TL;DR: In this paper, a polyelectrolyte composite nanofiltration membranes were prepared using layer-by-layer self-assembly of chitosan and poly(acrylic acid) on a microporous polyethersulfone substrate.
TL;DR: In this paper, polyvinyl alcohol grafted poly (acrylic acid) (PVA-g-PAA) is synthesized through graft polymerization of acrylic acid (AA) onto PVA backbone via a free radical reaction.
TL;DR: In this paper, a solution polymerization of acrylic acid in the presence of sodium alginate biopolymer and TiO2 nanoparticle was used to synthesize hydrogel nanocomposites.
Abstract: Hydrogel nanocomposites were synthesized by solution polymerization of acrylic acid in the presence of sodium alginate biopolymer and TiO2 nanoparticle. TiO2 nanoparticle and N,N-methylene-bis-acry...
TL;DR: The formation of the monolayer polymer inside mesoporous oxide channels represents a method for the development of highly promising functional nanocomposites.
Abstract: Polymer/inorganic nanocomposites exhibit special properties due to highly intimate interactions between organic and inorganic phases and thus have been deployed for various applications. Among them, nanocomposites with monolayer polymer coverage on the inorganic surface demonstrate the highest efficiency for applications. However, the controllable synthesis of the polymer monolayer in mesopores of inorganic substrates remains a challenge. In this study, poly(acrylic acid)/γ-alumina nanocomposites (PAA/alumina) were synthesized via the in situ polymerization of acrylic acid impregnated in mesopores of alumina. By applying the preneutralization of monomers, the polymerization was found to be highly controllable in generating monolayer PAA coverage. The formation of monolayers was verified by thermogravimetry, semiquantitative Fourier transform infrared spectroscopy, N2 adsorption–desorption, and Pb(II) adsorption. Alternatively, the organic loadings of PAA/alumina composite samples could be controlled in th...
TL;DR: Results suggest that hydration-controlled NO release from topical PAA:F127/GSNO hydrogels is a potential strategy for enhancing wound healing and a novel strategy to overcome challenges in topical nitric oxide delivery.
TL;DR: It was concluded that MIP-CMSs had specific binding property for PFOS on acidic condition and the electrostatic interaction and molecular size played important roles in recognizing the target compound in the adsorption process.
TL;DR: In this paper, a family of materials called polymer/inorganic nanocomposites (POMs) have been proposed to combine the unparalleled features of both the inorganic components and the organic macromolecules.
Abstract: Polymer/inorganic nanocomposites are a family of materials that have received tremendous attentions lately because of their potential applications in biological sciences,[1] nanotechnology,[2] optoelectronics,[3] therapeutics,[4] and catalysis.[5] These materials are not mere mixtures of inorganic phase and organic macromolecules. Instead, nanocomposites are able to coherently combine the unparalleled features of both the inorganic components and the organic Received: 17 November 2017 | Accepted: 7 March 2018 DOI: 10.1002/adv.21969
TL;DR: In this paper, an acrylic acid (AA) monomer was grafted onto sodium alginate (SA) using N,N′-methylene-bisacrylamide (MBA) and potassium persulfate (KPS) as a crosslinker-initiator system.
Abstract: Polyacrylic acid grafted sodium alginate (SA-cl-PAA)-based hydrogel was synthesized by an aqueous polymerisation method An acrylic acid (AA) monomer was grafted onto sodium alginate (SA) using N,N′-methylene-bisacrylamide (MBA) and potassium persulfate (KPS) as a crosslinker–initiator system The impact of various parameters such as reaction time, the amount of solvent, pH, crosslinker amount, initiator concentration and monomer concentration on the swelling behavior of the synthesized hydrogel was investigated We obtained a hydrogel with swelling percentage 41,298% which is quite high Swelling studies were carried out under acidic (pH 2 buffer) and basic (pH 10 buffer) conditions and evaluated kinetically The results revealed that the swelling process follows second order kinetics, and the water transport inside the hydrogel supports a Fickian mechanism The swelling results also indicate that the swelling properties of the synthesized hydrogel showed an on- and off-switchable behavior under basic and acidic conditions, respectively The synthesized hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) The hydrogel was used in the victoria blue R (VB) and rhodamine 6G (RG6) dye adsorption from wastewater It was found that hydrogel adsorbed 958 and 99% of VB and RG6 (132 ppm), respectively, within 77 min Adsorption of victoria blue is due to electrostatic interaction only, and removal of rhodamine 6G is explained on the basis of electrostatic interaction and hydrogen bonding
TL;DR: Higher scale-inhibition rate and lower corresponding optimal dose were obtained under the similar grafting ratios, while samples with higher number of branched chains with shorter grafted chains displayed better antiscaling performance.
TL;DR: In this paper, a new composite of black phosphorus and multiwall carbon nanotubes (BP-CNT) was constructed via a surface oxidation-assisted chemical bonding procedure, which was further fabricated into anodes for both Li- and Na-ion batteries, using a sodium carboxyl methyl cellulose-poly(acrylic acid) (NaCMC)-PAA) binary polymeric binder.
Abstract: We report a new composite of black phosphorus and multiwall carbon nanotubes (BP–CNT) prepared via a surface oxidation-assisted chemical bonding procedure. The controlled air exposure successfully changed the naturally hydrophobic BP powder to the desired hydrophilicity, which was found indispensable to stable bond formation between the BP and the functionalized CNTs during ball milling. The BP–CNT composites were further fabricated into anodes for both Li- and Na-ion batteries, using a sodium carboxyl methyl cellulose–poly(acrylic acid) (NaCMC–PAA) binary polymeric binder. The hydrophilicity of BP also played a very important role in forming strong bonds with the hydroxyl groups of NaCMC and the carboxylic acid groups of PAA. The plausible mechanisms of stable bond formation were comprehensively examined, and the results revealed two types of strong connections: P–O–C bonds and dehydration cross links. Consequently, the material delivered outstanding electrochemical performance in the anode, with a high discharge capacity of 1681 mA h g−1 after 400 cycles at a current density of 0.2C (1C = 2596 mA g−1) for Li-ion batteries. It also successfully delivered a first discharge capacity of 2073 and 850 mA h g−1 at 0.2C and 2C for Na-ion batteries, respectively, with excellent capacity retentions at both rates after 200 cycles. These salient results, which originated from the modified hydrophilic BP, will give further impetus to explore BP-based composites for use as high-performance materials for advanced energy storage applications.
TL;DR: It is concluded that highly stable SA and AA based polymeric matrixes are developed and have potential to be used as a carrier for controlled delivery of LSH.
Abstract: A series of sodium alginate-graft-poly(acrylic acid) hydrogels (SA-g-pAA hydrogels) were synthesized with sodium alginate (SA) and acrylic acid (AA) in aqueous solution, ethylene glycol dimethacrylate (EGDMA) as a cross-linker and ammonium peroxodisulfate (APS) as an initiator. Hydrogels were evaluated for thermal stability (TGA & DSC), revealing their higher strength toward thermal variation as compared to individual components. SEM micrographs show smooth and solid outer surface with a lack of porosity on it. FTIR results revealed the grafting reaction of AA on SA. Hydrogels were then evaluated for pH responsive behavior by equilibrium swelling ratio and swelling dynamics at low and high pH. Furthermore, these cross-linked networks were also tested for the release of Loxoprofen sodium hydrate (LSH). Drug was loaded by diffusion method and showed pH-dependent drug release characteristics. Korsmeyer–Peppas model is the best fit model to explain drug release from the cross-linked network. Maximum swelling, drug loading, and release has been observed at pH 7.4. It is concluded that highly stable SA and AA based polymeric matrixes are developed. These polymeric matrixes have potential to be used as a carrier for controlled delivery of LSH.
TL;DR: In this paper, a pH responsive hydrogel was prepared by grafting of a mixture of acrylic acid and N-vinyl imidazole (NVI) onto the katira gum (KG) by free radical co-polymerization technique using KPS as initiator and N,N′-methylene-bis-acrylamide (MBA) as a cross-linking agent in water medium.
TL;DR: Li et al. as mentioned in this paper demonstrate a strategy that graft poly(acrylic acid) (PAA) on the surface of polypropylene (PP) separator to improve the electrochemical performance of Li-S batteries by impeding the "shuttle effect" of polysulfide.
TL;DR: N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization and results showed that microspheres had a narrow size dispersity.
Abstract: N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization. Size and size distribution of particles were obtained using dynamic light scattering and field emission scanning electron microscopy( and results showed that microspheres had a narrow size dispersity. Proton nuclear magnetic resonance results indicated that amount of cross-linker in structure of particles is a little more than the molar percentage of feeded MBA because of greater activity ratio of MBA than AA. pH-responsive behavior of samples was investigated using UV-vis. absorption at 480 nm where each sample showed a sudden deplete in UV absorbance at a peculiar pH. Synthesized particles were used as carriers of anti-cancer drug doxorubicin using two different approaches including physically loading of drug and drug conjugation via an acid-labile hydrazone linkage. Release results showed that in the first case, amount of released drug has an inverse relationship with the amount of cross-linker in the structure and also, by adding an acid-labile linkage, the amount of burst release decreased drastically. Also, the amount of released drug for conjugated systems was much lesser than particles with physically loaded drug. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 342-348, 2018.
TL;DR: In this article, a grafted copolymer of guar gum/polyacrylic acid (GG/Poly(AA)) has been synthesized by two-step free radical graftcopolymerization using ammonium persulphate (APS) as initiator and N, N′−methylenebisacrylamide (MBA) as cross-linking agent.
TL;DR: In this paper, a superabsorbent copolymer was synthesized based on the tragacanth gum via graft polymerization of the acrylic acid onto the carboxymethyl traragacanth (CMT) in the aqueous solution.
TL;DR: The results obtained from this study revealed that as the content of clay increases, the uptake of cations increasing and the removal order of the composites were Pb2+ > Mg2’s2” Fe2‚¬2“¬3”, the biodegradability of grafted cellulose was increased by the addition of clay.
TL;DR: In this article, the sonochemically prepared magnetite nanoparticles (MNPs) were silylated with triethoxyvinylsilane to produce a core-shell structure containing vinyl moieties on the surface.
Abstract: In the current research, the sonochemically prepared magnetite nanoparticles (MNPs) were silylated with triethoxyvinylsilane to produce a core–shell structure containing vinyl moieties on the surface. The radical polymerization of the silylated product with acrylic acid in the presence of N,N-methylenebisacrylamide, as the cross-linker, led to the formation of novel magnetic hydrogel nanocomposites (MHNCs) in which some of polyacrylic acid (PAA) chains were chemically grafted onto MNPs (PAA-grafted MNPs). Vibrating sample magnetometry showed the unique phenomenon of superparamagnetism for the prepared MNPs, silylated MNPs, and PAA-grafted MNPs. Batch adsorption experiments were carried out for the removal of methylene blue (MB) using pure hydrogel and MHNCs as an adsorbent. The effects of contact time, PAA-grafted MNP content, adsorbent mass, and initial pH value of the dye solution on adsorption were investigated. Results showed the MHNC containing 10 wt% of PAA-grafted MNP (MHNC 10 wt%) had the maximum adsorption capacity. It was observed that the adsorption kinetics of MB followed pseudo–second-order kinetics. The adsorption equilibrium data obeyed Langmuir isotherm, and the maximum adsorption amount of MB reached 507.7 mg g–1 for MHNC 10 wt%. It was shown that the adsorbed MB could be desorbed from the MHNCs by using methanol solution containing acetic acid and the nanoadsorbents could be recycled.