Showing papers on "Acrylic acid published in 2017"
TL;DR: In this paper, the Pb 2+ ions formed Pb-O bonds by hydroxyl groups and carboxyl groups for efficient lead ion adsorption in LBPAA and organo-montmorillonite composites.
295 citations
TL;DR: A smart tree-like nanofiber membrane with pH-responsivity was successfully fabricated by electrospinning poly(vinylidene fluoride)-graft-poly(acrylic acid) (PVDF-g-PAA) as discussed by the authors.
137 citations
TL;DR: In this article, quaternary ammonium chitosan-g-poly(acrylic acid-co-acrylamide) superabsorbent hydrogels were successfully synthesized from acrylic acid (AA), acrylamides (AM), and Quaternary Ammonium Chitosans with high substitution degree.
Abstract: Quaternary ammonium chitosan-g-poly(acrylic acid-co-acrylamide) superabsorbent hydrogels were successfully synthesized from acrylic acid (AA), acrylamide (AM) and quaternary ammonium chitosan with high substitution degree. They were prepared using potassium persulfate (KPS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a crosslinker respectively. The structure and morphology of the superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water absorbency and antibacterial activities of the superabsorbent hydrogels against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated. The introduction of quaternary ammonium chitosan made the antibacterial activity improve. The crosslinker, initiator and AM contents had certain influences on the water absorbency as well as the antibacterial activity against E. coli. The AM could enhance the hydrogel strength apparently. In addition, the AM (the content was 10 wt%) could increase the water absorbency in 0.9 wt% NaCl solution obviously. The superabsorbent hydrogel also had pH sensitive property.
130 citations
TL;DR: In this paper, a modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation, where the used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance.
105 citations
TL;DR: The results demonstrate xanthan gum grafted polyacrylic acid (mw XG-g-PAA) absorbent had the universality for removal of dyes through the chemical adsorption mechanism.
88 citations
TL;DR: In this article, a smart environment-friendly and sustainable interpenetrating polymer network hydrogel has been synthesized by the grafting of guar gum (GG) and in situ adjunct allocation of 3-acrylamido propanoic acid (APA) during solution polymerization of acrylic acid (AA) and acrylamide (AM), using N,N′-methylenebisacryamide (MBA) and potassium persulfate (PPS)-sodium bisulfite (SBS) as a crosslinker and a
86 citations
TL;DR: In this paper, itaconic acid was monomethylated with methanol to produce itaconate, and then itaconated epoxidized soybean oil (IESO) was obtained by melt ring-opening esterification of monometric acid with ESO.
Abstract: In this paper, itaconic acid was monomethylated with methanol to produce monomethyl itaconate, and then monomethyl itaconated epoxidized soybean oil (IESO) was obtained by melt ring-opening esterification of monomethyl itaconate with ESO. For comparison, acrylated epoxidized soybean oil (AESO) was also synthesized from ESO and acrylic acid with the same synthetic method. The chemical structures of monomethyl itaconate, IESO, and AESO were characterized in detail by differential scanning calorimetry (DSC), FTIR, and 1H NMR. The isothermal thermogravimetric analysis at 30, 60, and 90 °C indicated that monomethyl itaconate exhibited extremely low volatility even at 90 °C, while acrylic acid volatilized very fast even at 30 °C, which suggested that monomethyl itaconate could be used as a green alternative to acrylic acid. Under UV radiation, IESO showed good copolymerization ability with reactive monomers such as glycidyl methacrylate modified itaconic acid (IG), trimethylolpropane triacrylate (TMPTMA), and s...
85 citations
TL;DR: In this article, a poly(acrylic acid-co-acrylamide)/bentonite/kaolin composite hydrogel was prepared to study the effect of composite clays on the mechanical properties, water absorption and salt tolerance.
Abstract: In order to study the effect of composite clays on the mechanical properties, water absorption and salt tolerance of a hydrogel, a poly(acrylic acid-co-acrylamide)/bentonite/kaolin composite hydrogel was prepared. Acrylic acid and acrylamide have been used as water absorbent monomers. N,N′-methylene bisacrylamide was used as a crosslinking agent while potassium persulfate was used as an initiator. The water preserving capability, repeated water absorption, salt resistance and the mechanical properties of the composite hydrogel are analyzed and discussed. The results show that a small quantity of bentonite can increase the storage modulus of the composite hydrogel, whereas the excess clay had an unfavorable effect on the mechanical strength of the composite hydrogel. Both bentonite and kaolin significantly improved the water preserving capability, repeated water absorption and salt resistance of the composite hydrogel. Optimum values for the amounts of bentonite and kaolin were found to be 10% and 5%, respectively.
82 citations
TL;DR: Carboxycellulose nanofibers (NOCNF) were extracted from untreated jute fibers using a simple nitro-oxidation method, employing nitric acid and sodium nitrite as mentioned in this paper.
Abstract: Carboxycellulose nanofibers (NOCNF) were extracted from untreated jute fibers using a simple nitro-oxidation method, employing nitric acid and sodium nitrite. The resulting NOCNF possessed high surface charge (−70 mV) and large carboxylate content (1.15 mmol/g), allowing them to be used as an effective medium to remove UO22+ ions from water. The UO22+ (or U(VI)) removal mechanism was found to include two stages: the initial stage of ionic adsorption on the NOCNF surface following by the later stage of uranyl hydroxide mineralization, as evidenced by the Fourier transform infrared, scanning electron microscopy with energy dispersive spectroscopy capabilities, transmission electron miscroscopy, and wide-angle X-ray diffraction results. Using the Langmuir isotherm model, the extracted NOCNF exhibited a very high maximum adsorption capacity (1470 mg/g), about several times higher than the most efficient adsorbent reported (poly(acrylic acid) hydrogel). It was also found that the remediation of UO22+ ions by N...
73 citations
TL;DR: In this paper, the synthesis of fluorescent single chain nanoparticles (SCNPs) via UV-light induced folding based on tetrazole chemistry directly in pure water was presented.
Abstract: We pioneer the synthesis of fluorescent single chain nanoparticles (SCNPs) via UV-light induced folding based on tetrazole chemistry directly in pure water. Water-soluble photoreactive precursor polymers based on poly(acrylic acid) (PAA) bearing tetrazole, alkene and tetraethylene glycol monomethyl ether moieties, (PAAn(Tet/p-Mal/TEG)), or simply tetrazoles moieties, PAAn(Tet), were generated via RAFT polymerization. While tetrazole, ene, and acrylic acid containing polymers fold via dual nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) as well as nitrile imine-carboxylic acid ligation (NICAL), tetrazole and acrylic acid only functional prepolymers fold exclusively via NICAL. A detailed study of the underpinning photochemistry of NITEC and NICAL is also included. The resulting water-soluble SCNPs were carefully characterized via analytical techniques such as NMR, UV–vis, and fluorescence spectroscopy, as well as SEC and DLS.
71 citations
TL;DR: In this paper, the colloidal stability of poly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAM-coAAc)] polymer microgels with different acrylic acid contents in aqueous medium under various conditions of temperature, pH and sodium chloride concentrations.
TL;DR: In this article, HNTs were chemically treated with different acids (sulphuric, acetic and acrylic acid), for 72h at a constant temperature of 50°C.
TL;DR: A detailed interpretation of experimental spectra is achieved, elucidating structure-spectra correlations of these molecules in the NIR region, and anharmonic DFT calculations provide insights on the manifestation of hydrogen bonding through distinctive spectral features corresponding to cyclic dimers.
Abstract: By near-infrared (NIR) spectroscopy and anharmonic density functional theory (DFT) calculations, we investigate five kinds of saturated and unsaturated carboxylic acids belonging to the group of short-chain fatty acids: propionic acid, butyric acid, acrylic acid, crotonic acid, and vinylacetic acid. The experimental NIR spectra of these five kinds of carboxylic acids are reproduced by quantum chemical calculations in a broad spectral region of 7500–4000 cm–1 and for a wide range of concentrations. By employing anharmonic GVPT2 calculations on DFT level, a detailed interpretation of experimental spectra is achieved, elucidating structure–spectra correlations of these molecules in the NIR region. We emphasize the spectral features due to saturated and unsaturated alkyl chains, the location of a C═C bond within the alkyl chain, and the dimerization of carboxylic acids. In particular, the existence of a terminal C═C bond leads to the appearance of highly specific NIR bands. These pronounced bands are located ...
TL;DR: In this paper, a core-shell structure of crosslinked poly(2-hydroxyethylmethacrylate) as corona and nanocrystalline cellulose (NCC) as core was synthesized by distillation precipitation polymerization.
Abstract: A core–shell structure of crosslinked poly(2-hydroxyethylmethacrylate) as corona and nanocrystalline cellulose (NCC) as core was synthesized by distillation precipitation polymerization. Then, it was reacted with a chain transfer agent of S-(thiobenzoylthioglycolic) acid to obtain NCC-RA. Homopolymers of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) as temperature- and pH-sensitive materials, as well as their dual-sensitive block copolymers, were grafted at the surface of NCC-RA by an in situ reversible addition-fragmentation chain transfer polymerization method via R-group approach. Grafting of chain transfer agent and polymer chains at the surface of nanocrystals was studied by X-ray photoelectron (XPS), Fourier transform infrared, and Raman spectroscopies. Thermogravimetric analysis and XPS were also used to study the graft content of chain transfer agent and polymers. Sensitivity of the polymer-grafted NCCs to temperature and pH were studied by UV–visible spectroscopy. By the addition of poly(N-isopropylacrylamide) block to the poly(acrylic acid)-grafted nanocrystals, phase transition is observed at 32 °C. When the poly(acrylic acid) block is the outer layer, phase transition is observed at higher temperatures and pH-responsivity is observed at pH 7.0–10.0. Finally, morphology of the neat and polymer-grafted NCCs was studied by scanning and transmission electron microscopies.
TL;DR: It is demonstrated that the cross-linking PAMM is an intriguing candidate for 5 V class high-voltage gel polymer electrolyte toward high-energy lithium-on batteries and suppresses the negative effect resulting from dissolution of Mn2+ ions at 25 and 55 °C.
Abstract: Electrochemical performance of high-voltage lithium batteries with high energy density is limited because of the electrolyte instability and the electrode/electrolyte interfacial reactivity. Hence, a cross-linking polymer network of poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) (PAMM)-based electrolyte was introduced via in situ polymerization inspired by “shuangjian hebi”, which is a statement in a traditional Chinese Kungfu story similar to the synergetic effect of 1 + 1 > 2. A poly(acrylic anhydride) and poly(methyl methacrylate)-based system is very promising as electrolyte materials for lithium-ion batteries, in which the anhydride and acrylate groups can provide high voltage resistance and fast ionic conductivity, respectively. As a result, the cross-linking PAMM-based electrolyte possesses a significant comprehensive enhancement, including electrochemical stability window exceeding 5 V vs Li+/Li, an ionic conductivity of 6.79 × 10–4 S cm–1 at room temperatu...
TL;DR: For the first time, derivatives of acrylic acid have been shown as surrogates for the unstable and expensive alkenyl boronic acids.
TL;DR: The lithium citrate layer derived from CA stabilizes the silicon surface and suppresses electrolyte reduction, which likely contributes to the enhanced cycling performance of the Si nanoparticle anode.
Abstract: Citric acid and its analogues have been investigated as surface-modifying agents for Si nanoparticle anodes using electrochemical cycling, attenuated total reflectance infrared (ATR IR), and X-ray photoelectron spectroscopy (XPS). A Si nanoparticle anode prepared with citric acid (CA) has better capacity retention than one containing 1,2,3,4-butanetetracarboxylic acid (BA), but both electrodes outperform Si-PVDF. The Si-CA anode has an initial specific capacity of 3530 mA h/g and a first cycle efficiency of 82%. Surprisingly, the Si-CA electrode maintains a high specific capacity of ∼2200 mA h/g after 250 cycles, corresponding to 64% capacity retention, which is similar to the Si prepared with long-chain poly(acrylic acid) (PAA). On the contrary, the silicon electrode prepared with PVDF has a fast capacity fade and retains only 980 mA h/g after 50 cycles. The IR and XPS data show that the Si-CA electrode has an SEI composed primarily of lithium citrate during the first 50 cycles, resulting from the electr...
TL;DR: In this paper, a new polymer binder system based on poly(acrylic acid) (PAA) and poly(ethylene glycol-co-benzimidazole (PEGPBI) is developed for silicon anodes.
TL;DR: In this article, the authors report a tough hydrogel of poly(1-vinylimidazole-co-acrylic acid) reinforced by the robust hydrogen bonds between imidazoles and carboxylic acid groups.
TL;DR: A set of chitosan-g-poly(acrylic acid)/rice husk ash hydrogel composites was successfully employed as methylene blue (MB) adsorbent.
Abstract: A set of chitosan-g-poly(acrylic acid)/rice husk ash hydrogel composites was successfully employed as methylene blue (MB) adsorbent. Maximum MB adsorption capacity of 1952 mg/g of dried hydrogel was obtained with the composite at 5 wt% of rice husk ash (RHA) at pH ≥ 5. The adsorption capacity varied from 1450 to 1950 mg/g with increasing the initial MB concentration from 1500 to 2500 mg/L. The MB removal efficiency was higher than 90% for all samples. At pH ≥ 5, negatively charged groups (–COO−) in the adsorbent were generated, which could strongly interact with the positive charges from MB, favoring adsorption. Adsorption kinetics followed the pseudo-second-order model, which is based on the chemisorption phenomenon, reaching saturation as fast as 1 h of experiments due to the formation of an adsorbed MB monolayer, as suggested by the Langmuir isotherm model (type I). Desorption experiments showed that 75% of loaded MB can be removed from the adsorbent by immersing it in a pH 1 solution. CHT-g-PAAc/RHA5% composite was submitted to five cycles of adsorption/desorption, maintaining its MB removal efficiency at 91%. Therefore, chitosan-g-poly(acrylic acid)/RHA hydrogel composites present outstanding capacity to be employed in the remediation of MB-contaminated wastewaters.
TL;DR: It was observed that 15% CNC/PAA hydrogel showed the potential to be used as drug carrier system.
Abstract: pH-sensitive poly(acrylic acid) (PAA) hydrogel reinforced with cellulose nanocrystals (CNC) was prepared. Acrylic acid (AA) was subjected to chemical cross-linking using the cross-linking agent MBA (N,N-methylenebisacrylamide) with CNC entrapped in the PAA matrix. The quantity of CNC was varied between 0, 5, 10, 15, 20, and 25 wt %. X-ray diffraction (XRD) data showed an increase in crystallinity with the addition of CNC, while rheology tests demonstrated a significant increase in the storage modulus of the hydrogel with an increase in CNC content. It was found that the hydrogel reached maximum swelling at pH 7. The potential of the resulting hydrogels to act as drug carriers was then evaluated by means of the drug encapsulation efficiency test using theophylline as a model drug. It was observed that 15% CNC/PAA hydrogel showed the potential to be used as drug carrier system.
TL;DR: The physicochemical characterizations of this semi-IPN hydrogel suggest this as a promising pH-tunable, biodegradable candidate for control drug delivery vehicle.
TL;DR: Hydroxyethylcellulose (HEC)/acrylic acid (AAc) copolymer gels with superabsorbent properties were synthesized from aqueous solutions by radiation-initiated crosslinking, leading to higher gel fraction and lower water uptake even in very low concentrations.
TL;DR: In this article, photo-initiated polymerization-induced self-assembly (photo-PISA) of isobornyl acrylate in ethanol/water at 40 °C using macro-CTAs was used to produce a set of block copolymer nano-objects having different morphologies.
TL;DR: The results revealed that PAA-AC could be considered as a potential candidate for Cd(II) removal and the sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively.
TL;DR: In this article, the authors used rice husk ash (RHA), poly(acrylamide/acrylic acid/sodium styrene sulfonate/silica in gel form) and grafted resins as novel adsorbents for adsorption of gadolinium.
TL;DR: In this article, a green ultrasonic method was applied to prepare glucan-g-poly(acrylic acid) (GL,g-PAA), sodium lignosulfonate (SLS), and glucan poly(acrylamide) (GPCA) hydrogels with the participation of initiator ammonium persulfate (APS) and cross-linker N′,N-methylenebis(ACrylamides) (NMBA) to remove the Cu2+ ion from aqueous solutions.
Abstract: In the paper, a green ultrasonic method was applied to prepare glucan-g-poly(acrylic acid) (GL-g-PAA), sodium lignosulfonate-g-poly(acrylic acid) (SLS-g-PAA), and glucan-g-poly(acrylic acid) /sodium lignosulfonate (GL-g-PAA/SLS) hydrogels with the participation of initiator ammonium persulfate (APS) and cross-linker N′,N-methylenebis(acrylamide) (NMBA), and these hydrogels were taken as absorbents to remove the Cu2+ ion from aqueous solutions. The structure, morphology, and stability of hydrogels were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The various experimental conditions that influence the adsorption capacity were investigated such as temperature (25–50 °C), pH (1.0–6.0), adsorbent dosage (10–60 mg), foreign ions (300 mg·L–1), and contact time (0–180 min) as well as the initial concentration of the Cu2+ ion solution (100–600 mg·L–1). In addition, the experimental results indicated that the adsorption isothe...
TL;DR: The gallium-modified chitosan/poly(acrylic acid) bilayer can be exploited as a promising titanium coating to limit bacterial adhesion and proliferation, while maintaining osseointegrative potential.
TL;DR: In this article, a biodegradable and ultrahigh content grafted chitosan-g-poly(acrylic acid) powder was successfully synthesized in a homogeneous system and used as adsorbents for the removal of Cu(II) in aqueous solution.
Abstract: Biodegradable and ultrahigh content grafted chitosan-g-poly(acrylic acid) powder was successfully synthesized in a homogeneous system and used as adsorbents for the removal of Cu(II) in aqueous solution. The copolymer was characterized by various techniques. The fundamental adsorption behaviors of the material were studied. The adsorption isotherm was well fitted with Langmuir equation, while the adsorption kinetics preferred to be described the pseudo-second order equation. The maximum adsorption capacity obtained from the Langmuir model was 210.13 mg/g, indicating that the adsorption capacity of chitosan was enhanced remarkably after grafting poly(acrylic acid). Moreover, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the adsorption mechanisms at molecular levels, which revealed that carboxyl groups are facile to form bidentate carboxylates with metal ions. Thus, the environment-friendly copolymer will be a promising candidate for application in removal of heavy metal ions.
TL;DR: The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized using the SEM, thermogravimetric, FTIR, and MS techniques.
Abstract: The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.