Showing papers on "Acrylic acid published in 2014"
TL;DR: A novel way for the production of self-healing hydrogels with shape memory behavior of high tensile strength (0.7–1.7 MPa) and stretch at break (800–900%).
Abstract: A promising strategy to design synthetic hydrogels with the ability to self-heal is to substitute the covalently cross-linked polymer chains by supramolecular ones. Although supramolecular hydrogels generally exhibit rapid self-healing without the need for any stimulus, they suffer from low mechanical strength which prevents them from any stress-bearing applications. Here, we describe a novel way for the production of self-healing hydrogels with shape memory behavior of high tensile strength (0.7–1.7 MPa) and stretch at break (800–900%). Hydrophobically modified poly(acrylic acid) (PAAc) chains with cetyltrimethylammonium (CTA) counterions form the physical network of such hydrogels. They were prepared via micellar copolymerization of acrylic acid with 2 mol % stearyl methacrylate (C18) as the hydrophobic comonomer in an aqueous NaBr solution of cetyltrimethylammonium bromide (CTAB). Extraction of free CTAB micelles from the physical gels results in a drastic increase in their Young’s moduli (from 8–30 to...
224 citations
TL;DR: In this paper, β-cyclodextrin/poly(acrylic acid) grafted onto graphene oxide (β-CD/PAA/GO) was successfully synthesized for the first time using an esterification reaction, and they were used to remove the cationic dyes methylene blue (MB) and safranine T (ST) from aqueous solutions.
170 citations
TL;DR: The salt sensitivity, good water absorbency, and excellent water retention capability of the hydrogels give this intelligentized polymer wide potential applications.
Abstract: A novel composite hydrogel was prepared via UV irradiation copolymerization of acrylic acid and maize bran (MB) in the presence of composite initiator (2,2-dimethoxy-2-phenylacetophenone and ammonium persulfate) and cross-linker (N,N'-methylenebis(acrylamide)). Under the optimized conditions, maize bran-poly(acrylic acid) was obtained (2507 g g(-1) in distilled water and 658 g g(-1) in 0.9 wt % NaCl solution). Effects of granularity, salt concentration, and various cations and anions on water absorbency were investigated. It was found that swelling was extremely sensitive to the ionic strength and cation and anion type. Swelling kinetics and water diffusion mechanism in distilled water were also discussed. Moreover, the product showed excellent water retention capability under the condition of high temperature or high pressure. The salt sensitivity, good water absorbency, and excellent water retention capability of the hydrogels give this intelligentized polymer wide potential applications.
165 citations
TL;DR: The mathematical analysis of the absorption kinetics shows that at conditions of practical interest, the rate of water penetration into the gel is determined by polymer chain relaxations and not by osmotic driven diffusion.
131 citations
TL;DR: A novel Hg(2+) responsive oil/water separation mesh with poly(acrylic acid) hydrogel coating with reversible change in oil contact angle is reported, which is an ideal candidate for oil-polluted water purification, especially for water that contains Hg (2+) contaminant.
Abstract: A novel Hg(2+) responsive oil/water separation mesh with poly(acrylic acid) hydrogel coating is reported. The mesh can separate oil and water because of the superhydrophilicity of the poly(acrylic acid) hydrogel coating on the mesh, and switch the wettability based on the chelation between Hg(2+) and poly(acrylic acid) . The reversible change in oil contact angle of as-prepared mesh is about 149° after immersion in Hg(2+) solution. This mesh is an ideal candidate for oil-polluted water purification, especially for water that contains Hg(2+) contaminant.
128 citations
TL;DR: In this article, a simple one-step method of silver nanoparticle (NPs) preparation with controlled size is introduced, where silver NPs were prepared by reduction of [Ag(NH3)2]-complex cation by d-maltose in the presence of low concentrations (1 × 10−10 mol/L to 1 × 10 −7 mol /L) of high-molecular-weight poly(acrylic acid) (PAA), this modification of the reduction reaction results in managing the prepared silver nanoparticles' size in the range from 28 nm
Abstract: In this work, a simple one-step method of silver nanoparticle (NPs) preparation with controlled size is introduced. Silver NPs were prepared by reduction of [Ag(NH3)2]+ complex cation by d-maltose in the presence of low concentrations (1 × 10–10 mol/L to 1 × 10–7 mol/L) of high-molecular-weight poly(acrylic acid) (PAA). This modification of the reduction reaction results in managing of the prepared silver nanoparticles’ size in the range from 28 nm (the reaction system without PAA) to 77 nm (system with the highest used PAA concentration). The presence of poly(acrylic acid) influences both nucleation process and also the subsequent stage of nanoparticle growth. The rate of nuclei formation by homogeneous nucleation is affected by PAA due to the formation of the strong complex with silver ions which results in a prolongation of the initiation phase of the reduction process proportionally to PAA concentration. The formation of the adsorption layer of PAA on the surface of the emerging silver nuclei prevents...
122 citations
TL;DR: Grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal that implied that this new cellulose-based absorbent had the universality for removal of dyes through the chemical adsorption mechanism.
Abstract: Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universality for removal of dyes through the chemical adsorption mechanism.
121 citations
TL;DR: In this paper, free and nanocrystalline cellulose (NCC) attached homopolymers of N-isopropylacrylamide and acrylic acid (AA) as temperature and pH-sensitive materials and also their dual-sensitive copolymers with different contents of AA were synthesized by RAFT polymerization.
Abstract: Free and nanocrystalline cellulose (NCC) attached homopolymers of N-isopropylacrylamide and acrylic acid (AA) as temperature- and pH-sensitive materials and also their dual-sensitive copolymers with different contents of AA were synthesized by RAFT polymerization. NCCs were obtained from microcrystalline cellulose by an acid hydrolysis process. Then, the surface of NCC was chemically modified by 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as chain transfer agent. In situ synthesis of polymers in the presence of 1 wt% of NCC was carried out at 70 °C via the R-group approach. Successful attachment of DDMAT and polymer chains on the backbone of NCC was studied by X-ray photoelectron (XPS), Fourier transform infrared, proton nuclear magnetic resonance, and Raman spectroscopies. Elemental analysis, thermogravimetric analysis, and XPS were also used to evaluate the grafting of DDMAT and polymers. Thermal behaviour of the NCC-attached polymers was also studied by differential scanning calorimetry. The lower critical solution temperatures (LCST) of polymers as phase separation temperatures were measured by the cloud point method using dynamic light scattering. Addition of NCC, AA content, and pH at higher pH values results in increase of LCST. At low pH values, increase of LCST occurred by an increase of NCC and also pH value. The morphology and crystalline structure of polymer-grafted NCCs were examined by transmission electron microscopy and X-ray diffraction respectively.
108 citations
TL;DR: In this paper, a series of polymeric compounds were tested as inhibitors of calcium carbonate and calcium sulfate dihydrate (gypsum) precipitation and as dispersion agents of hematite (Fe2O3) suspensions in electrolyte solutions.
105 citations
TL;DR: It was suggested that the reactive groups of GO and CSA can interact with the amino groups of dorzolamide and mainly the abundance of carboxyl groups ofGO/CSA composite was the main reason for its enhanced adsorption capacity.
102 citations
TL;DR: Evaluated cytotoxicity and cell proliferation properties indicates the potential of the new systems to be used in contact with biological media in drug delivery applications and thermal analysis revealed the formation of new functional groups.
TL;DR: In this paper, a novel poly(acrylic acid-aniline)-grafted gum ghatti based conducting hydrogel was synthesized by a simple two-step method.
TL;DR: The obtained superabsorbent have good swelling degree that greatly affected by its composition and preparation conditions, being economical and environment-friendly, it might be useful for its application in agriculture field.
TL;DR: In this paper, the HAPm-T sample with varying molar Ca/P ratios m (1.58-1.69) and calcination temperatures T (360-700 °C) were prepared and comprehensively characterized by nitrogen adsorption, TG, XPS, XRD, CO2-TPD, and NH3-tPD and were employed to catalyze the gas phase dehydration of lactic acid to produce acrylic acid (AA).
Abstract: Hydroxyapatites (HAPm-T) of varying molar Ca/P ratios m (1.58–1.69) and calcination temperatures T (360–700 °C) were prepared and comprehensively characterized by nitrogen adsorption, TG, XPS, XRD, CO2-TPD, and NH3-TPD and were employed to catalyze the gas-phase dehydration of lactic acid (LA) to produce acrylic acid (AA). While the texture and crystallinity of the HAPm-T sample were affected little by variation of m, its surface acidity decreased but basicity increased with the increase in m. The HAPm-T sample with a higher T showed a higher crystallinity but lower surface area, acidity, and basicity. The conversion of LA decreased with increasing either m or T of the HAPm-T catalyst; the selectivity for AA maximized at m = 1.62 but decreased steadily with the T increase. The HAP1.62-360 sample (m = 1.62, T = 360 °C) was identified as the most efficient catalyst, offering an AA yield as high as 50–62% for longer than 8 h (AA selectivity: 71–74 mol %) under optimized reaction conditions (360 °C, WHSVLA= 1...
TL;DR: In this paper, a pH-responsive poly(ether sulfone) (PES) composite membrane with amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) diblock copolymers is fabricated through simple phase inversion in water.
TL;DR: In this article, the graft copolymerization reaction of acrylic acid onto maize starch was investigated and the results showed that the adsorption efficiency is affected by the adsorbent graft yield and the medium temperature.
Abstract: In this paper, potassium bromate/thiourea dioxide redox system was used to initiate the graft copolymerization reaction of acrylic acid onto maize starch. The so obtained polyacrylic acid/starch graft copolymer was crosslinked by further treatment with alkaline epichlorohydrin to get three dimensional hydrogel. This crosslinked hydrogel was used for the removal of the heavy element, Cd2+ from its aqueous solution by adsorption. All factors which are expected to affect the adsorption process, like adsorbent concentration, immersion time, graft yield of the adsorbent, Cd2+ concentration and adsorption temperature were extensively studied and reported in the text. The study and investigations demonstrated that the adsorption efficiency is affected by the adsorbent graft yield and the adsorption medium temperature. In addition, on fitting the data obtained from the adsorption process, it was found that the adsorption obeys both Langmuir and Freundlich adsorption isotherms but the Langmuir isotherm shows better mathematical fitting for the equilibrium data than does Freundlich model, based on the higher R2 value for the Langmuir isotherm.
TL;DR: The results showed that the thermal reaction product of acrylic acid with chitosan might form N-carboxyethyl grafted and amide-linked polymer and this product could absorb water 644 times its own dry weight.
TL;DR: In this article, different mass fractions of antimony trioxide filler, Sb2O3, are added into poly(acrylic acid) (PAA)-based polymer electrolytes with N-lithiotrifluoromethane sulphonamide [LiN(SO2CF3)2] (LiTFSI) as doping salt.
Abstract: In this work, we investigate the electrical, structural, and thermal properties of composite polymer electrolytes (CPEs). Different mass fractions of antimony trioxide filler, Sb2O3, are added into poly(acrylic acid) (PAA)-based polymer electrolytes with N-lithiotrifluoromethane sulphonamide [LiN(SO2CF3)2] (LiTFSI) as doping salt. Characteristics such as alternating current (AC)–impedance spectroscopy, attenuated total reflectance–Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) are analyzed. The highest ionic conductivity of (2.15 ± 0.01) × 10−4 S cm−1 is achieved at room temperature with addition of 6 wt% of fillers. The ionic transportation is further proven in a transference number study under DC polarization, whereas ATR-FTIR is employed to explore the complexation between PAA, LiTFSI, and Sb2O3. TGA reveals the improved thermal stability of CPEs. The glass transition temperature (T
g) is reduced upon addition of Sb2O3 as shown in DSC analysis.
TL;DR: The NC gels showed tunable adhesion by changing the dose of Laponite and monomer as well as the neutralization degree of AA, as determined by 180° peel strength measurement.
Abstract: Biocompatible nanocomposite hydrogels (NC gels) consisting of poly(acrylic acid) (PAA) and nanosized clay (Laponite) were successfully synthesized by in situ free-radical polymerization of acrylic acid (AA) in aqueous solutions of Laponite. The obtained NC gels were uniform and transparent. Their viscosity, storage modulus G', and loss modulus G″ increased significantly upon increasing the content of Laponite and the dose of AA, while exhibiting a maximum with increasing the neutralization degree of AA. They showed tunable adhesion by changing the dose of Laponite and monomer as well as the neutralization degree of AA, as determined by 180° peel strength measurement. The maximal adhesion was shown when reaching a balance between cohesion and fluidity. A homemade Johnson-Kendall-Roberts (JKR) instrument was employed to study the surface adhesion behavior of the NC gels. The combination of peel strength, rheology, and JKR measurements offers the opportunity of insight into the mechanism of adhesion of hydrogels. The NC gels with tunable adhesion should be ideal candidates for dental adhesive, wound dressing, and tissue engineering.
TL;DR: This article reports on the application of a high performance biodegradable adsorbent based on amylopectin and poly(acrylic acid) (AP-g-PAA) for removal of toxic malachite green dye (MG) from aqueous solution.
TL;DR: In this article, BaSO4 was found to show an efficient activity for dehydration of lactic acid to acrylic acid due to the moderate acidity on its surface, achieving a 99.8% conversion and 74.0% acrylic acid selectivity.
TL;DR: In this paper, poly(acrylic acid) was selected to prepare the bio-adhesive hydrogel adhering to mucosal surfaces using a radiation process, and the solution was then irradiated by an electron beam at up to 75 kGy to make hydrogels.
Abstract: A mucoadhesive drug delivery system can improve the effectiveness of a drug by maintaining the drug concentration and allowing targeting and localization of the drug at a specific site. Acrylic-based hydrogels have been used extensively as a mucoadhesive system owing to their flexibility and excellent bioadhesion. In this experiment, poly(acrylic acid) was selected to prepare the bioadhesive hydrogel adhering to mucosal surfaces using a radiation process. Poly(acrylic acid) was dissolved in water to a prepare poly(acrylic acid) solution, and the solution was then irradiated by an electron beam at up to 75 kGy to make hydrogels. Their physical properties, such as gel percent, swelling percent and adhesive strength to mucosal surfaces, were investigated. Triamcinolone acetonide was used as a model drug. The dried poly(acrylic acid) film was dipped in a 0.1 wt% triamcinolone acetonide solution in ethanol, and then dried at 25 °C. The release of triamcinolone acetonide was determined at different time intervals, and UV (Ultraviolet)-Vis spectroscopy was used to determine the released concentration of triamcinolone acetonide at 238 nm. It was shown that poly(acrylic acid)-based drug carriers were successfully prepared for use in a bioadhesive drug delivery system.
TL;DR: In this article, a solution-based graft copolymerization of acrylic acid monomers on the canola protein backbones in the presence of a crosslinker (N,N′-methylenebis (acrylymide)) and initiators (sodium bisulfite and potassium persulfate).
TL;DR: In this paper, the optimal control of the two consecutive steps of acid-catalysed glycerol dehydration into acrolein and aldehyde oxidation into acrylic acid, and of the parallel reaction of acro-in transformation into by-products (ketals and oligomers), was achieved in the presence of a defined glycerolis-to-oxygen inlet ratio.
Abstract: We report on a study of the key reaction parameters in glycerol oxidehydration into acrylic acid over W–V–Nb mixed oxides with a hexagonal tungsten bronze structure. This investigation demonstrated that the optimal control of the two consecutive steps of acid-catalysed glycerol dehydration into acrolein and aldehyde oxidation into acrylic acid, and of the parallel reaction of acrolein transformation into by-products (ketals and oligomers), was achieved in the presence of a defined glycerol-to-oxygen inlet ratio. Indeed, oxygen played the fundamental role of accelerating the oxidation of the intermediately formed acrolein into acrylic acid, by allowing a greater concentration of the oxidizing V5+ sites. In fact, an unprecedented higher yield to acrylic acid and acrolein compared to W–V bronzes was registered (maximum acrylic acid yield 50.5%) together with an increase of more than one order of magnitude in productivity, because of both the greater concentration of glycerol used in the inlet feed and the lower contact time needed. Further experiments were carried out by reacting acrolein and methanol in oxidative conditions, the latter as a model molecule for the determination of surface acid and redox properties.
TL;DR: Vanadium phosphorus oxides (VPOs) fabricated by employing poly ethylene glycol (PEG) additive were used as catalysts for efficient conversion of acetic acid (methyl acetate) and formaldehyde to acrylic acid(methyl acrylate) as mentioned in this paper.
TL;DR: Interpenetrating network (IPN) type hydrogels of a biopolymer and a synthetic polymer were prepared from chitosan and crosslink copolymer of acrylic acid, sodium acrylate and hydroxyethyl methacrylate to study the swelling and diffusion characteristics, network parameters and adsorption of cationic methyl violet and anionic congo red dyes.
TL;DR: In this paper, a three-step modification process was performed to attach a reversible addition-fragmentation chain transfer (RAFT)-agent onto the GO surface and obtain GO-RAFT nanosheets.
Abstract: Natural graphite was oxidized via the Hummer's method and sonicated to obtain graphene oxide (GO). A three-step modification process was performed to attach a reversible addition–fragmentation chain transfer (RAFT)-agent onto the GO surface and obtain GO-RAFT nanosheets. RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) was performed by using azobisisobutyronitrile (AIBN) as initiator. After separation of free chains, GO-P(HEMA) and GO-P(HEMA-co-AA) were obtained. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) analysis, Raman spectroscopy, proton nuclear magnetic resonance (1H NMR), size exclusion chromatography (SEC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure of modified nanosheets. These modified nanosheets showed dual pH- and thermo-sensitive properties as measured by UV-visible spectroscopy. Due to the dark nature of GO-P(HEMA) and GO-P(HEMA-co-AA) nanosheets, the UV-visible absorption of their solutions is an effective parameter to examine the stimuli responsive behavior as measured here at different pH (3–12) and temperature (25–55 °C) values. According to the results, UV-visible absorption of GO-P(HEMA) decreases slightly as pH decreases while the decrease is more significant for GO-P(HEMA-co-AA). Also, a lower critical solution temperature (LCST) of 30 and 34 °C is observed for GO-P(HEMA) and GO-P(HEMA-co-AA) nanosheets respectively.
TL;DR: In this paper, carbonaceous materials (CM-SO 3 H, CM-COOH) were prepared and functionalized in a single step with SO 3 H or COOH groups by hydrothermal carbonization of glucose in the presence of sulfosalicylic acid or acrylic acid as co-monomer.
TL;DR: In this article, the adsorption of Zn2+, Co2+ and Mn2+ ions onto polyvinyl alcohol and acrylic acid (AAc) copolymerized in different compositions using gamma irradiation was investigated.
TL;DR: In this article, the authors describe the preparation of porous polymeric scaffolds via polymerization of the oil phase in high internal phase water-in-oil-emulsions using amphiphilic block copolymers.
Abstract: We describe the preparation of porous polymeric scaffolds via polymerization of the oil phase in high internal phase water-in-oil-emulsions using amphiphilic block copolymers polystyrene-b-poly(ethylene oxide), polystyrene-b-poly(acrylic acid), poly(1,4-butadiene)-b-poly(ethylene oxide), and poly(1,4-butadiene)-b-poly(acrylic acid) as surfactants. We show that the block copolymers anchor to the polymerized oil phase via the lipophilic block, which can occur by chemical and/or physical entanglement and consequent presentation of the hydrophilic block on the pore surfaces. The in situ polymerization enables the full surface functionalization of the porous materials with the final surface chemistry dictated by the hydrophilic block. Furthermore, the foam physical architecture may be tailored through controlling emulsion parameters such as the initiator, shear rate, and aqueous phase volume fraction.