Showing papers on "Acrylic acid published in 2012"
TL;DR: A series of novel graphene oxide (GO)/poly(acrylic acid-co-acrylamide) super-absorbent hydrogel nanocomposites were prepared by in situ radical solution polymerization as discussed by the authors.
276 citations
TL;DR: Experimental results revealed that the CS/PAA- MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorbent of Cu(II) ions, which indicated the significant separability of the MCM in the aqueous suspensions.
254 citations
TL;DR: In this paper, a 24−1 fractional factorial design was employed to evaluate the effect of acrylic acid/chitosan molar ratio, crosslinker, initiator, and filler in the swelling capacity of hydrogel composites.
226 citations
TL;DR: A facile, template-free synthetic route is reported toward poly(ionic liquid) complexes (PILCs) which for the first time exhibit stable micro-/mesoporous structure.
Abstract: A facile, template-free synthetic route is reported toward poly(ionic liquid) complexes (PILCs) which for the first time exhibit stable micro-/mesoporous structure. This is accomplished via in situ ionic complexation between imidazolium-based PILs and poly(acrylic acid) in various alkaline organic solvents. The PILC can be highly loaded with copper salts and can be used as a catalytic support for effective aerobic oxidation of activated hydrocarbons under mild conditions.
165 citations
TL;DR: In this paper, the removal of cationic dyes from water solution by adsorption with magnetic nanoparticles (MNPs) modified with 3-aminopropyltriethoxysilane and copolymers of acrylic acid and crotonic acid was explored.
150 citations
TL;DR: In this article, the surface of a highly crystalline MoVTeNb oxide catalyst for selective oxidation of propane to acrylic acid composed of the M1 phase has been studied by infrared spectroscopy, microcalorimetry, and in-situ photoelectron spectrography.
143 citations
TL;DR: In this article, a low-cost and eco-friendly cellulose-based superabsorbent was successfully prepared from flax yarn waste using a free-radical graft copolymerization of AA and AM onto a cellulose backbone in a homogeneous aqueous solution.
138 citations
TL;DR: In this paper, a series of nanocomposite hydrogels based on cellulose nanocrystals (CNCs) and poly(acrylic acid) (PAA) have been synthesized by in situ free radical polymerization within an aqueous medium.
Abstract: A novel series of nanocomposite hydrogels based on cellulose nanocrystals (CNCs) and poly(acrylic acid) (PAA) have been synthesized by in situ free radical polymerization within an aqueous medium. Rheological measurements were applied to monitor the gelation process and results indicated that the gelation took place as monomers (acrylic acid, AA) grafted from the CNC surface and PAA chains entangled to produce flexible CNC–PAA gels. By tailoring the concentration of CNC (CCNC) over a wide range of 0.02–1 wt%, two critical CCNC, C* and C**, were found which corresponded to polymer chains that occurred in overlapping entanglements and promoted conformational rearrangements on the basis of earlier gel precursors, respectively. The formation mechanism of CNC based nanocomposite hydrogels, in which the nanoparticles transformed from the isolated state below C* to the spatially continuous percolation structure above C**, was proposed. The CNC–PAA gels exhibited excellent, composition-dependent mechanical properties, such as a large elongation ratio (>1100%) and high tensile strength (>350 kPa). Transmission electron microscopy (TEM) revealed that the CNCs were surrounded by grafted chains and formed inter-connected network structures, where the CNCs acted as multifunctional cross-links with an average effective functionality of 75. The mechanical measurements indicated that the increase of CCNC led to an increase in the hydrogels viscous characteristics and contributed to the energy dissipating mechanism, which was responsible for CNC–PAA gels excellent flexibility. The swelling and partial dissolution behaviors of the hydrogels were examined, focusing on the effect of CCNC on the gels characteristic partial deswelling and gel-to-sol transition. Some new chain entanglements were formed under concentrated conditions after drying treatment above the glass transition temperature (Tg) which was verified by observation of the greater tensile strength and modulus. All the results corresponded to the self-consistent network structure model for CNC–PAA gels.
131 citations
TL;DR: Poly(acrylic acid) was plasma-grafted on commercial poly(vinylidene fluoride) (PVDF) to introduce functional groups on the membrane surface that can support the nanoparticles, and it was found that plasma treatment at 100 W for 120 s followed by liquid grafting with 70% aqueous AA at 60°C for 2h maximized the number of TiO(2) binding sites.
129 citations
TL;DR: Thermodynamic study, such as enthalpy, free energy (ΔG) and entropy change (ηS) indicated that the overall adsorption process was endothermic, spontaneous and randomness.
124 citations
TL;DR: An environmentally benign and efficient route of synthesis of polyacrylic acid grafted carboxymethyl cellulose (CMC-g-PAA) is developed using microwave radiation alone to initiate the grafting reaction.
TL;DR: A new three-component bio-inspired adhesive was synthesized that is a terpolymer composed of a water-soluble segment, an interfacial adhesion segment, and a cross-linking segment that allows for rapid optimization of properties for specific applications.
Abstract: A new three-component bio-inspired adhesive was synthesized that is a terpolymer composed of a water-soluble segment, an interfacial adhesion segment, and a cross-linking segment. Strong wet adhesion properties are obtained utilizing a 3,4-dihydroxy-l-phenylalanine (DOPA) moiety. Poly(acrylic acid) provides high water solubility due to strong ionic interactions with water. An acrylic acid N-hydroxysuccinimide ester (NHS) was included in the adhesive polymer to allow rapid cross-linking with thiol-terminated, 3-armed poly(ethylene glycol) cross-linking agents. The thiol terminal poly(ethylene glycol) was designed to be bulky to avoid possible penetration of molecules to the cell and tissue. The NHS and thiol groups react within 30 s to form covalent bonds. This design allows for rapid optimization of properties for specific applications. Lap shear strength tests on wet porcine skin demonstrated a 190% increased value in adhesion strength for adhesives having the DOPA moiety. After cross-linking, adhesion w...
TL;DR: In this article, the aqueous crystallization-driven sphere-to-rod transition of poly(lactide)-b-poly(acrylic acid), PLA-b-PAA block copolymers, with a short homochiral PLA core forming block and a 10 times longer PAA corona forming block is presented.
Abstract: The aqueous crystallization-driven sphere-to-rod transition of poly(lactide)-b-poly(acrylic acid), PLA-b-PAA block copolymers, with a short homochiral PLA core forming block and a 10 times longer (in terms of degree of polymerization) PAA corona forming block is presented. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) is utilized to follow the kinetics of the transition and wide angle X-ray diffraction (WAXD) to confirm the correlation between degree of crystallinity and morphology. Studies at different concentrations and solvent mixtures provide valuable information regarding the nucleation and growth mechanism of the system, showing that the micelle dynamics are a key aspect of the assembly process. Furthermore, the in situ crystallization-driven cylinder formation during the acrylate ester hydrolysis reaction is demonstrated. Finally, we report that the micelle morphology can be switched between cylinders and spheres by facilitating or blocking the crystallization of the core block, demonstrating a simple method to control the morphology of the resultant assembly.
TL;DR: In this article, the degree of hydrolysis and molecular weight of polyvinyl alcohol (PVA) and poly(methacrylic acid) were investigated in terms of their influence on growth behavior and pH stability.
Abstract: Multilayer thin films that consist of poly(vinyl alcohol) (PVA) and weak polyacids such as poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) were prepared by hydrogen bonding interactions. Both the degree of hydrolysis and molecular weight of PVA were investigated in terms of their influence on growth behavior and pH stability. Multilayer films containing PVA and PAA could be assembled successfully only by using partially hydrolyzed PVA and low-pH solutions. By comparing films containing PAA with those containing a more strongly interacting partner, PMAA, it was shown that the extent of PVA hydrolysis becomes significant only when weak hydrogen bonding pairs such as PVA and PAA were used. pH-triggered dissolution experiments demonstrated that the degree of hydrolysis can be used as an additional parameter by which to tune the pH stability of the film. Also, the presence of an abundance of free hydroxyl and carboxylic acid groups in the multilayer allowed enhanced pH stability to be obtained by th...
TL;DR: An effective metal organic framework (MOF) catalyst (DETA-MIL-101) was prepared by grafting an electron-rich triamine functional group to the open metal sites in MIL-101 as mentioned in this paper.
Abstract: An effective metal organic framework (MOF) catalyst (DETA-MIL-101) was prepared by grafting an electron-rich triamine functional group to the open metal sites in MIL-101. The samples were characterized via XRD, FT-IR, and N2 adsorption-desorption measurements, and their N content was measured using EA. The CO2 and H2O adsorption-desorption properties were measured and compared with those of non-functionalized MIL-101. Their catalytic performances in the Knoevenagel condensation between benzaldehyde and malononitrile were examined, and the catalyst stabilities were confirmed using recycling and hot filtering experiments. Finally, the Pd2+ ions (0.5, 1.0, and 3.0 wt%) were immobilized onto the amine species that were grafted to the MIL-101 using PdCl2 and were tested for Heck reactions of the acrylic acid and iodobenzene in N,N-dimethylacetamide as a solvent with triethylamine additives as a function of time. The catalyst stability was re-established via recycling and hot filtering experiments.
TL;DR: Biodistribution studies demonstrated comparable in vivo pharmacokinetic profiles of PCB-grafted dSCKs to their PEG-conjugated counterparts, indicating that PCB-functionalized dSCks have great potential as a theranostic platform for translational research.
Abstract: Nanoparticles with tunable pharmacokinetics are desirable for various biomedical applications. Poly(ethylene glycol) (PEG) is well-known to create “stealth” effects to stabilize and extend the blood circulation of nanoparticles. In this work, poly(carboxybetaine) (PCB), a new nonfouling polymer material, was incorporated as surface-grafted coatings, conjugated onto degradable shell cross-linked knedel-like nanoparticles (dSCKs) composed of poly(acrylic acid)-based shells and poly(lactic acid) cores, to compare the in vivo pharmacokinetics to their PEG-functionalized analogues. A series of five dSCKs was prepared from amphiphilic block copolymers, having different numbers and lengths of either PEG or PCB grafts, by supramolecular assembly in water followed by shell cross-linking, and then studied by a lactate assay to confirm their core hydrolytic degradabilities. Each dSCK was also conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid macrocyclic chelators and tyramine moieties to provi...
TL;DR: In this paper, selective dehydration of glycerol to acrolein was studied at 275-400°C over medium pore zeolites (HZSM-5, HBeta, HMordenite and HY.
Abstract: Acrylic acid can be successfully produced in a single reactor via subsequent oxidation of the glycerol-dehydrated products. Selective dehydration of glycerol to acrolein was studied at 275–400 °C over HZSM-5, HBeta, HMordenite and HY. The V–Mo oxides (15–70 mol%V) on silicic acid support (20–100 wt% mixed oxides loading) were then included as a second bed for subsequent oxidation of the dehydrated products. Over the acid zeolites, acrolein and acetol are mainly generated, together with acetaldehyde, propionaldehyde, pyruvaldehyde and other oxygenates as secondary products. A complete conversion of glycerol with high selectivity to acrolein (up to 81 mol%) can be obtained when medium pore zeolites (HZSM-5) and low glycerol concentration (10–30 wt%) was used at 300 °C. A separated-sequential bed system provides high selectivity for acrylic acid with small amount of acetic acid and acetaldehyde (∼15 mol%). The catalyst with high V content promotes total oxidation of the dehydrated products to CO while that with highly dispersed V–Mo–O phases affords 98% selectivity to acrylic acid with 48% acrolein conversion.
TL;DR: By the comprehensive comparison and analysis, the anionic polymer is more conductive to decrease the interfacial tension for the tertiary oil recovery process, while the cationic polymer isMore suitable for enhancing oil recovery in high-temperature and high-mineralization oilfield.
TL;DR: In this article, poly(acrylic acid) grafted multiwall carbon nanotubes (MWCNT -g- PAA) was synthesized by using plasma techniques, and was applied as a adsorbent to remove Co(II) from aqueous solution.
TL;DR: In this paper, Mehling et al. analyzed shape stabilized polymer blends using Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) techniques and found that polymers with acid groups formed interpolymer complexes (IPCs) and miscible and immiscible IPC-PEG blends when blended with PEGs.
TL;DR: In this paper, a complex, four-layered (or quadlayered) hybrid organic-inorganic architecture exploiting the Layer by Layer assembly is proposed to promote the formation of an aromatic and stable carbonaceous structure (char), able to thermally protect cotton, polyester and their blends.
Patent•
21 Feb 2012
TL;DR: In this paper, the negative electrode for a secondary battery including a negative electrode active material, a binder, and a water-soluble polymer, a copolymer containing 15% to 50% of an ethylenically unsaturated carboxylic acid monomer unit, 30% to 70% of a (meth)acrylic acid ester unit, and 0.5% to 10% of fluorine-containing (mETHCARO-IC ester monomer units, is used as the water soluble polymer.
Abstract: In a negative electrode for a secondary battery including a negative electrode active material, a binder, and a water-soluble polymer, a copolymer containing 15 wt % to 50 wt % of an ethylenically unsaturated carboxylic acid monomer unit, 30 wt % to 70 wt % of a (meth)acrylic acid ester monomer unit, and 0.5 wt % to 10 wt % of a fluorine-containing (meth)acrylic acid ester monomer unit is used as the water-soluble polymer.
TL;DR: A wheat straw-based superabsorbent was prepared by graft copolymerization of acrylic acid, acrylic amide and dimethyl diallyl ammonium chloride onto the cellulose of wheat straw, and its swelling and deswelling behavior was investigated.
TL;DR: In this paper, the authors investigated the catalysts for the one-pot oxidehydration of glycerol into acrylic acid and showed that the incorporation of Nb in the tri-component bronze structure allowed them to obtain the best acrylic acid yield of 34%.
TL;DR: An enhanced method to form stable dispersions of medium-sized silicon nanoparticles for solar cell applications by thermally induced grafting of acrylic acid to the nanoparticle surface is presented.
Abstract: We present an enhanced method to form stable dispersions of medium-sized silicon nanoparticles for solar cell applications by thermally induced grafting of acrylic acid to the nanoparticle surface. In order to confirm their covalent attachment on the silicon nanoparticles and to assess the quality of the functionalization, X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier spectroscopy measurements were carried out. The stability of the dispersion was elucidated by dynamic light scattering and Zeta-potential measurements, showing no sign of degradation for months.
Posted Content•
TL;DR: The excellent agreement between the predicted and the measured amounts of adsorbed dyes suggests that most carboxylates participate to the complexation and adsorption mechanisms.
Abstract: In this work, 6 to 12 nm iron oxide nanoparticles were synthesized and coated with poly(acrylic acid) chains of molecular weight 2100 g/mol. Based on a quantitative evaluation of the dispersions, the bare and coated particles were thoroughly characterized. The number densities of polymers adsorbed at the particle surface and of available chargeable groups were found to be 1.9 +/- 0.3 nm-2 and 26 +/- 4 nm-2, respectively. Occurring via a multi-site binding mechanism, the electrostatic coupling leads to a solid and resilient anchoring of the chains. To assess the efficacy of the particles for pollutant remediation, the adsorption isotherm of methylene blue molecules, a model of pollutant, was determined. The excellent agreement between the predicted and measured amounts of adsorbed dyes suggests that most carboxylates participate to the complexation and adsorption mechanisms. An adsorption of 830 mg/g was obtained. This quantity compares well with the highest values available for this dye.
TL;DR: In this paper, a pulsed-arc atmospheric pressure plasma jet was used to grow polyacrylic acid thin films for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR-3).
Abstract: Polyacrylic acid thin films have been deposited by an original and fast technique to grow organic coatings: a pulsed-arc atmospheric pressure plasma jet. Liquid acrylic acid was introduced in the nitrogen plasma jet and OES was used to measure the fragmentation of the precursor. The films were characterized by XPS, FTIR and SEM analyses before and after soaking in water. The water stability was also investigated by weight loss measurement. A high retention of carboxylic moieties, i.e. functional groups of the monomer has been observed for coatings deposited under mild conditions for the jet (low frequency and high jet speed). These films have been used for cell adhesion using human ovarian carcinoma cells (NIH:OVCAR-3). Good results have been obtained depending on the plasma parameters, showing that atmospheric pressure plasma jet is a promising technique to grow organic thin films for biomedical applications.
TL;DR: In this article, a mesoporous poly(acrylic acid)/SiO 2 composite nanofiber membranes were prepared through a sol-gel electrospinning process and the sorption behavior of malachite green on the membranes was studied.
TL;DR: In this paper, a novel type of amphiphilic ionic copolymer comprising a hydrophilic poly(acrylic acid) (PAA) block and an amphiphilic poly(acid acid)-grad-poly(styrene)(PAA-grad-PS) block was synthesized using a one step direct nitroxide-mediated polymerization (NMP).
Abstract: A novel type of amphiphilic ionic copolymer comprising a hydrophilic poly(acrylic acid) (PAA) block and an amphiphilic poly(acrylic acid)-grad-poly(styrene) (PAA-grad-PS) copolymer block was synthesized using a one step direct nitroxide-mediated polymerization (NMP). A strong influence of the macroinitiator on the values of the reactivity ratios of the co-monomers is confirmed by 1H NMR. The aggregation behaviour of the copolymers in the aqueous medium was studied by small-angle neutron scattering (SANS) and dynamic light scattering (DLS) and by transmission electron microscopy (TEM) in a wide range of pHs and ionic strengths. It has been demonstrated that PAA-b-(PAA-grad-PS) copolymers are soluble in alkaline water at room temperature without the special experimental procedures (addition of co-solvent, heating, etc.) that are usually required for solubilisation of classical PAA-b-PS diblock copolymers. The self-assembly of the PAA-b-(PAA-grad-PS) copolymers into nano-scale aggregates at low/moderate pH and/or high ionic strength was demonstrated by SANS and DLS experiments. The SANS spectra for the copolymer solution exhibit a correlation peak pointing to the formation of micelles with repulsive coronae. TEM images indicate that the micelles have an approximately spherical shape and exhibit a wide size distribution. Our results prove, that in contrast to “frozen” aggregates formed by PAA-b-PS copolymers in aqueous media, the micelles of PAA-b-(PAA-grad-PS) amphiphilic copolymers exhibit “dynamic” pH-responsive properties, i.e. they can reversibly change their aggregation number upon a variation in the pH or salinity of the solution.
TL;DR: The modified substrates using the prepared adduct showed a remarkable improvement in their sizing, hand building and/or functional properties, i.e. antibacterial, anti-UV, and self cleaning, in addition to durability to wash.