Showing papers on "Acrylic acid published in 1996"
TL;DR: In this paper, the insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt % and the micelle cores, formed by aggregation of the PS blocks, were generally monodisperse.
Abstract: Crew-cut micelle-like aggregates of various morphologies prepared from polystyrene-b-poly(acrylic acid), PS-b-PAA, diblock copolymers under near-equilibrium conditions, were studied by transmission electron microscopy (TEM). The insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt %. In spherical micelles, the micelle cores, formed by aggregation of the PS blocks, were generally monodisperse. A comparison between star and crew-cut micelles showed that the latter are distinguished by a low density of corona chains on the core surface and a low degree of stretching of the PS blocks in the cores. As the PAA content in block copolymer decreased, the morphology of the aggregates changed progressively from spheres to cylinders, to bilayers (both vesicles and lamellae), and eventually to compound micelles consisting of an assembly of inverted micelles surrounded by a hydrophilic surface. The compound micelles are believed to be a new morphology for block copolymers. The addition of homopolysty...
1,167 citations
TL;DR: In this article, the thermal decomposition of biologically degradable polymer poly(lactic acid) (PLA) was investigated by means of several thermoanalytical techniques: thermogravimetric, differential scanning calorimetry, time resolved pyrolysis-MS and pyrolynsis-GC/MS.
532 citations
TL;DR: In this article, cloud-point data to temperatures of 270 °C and 3000 bar are presented for CO2 with the family of poly(acrylates) including methyl, ethyl, propyl, butyl, poly(butyl methacrylate), with poly(vinyl acetate), with statistically random copolymers of poly (ethylene-co-methyl acrylate) with 41, 31, and 18 mol % acrylated, with poly (tetrafluoroethylene)-co-hexafluoropropylene)
Abstract: Cloud-point data to temperatures of 270 °C and 3000 bar are presented for CO2 with the family of poly(acrylates) including methyl, ethyl, propyl, butyl, ethylhexyl, and octadecyl, with poly(butyl methacrylate), with poly(vinyl acetate), with statistically random copolymers of poly(ethylene-co-methyl acrylate) with 41, 31, and 18 mol % acrylate, with poly(tetrafluoroethylene-co-hexafluoropropylene) and poly(vinylidene-co-hexafluoropropylene) copolymers, each with ∼20 mol % hexafluoropropylene, and with Teflon AF. Over the same range of conditions, CO2 cannot dissolve polyethylene, poly(acrylic acid), poly(methyl methacrylate), poly(ethyl methacrylate), polystyrene, poly(vinyl fluoride), or poly(vinylidene fluoride). CO2 is a weak solvent that exhibits the temperature-sensitive characteristics observed with polar solvents. The solubility of a nonpolar hydrocarbon polymer or a copolymer in CO2 can be increased by at least partially fluorinating the polymer or by incorporating some polar groups into the backb...
411 citations
TL;DR: In this article, the morphology of crew-cut aggregates of amphiphilic block copolymers in dilute solutions can be controlled by the addition of ions in micromolar (HCl, NaOH, CaCl2, Ca(Ac)2) or millimolar (NaCl) concentrations.
Abstract: The morphology of crew-cut aggregates of amphiphilic block copolymers in dilute solutions can be controlled by the addition of ions in micromolar (HCl, NaOH, CaCl2, Ca(Ac)2) or millimolar (NaCl) concentrations. The copolymers are highly asymmetric polystyrene-b-poly(acrylic acid) diblocks, PS-b-PAA, in which the lengths of the insoluble PS blocks are much longer than those of the soluble PAA blocks. In addition to spherical, rodlike, and univesicular or lamellar aggregates, large compound vesicles (LCVs), a new morphology, can be obtained from a single block copolymer. The morphogenic effect of different added ions on the crew-cut aggregates can be ascribed to the changed repulsive interactions among the hydrophilic PAA segments, due to neutralization by NaOH, protonation by HCl, ion-binding or bridging by Ca2+, and electrostatic screening by NaCl, respectively. The formation of the LCVs may involve a secondary aggregation of individual vesicles and a subsequent fusion process. Some features of the sponta...
367 citations
TL;DR: Aqueous colloidal microgels have been prepared, based on poly(N-isopropylacrylamide)[poly(NIPAM)], cross-linked with bisacryamide, containing 5% w/w acrylic acid (AAc) as a comonomer as discussed by the authors.
Abstract: Aqueous colloidal microgels have been prepared, based on poly(N-isopropylacrylamide)[poly(NIPAM)], cross-linked with bisacrylamide, containing 5% w/w acrylic acid (AAc) as a comonomer. Transmission electron micrographs of the microgels show that the copolymer microgels are monodisperse spheres. The size of the microgel particles containing 5% AAc has been studied, using dynamic light scattering, as a function of pH (3–10), ionic strength (10–4–10–1M NaCl) and temperature (20–75 °C). The hydrodynamic diameter of the copolymer microgels decrease both with increasing ionic strength (at pH 6 and 25 °C) and reversibly with increasing temperature at pH values of 2.6, 3.4 and 6.5. However, under isothermal conditions in 10–3M NaCl at 25 °C, the hydrodynamic diameter increases in going from pH 3.3–9.4. In addition, the temperature-induced conformational changes in the polymer chains have been followed using high-sensitivity differential scanning calorimetry (HSDSC). A comparison is made with the behaviour of poly(NIPAM) microgel particles, not containing AAc. Explanations are offered to account for the pronounced difference in the physico-chemical properties observed.
287 citations
TL;DR: Several morphologies of crew-cut aggregates have been prepared from highly asymmetric diblock copolymers of polystyrene-b-poly(ethylene oxide) (PS-B-PEO) as mentioned in this paper.
Abstract: Several novel morphologies of “crew-cut” aggregates have been prepared from highly asymmetric diblock copolymers of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) and polystyrene-b-poly(acrylic acid...
252 citations
TL;DR: In this article, an angle-resolved X-ray photoelectron spectroscopy (XPS) was used to characterize the surface compositions and microstructures of polytetrafluoroethylene (PTFE) films.
Abstract: Argon plasma-pretreated polytetrafluoroethylene (PTFE) films were subjected to further surface modification by near-UV light-induced graft copolymerization with acrylic acid (AAc), sodium salt of styrenesulfonic acid (NaSS), and N,N-dimethylacrylamide (DMAA). The surface compositions and microstructures of the modified films were characterized by angle-resolved X-ray photoelectron spectroscopy (XPS). A stratified surface microstructure with a significantly higher substrate-to-graft chain ratio in the top surface layer than in the subsurface layer was always obtained for PTFE surface with a substantial amount of the hydrophilic graft. The stratified surface microstructure was consistent with the observed hysteresis in advancing and receding water contact angles. The graft yield increased with Ar plasma pretreatment time and monomer concentration. Covalent immobilization of trypsin on the AAc polymer-grafted PTFE films was facilitated by water-soluble carbodiimide (WSC). The effective enzyme activities incr...
214 citations
TL;DR: In this paper, poly(acrylic acid), poly(vinylsulfonate) and poly(styrenesulfonates) have been incorporated between the positively charged sheets of layered double hydroxides (LDHs) to form layered nanocomposites.
Abstract: Poly(acrylic acid), poly(vinylsulfonate) and poly(styrenesulfonate) have been incorporated between the positively charged sheets of layered double hydroxides (LDHs)M1–xAlx(OH)2+(M = Mg, Ca, Co) and Zn1–xM′x(OH)2+(M′= Al, Cr) to form layered nanocomposites. The resulting nanocomposites contained the LDH sheet structures separated by 7.6–16.0 A, which is sufficient to accommodate polymer bilayers between the LDH sheets. Preparations were carried out in deaerated aqueous base by a template reaction, involving the formation and precipitation of nanocomposites from metal nitrate-salt precursors in the presence of the dissolved polymer. Structural and compositional details were provided by X-ray diffraction (XRD), FTIR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) and thermogravimetry (TG). Scanning electron microscopy (SEM) indicates that the nanocomposition of LDHs with ionomers significantly alters the particle microstructure from that of the LDH carbonates derived from aqueous precipitation.
198 citations
160 citations
TL;DR: In this article, the influence of possible solute binding on the transport process through polymeric networks of poly(vinyl alcohol) and poly(acrylic acid) at pH 3 or 6 was investigated.
Abstract: Solute transport through interpenetrating polymeric networks of poly(vinyl alcohol) and poly(acrylic acid) at pH 3 or 6 was studied in order to investigate the influence of possible solute binding on the transport process through the networks. Diffusion of theophylline, vitamin B12, and myoglobin was analyzed, and diffusion and partition coefficients were determined. Analysis using the free volume-based theory of Peppas and Reinhart indicated that solute binding occurred only in those hydrogels that were in the ionized state. ATR-FTIR spectroscopic studies were used to determine the level of binding in the case of myoglobin in contact with these IPN hydrogels.
141 citations
TL;DR: In this paper, the authors demonstrate that mini-emulsion polymerization is the preferred process, probably because of mass transport limitations of the alkyd in the conventional emulsion polymerisation reactions.
Abstract: Emulsion and miniemulsion copolymerizations were carried out with acrylic monomers (methyl methacrylate, butyl acrylate, and acrylic acid) in the presence of an alkyd resin. Poly(methyl methacrylate) was used as a hydrophobe or cosurfactant in the miniemulsion reactions. The results demonstrate that miniemulsion polymerization is the preferred process, probably because of mass transport limitations of the alkyd in the conventional emulsion polymerization reactions. The monomer emulsions prepared for the miniemulsion reactions were much more stable and the polymerizations were free of coagulum. Reaction rates, particle size characteristics, grafting efficiencies, and some film properties were measured. © 1996 John Wiley & Sons, Inc.
TL;DR: In this paper, the swelling behavior of novel pH and temperature-sensitive interpenetrating polymer networks (IPNs) composed of polyvinyl alcohol (PVA) and poly(acrylic acid) (PAAc) in water was investigated.
Abstract: The swelling behavior of novel pH- and temperature-sensitive interpenetrating polymer networks (IPNs) composed of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAAc) in water was investigated. The PVA/PAAc IPN hydrogels were synthesized by UV irradiation, followed by a repetitive freezing and thawing process by which PVA hydrogel networks were formed inside of cross-linked PAAc chains. The swelling behaviors of these IPNs were analyzed in buffer solution at various pH and temperature ranges. Swelling ratios of all IPNs were relatively high, and they showed reasonable sensitivity to both pH and temperature. Hydrogels showed both the positive and negative swelling behaviors depending on PAAc content. IPN46 showed the positive temperature-sensitive swelling behaviors and its stepwise changes in swelling ratio was about 1.8 and 2.0 obtained between 25 and 45°C at pH 7, and between pH 4 and 7 at 35°C, respectively. The positive temperature dependence is attributed to the formation and dissociation of hydrogen bonding complexes between PVA and PAAc. These IPNs are expected to show a pH- and temperature-sensitive drug release according to the stepwise behavior at this temperature region. © 1996 John Wiley & Sons, Inc.
TL;DR: In this article, the authors synthesize surface-grafted, hyperbranched poly(acrylic acid) (PAA) films on self-assembled organomercaptan monolayers.
Abstract: In this paper we report the preparation of thin films of new highly branched polymers which are relevant to boundary layer phenomena such as adhesion, wetting, and chemical sensing. Specifically, we synthesized surface-grafted, hyperbranched poly(acrylic acid) (PAA) films on self-assembled organomercaptan monolayers. These films grow in discrete steps, but unlike most layer-by-layer approaches, film thickness increase nonlinearly as a function of the number of layers because of the branched polymer architecture. Moreover, these polymer films contain a high density of carboxylic acid groups, which can selectively bind metal ions or serve as reactive sites for subsequent derivatization. Hyperbranched polymer films thus provide new platforms for chemical sensing applications and for tailoring polymer surface properties for a wide variety of technological applications. 24 refs., 4 figs.
TL;DR: In this paper, the role of hydrophobic effect in polyelectrolyte gel/ionic surfactant interactions was investigated and a series of poly(acrylic acid) gels with well-controlled hydrophob...
Abstract: The role of the hydrophobic effect in polyelectrolyte gel/ionic surfactant interactions was investigated. A series of hydrophobically modified poly(acrylic acid) gels with well-controlled hydrophob...
TL;DR: In this paper, the authors define the polymer structure and elucidate the swelling behavior of ionizable hydrophilic polymers (hydrogels) in water and buffered media, and demonstrate the significance of the swelling medium pH on the hydrated state of the polymers relative to crosslinking or copolymerization composition.
Abstract: SYNOPSIS The purpose of this investigation was to define the polymer structure and elucidate the swelling behavior of ionizable hydrophilic polymers (hydrogels) in water and buffered media. Poly(acry1ic acid) (PAA) and poly(acry1ic acid-co-2-hydroxyethyl methacrylate) [P(AA-coHEMA)] hydrogels were synthesized with varying degrees of hydrophilicity and crosslinking and were designed as potential bioadhesive controlled-release dosage forms. The thermal initiation procedure employed during polymerization was optimized to eliminate unreacted residuals. Equilibrium and dynamic swelling studies were undertaken to determine the polymer mesh size and molecular weight between crosslinks of the hydrogels in the ionized and nonionized states. The PAA hydrogel mesh sizes ranged from 100 to 400 8, over pH values of 3-7, whereas the P(AA-co-HEMA) hydrogel mesh sizes were between 13 and 140 A. These results demonstrated the significance of the swelling medium pH on the hydrated state of the polymers relative to crosslinking or copolymerization composition. 0 1996 John Wiley & Sons, Inc.
TL;DR: In this article, a solution copolymerization of acrylonitrile with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using α,α′-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012-0.092 mol %.
Abstract: Solution copolymerization of acrylonitrile (AN) with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using α,α′-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012–0.092 mol %. Copolymers were characterized by FTIR, CHN analysis, 1H-and 13C-NMR, and viscometry. The reactivity ratios were calculated using Fineman–Ross and Kelen–Tudos methods. In all three systems, the value of r1 (AN) is much less than the value of r2. However, the r2 (MAA) is higher than r2 of (AA) and (IA). The reactivity ratios were calculated using Q and e schemes also. The results are in good agreement with experimentally calcualted data. The tacticity and sequence length distribution of these copolymers were calculated using 13C-NMR from CN and CH signals. It was observed that the isotacticity of acrylonitrile–itaconic acid copolymer P(AN–IA) with 8.2 mol % of a comonomer is lower than that of P(AN–MAA) with 10.3 mol % and P(AN–AA) with 7.61 mol %. © 1996 John Wiley & Sons, Inc.
TL;DR: In this paper, X-ray photoelectron spectroscopy (XPS), IRAS, and static secondary ion mass spectrometry (SIMS) were used to characterize acrylic polymers of acrylic (propenoic) acid and propanoic acid.
Abstract: Plasma polymers of acrylic (propenoic) acid and propanoic acid were prepared from inductively coupled, radio-frequency-induced plasmas excited in vapors of the starting materials. The plasma polymers were characterized by X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRAS), and static secondary-ion mass spectrometry (SIMS). Detailed interpretation of the spectra allows determination of the distribution of chemical functionalites at the surface of the product and of the influence of unsaturation and plasma power on this distribution. The results are discussed in the context of previously proposed mechanisms of plasma polymerization of the compounds under investigation.
TL;DR: In rebinding assays and enzyme activity tests, a specific binding capacity for glucose oxidase of up to 0.557 microgram GOD/100 mg dry weight of polymer particles could be determined and have the potential to be used as specific separation or detection material.
Patent•
26 Apr 1996
TL;DR: In this article, a ready-mixed setting-type joint compound is proposed for the use of calcium sulfate hemihydrate, water, and a set-retarding agent.
Abstract: A process for the production of a ready-mixed setting-type joint compound includes the use of calcium sulfate hemihydrate, water, and a set-retarding agent. The retarder includes a polymer composition including acrylic acid and acrylamide monomer units, for example a copolymer (or a mixture of copolymers) of acrylic acid and acrylamide or a blend of a homopolymer of acrylic acid and a homopolymer of acrylamide. The joint compound can be combined with an accelerator including a metallic salt. The joint compound of the invention can be formulated either as a lightweight joint compound or as a conventional weight joint compound. The joint compounds provide short setting times, reduced shrinkage, reduced preparation time, and beneficial application properties.
TL;DR: In this article, a weakly crosslinked poly(acrylic acid) is used for bioadhesive delivery systems, which is a polycarbophil (PC) that is used in bio-adhesive packages.
TL;DR: The plasma copolymerization of allyl amine with 1,7-octadiene and of acrylic acid with hexane has been investigated in this article, and it is shown to be a promising route to the fabrication of new surfaces with controlled concentrations of specific surface functionalities; in this case, amine and carboxylic acid.
TL;DR: In this article, 12-molybdophophosphates have been found to catalyze the selective oxidation of isobutane, propane, and ethane into methacrylic acid, acrylic acid, and ethene, respectively, with molecular oxygen.
Abstract: Keggin-type 12-molybdophosphates have been found to catalyze the selective oxidation of isobutane, propane, and ethane into methacrylic acid, acrylic acid, and ethene, respectively, with molecular oxygen. Cs + -, Fe 3+ -, or Ni 2+ -substitution for H + and V 5+ -substitution for Mo 6+ in H 3 PMo 12 O 40 enhanced the catalytic activity for the oxidation of propane. Among the catalysts tested Cs 2.5 Fe 0.08 H 1.26 PVMo 11 O 40 gave the highest yield of acrylic acid: 13%. It was suggested by IR, XRD, TG-DTA data that the Keggin structure was maintained during the oxidation.
TL;DR: In this article, the authors show that Acrylamide (AM)/acrylic acid (AA) copolymers and AM/AA/N-(4-hexylphenyl)acrylamides (HPAM, 0.5 mol %) terpolymers with varied AA content have been synthesized by micellar copolymerization.
Abstract: Acrylamide (AM)/acrylic acid (AA) copolymers and AM/AA/N-(4-hexylphenyl)acrylamide (HPAM, 0.5 mol %) terpolymers with varied AA content have been synthesized by micellar copolymerization. Co- and terpolymers with 5−37 mol % AA and similar hydrodynamic volumes were prepared. Solution viscosity studies of the copolymers as a function of pH and copolymer concentration in deionized water and NaCl solution indicate normal polyelectrolyte behavior. In aqueous solutions, intra- or intermolecular hydrophobic associations may be favored by variation of terpolymer composition. Three-dimensional plots of both I3/I1 (from pyrene probe fluorescence) and viscosity as functions of pH and terpolymer concentration demonstrate the responsive nature of associations in water and in 0.5 M NaCl. Terpolymers containing approximately 9 and 21 mol % AA exhibit intermolecular (open) associations at ≤pH 5 and in the presence of NaCl. The terpolymer containing approximately 37 mol % AA, however, exhibits no intermolecular associatio...
TL;DR: The use of amino acid-modified acrylic monomers to produce water soluble copolymers of acrylic-itaconic acid offers a new route of discovery to produce chemical-cured glass ionomers with improved physical properties.
TL;DR: In this article, the interactions of propanoic acid, acrylic acid, acrolein and methylmethacrylate (MMA) with Pt(111) at 95 K were examined to identify the nature of the interactions on this surface.
TL;DR: In this article, a transition from a lamellar to two different types of modulated-lamellar phases with a different cubic packing of undulations is observed, and the behavior of these copolymers was analyzed by scattering of synchrotron radiation as well as with DSC.
Abstract: Copolymers of N-alkylacrylamide and ionic monomers which are complexed with surfactants represent a new type of highly ordered, solid mesomorphous materials where thermomechanical behavior as well as the phase structure can be adjusted to customer-specific demands. One synthetic route toward such complexes lies in a polymer-analogous amidation of poly(acrylic acid) with tetradecylamine to various extents and subsequent complexation with cetyltrimethylammonium counterions. The behavior of these copolymers was analyzed by scattering of synchrotron radiation as well as with DSC. In these experiments, a transition from a lamellar to two different types of modulated-lamellar phases with a different cubic packing of undulations is observed. In a second set of experiments, similar materials were made by copolymerization of N-octadecylacrylamide and sodium 2-acrylamido-2-methyl-1-propanesulfonate and subsequent complexation of cetyltrimethylammonium counterions. The different copolymers in the series are characte...
Patent•
08 Mar 1996
TL;DR: In this article, a process for preparing acrolein or acrylic acid or a mixture thereof from propane, in which the propane is initially dehydrogenated under heterogeneous catalysis to give propene, secondary components are removed and the remaining gas mixture, comprising propane and propene is subjected to the heterogeneously catalyzed partial oxidation.
Abstract: A process for preparing acrolein or acrylic acid or a mixture thereof from propane, in which the propane is initially dehydrogenated under heterogeneous catalysis to give propene, secondary components are removed and the remaining gas mixture, comprising propane and propene, is subjected to the heterogeneously catalyzed partial oxidation to acrolein or acrylic acid or a mixture thereof as the target product, target product is removed from the product gas mixture and the remaining residual gas, comprising excess oxygen and unconverted propane, is recycled into the propane dehydrogenation in such a way that the other propane fed to the dehydrogenation is at least partly converted under dehydrogenating conditions at the recycle point.
TL;DR: PVDF membrane with 30 s plasma exposure and subsequently grafted with acrylic acid (AA-3) showed the greatest O1s/F1s area ratio in XPS spectra and its graft density and degree of polymerization were the largest among the graft membranes.
Abstract: Acrylic acid was grafted onto the surface of commercial poly(vinylidene fluoride) (PVDF) membrane using plasma polymerization techniques. Graft reaction was confirmed by X-ray photoelectron spectroscopy (XPS) spectra and attenuated total reflectance Fourier transform infrared spectra. Grafting rate was dependent on plasma exposure time. For argon plasma at 30 W, grafting rate decreased after maximum rate was observed at 30 s exposure. PVDF membrane with 30 s plasma exposure and subsequently grafted with acrylic acid (AA-3) showed the greatest O1s/F1s area ratio in XPS spectra. Thus its graft density and degree of polymerization were the largest among the graft membranes. Permeation of riboflavin through all poly(acrylic acid)-g-PVDF membranes showed a decrease in permeability of riboflavin in pH 4–5. © 1996 John Wiley & Sons, Inc.
Patent•
03 Jun 1996
TL;DR: In this article, pressure sensitive and heat activatable adhesives are defined as the reaction product of an acrylic acid ester of a monohydric alcohol whose homopolymer has a Tg less than 0 °C; a non-polar ethylenically unsaturated monomer with a solubility parameter no greater than 10.50 and Tg greater than 15 °C.
Abstract: Pressure sensitive adhesives and heat activatable adhesives that are the reaction product of an acrylic acid ester of a monohydric alcohol whose homopolymer has a Tg less than 0 °C; a non-polar ethylenically unsaturated monomer whose homopolymer has a solubility parameter of no greater than 10.50 and a Tg greater than 15 °C; 0-5 parts by weight of a polar ethylenically unsaturated monomer whose homopolymer has a solubility parameter of greater than 10.50 and a Tg greater than 15 °C; and an electrically conductive agent.
TL;DR: In this article, the interpolymer complexation, through successive hydrogen bonding, between poly(acrylamide) (PAAm) and poly(N-isopropylacryamide)(PNiPAA) with poly (acrylic acid) (PA) in aqueous solution has been viscometrically and potentiometrically investigated.
Abstract: The interpolymer complexation, through successive hydrogen bonding, between poly(acrylamide) (PAAm) and poly(N-isopropylacrylamide) (PNiPAAm) with poly(acrylic acid) (PAA) in aqueous solution has been viscometrically and potentiometrically investigated. The stoichiometry of the complexes formed was determined. By comparing the strength of the two complexes the very important contribution of the hydrophobic interaction in their formation has been indicated.