Showing papers on "Methacrylic acid published in 2001"

Polymer gels for magnetic resonance imaging of radiation dose distributions at normal room atmosphere.

Abstract: Polymer gels whose NMR and optical properties change when irradiated offer unique advantages for measuring radiation dose distributions. To date, all acrylic polymer gel dosimeters must be manufactured, stored and irradiated in hypoxic conditions which severely limits their use and stability. A new formulation of acrylic dosimeter gel has been developed that responds well in normal atmosphere and which we have named MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper). To produce dosimeter gels, an aqueous solution of gelatin, open to the atmosphere, is mixed with methacrylic acid, copper(II) ions, ascorbic acid and hydroquinone. It is believed that the copper(II) and ascorbic acid form a complex with oxygen which (with radiolysis of water) serves as a free radical source for the initiation of the polymerization of methacrylic acid. At room air the water proton spin relaxation rate R2 in MAGIC gels is proportional to absorbed dose though the precise relationship depends on the composition of the gel and the initiating complex. For example, in the range 0-30 Gy the slope of the response of R2 versus dose at 20 MHz was 0.300, 0.519 and 0.681 s(-1) Gy(-1), respectively, when the concentration of MAA was 3, 6 and 9%. The slopes increased to 0.310, 0.567 and 0.868 s(-1) Gy(-1) at 85 MHz. An important determinant of the sensitivity to detect small dose changes is shown to be the slope-to-intercept ratio of the dose-response curve. These varied from 0.08 to 0.17, comparable to hypoxic gels described earlier. MAGIC gels can be manufactured and used much more easily than the previous formulations and can be imaged by magnetic resonance imaging or optical scanning, and thus they will likely be of considerable interest to radiation physicists.

Water-Soluble Complexes Formed by Poly(2-vinylpyridinium)-block-poly(ethylene oxide) and Poly(sodium methacrylate)-block-poly(ethylene oxide) Copolymers

Abstract: Formation of interpolyelectrolyte complexes (IPEC) by mixing protonated poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) with neutralized poly(methacrylic acid)-block-poly(ethylene oxide) (PMAA-b-PEO) has been investigated in water. It was observed that (i) IPEC are formed in a limited pH range, which is controlled by the degree of ionization of the PMAA and P2VP blocks; (ii) IPEC self-assemble to form the core of monodisperse spherical micelles surrounded by a corona of PEO blocks; (iii) IPEC are salt-sensitive, falling apart above a critical salt concentration; (iv) IPEC are not observed at high pH, but micelles are formed by the P2VP-b-PEO copolymers, which contain an uncharged P2VP core surrounded by a PEO corona; (v) IPEC are not observed at low pH, but the PMAA-b-PEO diblocks aggregate into micelles, the core of which is formed by a hydrogen-bonded complex between PMAA and PEO; and (vi) these PMAA-b-PEO micelles, which are temperature-sensitive, show a complete reorganization of the mic...

Design and synthesis of superabsorbent polymers

Abstract: A series of novel copolymer superabsorbents based on the monomers acrylamide (AM), acrylic acid (AA), acrylonitrile, methacrylic acid, sodium acrylate (SA), and 2-hydroxyethyl methacrylate (HEMA) were prepared by copolymerization using ammonium persulfate as an initiator and N,N-methylenebisacrylamide as a crosslinking agent. The experimental results of superabsorbent polymers (SAPs) show that the absorbency in water and NaCl solutions is maximum for AM, SA, HEMA and AM, AA, SA combinations. The copolymers were characterized by IR spectroscopy. The water retention of soil was also enhanced using the above superabsorbents. Use of SAPs for the growth of the croton plant was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2635–2639, 2001

Effect of reaction medium on radical copolymerization of acrylonitrile with vinyl acids

Abstract: Radical polymerization of acrylonitrile (AN) with methacrylic acid (MAA) and itaconic acid (IA) was carried out in a mixture of dimethylformamide (DMF) and water at 70°C using α, α′-azobisisobutyronitrile (AIBN) as an initiator. Monomer feed in the polymerization vessel was 98:2 (AN:MAA/IA) in the molar ratio, and the DMF:H2O ratio was varied between 20:80 and 80:20 (w/w). Copolymers were characterized by FTIR, carbon, hydrogen, nitrogen elemental CHN analysis, 1H- and 13C-NMR, and viscometry. The rate of polymerization (Rp) was found to decrease with an increase in DMF concentration in the reaction medium, that is, in 20% DMF for AN–MAA system, the Rp is 1.23% min−1 in 1 h of polymerization, while in 80% DMF, Rp is reduced to 0.37% min−1. The nature of the vinyl acid also affects the Rp. It has been shown that the rate of polymerization is higher for an AN–MAA system as compared to an AN–IA system (Rp = 1.0% min−1) and the methacrylic or itaconic acid content in the copolymer increases with an increase in the DMF concentration. The MAA content in the poly(AN–MAA) polymer produced in 20% DMF is 3.2 mol %, which increases to 6.1 mol % (calculated through FTIR spectra) when DMF is increased to 80% in the reaction medium. The intrinsic viscosity [η] of the poly(AN–IA) and poly(AN–MAA) copolymers in DMF was found to be in the range of 0.67–2.90 dLg−1 depending on the reaction medium. In determining the intrinsic viscosity, a definite deviation from rectilinearity of the concentration dependence in the high-dilution region is observed, thereby demonstrating the polyelectrolyte behavior of these polymers. Through FTIR and NMR spectral studies, PAN homopolymer and other copolymers have shown the formation of a small quantity of acrylamide units. In addition copolymer P10, which contains 10.1 mol % IA, has shown anhydride formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1640–1652, 2001

Swelling behavior and thermal stability of poly(methylmethacrylate) crosslinked by the oxozirconium cluster Zr4O2(methacrylate)12

Abstract: A new isomer of the oxozirconium cluster Zr 4 O 2 (methacrylate)12 was obtained by reaction of zirconium butoxide with an excess of methacrylic acid. Contrary to the known isomer, the structure is centrosymmetric with a planar, rhombic Zr 4 core. Copolymerization with a 56-207-fold excess of methylmethacrylate results in cluster-crosslinked poly(methylmethacrylate) that swells in ethyl acetate but does not dissolve. The solvent uptake during swelling decreases and the thermal stability improves with an increasing portion of the cluster.

Dental composites reinforced with hydroxyapatite: mechanical behavior and absorption/elution characteristics.

Abstract: The purpose of this study was to analyze the behavior in water as well as the mechanical and surface properties of experimental composites designed for dental restoration. Studied materials were composed of a visible- light-cured monomer mixture as a matrix (bisphenol-a- glycidyl methacrylate with triethyleneglycol dimethacrylate or hydroxyethyl methacrylate) and either micrometric or nanometric hydroxyapatite (HA) particles as a reinforcing filler. The surface of the filler particles was modified by using different coupling agents (citric, hydroxysuccinic, acrylic, or methacrylic acid). The hydrolytic stability of the evaluated materials was studied through elution-in-water and water-uptake tests. Mechanical and surface properties were examined through the results of flexural, hardness, and surface roughness tests. Means and standard deviations were calculated for each variable. Analysis of variance and multiple comparison tests were performed. Materials con- taining bisphenol-a-glycidyl methacrylate:triethyleneglycol dimethacrylate and micrometric-HA coated with citrate, ac- rylate, or methacrylate displayed the most favorable results. Improvements should be obtained by increasing the total filler amount, and by the introduction of nanometric-HA filler into a micrometric-HA reinforced composite resin sys- tem. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 56: 297-305, 2001

Self-assembled thin film coating to enhance the biocompatibility of materials

Abstract: We make a subtrate biocompatible by contacting it with a starting material and initiating alternating charge layer electrostatic self-assembly to form a thin film. Starting materials may be poly(vinylpyrrolidone), poly{bis-(carboxylatophenoxy)phosphazene}, poly(methacrylic acid), poly(l)-lysine, poly(ethylene glycol), poly(D-glucosamine), poly(l-glutamic acid), poly(diallyldimethylamine), poly(ethylenimine), hydroxy fullerene, long-sidechain fullerene, or other polymers that participate in electrostatic self-assembly. The thin film fabrication advantageously may be at room temperature. A biocompatible thin film that is uniform and homogeneous can be provided. Optionally, ZrO2, Al2O3 or TiO2 nanoclusters also may be used in the film assembly. The film may be used in a drug delivery device or a medical device. The film may be used for tissue engineering. We also provide a biocompatible composition in which are present a plurality of layers electrostatically self-assembled from at least a polymer or fullerene asmentioned. The substrate is not particulary limited, and may be quartz, glass, plastic, metal or ceramic, a material for a bone implant, bioactive glass, polyester or other polymers, plastic or rubber tubing, bandaging material, composite material, insulator material, semi-conductor material, an artificial hip, a pacemaker, a catheter, a stent or other substrates.

Multilayer pharmaceutical product for release in the colon

Abstract: The invention relates to the use of a multilayer pharmaceutical product that substantially comprises a) a core containing a pharmaceutically active substance, b) an inner coating consisting of a copolymer or a mixture of copolymers that are composed of 85 to 98 wt.- % of radically polymerized C1 to C4 alkyl esters of the acrylic or methacrylic acid and 15 to 2 wt.- % of (meth)acrylate monomers with a quaternary ammonium group in the alkyl group, and c) an outer coating consisting of a copolymer that is composed of 75 to 95 wt.- % of radically polymerized C1 to C4 alkyl esters of the acrylic or methacrylic acid and 5 to 25 wt.- % of (meth)acrylate monomers with an anionic group in the alkyl group. The inventive product is used for producing a pharmaceutical product that releases the active substance contained therein according to the USP release test, at pH 1.2 during 2 hours and subsequent rebuffering to pH 7.0, by less than 5 % after 2.0 hours after start of the test and by 30 to 80 % after eight hours after start of the test.

Pharmaceutical dosage form with multiple coatings for reduced impact of coating fractures

Abstract: The present invention relates to a pharmaceutical composition in a solid unit dosage form for oral administration in a human or lower animal comprising: a. a safe and effective amount of a therapeutically active agent; b. an inner coating layer selected from the group consisting of poly(methacrylic acid, methyl methacrylate) 1:2, poly(methacrylic acid, methyl methacrylate) 1:1, and mixtures thereof; and c. an outer coating layer comprising an enteric polymer or film coating material; wherein the inner coating layer is not the same as the outer coating layer; wherein if the inner coating layer is poly(methacrylic acid, methyl methacrylate) 1:1 then the outer coating layer is not poly(methacrylic acid, methyl methacrylate) 1:2 or is not a mixture of poly(methacrylic acid, methyl methacrylate) 1:1 and poly(methacrylic acid, methyl methacrylate) 1:2; and wherein the inner coating layer and the outer coating layer do not contain any therapeutically active agent. This invention further relates to a method of maintaining the desired site of delivery of a therapeutic agent in the gastrointestinal tract by administering the above compositions to a human or lower animal.

Polymers designed to control nucleation and growth of inorganic crystals from aqueous media.

Abstract: Water soluble graft polymers prepared by copolymerization of either methacrylic acid (MAA) or vinylsulfonic acid (VS) with α-methoxy-ω-methacroyl-oligo(oxyethylene)s (PEO n -MA) serve to control nucleation and crystal growth during precipitation of inorganic crystals from aqueous media. Precipitation of zinc oxide crystals ('zincite') is used as example for such mineralization processes. Homogeneous and narrow crystal size distributions are obtained in presence of ppm-amounts of graft copolymers. Copolymer is incorporated into the crystals demonstrated by using latex particles with -CO 2 H-group rich surfaces as controlling additives. Incorporation of these particles leads to single crystals with pores of the size of the particles ('Swiss cheese' morphologies).

Molecular interactions in poly(methacrylic acid)/poly(N-isopropyl acrylamide) interpenetrating polymer networks

Abstract: The molecular interactions between the component networks in poly(methacrylic acid)/poly(N-isopropyl acrylamide) (PMAA/PNIPAAm) interpenetrating polymer networks (IPNs) were investigated using attenuated total reflectance (ATR)-Fourier transform IR (FTIR) spectroscopy. Hydrogen-bond formation was noted between the carboxyl groups of PMAA and the amide groups of PNIPAAm. The ATR-FTIR results showed shifts in the carboxylic and amide groups, indicating the existence of hydrogen bonding between these two individual networks within the IPNs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1077–1082, 2001

Nanoemulsions, compositions comprising such nanoemulsions, and methods of using such nanoemulsions

Abstract: The present application relates to an oil-in-water nanoemulsions which comprising an oily phase dispersed in an aqueous phase, the oil globules of which have a mean size of less than 100 nm, characterized in that it comprises at least one amphiphilic lipid chosen from nonionic amphiphilic lipids, anionic amphiphilic lipids and their mixtures and at least one anionic polymer which contains at least one hydrophobic chain and in which the weight ratio of the amount of oily phase to the amount of amphiphilic lipid ranges from 1.2 to 10. The anionic polymer can in particular be an acrylic or methacrylic acid copolymer or a 2-acrylamido-2-methylpropanesulphonic acid copolymer, in particular an acrylic or methacrylic acid terpolymer. The nanoemulsion obtained is transparent and stable on storage. It can constitute a composition for topical use and in particular for cosmetic or dermatological use, a pharmaceutical composition, or an ophthalmological composition.

Functionalization of silicone rubber for the covalent immobilization of fibronectin.

Abstract: Surface modification techniques were employed in order to provide functionalized silicone rubber with enhanced cytocompatibility Acrylic acid (AAc), methacrylic acid (MAAc) and glycidylmethacrylate (GMA) were graft-co-polymerized onto the surface of silicone induced by an argon plasma and thermal initiation The polymerizations were carried out in solution, in the case of acrylic acid a vapor phase graft-co-polymerization subsequent to argon plasma activation was carried out as well Human fibronectin (hFn), which acts as a cell adhesion mediator for fibroblasts, was immobilized by making use of the generated carboxylic or epoxy groups, respectively Surface analysis was accomplished by means of X-ray photoelectron spectroscopy (XPS), infrared spectroscopy in attenuated total reflection mode (IR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic contact angle measurements using the Wilhelmy-plate method The amount of immobilized active hFn was semiquantified by enzyme-linked immunosorbent assay (ELISA) using a structure-specific antibody against the cell-binding domain of hFn In vitro testing showed a remarkable difference between surfaces exposing adsorbed-only and surfaces with covalently immobilized hFn © 2001 Kluwer Academic Publishers

Particulate compositions and their manufacture

Abstract: A composition comprising particles which comprise a core material within a polymeric shell, wherein the core material comprises a hydrophobic substance, characterised in that the polymeric shell comprises a copolymer formed from a monomer blend which comprises, A) 30 to 90 % by weight methacrylic acid B) 10 to 70 % by weight alkyl ester of (meth)acrylic acid which is capable of forming a homopolymer of glass transition temperature in excess of 60 °C and C) 0 to 40 % by weight other ethylenically unsaturated monomer. The core material can comprise an active ingredient selected from the group consisting of UV absorbers, UV reflectors, pigments, dyes, colorants, scale inhibitors, corrosion inhibitors, antioxidants, pour point depressants, wax deposition inhibitors, dispersants, flame retardants, biocides, active dye tracer materials and phase change materials. The composition has the advantage that the polymeric shell is highly impermeable to the core material even at elevated temperatures.

Noncovalently Connected Polymeric Micelles in Aqueous Medium

Abstract: Differing from the conventional micelles made of block or graft copolymers, in which the core and corona are connected by covalent bonding, the micelles reported in this paper are composed of a polymer pair and the core and corona are connected by hydrogen bonding. Poly(styrene-co-methacrylic acid) (SMAA) and poly(vinylpyrrolidone) (PVPo) self-assembled into spherical micelles with hydrodynamic radii around 100 nm in aqueous medium. These stable micelles are composed of the core of collapsed SMAA chains and the corona of solvated PVPo chains. The hydrogen bonding between methacrylic acid and PVPo units and the difference in the solubility in water between SMAA and PVPo are the main factors responsible for the micelle formation. Using dynamic light scattering, it was found that the hydrodynamic radius of the micelles significantly increases with increasing initial concentrations of both SMAA and PVPo. The micelle size dose not depend on the MAA content (3.55−13.1 mol %) in SMAA monotonically, which can be ...

Hyperbranched polyesters and their application in dental composites: monomers for low shrinking composites

Abstract: Using trimethylolpropane (TMP) and 2,2-bishydroxymethylpropionic acid (Bis-MPA), aliphatic hyperbranched polyesters (HBP) were synthesized, with a degree of branching of DB = 0.47 and a degree of polymerization of Pn = 16.5. Aromatic HBPs with repetitive units of 2,2-bis(4-hydroxyphenyl)pivalonic acid (Bis-PVA) lead to a higher DB = 0.48 and Pn = 30.5 compared to the aliphatic HBP. Reactive functionalization of the hyperbranched polymers was achieved via esterification of mixtures of methacrylic acid and carboxylic acids. In this manner, i-butyric acid and methacryloyl terminated HBPs were obtained. They have a low viscosity ranging from 200 to 364 Pa*s and exhibit relatively low volume shrinkage (1.9 to 3.6%) during photoinitiated cure. Dental composites with volume shrinkage of 0.5 to 1.5% have been prepared using these methacryloyl terminated HBPs in combination with a Ba/alumosilicate glass filler. Copyright © 2001 John Wiley & Sons, Ltd.

Emulsion copolymerization of styrene with acrylic or methacrylic acids – distribution of the carboxylic group

Abstract: Studies on batch emulsion copolymeization of styrene with acrylic acid (AA) or methacrylic acid (MAA) were carried out. The effect of AA or MAA on the total conversion of the monomers was studied by a gravimetric method. The distribution of the carboxylic group in the copolymer microspheres was investigated by X-ray photoelectron spectroscopy and elemental analysis. The surface content of the carboxylic groups of styrene (St)/AA copolymer microspheres was found to be higher than that of St/MAA copolymer microspheres. The effects of partial neutralization of MAA in emulsifier-free emulsion copolymerization and seeded emulsion copolymerization on the distribution of the carboxylic group was also investigated.

Simultaneous multiple-point adsorption of aluminum ions and charged molecules by a polyampholyte thermosensitive gel: Controlling frustrations in a heteropolymer gel

Abstract: We report the data on concurrent multiple point adsorption of two oppositely charged species of “target molecules” (aluminum ions and 1,3,6,8-pyrenetetrasulfonic sodium salt (Py-4)) by a polyampholyte gel of N-isopropylacrylamide (NIPA, 6 M) with methacrylic acid (MAA, 80 mM) and methacrylamidopropyl trimethylammonium chloride (MAPTAC, 80 mM). The goal of this study is to test the mutual frustrations created by adsorption of one species on the adsorption of the other. Understanding these frustrations is an important step toward elucidating the memory of conformations in heteropolymer systems. We found that in the absence of aluminum, the adsorption of Py-4 was suppressed by gel collapse, presumably because of an increase in MAA/MAPTAC ionic pairs that prevents the formation of potential adsorbing centers. Adding a moderate amount of aluminum significantly enhances adsorption of Py-4 by the collapsed gel, indicating that aluminum ions compete for bonds with MAA and help release vacant MAPTAC centers. Final...

Hybrid Polymeric Micelles with Hydrophobic Cores and Mixed Polyelectrolyte/Nonelectrolyte Shells in Aqueous Media. 2. Studies of the Shell Behavior†

Abstract: The behavior of mixed poly(methacrylic acid)/poly(ethylene oxide) (PMA/PEO) shells of hybrid polymeric micelles with polystyrene cores was studied in detail by a combination of light scattering, fluorometric, potentiometric, and other techniques. The results show that the dissociation of poly(methacrylic acid) in the inner layer close to the polystyrene core is suppressed, in part because of the relatively low polarity of the medium and because of a high concentration of carboxylic groups. The dissociation degree does not correspond to the bulk pH. The PMA chains form a hydrogen-bond-stabilized interpolymer complex with PEO chains in the inner shell. The compact layer of the PMA−PEO complex around the polystyrene core is very stable and resistant to changes in the bulk solvent properties. Potentiometric titration shows that an important fraction of PMA, which is engaged in the complex formation, cannot be neutralized even in a considerable excess of the base. The peripheral part of the layer is formed pre...

Pigment dispersing resins

Abstract: This invention relates to use of a copolymer of a high acid value macromonomer which is obtained through copolymerization of specific monomeric components including methacrylic acid in the presence of a metal complex which is a catalytic chain transfer agent or an addition cleavage-type chain transfer agent, and optionally a radical-polymerization initiator, or this macromonomer into which a polymerizable unsaturated group is further introduced, with an ethylenically unsaturated monomer; and said copolymer into which further a long chain alkyl group is introduced; as pigment-dispersing resins to be used in water-based paint.

Triblock copolyampholytes from 5-(N,N-dimethylamino)isoprene, styrene, and methacrylic acid: Synthesis and solution properties

Abstract: ABC triblock copolymers of the type poly[5-(N,N-dimethylamino)isoprene]-block-polystyrene-block-poly(tert-butyl methacrylate) (AiST) were synthesized and hydrolyzed to yield poly[5-(N,N-dimethylamino)isoprene]-block-polystyrene-block-poly(methacrylic acid) (AiSA) triblock copolyampholytes. Due to a complex solubility behavior the solution properties of these materials had to be investigated in THF/water solvent mixtures. Potentiometric titrations of AiSA triblock copolyampholytes showed two inflection points with the A block being deprotonated prior to the Ai hydrochloride block thus forming a polyzwitterion at the isoelectric point (iep). The aggregation behavior was studied by dynamic light scattering (DLS) and freeze-fracture/transmission electron microscopy (TEM). Large vesicular structures with almost pH-independent radii were observed.

Cement dispersing polymers for high flow, high strength and selfcompacting concrete

Abstract: A multipurpose cement dispersing, shrinkage compensating and anticorrosive polymer and an admixture comprising said polymer, which improve the workability and the early strength development of fresh concrete, are described. Said polymer is an ester- and amid group-modified acrylic polymer, obtainable by aqueous solution radical copolymerization of (1) acrylic or methacrylic acid with (2) an acrylic or methacrylic methoxy-polyalkyleneglycolester monomer having 2 to 300 moles of an oxyalkylene group each having 2 to 3 carbon atoms, (3) optionally an acrylic or methacrylic methoxy-polyalkyleneglycolamide monomer having 2 to 300 moles of an oxyalkylene group each having 2 to 3 carbon atoms, (4) an acrylic or methacrylic ester of a tertiary aminoalkanol and (5) optionally an acrylic amide of a primary or secondary aliphatic, cycloaliphatic or aromatic amine.