Showing papers on "Methacrylic acid published in 1996"

Antibody-Mimicking Polymers as Chiral Stationary Phases in HPLC

Abstract: Antibody-mimicking synthetic polymers, selective for various optically active amino acid derivatives and peptides, were prepared by noncovalent molecular imprinting. A novel approach, in which the branched, trifunctional cross-linkers pentaerythritol triacrylate and 2,2-bis(hydroxymethyl)butanol trimethacrylate were copolymerized with methacrylic acid, is described. The polymers were subsequently applied as chiral stationary phases in high-performance liquid chromatography. They were superior to previously reported noncovalent molecularly imprinted polymers used for chiral separations in that they showed considerably higher load capacity, increased selectivity, and better resolving capability.

Surface macromolecular architectural designs using photo-graft copolymerization based on photochemistry of benzyl N,N-diethyldithiocarbamate

Abstract: Surface macromolecular architectures with regional dimensional precision, control of the thickness of a graft layer, and blocks of graft chains were attempted using the surface photo-graft copolymerization method pioneered by Otsu et al. This is based on the photochemistry of benzyl N,N-diethyldithiocarbamate, which can be photolyzed into a radical pair (one radical can initiate radical polymerization and the other tends to recombine with the former radical). Ultraviolet light (UV) irradiation of a benzyl N,N-diethyldithiocarbamyl group-immobilized polymer surface in the presence of a vinyl monomer such as N,N-dimethylacrylamide, N-[3-(dimethylamino)propyl]acrylamide, methacrylic acid, or styrene at room temperature allowed precise control of the macromolecular architectures of the grafted surfaces. X-ray photoelectron spectroscopy (XPS) analyses and water contact angle measurements before and after UV irradiation in a monomer solution provided evidence that the graft copolymerization proceeded only durin...

Investigations on Polymeric and Monomeric Intramolecularly Hydrogen-Bridged UV Absorbers of the Benzotriazole and Triazine Class

Abstract: Various copolymers of MA-TIN 1, 2-[2-hydroxy-3-tert-butyl-5-(O-[2-hydroxy-3-(2-methylpropenoyloxy)propyl]-2-carbonyloxyethyl)phenyl]benzotriazole, and MA-TZ 1, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(2-hydroxy-3-[2-methylpropenoyloxy])propoxyphenyl]-1,3,5-triazine, with styrene, methyl methacrylate, and methacrylic acid have been synthesized by radical polymerization. Their absorption spectra in the long-wavelength UV region appear unchanged compared to those of the monomeric UV absorbers, indicating the stabilizer chromophore to remain unimpaired in the course of the polymerization. Both the monomeric and the polymeric stabilizers exhibit a strongly Stokes-shifted, temperature-dependent, low-quantum-yield fluorescence which arises from an intermediate species formed by intramolecular proton transfer. The intramolecular hydrogen bond which is essential for the photostability of this type of UV absorbers thus is still intact in the copolymers. Activation energies for the radiationless deactivation proc...

Low-shear melt rheology of partially-neutralized ethylene-methacrylic acid ionomers

Abstract: We examine the melt rheology of a series of ethylene−methacrylic acid (E/MAA) ionomers, all based on the same E/MAA copolymer, with an emphasis on the low-shear-rate Newtonian region. All ionomers show Newtonian behavior at sufficiently low shear rates. The zero-shear viscosity η0 is a strong function of neutralization level and is significantly higher for Zn ionomers than for Na ionomers at the temperatures and neutralization levels examined. The recoverable compliance Je0 is independent of cation type and neutralization level, indicating that the ionic associations bear no stress during steady flow in the terminal region. Therefore, the individual ionic associations have lifetimes much shorter than the terminal relaxation time of the polymer chain. We probe the effect of unneutralized acid groups on η0 by removing these groups through esterification. Unneutralized acid groups substantially lower the viscosity of Na ionomers but have no discernable effect in Zn ionomers. An “acid-cation exchange” mechani...

Molecularly imprinted polymer as chiral selector for enantioseparation of amino acids by capillary gel electrophoresis

Abstract: A capillary electrophoresis method for the enantioseparation of D,L-aromatic amino acids using molecularly imprinted polymer as chiral selector has been developed Methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate (EDMA) as crosslinking monomer The molecularly imprinted polymer was packed in capillaries by incorporating with acrylamide gel The composition of the polymerization mixtures affects the separation factor to some extent The molar ratio of cross-linker to functional monomer to print molecule was 20∶4∶1, which gives the best separation for aromatic amino acid enantiomers by using L-phenylalanine anilide (L-pheAN) as print molecule Under the same conditions, however, separation of D,L-phenylalanine using L-phenylalanine as print molecule is poorer than that using L-pheAN Polymer particles (≤5 μm) were supported by 6% acrylamide and 5% bisacrylamide gel in the capillary The effects of organic solvents, electrophoretic buffer and pH on separation were also investigated

Solution polymerization of acrylonitrile with vinyl acids in dimethylformamide

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.

Catalytic performance of Cs2.5Fe0.08H1.26PVMo11O40 for direct oxidation of lower alkanes

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.

Acrylate-containing polymer blends

Abstract: A polymer blend comprising (a) a modified block copolymer comprising (i) a polystyrene block and (ii) a polydiene block or a hydrogenated polydiene block, said polydiene block or hydrogenated polydiene block being modified to contain an average of one or more carboxyl groups; and (b) a polymer comprising a polymerization reaction product (i) at least one acrylic or methacrylic acid ester of a non-tertiary alcohol having 1 to 14 carbon atoms, inclusive, (ii) at least one monomer having carboxylic acid functionality which is present in an amount ranging from about 1 to about 15 parts by weight, based on 100 parts by weigth of polymer (b); and (iii) a titanate selected from the group consisting of (ethanol,2,2',2'-nitrilotris-titanium(4+) salt); titanium bis(ethyl-3-oxobutanolato-O1O3)bis2-propanolato; a reaction product of tetraalkyltitanate with a β-diketone and an alkanolamine; and tetrabutyltitanate (1-butanol,titanium(4+) salt).

Chemical Attachment of Polystyrene-block-poly(methacrylic acid) Micelles on a Silicon Nitride Surface

Abstract: Polystyrene-block-poly(methacrylic acid) micelles were chemically attached to an activated silicon nitride surface using a 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide methiodide coupling reaction. It has been found that this attachment method is very efficient from mixed 1,4-dioxane−water solvents and less efficient in purely aqueous media. The modified surfaces were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental conditions for surface attachment have been found such that no changes in micellar size or polydispersity occur. The SEM and AFM images allow an additional method for the evaluation of size distributions of micelles. A comparison with the quasi-elastic light scattering data from solutions shows that the distribution functions based on the SEM and AFM data for dried micelles fixed on the surface correlate reasonably well with the light scattering data on micelles in solutions.

Mixed polyelectrolyte/ionomer behavior of poly(methacrylic acid) gel upon titration

Abstract: The titration of poly(methacrylic acid) gel with sodium methoxide was studied in water, methanol, dioxane, and their mixtures. There are three main regimes of the swelling behavior of the gels depending on the dielectric constant e of the medium. In polar media with e larger than a critical value e1, the gel swells monotonically with the increase of the degree of ionization, α, due to the osmotic pressure of counterions. In media with e smaller than a critical value e2, the gel always shrinks with increasing α due to ion-pair formation with their aggregation to multiplets. In media with dielectric constants ranging from e1 to e2, the gel swells at α up to ca. 0.1 and then collapses. The collapse induced by ionization is in agreement with recent theoretical findings.

Trifluoroethanol derivatization of carboxylic acid-containing polymers for quantitative XPS analysis

Abstract: The carboxylic acid groups of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) were derivatized in the solid state using a procedure resulting in esterification by trifluoroethanol vapour. X-ray photoelectron spectroscopy analyses indicate that stoichiometric reaction with PAA was reached after 10 h. However, PMAA did not attain a yield greater than 60%, an effect rationalized in terms of steric hindrance. It is postulated that steric restraints are imposed by conformational inflexibility related to the pendant methyl group within isotactic portions of the chain.

Effect of the nature and mole fraction of acidic comonomer on the stabilization of polyacrylonitrile

Abstract: Differential scanning calorimetry (DSC) and thermogravimetric analysis measurements were used to study the influence of the acidic comonomers acrylic acid, methacrylic acid, and itaconic acid on the exothermic reactions occurring during the heat treatment of acrylonitrile copolymers under air atmosphere. The presence of these reactions was noticed in the DSC exotherms of the copolymers, which appear as doublets. These doublets were resolved into their constituent peaks, arising due to the occurrence of oxidative and cyclization reactions, and the area under the resolved peaks was considered as the extent of the reaction. The comonomers under study were found to enhance the secondary oxidation reactions and retard the extent of cyclization reactions. The degree of cyclization decreases abruptly with the increase in the comonomer content beyond ⋍ 2 mol %. © 1996 John Wiley & Sons, Inc.

Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene in batch and distillation column reactors: ion-exchange resins as catalysts

Abstract: Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene was carried out in the presence of cation-exchange resins as catalysts. Effect of various parameters, e.g. speed of agitation, catalyst particle size, catalyst loading, types of catalyst, temperature, mole ratio of the reactants, was studied to optimise the reaction conditions. The reaction of formic acid, with different concentrations in aqueous solutions, with cyclohexene was studied. Experiments were carried out in the presence of homogeneous catalyst, p-toluene sulphonic acid (p-TSA), to compare results with the heterogeneous catalyst. A comparison of anhydrous esterification between acrylic acid and that of methacrylic acid with cyclohexene has been reported. The conversion of formic acid in aqueous solutions to cyclohexyl formate, by reaction with cyclohexene, in a distillation column reactor (DCR), packed with an acidic ion-exchange resin catalyst was studied; the effect of variables such as feed flow rate, molar ratio of reactants, amount of catalyst in the reboiler, concentration of formic acid, location of the feed point, etc., was studied. A comparison between the rate of esterification of formic acid with cyclohexene in batch mode and in distillation column reactor has been made. An attempt was also made for the selective esterification of formic acid with cyclohexene from a mixture of formic acid and acetic acid in a DCR.

Acrylate-containing polymer blends and methods of using

Abstract: A polymer blend comprising (a) a block copolymer, in an amount sufficient to associate with the substrate, comprising (i) a polystyrene block; and (ii) a polydiene block or a hydrogenated polydiene block, said block copolymer (a) being non-maleated, and (b) a polymer, in an amount sufficient to bond to block copolymer (a), comprising a polymerization reaction product of (i) at least one mono-ethylenically unsaturated acrylic or methacrylic acid ester of a non-tertiary alcohol having 1 to 14 carbon atoms, inclusive; (ii) at least one mono-ethylenically unsaturated nitrogen-containing monomer selected from the group consisting of an N-vinyllactam and N,N-dialkylacrylamide; and (iii) from 1-10 parts, based upon 100 parts of polymer (b), of a monomer having at least one of carboxylic acid functionality, hydroxy functionality, and epoxy functionality.

Secondary coating for fiber strands, coated strand reinforcements, reinforced polymeric composites and a method of reinforcing a polymeric material

Abstract: The present invention provides aqueous coating compositions adapted to coat a fiber strand having thereon a sizing composition. The aqueous coating compositions include a urethane-containing polymer and a polymer prepared by addition polymerization of a monomer selected from the group consisting of acrylic acid, methacrylic acid and a mixture thereof. Also provided by the present invention are sized fiber strands coated with the secondary coating composition and composites reinforced with the same.

Reactivity of Keggin-type heteropolycompounds in the oxidation of isobutane to methacrolein and methacrylic acid : Reaction mechanism

Abstract: The oxidation of isobutane to methacrolein and methacrylic acid over a Keggin-type heteropolycompound of composition K 1 (NH 4 ) 2 PMo 12 O 40 Fe 1 O 1.5 was studied in both flow reactor studies and with FT-IR spectroscopy of species which develop at the surface. In both cases either isobutane or possible reaction intermediates were used as probe molecules. It is proposed that the activation of the isobutane at the tertiary CH bond leads to the formation of an alkoxy species, which is then converted to an allylic alkoxy species, precursor for the formation of methacrolein and methacrylic acid. The mechanism proposed explains the experimental evidence relative to the absence of isobutene among the reaction products, and the parallel pathways to the two products. Competitive pathways are the formation of acetic acid, maleic anhydride and carbon oxides.

Determination of the Rate Constant for Chain Insertion into Poly(methyl methacrylate)-block-poly(methacrylic acid) Micelles by a Fluorescence Method

Abstract: Poly(methyl methacrylate)-block-poly(methacrylic acid) (PMMA-b-PMAA) with and without pyrene labels attached to the end of the PMAA block have been synthesized and characterized. These polymers formed micelles with PMAA as the core in ethyl acetate/methanol mixtures when the ethyl acetate volume fraction was higher than 80%. After mixing a micelle solution of PMMA-b-PMAA without pyrene labels, i.e., polymer I, with a unimer solution of the sample with pyrene, i.e., polymer II, the fluorescence intensity IPy(t) of pyrene increased with time. This was caused by the insertion of the pyrene group of polymer II chains into the rigid core of polymer I micelles. The pyrene fluorescence quantum yield is higher in a more rigid environment due to the reduced quenching of pyrene fluorescence by oxygen and the possible suppression of certain nonradiative deactivation pathways. A kinetic model has been proposed for describing the chain insertion process. Fitting the experimental fluorescence intensity data using the d...

Mechanism and Kinetics of Stabilization Reaction of Polyacrylonitrile and Related Copolymers I. Relationship between Isothermal DSC Thermogram and FT/IR Spectral Change of an Acrylonitrile/Methacrylic Acid Copolymer

Abstract: Mechanism and Kinetics of Stabilization Reaction of Polyacrylonitrile and Related Copolymers I. Relationship between Isothermal DSC Thermogram and FT/IR Spectral Change of an Acrylonitrile/Methacrylic Acid Copolymer

Production of submicron-sized multihollow polymer particles having high transition temperatures by the stepwise alkali/acid method

Abstract: Submicron-sized multihollow styrene-methacrylic acid (92.6/7.4, molar ratio) copolymer particles having high transition temperature above 100°C were produced by using the stepwise alkali/acid method proposed by the authors. The original particles were prepared by emulsion copolymerization of styrene and methacrylic acid. The effects of pH, temperature and time in the alkali treatment process as the first step on the multihollow structure were clarified under the same acid treatment conditions.

Oxidative dehydrogenation of isobutyric acid: Characterization and modeling of vanadium containing polyoxometalate catalysts

Abstract: The catalyzed oxidative dehydrogenation of isobutyric acid by H4[PMo11VO40] and VOH[PMo12O40] was studied at 593 K. Thermal evolution of H4[PMo11VO40] at 593 K leads to a complex mixture of different species with or without vanadium inside the Keggin structure. After reaction, the one and only heteropolyanion is partly reduced [PMo12O40]3− and vanadium is present as vanadyl cations. Vanadyl cations are bound to the oxygen atoms of the heteropolyanion at 593 K and enhance the selectivity to methacrylic acid with respect to acetone. On the other hand, copper cations improve the reoxidation of the catalyst and increase the IBA conversion. Synergism between copper and vanadyl cations was observed.

An efficient method for lipase-catalysed preparation of acrylic and methacrylic acid esters

Abstract: Novozym 435 — a commercially available immobilized lipase from Candida antarctica — shows an activity for the transesterification using acrylic or methacrylic methylester as solvent and as acylating agent superior to all other enzymes tested. This transesterification is very fast compared to other enzyme-catalysed reactions (1.5 h). Novel acrylic and methacrylic esters from unsaturated fatty alcohols can be prepared this way in yields of 65 to 94 % and under mild conditions (30 °C, atmospheric pressure).

Production of submicron-sized multihollow polymer particles by alkali/cooling method

Abstract: Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named “alkali/cooling method”. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.

Polycarbonate resin composition

Abstract: Polycarbonate resin compositions comprising (A) a composition comprising a polycarbonate resin (A-1) and a specific polyethylene terephthalate resin polymerized by using a germanium catalyst (A-2) in an (A-1)/(A-2) ratio of 99/1 to 40/60 by weight, (B) 1 to 10 parts by weight, per 100 parts by weight of the composition (A), of an olefin-alkyl (meth)acrylate copolymer having an MI of 0.1 to 300 g/10 minutes and optionally (C) 2 to 10 parts by weight, per 100 parts by weight of the composition (A), of a graft copolymer in which at least one monomer selected from an aromatic vinyl compound, a vinyl cyanide compound, an acrylic acid ester, a methacrylic acid ester and vinyl compounds copolymerizable therewith is copolymerized with a rubbery elastomer. The polycarbonate resin compositions can meet recent demand of high level solvent resistance and also have excellent heat stability and flow property in molding.

Grafting of acrylamide-methacrylic acid mixture onto poly(ethylene terephthalate) fibers by azobisisobutyronitrile

Abstract: The chemical grafting of acrylamide methacrylic acid (AAM-MAA) mixture onto poly(ethylene terephthalate) (PET) fibers using azobisisobutyronitrile as a chemical initiator was investigated. The use of MAA as a comonomer increased the amount of AAM introduced to the PET fiber up to 33.0%, while the grafting of AAM onto fibers alone gave low graft yields. This synergistic effect was found to be at its highest when an AAM-MAA mixture having 30 wt % AAM was used. The grafting increased dyeability with both acidic and basic dyes, and increased diameter and decreased the density of the fibers. The thermogravimetric analysis results revealed that the decomposition temperature of the fibers decreased with grafting. The electron micrographs showed that grafting changed the surface morphology of the fiber and a shell-like heterogeneous structure occurred at the surface at high graft yields.

Electrode and secondary battery using it

Abstract: PROBLEM TO BE SOLVED: To improve the adhesiveness between an electrode active material and a current collector by specifying the constituting components and their compositions of the binder of a battery electrode. SOLUTION: A binder is constituted of the following materials: (a) an acrylic copolymer made of at least one kind of monomer selected from a monomer having the carboxylic acid group or carboxylic acid anhydride group, acrylic acid ester, and methacrylic acid ester, (b) a vinylidene fluoride copolymer, and (c) a vinylidene fluoride homopolymer. The percentage content of (a) is 0.5-20wt.% of the binder, and the percentage of the content of (b)is 0.5-50wt.% of the binder. When the added quantity of them is too little, the improving effect of adhesiveness is insufficient. When the added quantity is too much, the chemical resistance of the binder is reduced, or the swelling by an organic solvent (ethylene carbonate or the like) used for an electrolyte is increased, and an adverse effect is inflicted on an electrode and the battery performance. COPYRIGHT: (C)1997,JPO