Showing papers on "Methacrylic acid published in 1997"

Dynamic Behavior of Glucose-Responsive Poly(methacrylic acid-g-ethylene glycol) Hydrogels

Abstract: Glucose-sensitive poly(methacrylic acid-g-ethylene glycol) (P(MAA-g-EG)) gels were synthesized by copolymerizing methacrylic acid and poly(ethylene glycol) monomethacrylate in the presence of activated glucose oxidase. The dynamic and equilibrium swelling behavior of the gels was examined as a function of pH. At low pH values the gels were in a collapsed state due to complexation between carboxyl and etheric groups. At high pH values, the gels swelled to approximately 20 times their dry weights. The glucose oxidase containing gels exhibited a higher rate of expansion than the non glucose oxidase containing gels as the former had fewer entanglements. Relaxation times were determined for the swelling and deswelling processes, and a time-dependent swelling behavior was obtained for partial swellings in different pH values.

Poly(methyl methacrylate)-co-(methacrylic acid) microgel particles: swelling control using pH, cononsolvency and osmotic deswelling

Abstract: The swelling of poly[(methyl methacrylate)-co-(methacrylic acid)] (PMA-MAA) microgel particles (prepared using 17 mol % MAA) dispersed in water can be controlled by pH adjustment, addition of alkanols, and addition of water soluble homopolymer. Transmission electron microscopy revealed two-dimensional order for PMA-MAA particles deposited on a grid from alkaline solution. The swelling of the microgel particles was studied by means of photon correlation spectroscopy. The stability of the particles was investigated using turbidity−wavelength measurements; flocculation occurred when the pH was less than 6. A buffer (NaHCO3/NaOH) was employed to stabilize the pH of the PMA-MAA dispersions at about pH = 10. The hydrodynamic diameter of the PMA-MAA particles is sensitive to pH with a maximum at about pH = 8. PMA-MAA microgel particles deswell upon addition of an alcohol (methanol or 2-propanol) or poly(ethylene glycol) (PEG). Poly(N-isopropylacrylamide) (PNP) microgel particles also deswell in aqueous alcohol s...

Analysis of the Complexation/Decomplexation Phenomena in Graft Copolymer Networks

Abstract: Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) exhibiting pH-dependent swelling behavior due to the formation of interpolymer complexes were prepared by free radical solution polymerization of methacrylic acid and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies established the swelling/deswelling process due to hydrogen bonding. Additionally, the effects of copolymer composition, graft chain molecular weight, and environmental pH on network structure were studied. The average network correlation length changed significantly due to changes in environmental pH. The largest changes in network structure were observed in gels containing nearly equimolar amounts of methacrylic acid and ethylene glycol and the longest molecular weight poly(ethylene glycol) grafts. Water diffusion coefficients, determined through dynamic swelling analysis, varied by 2 orders of magnitude between the uncomplexed and complexed states.

Temperature- and pH-sensitive terpolymers for modulated delivery of streptokinase

Abstract: Controlled release devices were designed which respond to changes in pH and temperature by reversibly swelling and deswelling to control release of streptokinase. Copolymer hydrogels composed of N-isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) as well as terpolymer hydrogels containing NIPAAm, acrylic acid (AA), and 2-hydroxyethyl methacrylate (HEMA) were synthesized. Hydrogels containing NIPAAm display a change in swelling behavior across the lower critical solubility temperature of PNIPAAm, whereas hydrogels with MAA and AA swelled only at high pH values due to the ionization of carboxylic pendant groups. HEMA was chosen as a third component to add mechanical strength and integrity to the hydrogel. Pulsatile pH- and temperature-dependent swelling studies were performed to determine the extent and rate at which the hydrogels swell in response to changing conditions. Results showed that increasing the NIPAAm concentration in the copolymers or terpolymers resulted in a higher degree of temperature...

Metallized multilayer packaging film

Abstract: A metallized multilayer film comprising a film substrate having a polymer core layer, e.g., a polypropylene homopolymer (OOP), on at least one surface of which is a polymer skin layer having a lower melting temperature than that of said core layer, the exposed surface of skin layer having been treated, e.g., flame or corona discharge treated, prior to coating to increase its adherence to other materials, the film substrate containing a metal deposit, e.g., aluminum, coated on the treated surface of the polymer skin layers, and a polymeric, low temperature sealable coating (LTSC) comprising a copolymer of 10 to 35 wt.% of at least one alpha, beta-ethylenically unsaturated carboxylic acid, e.g., acrylic or methacrylic acid, with 65 to 90 wt.% of ethylene, an alkyl acrylate or methacrylate, acrylonitrile, or mixtures thereof on the surface of the metal deposit.

New water-soluble photo crosslinkable polymers based on modified poly(vinyl alcohol)

Abstract: Poly(vinyl alcohol) (PVA) was partially modified by polymer analogous reaction with acrylic and methacrylic acid and with 2-vinyl-4,4-dimethyl-azlactone to obtain water-soluble polymers with pendant (meth)acrylate and acrylamide groups. Aqueous solutions of these polymers were crosslinked by UV-irradiation within seconds to form transparent networks with potential for use in contact lenses. The water content of these hydrogels was studied as a function of polymer molecular weight, the acetate, (meth)acrylate, and methacrylamide contents and irradiation conditions. The hydrogels showed good mechanical properties, even at low crosslinker (<5 mol %) and high water contents (60–80%). The formation kinetics and stability of aggregates, investigated by combined GPC/light-scattering measurements of samples annealed and/or stored at different temperatures (−20 to 100°C), give insight into PVA secondary structures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3603–3611, 1997

Uv-absorbing polymer particle

Abstract: PROBLEM TO BE SOLVED: To enhance stability of a UV absorber. SOLUTION: The UV absorbing polymer particles are polymerization product of an unsaturated monomer of ethylene series selected from a group consisting of esters and amides of acrylic acid or methacrylic acid, vinyl esters, vinyl ethers and vinyl nitriles, an initiator, a surfactant and a UV absorber expressed by the formula (Rs are each independently H, a halogen, an alkyl, a 6-20C aryl, an alkoxy, an aryloxy, an alkylthio, an arylthio, an amine, an alkylamino, an arylamino, hydroxyl, cyano, nitro, an acylamino, sulfonyl, a sulfamide, an acyloxy and oxycarbonyl).

ABC triblock polyampholytes containing a neutral hydrophobic block, a polyacid and a polybase

Abstract: Well defined ABC triblock copolymers of polystyrene-block-poly(2-vinylpyridine)-block-poly(tert-butyl methacrylate) and polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) were synthesized by sequential living anionic polymerization in tetrahydrofuran. Triblock copolymers with narrow molecular weight distribution were obtained. Hydrolysis of the poly(tert-butyl methacrylate) block yields polystyrene-block-polyvinylpyridine-block-poly(methacrylic acid) which demonstrates pH-dependent solution properties. Interpolymer complexation of the polyvinylpyridine and poly(methacrylic acid) blocks in the micellar solution is studied in dependence of the pH in solution by potentiometric, conductometric and turbidimetric titration, and in bulk by FTIR spectroscopy.

Dynamic–Mechanical Properties of Bioartificial Polymeric Materials

Abstract: Bioartificial polymeric materials represent a new class of polymeric materials based on blends of synthetic and natural polymers, designed with the purpose of producing new materials with enhanced properties with respect to the single components. The mechanical properties of bioartificial materials prepared using poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as synthetic components, and collagen (SC), gelatin, starch, hyaluronic acid (HA) and dextran as biological components, were investigated by dynamic mechanical thermal analysis. The materials were prepared in the form of films or hydrogels and treated by glutaraldehyde (GTA) vapour or thermal dehydration in order to reduce their solubility in water. The results indicate that SC/PVA, gelatin/PVA and starch/PVA films behave as biphasic systems, showing good mechanical properties over a wide range of temperature. It was observed that the GTA procedure affects only the biological component of the SC/PVA and gelatin/PVA blends, whilst the thermal treatment influences mainly the synthetic polymer. In the case of HA/PVA hydrogels, a modulus variation was found with the HA content related to the organization degree and perfection of the PVA network structure. It seems evident that, in the experimental conditions used, dextran/PAA mixtures behave as miscible blends showing a glass transition intermediate between those of the pure components. With both untreated and GTA-treated gelatin/PMAA blends, it was not possible to evaluate the miscibility of the systems; it could only be affirmed that these materials show good mechanical properties over a wide range of temperature. © 1997 SCI.

Fluorescence Studies of an Alkaline Swellable Associative Polymer in Aqueous Solution

Abstract: Rheology measurements and fluorescent probe experiments were used to study the association process in aqueous solutions of an alkali swellable copolymer of methacrylic acid, ethyl acrylate, and an ethoxylated hydrophobic monomer The pyrene-probe experiments monitor hydrophobic cluster formation in the polymer solution and indicate a rearrangement of the system as a function of pH The polymer, present as a latex at pH < 4, dissolves at pH 57 In this solution, many small hydrophobic domains are present As the pH is raised and the polymer further neutralized, the viscosity of the solution increases, accompanied by formation of a smaller number of larger hydrocarbon domains, detected as a large increase in the extent of pyrene excimer emission

Effect of water on polymer diffusion in latex films

Abstract: The role of water in polymer diffusion in latex films was examined. For a hydrophobic polymer (poly(butyl methacrylate), PBMA), water has little influence on the polymer diffusion rate. Water absorption in PBMA latex films does increase film turbidity, both for nascent and for well-annealed films. For a hydrophilic polymer (a copolymer of 5 wt % methacrylic acid and 95 wt % butyl methacrylate, P(MAA-co-BMA)], the presence of water (e.g., 5 wt %) increases the diffusion coefficient by a factor of 5 at 60 °C. Upon neutralization of the carboxylic acid groups of P(MAA-co-BMA) with NaOH, the polymer diffusion is much retarded in dry films but greatly enhanced in wet films: the polymer diffusion coefficients for the wet films are about 2 orders of magnitude larger than those for the corresponding dry films. Neutralization with NH3 results in intermediate diffusion rates, between those of unneutralized and NaOH-neutralized films under both dry and wet conditions.

Short-Chain Branching Structures in Ethylene Copolymers Prepared by High-Pressure Free-Radical Polymerization: An NMR Analysis

Abstract: It is well-known that short-chain branching (SCB) reactions (intramolecular H-abstraction) play an important role in determining the properties of ethylene homopolymers produced under high pressure by free-radical polymerization. There is little information, however, regarding SCB mechanisms that occur during the synthesis of ethylene copolymers under similar reaction conditions. This work describes SCB structures for a wide range of ethylene copolymers of varying composition (ethylene with n-butyl acrylate (nBA), methyl acrylate (MA), vinyl acetate (VAc), n-butyl methacrylate (nBMA), acrylic acid (AA), and methacrylic acid (MAA)), as determined by proton, 13C, and 2D NMR techniques. Close examination of the resonances reveals that for many (if not all) of these copolymers, a significant fraction of the SCBs contain comonomer as a result of CH2-radical to CH2 backbiting around a comonomer unit. In addition, SCBs are formed not only by hydrogen abstraction from CH2 polyethylene units but also by abstractio...

Temperature effect on chiral recognition of some amino acids with molecularly imprinted polymer filled capillary electrochromatography.

Abstract: L-Aromatic amino acid imprinted polymers were prepared using azobisnitriles as either photoinitiators or thermal initiators at temperature ranging from 4 to 60 degrees C. Methacrylic acid (MAA) was used as functional monomer and ethylene glycol dimethacrylate (EDMA) was used as cross-linker. The result polymers were ground and sieved to particles < or = 10 microns, filled into the capillary columns and used for enantiomeric separations in capillary electrochromatographic (CEC) mode. The polymer particles < or = 25 were packed into high performance liquid chromatographic (HPLC) columns and used for enantioseparations in the HPLC mode. The mobility and chiral separation of some amino acids were studied on CEC and HPLC columns at different temperature. The relationships of separation factor and column temperatures and demonstrated in linear between logarithm of the separation factor (in alpha) and the inverse of absolute temperature (1/T). Some thermodynamic parameters, such as the apparent change of enthalpy (delta H zero) and the apparent change of entropy (delta S zero), were obtained using van't Hoff plots. The information obtained from the thermodynamic study is discussed in developing strategies for chiral recognitions of amino acids by molecular imprinting technique.

Enantioseparation of D, L-Phenylalanine By Molecularly Imprinted Polymer Particles Filled Capillary Electrochromatography

Abstract: The chromatographic properties of molecularly imprinted polymer filled capillary electrochromatography (CEC) have been studied. The network polymers were prepared using L-phenylalanine anilide (L-pheAN) or L-phenylalanine as print molecules. Methacrylic acid was used as functional monomer, such that the acid function of monomer interacts ionically with the amine function and via hydrogen bonding with the carboxyl group of the print molecules. Ethylene glycol dimethacrylate was used as cross-linker and the reaction initiator was α, α′-azobis(isobutyronitrile). The obtained polymers were ground and sieved to particles<10 μm for filling into capillary for CEC and <30μm for packing into high performance liquid chromatographic columns. The separations of D, L-phenylalanine by using the molecularly imprinted polymers against L-pheAN and L-phenylalanine were compared. It was interesting to find that the resolution of D, L-phenylalanine using L-pheAN printed polymer was higher than that using L-phenylala...

Optical Detection System for Triazine Based on Molecularly-Imprinted Polymers

Abstract: A new system for the detection of triazine herbicide was prepared using the molecular imprinting approach. This method is based on the competition between fluorescent-labeled and the unlabeled substance-analyte for the specific binding sites, that were produced in polymer by the imprinting of the template. Polymer synthesis consists of radical polymerization of functional monomer (diethylaminoethyl methacrylate or methacrylic acid) and cross – linker (ethylene glycol dimethacrylate) in the presence of triazine as a template. After grinding of the polymer block and splitting off the template molecules a suspension of the polymer was used for the herbicide-specific sensor system. Selective detection of triazine in the concentration range of 0.01-100 mM was achieved within 4 hours. This method seems to be applicable for the development of optical sensors, combining the high sensitivity and selectivity characteristic for biological receptors and the high stability of the synthetic molecularly imprint...

Propagation Kinetics of Methacrylic Acid Studied by Pulsed-Laser Polymerization

Abstract: Propagation rate coefficients kp have been determined for free radical polymerizations of methacrylic acid (MAA) using pulsed-laser polymerizations (PLP) combined with size exclusion chromatography (SEC). The temperature dependence of kp has been studied for polymerizations of 33 vol % monomer in methanol in the temperature range from 20 to 60 °C. kp is described by the following Arrhenius relation: ln[kp/L·mol-1·s-1] = (13.31 ± 0.49) − (2132 ± 133)K/T. Variations in MAA concentration and the type of solvent do not influence kp significantly. Any distinctions elicited in kp by these variations are of the order of the experimental uncertainty and are much smaller than the relative changes in the MAA monomer−dimer equilibrium observed by FTIR spectroscopy. The magnitude of kp and its variation with temperature are similar to results reported for methyl methacrylate and the rest of the methacrylate family.

Polymeric rheology modifiers

Abstract: The present invention relates to acrylate-based, associative polymeric rheology modifier prepared by polymerization of a C1-C6 alkyl ester of acrylic acid and/or a C1-C6 alkyl ester of methacrylic acid, a monomer chosen from a vinyl-substituted heterocyclic compound containing at least one of a nitrogen or sulfur atom, (meth)acrylamide, a mono- or di- (C1-C4)alkylamino (C1-C4)alkyl (meth)acrylate, a mono or di-(C1-C4)alkylamino (C1-C4)alkyl (meth)acrylamide, and an associative monomer.

Polycarboxy polymer acid binders having reduced cure temperatures

Abstract: By carefully adjusting the molecular weight and amounts of methacrylic acid and maleic acid and/or maleic anhydride comonomers in polyacrylic acid-based fiberglass binders, binder-treated fiberglass cured and B-staged product throughput may be maintained at production rates designed for phenol/formaldehyde binders due to the lower thermal requirements for cure as compared to homopolyacrylic acid-based binder systems.

Syntheses and characterization of starch‐poly(methacrylic acid) graft copolymers

Abstract: Methacrylic acid (MA) was graft polymerized onto starch using Ce4+ initiator in aqueous medium. The dependence of grafting on the reaction variables, such as monomer and initiator concentration and time and temperature, was studied in detail. Acid hydrolysis and infrared (IR) spectroscopy were used for the confirmation of graft copolymer formation. Further, a representative graft copolymer was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The solubility/swellability and the gelatinization characteristics of the copolymers are also reported. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1399–1403, 1997

A Molecularly Imprinted Polymer Rod as Nicotine Selective AffinityMedia Prepared With 2-(Trifluoromethyl)acrylic Acid

Abstract: In situ molecular imprinting was performed using 2-(trifluoromethyl)acrylic acid (TFMAA) as a functional monomer to prepare rod-type affinity media for nicotine in liquid chromatography. The capacity factor of nicotine was 28.4 using an eluent of acetonitrile–acetic acid (98:2, v/v), while a polymer rod prepared by a conventional in situ method, employing methacrylic acid as functional monomer, resulted in a capacity factor of 2.4, showing that TFMAA is useful in in situ molecular imprinting for developing high-affinity chromatographic media.

Adhesive compositions with durability under conditions of high humidity

Abstract: A thermosettable adhesive composition that includes a monomeric or partially polymerized composition that includes at least one polymerizable acrylic or methacrylic acid ester of a non-tertiary alcohol, a thermosettable epoxy resin, an amine curative, a silane coupling agent, and a chelating agent.

Pressure-Induced Binding Sites in Molecularly Imprinted Network Polymers

Abstract: Molecular imprinting in network polymers under high pressure was studied as a means of inducing selective binding sites for molecular recognition. Network polymers of methacrylic acid and ethylene ...