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 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The spermicidal effect in vitro of 3 copolymers, maleic anhydride-vinyl acetate-butyl acrylate, acrylic acid-butyl acrylate, and methacrylic acid-butyl acrylate was evaluated. The copolymers were synthesized by solution polymerization using 2-azo-bis-iso-butyronitrile as initiator. The effect of mole ratio of co-monomers, initiator concentration, and temperature on polymerization were investigated. The acidity of the copolymer increased with acidity, while solubility decreased. The polymers were insoluble at pH 5, but soluble at pH 7.35. Swelling in water, determined gravimetrically, also varied with pKa. For spermicidal assays, co-polymers were soaked in Tyrode's solution pH 7.4 at 37 degrees Celsius for 48 hours, and samples of the supernatant were tested with motile human sperm according to the WHO Laboratory Manual. All 3 co-polymers were spermicidal in vitro. These materials were judged suitable for research on reversible vas sterilization.
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PMID:Occlusive or non-occlusive methods of vas deferens in males. 1228 64

A new nanometer complex heteropoly acid with Keggin structure, H3PW12O40/SiO2, were prepared by sol-gel method, and were characterized with IR, UV, XRD and TEM techniques. By means of this nanometer catalytic materials, the optimum conditions of the n-butyl acrylate synthesis have been studied. The results show that the complex heteropoly acid H3PW12O40/SiO2 nanoparticles have the mean grain size of 40 nm and they are typical amorphous. A strong chemical interaction exists between H3PW12O40 and silica surface. The nanoparticles have high catalytic activity for synthesizing n-butyl acrylate. The optimum catalytic conditions are as follows: the mole ratio of acrylic acid and n-butyl alcohol is 1:1.2, the reaction temperature is approximately 90-96 degrees C, and the catalyst quantity in the reaction is 10% of the acid mass. The conversion proportion is 94.37% and product yield 91.2% in 5 h. Apparently, the unique structure of the Keggin anions and surface acid center and the high specific surface area and the pseudoliquid phase of H3PW12O40/SiO2 play an important role in the esterification reactions with the acid catalyst.
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PMID:[Catalytic application of synthesizing n-butyl acrylate by a new type nanometer complex heteropoly acid catalyst H3PW12O40/SiO2]. 1576 24

In the present paper, butyl acrylate and phenylethylene were used as monomers, benzoyl peroxide as evocator, n-butyl acetate and methylbenzene as solvent, a new type of solid-phase micro extraction adsorbent that is phenylethylene-butyl acrylate copolymer was synthesized by solution polymerization. The polymer has good behaviour for adsorbing arenas. According to Lambert-Beer law and some calculation process, the linear relation between the absorptance (y) of the two functional groups, which are benzene and ester, and the two monomers' mole ratio (x) was obtained. The absorptances were determined by IR. The standard curve was obtained by external standard method. The linear regression equation is y = 0.1362 + 0.0841x. The precisions and recoveries were investigated. RSD is 2.464%, and recoveries are 92.89%-103.94%. The results are satisfactory. This method is rapid and accurate.
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PMID:[Determining mole ratio of monomers in new adsorbent of solid-phase microextraction by infrared spectroscopy]. 1576 76

In the present paper, phenylethylene-butyl acrylate-vinyl triethoxy siloxane terpolymer, as SPME coating, was synthesized. Combining infrared spectrum and ultraviolet spectrum, the contents of the monomers were determined. The two monomers' mole ratio of phenylethylene to butyl acrylate was obtained by IR. The content of phenylethylene was obtained by UV. Then the contents of butyl acrylate and vinyl triethoxy siloxane were calculated from the phenylethylene quantity and the mole ratio. For the determination of the mole ratio of phenylethylene to butyl acrylate, the standard curve was A(r) = 0.114m(r) +/- 0.032 (A: absorptance ratio, m(r): mole ratio), and the correlation efficient(r2) was 0. 999 3; for the determination of the content of phenylethylene, the standard curve was deltaA = 0.078 6c + 0.081 2(deltaA: absorptance difference, c: concentration of phenylethylene), and the correlation efficient(r2) was 0.998 9. The relative standard deviation (RSD) for phenylethylene was 0.410%, and recoveries were 97.8%-104%. The relative standard deviation (RSD) for butyl acrylate was 0.39%, and the recoveries were 97.1%-99.6%.
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PMID:[Determination of the monomers in phenylethylene-butyl acrylate-vinyl triethoxy siloxane terpolymer for solid phase microextraction coating by combining IR and UV]. 1826 Apr 2

The copolymers, poly(methyl methacrylate-co-methyl acrylate) (PMMAMA), poly(methyl methacrylate-co-ethyl acrylate) (PMMAEA) and poly(methyl methacrylate-co-butyl acrylate) (PMMABA), of different compositions were synthesized and characterized. The effect of alkyl acrylate content, alkyl group substituents and solvents on the ultrasonic degradation of these copolymers was studied. A model based on continuous distribution kinetics was used to study the kinetics of degradation. The rate coefficients were obtained by fitting the experimental data with the model. The linear dependence of the rate coefficients on the logarithm of the vapor pressure of the solvent indicated that vapor pressure is the crucial parameter that controls the degradation process. The rate of degradation increases with an increase in the alkyl acrylate content. At any particular copolymer composition, the rate of degradation follows the order: PMMAMA>PMMAEA>PMMABA. It was observed that the degradation rate coefficient varies linearly with the mole percentage of the alkyl acrylate in the copolymer.
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PMID:Ultrasonic degradation of poly(methyl methacrylate-co-alkyl acrylate) copolymers. 1977 25

Thermal field-flow fractionation coupled with online multiangle light scattering, differential refractive index and quasielastic light scattering (ThFFF-MALS/dRI/QELS) was used to simultaneously determine the molecular weight (MW) and composition of polystyrene-poly(n-butyl acrylate) (PS-PBA) and polystyrene-poly(methyl acrylate) (PS-PMA) copolymers. The online measurement of the normal diffusion coefficient (D) by QELS allowed calculation of the copolymer thermal diffusion coefficient (D(T)) of sample components as they eluted from the ThFFF channel. DT was found to be independent of MW for copolymers with similar compositions and dependent on composition for copolymers with similar MW in a non-selective solvent. By using a solvent that is non-selective to both blocks of the copolymer, it was possible to establish a universal calibration plot of DT versus mole fraction of one of the monomer chemistries comprising the copolymer. PS-PBA and PS-PMA linear diblock polymers were determined to vary in composition from 100/0 to 20/80 wt% PS/acrylate and ranged in MWs between 30 and 360 kDa. The analysis of a PS-PBA miktoarm star copolymer revealed a polydisperse material with a weight percent PBA of 50-75% and MW ranging from 100 to 900 kDa. The presented ThFFF-MALS/dRI/QELS method allowed rapid characterization of polymers with MW and chemical distributions in a single analysis.
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PMID:Composition and molecular weight analysis of styrene-acrylic copolymers using thermal field-flow fractionation. 2185 81

Polymer nanoparticle coated micelle assemblies of lauryl ester of tyrosine (LET) act as potential nanocarriers for the model solid lipid stearyl alcohol. The coating is afforded by a simple methodology of heterophase polymerization reaction of styrene or the mixture of styrene and butyl acrylate at a mole ratio of 0.8:0.2 in the presence of 200 mM LET in water. On the contrary, the polymer nanoparticles produced under similar conditions in the presence of a structurally similar surfactant, lauryl ester of phenyl alanine (LEP), failed to act as nanocarrier. The micelle templates of LET and LEP favored polymerization under controlled conditions as observed from the near monodisperse distribution of molecular weight and size of the polymers. The particle size distribution of poly(styrene) (PS) and poly(styrene-co-butyl acryalte) (PS-co-PBA) nanoparticles from LET was smaller at 24 and 20 nm in comparison to those from LEP. The encapsulation efficiency of polymer nanoparticles from LET surfactant is explained on the basis of difference in the coating of micelle assemblies, which we believe must be arising due to difference in the solubilization site of the monomers in the surfactant micelles before polymerization reaction. The solubilization of the model monomer, benzene at different regions, varying between shell and core of LET and LEP micelles is established from (1)H nuclear magnetic resonance spectra. The evidence for the coating of micelle assemblies from surface tension measurements and the encapsulation of stearyl alcohol in the polymer nanoparticle dispersions from LET drawn from transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis is discussed.
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PMID:Nanocarriers of solid lipid from micelles of amino acids surfactants coated with polymer nanoparticles. 2371 41