René Peralta | Applied Chemistry Research Center (original) (raw)
Papers by René Peralta
Colloid and Polymer Science, 2014
ABSTRACT Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulf... more ABSTRACT Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as surfactant and n-butanol (n-BuOH) as the cosurfactant (1:1, wt/wt) with potassium persulfate (KPS) as initiator. The effects of monomer, surfactant, and initiator concentration, as well as the temperature on the kinetics, particle size, and molar masses were studied. It was observed that polymerization rate increases as monomer, initiator, and temperature increases; however, the opposite was observed as surfactant concentration increases. Average particle diameters (Dp) 5 and 7.5 × 105 g/mol were obtained. For low amounts of stabilizing agents (AOT and n-BuOH), a bimodal molar mass distribution (MMD) was obtained. As n-butanol concentration increased, Mw decreases and a monomodal MMD was observed, which can be explained because chain transfer events are promoted by the presence of n-BuOH. A thermodynamic model was implemented to simulate the partitioning of VAc in the presence of n-BuOH between the phases throughout polymerization. It was found from simulations that microemulsion droplets are depleted fast at 5 % conversion and, due to the high water solubility of VAc, most of the monomer (70 %) and n-BuOH (97 %) reside in the aqueous phase at the beginning of polymerization, which indicates that both homogeneous and micellar nucleation are present.
Polymer Bulletin, May 7, 1999
Polymerization of vinyl acetate (VA) in three component oil/water (o/w) microemulsions stabilized... more Polymerization of vinyl acetate (VA) in three component oil/water (o/w) microemulsions stabilized with a mixture of two cationic surfactants (DTAB/DDAB in a weight ratio of 3), was carried out at 40, 50 and 60°C using a water soluble initiator, V-50. In all cases studied, stable latexes containing particles with diameters between 70 and 110 nm were obtained. Particle size increased with conversion yielding uncommonly large particles for microemulsion polymerization, probably because particle coagulation. Multimodal molar mass distributions with average molar masses between 1.2 to 2.0x10 6 g/mol were obtained. Chain transfer to polymer and bimolecular termination reactions play important roles in the microemulsion polymerization of this monomer.
Phyton, 2014
Tomato fruits are perishable products that require treatments such as coating films to extend the... more Tomato fruits are perishable products that require treatments such as coating films to extend their shelf life. Because of this and to avoid use of synthetic chemicals to prevent physical deterioration during postharvest, we evaluated the effects of an edible coating polymer latex poly (vinyl acetate-co-vinyl alcohol), P (VAc-co-VA), at three concentrations (0, 50 and 100%) in tomato fruits. The trial was conducted at room temperature conditions (31 ± 4 °C; with RH of 30 ± 5%) and temperature-controlled (12 ± 1˚C; with RH of 75 ± 5%). Fruits coated with P (VAc-co-VA) at 100 and 50% showed significantly higher physical properties (weight and firmness) after storage than fruits without the coating. Total soluble solids (° Brix) were also significantly higher in fruits either stored at controlled temperature or coated with P (VAc-co-VA) at 100 and 50% than in fruits stored at room temperature or without coating. Our results suggest that P (VAc-co-VA) coatings are suitable agents to preserve tomato fruit shelf life for a longer time.
Journal of Food Quality, 2017
There exists an increasing interest from consumers and scientific community in developing edible-... more There exists an increasing interest from consumers and scientific community in developing edible-natural-biodegradable coatings to replace commercial wax-based coatings for maintaining postharvest quality of vegetables. In this work, the effectiveness of guar gum coating on various quality characteristics of Roma tomato at 22±2°C over a 20 d storage period was investigated. Tomatoes were covered with a 1.5% guar gum coating plasticized with glycerol at 30% and stored at 22±2°C and 40% RH for 20-d. Tomatoes covered with edible coating significantly enhanced firmness and reduced weight loss, delayed changes on soluble-solids-content, retarded loss of total acidity, and decreased respiration rate compared with uncoated-control fruit. Sensory analysis by trained panelists revealed that the use of the edible coating influenced the acceptability of tomatoes. There were significant differences on the scores given by panelists when comparing the coated and uncoated tomatoes. It was conclude...
Chemical Engineering Communications, Dec 1, 2005
Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl... more Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess volumes are negative for the four binaries, probably as a result of the large dipole moment of DMSO, becoming smaller as the monomer becomes more branched or longer, and the dipole moment per monomer unit becomes larger.
Colloid and Polymer Science, Dec 7, 2014
Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinat... more Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as surfactant and n-butanol (n-BuOH) as the cosurfactant (1:1, wt/wt) with potassium persulfate (KPS) as initiator. The effects of monomer, surfactant, and initiator concentration, as well as the temperature on the kinetics, particle size, and molar masses were studied. It was observed that polymerization rate increases as monomer, initiator, and temperature increases; however, the opposite was observed as surfactant concentration increases. Average particle diameters (Dp)< 50 nm and polymers with weight average molar masses (Mw) between 2.7×10 5 and 7.5×10 5 g/mol were obtained. For low amounts of stabilizing agents (AOT and n-BuOH), a bimodal molar mass distribution (MMD) was obtained. As nbutanol concentration increased, Mw decreases and a monomodal MMD was observed, which can be explained because chain transfer events are promoted by the presence of n-BuOH. A thermodynamic model was implemented to simulate the partitioning of VAc in the presence of n-BuOH between the phases throughout polymerization. It was found from simulations that microemulsion droplets are depleted fast at 5 % conversion and, due to the high water solubility of VAc, most of the monomer (70 %) and n-BuOH (97 %) reside in the aqueous phase at the beginning of polymerization, which indicates that both homogeneous and micellar nucleation are present.
Journal of Applied Polymer Science, May 14, 2012
Journal of Solution Chemistry, Feb 1, 2005
Densities of the ternary system 1,4-dioxane + butyl acrylate + ethyl acrylate and its binary buty... more Densities of the ternary system 1,4-dioxane + butyl acrylate + ethyl acrylate and its binary butyl acrylate + ethyl acrylate have been measured in the whole composition range, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes of the binary system are positive and were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several models were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.
Physics and Chemistry of Liquids, Aug 1, 2003
Densities of the binary systems of tetrahydrofuran (THF) with ethyl acrylate, butyl acrylate, met... more Densities of the binary systems of tetrahydrofuran (THF) with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess volumes are negative for all the systems studied. The system THF + methyl methacrylate behaves almost ideally.
The Journal of Chemical Thermodynamics, Jul 1, 2005
ABSTRACT
The Journal of Chemical Thermodynamics, 2007
Densities of the ternary system toluene + butyl acrylate + methyl methacrylate and its three bina... more Densities of the ternary system toluene + butyl acrylate + methyl methacrylate and its three binaries have been measured in the whole composition range, at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes are positive for the binary systems toluene + methyl methacrylate and butyl acrylate + methyl methacrylate and negative for the system toluene + butyl acrylate. The corresponding data were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several empirical equations were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.
Polymer Bulletin, Apr 1, 1997
Langmuir, 2000
The polymerization of vinyl acetate in one-phase o/w microemulsions stabilized with Aerosol OT (A... more The polymerization of vinyl acetate in one-phase o/w microemulsions stabilized with Aerosol OT (AOT) is examined as a function of concentration and type of initiator (V-50 and KPS) and temperature. Conversions and reaction rates increase with increasing concentration of V-50 and temperature. Faster polymerization rates and higher conversions are achieved with KPS because of the different electrostatic interactions between the charged microemulsion droplets and the free radicals of KPS and V-50. Average molar masses and polydispersity indexes (M h w/M h n) are much smaller than those observed in emulsion polymerization using the same surfactant, even at high conversions. Analysis of the molar mass distribution indicates that chain-transfer reactions to monomer are the controlling chain-growth mechanism in the polymerization of vinyl acetate in AOT microemulsions at all conversions.
The Journal of Chemical Thermodynamics, Feb 1, 2003
Densities of binary mixtures of 1, 4-dioxane with either ethyl acrylate, or butyl acrylate, or me... more Densities of binary mixtures of 1, 4-dioxane with either ethyl acrylate, or butyl acrylate, or methyl methacrylate, or styrene have been measured as a function of composition at T= 298.15 K and atmospheric pressure with an Anton Paar DMA 5000 oscillating U-tube ...
Ceramics International, 2019
CuO and ZnO nanoparticles (NPs) were synthesized at room-temperature following a novel, direct, h... more CuO and ZnO nanoparticles (NPs) were synthesized at room-temperature following a novel, direct, high-yield (> 91%) and green method based on a mechanically activated metathesis reaction. The CuO-NPs exhibited a rod-like shape with average length and diameter of 22 and 6 nm, respectively, while the ZnO-NPs showed spherical-like morphology and mean diameter of 15 nm, as determined by TEM. The antimicrobial properties of the NPs and commercially available micrometric counterparts were evaluated by the micro dilutions method to determine the minimum inhibitory concentrations against reference strains from ATCC microorganisms, which were representative of the main groups of bacteria related to human infections, such as E. coli, S. aureus, E. faecalis and P. aeruginosa. The CuO and ZnO-NPs showed better antibacterial properties (500 μg/mL) in comparison with the commercial micrometric particles (1000 μg/mL). The analysis of the synergism between both NPs and ampicillin showed a decrease of their concentrations against all the microorganisms studied, with the ZnO-NPs showing better synergism activity than CuO-NPs, whereas the combination of the antibiotic with ZnO-NPs showed a six-fold decrease against all the microorganisms studied except to P. aeruginosa. The FIC index was calculated with both NPs and ampicillin to each bacterium. In most cases, the effect was partial synergism, and an additive effect was achieved when those combinations were evaluated against P. aeruginosa. The cell viability tests showed that the CuO and ZnO-NPs synthesized and mixed with the antibiotic are biocompatible in effective doses (< 25 μg/mL). The NPs used in this study, prepared by a green innovative synthesis, and their combination with a basic antibiotic showed interesting results, suggesting the possibility of one alternative to biological applications.
Journal of Solution Chemistry
Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl... more Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich– Kister equation and with a series of Legendre polynomials. The excess volumes are negative for the four binaries, probably as a result of the large dipolemoment of DMSO, becoming smaller as the monomer becomes more branched or longer, and the dipole moment per monomer unit becomes larger.
Physics and Chemistry of Liquids, 2001
Densities of the binary systems 2,2′-oxybis[propane] with benzene, toluene, cyclohexane, and meth... more Densities of the binary systems 2,2′-oxybis[propane] with benzene, toluene, cyclohexane, and methyl ethanoate have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube den-sitometer. The calculated excess volumes were correlated with the Redlich-Kister equation and with Legendre&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s polynomials. The excess volumes are negative for the systems of
International Journal of Thermophysics, 2005
Polymers
We investigate the use of an ionic liquid (IL) as a surfactant in emulsion polymerization (EP) re... more We investigate the use of an ionic liquid (IL) as a surfactant in emulsion polymerization (EP) reactions. ILs have been proposed as surfactants for micellar dispersions, emulsions, micro-emulsions and suspensions. Thus, it is important to acquire knowledge of the application of ILs in heterogeneous polymerizations. We selected the amphiphile cationic oligoether IoLiLyte C1EG™ as an IL for this purpose and compared its performance to that of the conventional surfactant dodecyl trimethyl ammonium bromide (DTAB) in the EP of methyl methacrylate and styrene. After we found the proper concentration range of the IL, this amphiphile showed similar polymerization rates to those observed with DTAB for both monomers. The evolution of monomer conversion and the final average diameter of formed polymeric particles were similar for both evaluated surfactants, demonstrating their capability to stabilize the EPs of the investigated monomers. We simulated the evolution of monomer conversion and par...
Colloid and Polymer Science, 2014
ABSTRACT Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulf... more ABSTRACT Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as surfactant and n-butanol (n-BuOH) as the cosurfactant (1:1, wt/wt) with potassium persulfate (KPS) as initiator. The effects of monomer, surfactant, and initiator concentration, as well as the temperature on the kinetics, particle size, and molar masses were studied. It was observed that polymerization rate increases as monomer, initiator, and temperature increases; however, the opposite was observed as surfactant concentration increases. Average particle diameters (Dp) 5 and 7.5 × 105 g/mol were obtained. For low amounts of stabilizing agents (AOT and n-BuOH), a bimodal molar mass distribution (MMD) was obtained. As n-butanol concentration increased, Mw decreases and a monomodal MMD was observed, which can be explained because chain transfer events are promoted by the presence of n-BuOH. A thermodynamic model was implemented to simulate the partitioning of VAc in the presence of n-BuOH between the phases throughout polymerization. It was found from simulations that microemulsion droplets are depleted fast at 5 % conversion and, due to the high water solubility of VAc, most of the monomer (70 %) and n-BuOH (97 %) reside in the aqueous phase at the beginning of polymerization, which indicates that both homogeneous and micellar nucleation are present.
Polymer Bulletin, May 7, 1999
Polymerization of vinyl acetate (VA) in three component oil/water (o/w) microemulsions stabilized... more Polymerization of vinyl acetate (VA) in three component oil/water (o/w) microemulsions stabilized with a mixture of two cationic surfactants (DTAB/DDAB in a weight ratio of 3), was carried out at 40, 50 and 60°C using a water soluble initiator, V-50. In all cases studied, stable latexes containing particles with diameters between 70 and 110 nm were obtained. Particle size increased with conversion yielding uncommonly large particles for microemulsion polymerization, probably because particle coagulation. Multimodal molar mass distributions with average molar masses between 1.2 to 2.0x10 6 g/mol were obtained. Chain transfer to polymer and bimolecular termination reactions play important roles in the microemulsion polymerization of this monomer.
Phyton, 2014
Tomato fruits are perishable products that require treatments such as coating films to extend the... more Tomato fruits are perishable products that require treatments such as coating films to extend their shelf life. Because of this and to avoid use of synthetic chemicals to prevent physical deterioration during postharvest, we evaluated the effects of an edible coating polymer latex poly (vinyl acetate-co-vinyl alcohol), P (VAc-co-VA), at three concentrations (0, 50 and 100%) in tomato fruits. The trial was conducted at room temperature conditions (31 ± 4 °C; with RH of 30 ± 5%) and temperature-controlled (12 ± 1˚C; with RH of 75 ± 5%). Fruits coated with P (VAc-co-VA) at 100 and 50% showed significantly higher physical properties (weight and firmness) after storage than fruits without the coating. Total soluble solids (° Brix) were also significantly higher in fruits either stored at controlled temperature or coated with P (VAc-co-VA) at 100 and 50% than in fruits stored at room temperature or without coating. Our results suggest that P (VAc-co-VA) coatings are suitable agents to preserve tomato fruit shelf life for a longer time.
Journal of Food Quality, 2017
There exists an increasing interest from consumers and scientific community in developing edible-... more There exists an increasing interest from consumers and scientific community in developing edible-natural-biodegradable coatings to replace commercial wax-based coatings for maintaining postharvest quality of vegetables. In this work, the effectiveness of guar gum coating on various quality characteristics of Roma tomato at 22±2°C over a 20 d storage period was investigated. Tomatoes were covered with a 1.5% guar gum coating plasticized with glycerol at 30% and stored at 22±2°C and 40% RH for 20-d. Tomatoes covered with edible coating significantly enhanced firmness and reduced weight loss, delayed changes on soluble-solids-content, retarded loss of total acidity, and decreased respiration rate compared with uncoated-control fruit. Sensory analysis by trained panelists revealed that the use of the edible coating influenced the acceptability of tomatoes. There were significant differences on the scores given by panelists when comparing the coated and uncoated tomatoes. It was conclude...
Chemical Engineering Communications, Dec 1, 2005
Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl... more Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess volumes are negative for the four binaries, probably as a result of the large dipole moment of DMSO, becoming smaller as the monomer becomes more branched or longer, and the dipole moment per monomer unit becomes larger.
Colloid and Polymer Science, Dec 7, 2014
Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinat... more Vinyl acetate (VAc) was polymerized in microemulsion using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as surfactant and n-butanol (n-BuOH) as the cosurfactant (1:1, wt/wt) with potassium persulfate (KPS) as initiator. The effects of monomer, surfactant, and initiator concentration, as well as the temperature on the kinetics, particle size, and molar masses were studied. It was observed that polymerization rate increases as monomer, initiator, and temperature increases; however, the opposite was observed as surfactant concentration increases. Average particle diameters (Dp)< 50 nm and polymers with weight average molar masses (Mw) between 2.7×10 5 and 7.5×10 5 g/mol were obtained. For low amounts of stabilizing agents (AOT and n-BuOH), a bimodal molar mass distribution (MMD) was obtained. As nbutanol concentration increased, Mw decreases and a monomodal MMD was observed, which can be explained because chain transfer events are promoted by the presence of n-BuOH. A thermodynamic model was implemented to simulate the partitioning of VAc in the presence of n-BuOH between the phases throughout polymerization. It was found from simulations that microemulsion droplets are depleted fast at 5 % conversion and, due to the high water solubility of VAc, most of the monomer (70 %) and n-BuOH (97 %) reside in the aqueous phase at the beginning of polymerization, which indicates that both homogeneous and micellar nucleation are present.
Journal of Applied Polymer Science, May 14, 2012
Journal of Solution Chemistry, Feb 1, 2005
Densities of the ternary system 1,4-dioxane + butyl acrylate + ethyl acrylate and its binary buty... more Densities of the ternary system 1,4-dioxane + butyl acrylate + ethyl acrylate and its binary butyl acrylate + ethyl acrylate have been measured in the whole composition range, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes of the binary system are positive and were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several models were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.
Physics and Chemistry of Liquids, Aug 1, 2003
Densities of the binary systems of tetrahydrofuran (THF) with ethyl acrylate, butyl acrylate, met... more Densities of the binary systems of tetrahydrofuran (THF) with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess volumes are negative for all the systems studied. The system THF + methyl methacrylate behaves almost ideally.
The Journal of Chemical Thermodynamics, Jul 1, 2005
ABSTRACT
The Journal of Chemical Thermodynamics, 2007
Densities of the ternary system toluene + butyl acrylate + methyl methacrylate and its three bina... more Densities of the ternary system toluene + butyl acrylate + methyl methacrylate and its three binaries have been measured in the whole composition range, at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes are positive for the binary systems toluene + methyl methacrylate and butyl acrylate + methyl methacrylate and negative for the system toluene + butyl acrylate. The corresponding data were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several empirical equations were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found equally good to fit the data. The best fit was based on a direct approach, without information on the component binary systems.
Polymer Bulletin, Apr 1, 1997
Langmuir, 2000
The polymerization of vinyl acetate in one-phase o/w microemulsions stabilized with Aerosol OT (A... more The polymerization of vinyl acetate in one-phase o/w microemulsions stabilized with Aerosol OT (AOT) is examined as a function of concentration and type of initiator (V-50 and KPS) and temperature. Conversions and reaction rates increase with increasing concentration of V-50 and temperature. Faster polymerization rates and higher conversions are achieved with KPS because of the different electrostatic interactions between the charged microemulsion droplets and the free radicals of KPS and V-50. Average molar masses and polydispersity indexes (M h w/M h n) are much smaller than those observed in emulsion polymerization using the same surfactant, even at high conversions. Analysis of the molar mass distribution indicates that chain-transfer reactions to monomer are the controlling chain-growth mechanism in the polymerization of vinyl acetate in AOT microemulsions at all conversions.
The Journal of Chemical Thermodynamics, Feb 1, 2003
Densities of binary mixtures of 1, 4-dioxane with either ethyl acrylate, or butyl acrylate, or me... more Densities of binary mixtures of 1, 4-dioxane with either ethyl acrylate, or butyl acrylate, or methyl methacrylate, or styrene have been measured as a function of composition at T= 298.15 K and atmospheric pressure with an Anton Paar DMA 5000 oscillating U-tube ...
Ceramics International, 2019
CuO and ZnO nanoparticles (NPs) were synthesized at room-temperature following a novel, direct, h... more CuO and ZnO nanoparticles (NPs) were synthesized at room-temperature following a novel, direct, high-yield (> 91%) and green method based on a mechanically activated metathesis reaction. The CuO-NPs exhibited a rod-like shape with average length and diameter of 22 and 6 nm, respectively, while the ZnO-NPs showed spherical-like morphology and mean diameter of 15 nm, as determined by TEM. The antimicrobial properties of the NPs and commercially available micrometric counterparts were evaluated by the micro dilutions method to determine the minimum inhibitory concentrations against reference strains from ATCC microorganisms, which were representative of the main groups of bacteria related to human infections, such as E. coli, S. aureus, E. faecalis and P. aeruginosa. The CuO and ZnO-NPs showed better antibacterial properties (500 μg/mL) in comparison with the commercial micrometric particles (1000 μg/mL). The analysis of the synergism between both NPs and ampicillin showed a decrease of their concentrations against all the microorganisms studied, with the ZnO-NPs showing better synergism activity than CuO-NPs, whereas the combination of the antibiotic with ZnO-NPs showed a six-fold decrease against all the microorganisms studied except to P. aeruginosa. The FIC index was calculated with both NPs and ampicillin to each bacterium. In most cases, the effect was partial synergism, and an additive effect was achieved when those combinations were evaluated against P. aeruginosa. The cell viability tests showed that the CuO and ZnO-NPs synthesized and mixed with the antibiotic are biocompatible in effective doses (< 25 μg/mL). The NPs used in this study, prepared by a green innovative synthesis, and their combination with a basic antibiotic showed interesting results, suggesting the possibility of one alternative to biological applications.
Journal of Solution Chemistry
Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl... more Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess volumes were correlated with the Redlich– Kister equation and with a series of Legendre polynomials. The excess volumes are negative for the four binaries, probably as a result of the large dipolemoment of DMSO, becoming smaller as the monomer becomes more branched or longer, and the dipole moment per monomer unit becomes larger.
Physics and Chemistry of Liquids, 2001
Densities of the binary systems 2,2′-oxybis[propane] with benzene, toluene, cyclohexane, and meth... more Densities of the binary systems 2,2′-oxybis[propane] with benzene, toluene, cyclohexane, and methyl ethanoate have been measured as a function of the composition, at 298.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube den-sitometer. The calculated excess volumes were correlated with the Redlich-Kister equation and with Legendre&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s polynomials. The excess volumes are negative for the systems of
International Journal of Thermophysics, 2005
Polymers
We investigate the use of an ionic liquid (IL) as a surfactant in emulsion polymerization (EP) re... more We investigate the use of an ionic liquid (IL) as a surfactant in emulsion polymerization (EP) reactions. ILs have been proposed as surfactants for micellar dispersions, emulsions, micro-emulsions and suspensions. Thus, it is important to acquire knowledge of the application of ILs in heterogeneous polymerizations. We selected the amphiphile cationic oligoether IoLiLyte C1EG™ as an IL for this purpose and compared its performance to that of the conventional surfactant dodecyl trimethyl ammonium bromide (DTAB) in the EP of methyl methacrylate and styrene. After we found the proper concentration range of the IL, this amphiphile showed similar polymerization rates to those observed with DTAB for both monomers. The evolution of monomer conversion and the final average diameter of formed polymeric particles were similar for both evaluated surfactants, demonstrating their capability to stabilize the EPs of the investigated monomers. We simulated the evolution of monomer conversion and par...