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Jorge F. B. Pereira – One of the best experts on this subject based on the ideXlab platform.

  • controlling the formation of ionic liquid based aqueous biphasic systems by changing the hydrogen bonding ability of polyethylene Glycol end groups
    ChemPhysChem, 2015
    Co-Authors: Joao A P Coutinho, Jorge F. B. Pereira, Robin D Rogers, Kiki A Kurnia, Mara G Freire
    Abstract:

    The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene Glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen-bond-donating/-accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen-bond-donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups.

  • Evidence for the Interactions Occurring Between Ionic Liquids and Tetraethylene Glycol in Binary Mixtures and Aqueous Biphasic Systems
    AMER CHEMICAL SOC, 1
    Co-Authors: Tome, Luciana I. N., Jorge F. B. Pereira, Rogers, Robi D., Freire, Mara G., Jose R. B. Gomes, Coutinho, Joao A. P.
    Abstract:

    The well-recognized advantageous properties of poly(ethylene Glycol)s (PEGs) and ionic liquids (ILs) in the context of an increasing demand for safe and efficient biotechnological processes has led to a growing interest in the study of their combinations for a wide range of procedures within the framework of green chemistry. Recently, one of the most promising and attractive applications has been the novel IL/polymer-based aqueous biphasic systems (ABS) for the extraction and purification of biomolecules. There still lacks, however, a comprehensive picture of the molecular phenomena that control the phase behavior of these systems. In order to further delve into the interactions that govern the mutual solubilities between ILs and PEGs and the formation of PEG/IL-based ABS, H-1 NMR spectroscopy in combination with classical molecular dynamics (MD) simulations performed for binary mixtures of tetraethylene Glycol (TEG) and 1-alkyl-3-methylimidazoliumchloride-based ILs and for the corresponding ternary TEG/IL/water solutions, at T = 298.15 K, were employed in this work. The results of the simulations show that the mutual solubilities of the ILs and TEG are mainly governed by the hydrogen bonds established between the chloride anion and the -OH group of the polymer in the binary systems. Additionally, the formation of IL/PEG-based ABS is shown to be controlled by a competition between water and chloride for the interactions with the hydroxyl group of TEG

  • Aqueous biphasic systems composed of ionic liquids and polypropylene Glycol: insights into their liquid-liquid demixing mechanisms
    ROYAL SOC CHEMISTRY, 1
    Co-Authors: Neves, Catarina M. S. S., Jorge F. B. Pereira, Freire, Mara G., Shahriari Shahla, Lemus Jesus, Coutinho, Joao A. P.
    Abstract:

    Novel ternary phase diagrams of aqueous biphasic systems (ABSs) composed of polypropylene Glycol with an average molemolecular weight of 400 g mol(-1) (PPG-400) and a vast number of ionic liquids (ILs) were determined. The large array of selected ILs allowed us to evaluate their tuneable structural features, namely the effect of the anion nature, cation core and cation alkyl sideside chain length on the phase behaviour. Additional evidence on the molecular-level mechanisms which rule the phase splitting was obtained by H-1 NMR (Nuclear Magnetic ResoResonance) spectroscopy and by COSMO-RS (Conductor-like Screening Model for Real Solvents). Some systems, for which the IL-PPG-400 pairs are completely miscible, revealed to be of type \”0”. All data collected suggest that the formation of PPG-IL-based ABSs is controlled by the interactions established between the IL and PPG, contrarily to previous reports where a \”salting-out” phenomenon exerted by the IL over the polymer in aqueous media was proposed as the dominant effect in ABS formation. The influence of temperature on the liquid-liquid demixing was also evaluated. In general, an increase in temperature favours the formation of an ABS in agreement with the lower critical solution temperature (LCST) phase behaviour usually observed in polymer-IL binary mixtures. Partition results of a dye (chloroanilic acid, in its neutral form) further confirm the possibility of tailoring the phases’ polarities of IL-PPG-based ABSs

Coutinho, Joao A. P. – One of the best experts on this subject based on the ideXlab platform.

  • Thermophysical Properties of Glycols and Glymes
    AMER CHEMICAL SOC, 1
    Co-Authors: Carvalho, Pedro J., Fonseca, Cristofe H. G., Moita, Maria-luisa C. J., Santos, Angela F. S., Coutinho, Joao A. P.
    Abstract:

    Experimental data for density, viscosity, refractive index and sound speed of 11 Glycols and glymes were measured in the temperature range between (283.15 and 373.15) K and at atmospheric pressure. The compounds evaluated include ethylene Glycol (EG), diethylene Glycol (DEG), triethylene Glycol (TriEG), tetraethylene Glycol (TeEG), ethylene Glycol ethyl ether (EGEE), diethylene Glycol methyl ether (DEGME), diethylene Glycol dimethyl ether (DEGDME), diethylene Glycol ethyl ether (DEGEE), diethylene Glycol diethyl ether (DEGDEE), triethylene Glycol dimethyl ether (TriEGDME), and tetraethylene Glycol dimethyl ether (TeEGDME). Additionally, derivative properties, such isobaric thermal expansion coefficient and isentropic compressibilities were also estimated and discussed. The compounds evaluated were selected to evaluate the impact of molecular structure changes on their thermophysical properties. Effects like the increase in the number of ethoxy groups, shown to lead to an increase of the density, molar volume, viscosity, and refractive index, or the loss of the hydroxyl groups through the substitution of the hydroxyl groups hydrogen by a methyl or ethyl group, shown to lead to a significant decrease on the density, viscosity, and sound speed, are evaluated and discussed

  • Structural insights into the effect of cholinium-based ionic liquids on the critical micellization temperature of aqueous triblock copolymers
    ROYAL SOC CHEMISTRY, 1
    Co-Authors: Kha Imra, Coutinho, Joao A. P., Umapathi Reddicherla, Neves, Marcia C., Venkatesu Pannuru
    Abstract:

    Symmetrical poly(ethylene Glycol)-block-poly(propylene Glycol)-block-poly(ethylene Glycol) (PEG-PPG-PEG) triblock copolymer with 82.5% PEG as the hydrophilic end blocks, and PPG as the hydrophobic middle block, was chosen to study the effect of ionic liquids (ILs) on the critical micellization temperature (CMT) of block copolymers in aqueous solution. In the present work, cholinium-based ILs were chosen to explore the effect of the anions on the copolymer CMT using fluorescence spectroscopy, dynamic light scattering (DLS), viscosity (Z), FT-IR specspectroscopy, nuclear magnetic resoresonance (NMR), and direct visualization of the various self-assembled nanostructures by scanning electron microscopy (SEM). The result suggests that ILs have the ability to decrease the CMT of the aqueous copolymer solution which is dependent on the nature of the anions of the ILs. The present study reveals that the hydrophobic part PPG of the copolymer has more influence on this behavior than the PEG hydrophilic part

  • Evidence for the Interactions Occurring Between Ionic Liquids and Tetraethylene Glycol in Binary Mixtures and Aqueous Biphasic Systems
    AMER CHEMICAL SOC, 1
    Co-Authors: Tome, Luciana I. N., Jorge F. B. Pereira, Rogers, Robi D., Freire, Mara G., Jose R. B. Gomes, Coutinho, Joao A. P.
    Abstract:

    The well-recognized advantageous properties of poly(ethylene Glycol)s (PEGs) and ionic liquids (ILs) in the context of an increasing demand for safe and efficient biotechnological processes has led to a growing interest in the study of their combinations for a wide range of procedures within the framework of green chemistry. Recently, one of the most promising and attractive applications has been the novel IL/polymer-based aqueous biphasic systems (ABS) for the extraction and purification of biomolecules. There still lacks, however, a comprehensive picture of the molecular phenomena that control the phase behavior of these systems. In order to further delve into the interactions that govern the mutual solubilities between ILs and PEGs and the formation of PEG/IL-based ABS, H-1 NMR spectroscopy in combination with classical molecular dynamics (MD) simulations performed for binary mixtures of tetraethylene Glycol (TEG) and 1-alkyl-3-methylimidazolium-chloride-based ILs and for the corresponding ternary TEG/IL/water solutions, at T = 298.15 K, were employed in this work. The results of the simulations show that the mutual solubilities of the ILs and TEG are mainly governed by the hydrogen bonds established between the chloride anion and the -OH group of the polymer in the binary systems. Additionally, the formation of IL/PEG-based ABS is shown to be controlled by a competition between water and chloride for the interactions with the hydroxyl group of TEG

Freire, Mara G. – One of the best experts on this subject based on the ideXlab platform.

  • Evidence for the Interactions Occurring Between Ionic Liquids and Tetraethylene Glycol in Binary Mixtures and Aqueous Biphasic Systems
    AMER CHEMICAL SOC, 1
    Co-Authors: Tome, Luciana I. N., Jorge F. B. Pereira, Rogers, Robi D., Freire, Mara G., Jose R. B. Gomes, Coutinho, Joao A. P.
    Abstract:

    The well-recognized advantageous properties of poly(ethylene Glycol)s (PEGs) and ionic liquids (ILs) in the context of an increasing demand for safe and efficient biotechnological processes has led to a growing interest in the study of their combinations for a wide range of procedures within the framework of green chemistry. Recently, one of the most promising and attractive applications has been the novel IL/polymer-based aqueous biphasic systems (ABS) for the extraction and purification of biomolecules. There still lacks, however, a comprehensive picture of the molecular phenomena that control the phase behavior of these systems. In order to further delve into the interactions that govern the mutual solubilities between ILs and PEGs and the formation of PEG/IL-based ABS, H-1 NMR spectroscopy in combination with classical molecular dynamics (MD) simulations performed for binary mixtures of tetraethylene Glycol (TEG) and 1-alkyl-3-methylimidazolium-chloride-based ILs and for the corresponding ternary TEG/IL/water solutions, at T = 298.15 K, were employed in this work. The results of the simulations show that the mutual solubilities of the ILs and TEG are mainly governed by the hydrogen bonds established between the chloride anion and the -OH group of the polymer in the binary systems. Additionally, the formation of IL/PEG-based ABS is shown to be controlled by a competition between water and chloride for the interactions with the hydroxyl group of TEG

  • Aqueous biphasic systems composed of ionic liquids and polypropylene Glycol: insights into their liquid-liquid demixing mechanisms
    ROYAL SOC CHEMISTRY, 1
    Co-Authors: Neves, Catarina M. S. S., Jorge F. B. Pereira, Freire, Mara G., Shahriari Shahla, Lemus Jesus, Coutinho, Joao A. P.
    Abstract:

    Novel ternary phase diagrams of aqueous biphasic systems (ABSs) composed of polypropylene Glycol with an average molecular weight of 400 g mol(-1) (PPG-400) and a vast number of ionic liquids (ILs) were determined. The large array of selected ILs allowed us to evaluate their tuneable structural features, namely the effect of the anion nature, cation core and cation alkyl side chain length on the phase behaviour. Additional evidence on the molecular-level mechanisms which rule the phase splitting was obtained by H-1 NMR (Nuclear Magnetic Resonance) spectroscopy and by COSMO-RS (Conductor-like Screening Model for Real Solvents). Some systems, for which the IL-PPG-400 pairs are completely miscible, revealed to be of type \”0”. All data collected suggest that the formation of PPG-IL-based ABSs is controlled by the interactions established between the IL and PPG, contrarily to previous reports where a \”salting-out” phenomenon exerted by the IL over the polymer in aqueous media was proposed as the dominant effect in ABS formation. The influence of temperature on the liquid-liquid demixing was also evaluated. In general, an increase in temperature favours the formation of an ABS in agreement with the lower critical solution temperature (LCST) phase behaviour usually observed in polymer-IL binary mixtures. Partition results of a dye (chloroanilic acid, in its neutral form) further confirm the possibility of tailoring the phases’ polarities of IL-PPG-based ABSs

  • Extraction of tetracycline from fermentation broth using aqueous two-phase systems composed of polyethylene Glycol and cholinium-based salts
    ELSEVIER SCI LTD, 1
    Co-Authors: Jorge F. B. Pereira, Freire, Mara G., Vicente Filipa, Santos-ebinuma, Valeria C., Araujo, Janete M., Pessoa Adalberto, Coutinho, Joao A. P.
    Abstract:

    Aiming at developing not only cheaper but also biocompatible and sustainable extraction and purification processes for antibiotics, in this work it was evaluated the ability of aqueous two-phase systems (ATPS) composed of polyethylene Glycol (PEG) and cholinium-based salts to extract tetracycline from the fermented broth of Streptomyces aureofaciens. Conventional polymer/salt and salt/salt ATPS were also studied for comparison purposes. The novel systems here proposed are able to extract tetracycline directly from the fermentation broth with extraction efficiencies higher than 80%. A tailored extraction ability of these systems can also be achieved, with preferential extractions either for the polymer– or salt-rich phases, and which further depend on the cholinium-based salt employed. The gathered results support the applicability of biocompatible ATPS in the extraction of antibiotics from complex matrices and can be envisaged as valuable platforms to be applied at the industrial level by pharmaceutical companies. (c) 2013 Elsevier Ltd. All rights reserved

Joao A P Coutinho – One of the best experts on this subject based on the ideXlab platform.

  • Fractionation of phenolic compounds from lignin depolymerisation using polymeric aqueous biphasic systems with ionic surfactants as electrolytes
    Green Chemistry, 2016
    Co-Authors: João H.p.m. Santos, Margarida Martins, António Jorge Silvestre, Joao A P Coutinho, Sonia P M Ventura
    Abstract:

    Lignin-based materials and chemicals represent a large class of potential added-value compounds for biorefineries; however, the difficulty in fractionating heterogenous phenolic compounds that result from lignin depolymerisation still remains a challenge. Herein, a set of polymer-based aqueous biphasic systems (ABS) comprising sodium polyacrylate (NaPA 8000) and polyethylene Glycol (PEG 8000), in which ionic surfactants and ionic liquids are used as electrolytes at concentrations below 1 wt%, is investigated for this purpose. Binodal curves were determined for three electrolyte concentrations, namely, 0.01, 0.1 and 1.0 wt%, and an intermediate electrolyte concentration was selected to investigate the partition of five phenolic compounds, caffeic acid, vanillic acid, gallic acid, vanillin and syringaldehyde, on these systems. The results show that the ABS allow the manipulation of the partition of the five phenolic compounds, which culminates with their selective isolation, with vanillin selectivities of SVN/VA = 23.75, SVN/GA = 12.52 and SVN/CA = 8.47. The electrolyte nature seems to play an important role in the fractionation of the phenolic compounds, due to the difference in their hydrophobic nature and speciation. This study demonstrates the ability of polymeric-based ABS, using ionic surfactants or ionic liquids as electrolytes, to efficiently separate and isolate five structurally similar phenolic compounds using a low-cost and very eco-friendly integrated process.

  • controlling the formation of ionic liquid based aqueous biphasic systems by changing the hydrogen bonding ability of polyethylene Glycol end groups
    ChemPhysChem, 2015
    Co-Authors: Joao A P Coutinho, Jorge F. B. Pereira, Robin D Rogers, Kiki A Kurnia, Mara G Freire
    Abstract:

    The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene Glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen-bond-donating/-accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen-bond-donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups.

Robin D Rogers – One of the best experts on this subject based on the ideXlab platform.

  • controlling the formation of ionic liquid based aqueous biphasic systems by changing the hydrogen bonding ability of polyethylene Glycol end groups
    ChemPhysChem, 2015
    Co-Authors: Joao A P Coutinho, Jorge F. B. Pereira, Robin D Rogers, Kiki A Kurnia, Mara G Freire
    Abstract:

    The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene Glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen-bond-donating/-accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen-bond-donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups.