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Comparison of temperature effects on the salting out of poly(ethylene glycol) versus poly(ethylene oxide)−poly(propylene oxide) random copolymer / Meghna Dilip in Industrial & engineering chemistry research, Vol. 49 N° 5 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2371–2379 Titre : Comparison of temperature effects on the salting out of poly(ethylene glycol) versus poly(ethylene oxide)−poly(propylene oxide) random copolymer Type de document : texte imprimé Auteurs : Meghna Dilip, Auteur ; Scott T. Griffin, Auteur ; Scott K. Spear, Auteur Année de publication : 2010 Article en page(s) : pp. 2371–2379 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Random  Copolymer;  Poly(ethylene  glycol);  Poly(ethylene  oxide);  Poly(propylene  oxide);  Aqueous  biphasic  systems Résumé : In common with many poly(ethylene glycol)s (PEGs), a poly(ethylene oxide)−poly(propylene oxide) random copolymer (EO−PO, with EO/PO = 1:1.3) of molecular weight 3320 g·mol−1, known as Sunbright-3320 (SB-3320), can be salted out of aqueous solution using kosmotropic salts such as (NH4)2SO4 to form aqueous biphasic systems (ABSs) comprising upper polymer-rich and lower salt-rich aqueous phases. The effects of temperature on these liquid/liquid ABSs and related solid/liquid resin-based systems, where one end of the polymer has been covalently attached to a solid support, have been studied. Distribution ratios of NH499TcO4 were determined radiometrically at various polymer and salt concentrations and temperatures. SB-3320-grafted poly(styrene) resins exhibit opposite effects of variable-temperature partitioning compared to the SB-3320-based ABS. However, the results are complicated because of the conformational changes that are possible for the SB-3320 polymer. Enthalpy and entropy changes were found to be temperature-dependent. The differences observed between the distribution of 99TcO4− in EO−PO-based systems versus PEG-based systems can be attributed to the lower cloud point temperatures and probable conformational changes for the EO−PO systems. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901268m [article] Comparison of temperature effects on the salting out of poly(ethylene glycol) versus poly(ethylene oxide)−poly(propylene oxide) random copolymer [texte imprimé] / Meghna Dilip, Auteur ; Scott T. Griffin, Auteur ; Scott K. Spear, Auteur . - 2010 . - pp. 2371–2379. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2371–2379 Mots-clés : Random  Copolymer;  Poly(ethylene  glycol);  Poly(ethylene  oxide);  Poly(propylene  oxide);  Aqueous  biphasic  systems Résumé : In common with many poly(ethylene glycol)s (PEGs), a poly(ethylene oxide)−poly(propylene oxide) random copolymer (EO−PO, with EO/PO = 1:1.3) of molecular weight 3320 g·mol−1, known as Sunbright-3320 (SB-3320), can be salted out of aqueous solution using kosmotropic salts such as (NH4)2SO4 to form aqueous biphasic systems (ABSs) comprising upper polymer-rich and lower salt-rich aqueous phases. The effects of temperature on these liquid/liquid ABSs and related solid/liquid resin-based systems, where one end of the polymer has been covalently attached to a solid support, have been studied. Distribution ratios of NH499TcO4 were determined radiometrically at various polymer and salt concentrations and temperatures. SB-3320-grafted poly(styrene) resins exhibit opposite effects of variable-temperature partitioning compared to the SB-3320-based ABS. However, the results are complicated because of the conformational changes that are possible for the SB-3320 polymer. Enthalpy and entropy changes were found to be temperature-dependent. The differences observed between the distribution of 99TcO4− in EO−PO-based systems versus PEG-based systems can be attributed to the lower cloud point temperatures and probable conformational changes for the EO−PO systems. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901268m

Dual nature of polyethylene glycol-based aqueous biphasic extraction chromatographic (ABEC) resins / Meghna Dilip in Industrial & engineering chemistry research, Vol. 47 N°19 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7390–7396 Titre : Dual nature of polyethylene glycol-based aqueous biphasic extraction chromatographic (ABEC) resins : uptakes of perchlorate versus mercury(II) Type de document : texte imprimé Auteurs : Meghna Dilip, Auteur ; Scott T. Griffin, Auteur ; Scott K. Spear, Auteur Année de publication : 2008 Article en page(s) : p. 7390–7396 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyethylene  glycol  ABEC  resins  Mercury(II)  cations  Perchlorate  anions Résumé : Polyethylene glycol (PEG)-grafted aqueous biphasic extraction chromatographic (ABEC) resins have been shown to remove both mercury(II) cations (Hg2+) or perchlorate anions (ClO4−) from aqueous media under different conditions. Water destructuring (chaotropic) anions such as perchlorate (ΔGhyd = −214 kJ/mol) partitioned to ABEC resin in the presence of water structuring (kosmotropic) anions, with increased affinity for the resin as the kosmotropic nature of the anion increased (Cl− < SO42− < PO43−), and could be easily stripped using water. However, while the partitioning of ClO4− to the resin was possible only in the presence of a kosmotropic salt; Hg2+ was retained from the resin only in the absence of such salts (i.e., from pure water) and stripped from the resin when eluted with kosmotropic salt solutions. Here, the different mechanisms for uptake of these ions by an ABEC resin are explored. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800841j [article] Dual nature of polyethylene glycol-based aqueous biphasic extraction chromatographic (ABEC) resins : uptakes of perchlorate versus mercury(II) [texte imprimé] / Meghna Dilip, Auteur ; Scott T. Griffin, Auteur ; Scott K. Spear, Auteur . - 2008 . - p. 7390–7396. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7390–7396 Mots-clés : Polyethylene  glycol  ABEC  resins  Mercury(II)  cations  Perchlorate  anions Résumé : Polyethylene glycol (PEG)-grafted aqueous biphasic extraction chromatographic (ABEC) resins have been shown to remove both mercury(II) cations (Hg2+) or perchlorate anions (ClO4−) from aqueous media under different conditions. Water destructuring (chaotropic) anions such as perchlorate (ΔGhyd = −214 kJ/mol) partitioned to ABEC resin in the presence of water structuring (kosmotropic) anions, with increased affinity for the resin as the kosmotropic nature of the anion increased (Cl− < SO42− < PO43−), and could be easily stripped using water. However, while the partitioning of ClO4− to the resin was possible only in the presence of a kosmotropic salt; Hg2+ was retained from the resin only in the absence of such salts (i.e., from pure water) and stripped from the resin when eluted with kosmotropic salt solutions. Here, the different mechanisms for uptake of these ions by an ABEC resin are explored. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800841j