Authors: Spelzini, Dario¹; Rigatusso, Ruben¹; Farruggia, Beatriz¹; Picó, Guillermo²

Source: Cellulose, Volume 12, Number 3, June 2005 , pp. 293-304(12)

Publisher: Springer

Abstract:

The formation of a biphasic system from aqueous solutions of methyl cellulose induced by temperature was studied through heating curves of the polymer solution measured by absorbance spectroscopy, differential scanning calorimetry and solution viscosimetry. The treatment of the heating curve data according to a reversible two-state transition model allows us to calculate the middle point temperature (T_m) of the formation of the two phases and the thermodynamic functions associated to the polymer aggregation. The middle point temperature was found within the range 50–70 °C. It decreased significantly in a Na₂SO₄ 0.3 M medium when the polymer concentration increased. The heat associated to the two-phase formation was positive and it increased with increases in temperature. Cosolutes that affect the water structure induced changes in the T_m values, which suggests the presence of a hydrophobic effect in the two-phase formation from the polymer solution. Hydrophilic proteins were partitioned in favour of the methyl cellulose rich phase according to their surface hydrophobicity. The partition was also influenced by the presence of salts that modify the protein hydrophobicity such as sodium sulphate.

Keywords: Methyl cellulose; Partitioning; Temperature; Two phases

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10570-004-5865-2

Affiliations: 1: Physical Chemistry Department. Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, Rosario, S2002RLK, Argentina, 2: Physical Chemistry Department. Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, Rosario, S2002RLK, Argentina, Email: gpico@fbioyf.unr.edu.ar

Publication date: 2005-06-01

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• In this Subject: Anatomy & Physiology ,  Biology ,  Chemical Engineering ,  Organic Chemistry ,  Materials & Manufacturing
• By this author: Spelzini, Dario ;  Rigatusso, Ruben ;  Farruggia, Beatriz ;  Picó, Guillermo

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