title: Synthesis, characterization and solution behaviour of oxidized pullulan.
abstract: Various amounts of carboxyl groups were introduced at C-6 of the non-ionic, water soluble polysaccharide, i.e. pullulan, by applying the well-established TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), sodium hypochlorite/sodium bromide oxidation protocol, varying the reaction time. The oxidized products, more water-soluble than pullulan, were further characterized by FT-IR, (1)H NMR and (13)C NMR techniques, in order to assess the degree of oxidation. The absolute molecular weight measurements performed using a multiangle laser light scattering molecular weight analyzer, reveals a sharp drop of the molecular weight of the samples oxidized for longer reaction times. The second virial coefficients (A2), increased from unoxidized pullulan to the oxidized samples. Dynamic light scattering (DLS) measurements provide zeta potentials and hydrodynamic radius for all studied samples. The viscosity of the initial and oxidized pullulan dilute aqueous solutions was studied in detail. All oxidized samples except the highest oxidized pullulan sample (OxPu8) showed strong polyelectrolyte behaviour, whereas this effect is less pronounced for OxPu8 due to the high degradation of the chains. The intrinsic viscosity and the interaction parameter were determined at 25 °C as a function of solvent ionic strength according to Wolf approach. The dependence of these parameters on the salt concentration follows Boltzmann sigmoid model.
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry of Romanian Academy, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Alina
authors.initials: A
authors.lastname: Spatareanu
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry of Romanian Academy, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania; Centre de Mise en Forme des Matériaux, MINES ParisTech, UMR CNRS 7635, Rue Claude Daunesse, BP 207, 06904 Sophia Antipolis, France.
authors.forename: Maria
authors.initials: M
authors.lastname: Bercea
authors.affiliation: Centre de Mise en Forme des Matériaux, MINES ParisTech, UMR CNRS 7635, Rue Claude Daunesse, BP 207, 06904 Sophia Antipolis, France.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Budtova
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry of Romanian Academy, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Valeria
authors.initials: V
authors.lastname: Harabagiu
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry of Romanian Academy, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Liviu
authors.initials: L
authors.lastname: Sacarescu
authors.affiliation: Petru Poni Institute of Macromolecular Chemistry of Romanian Academy, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania. Electronic address: coseris@icmpp.ro.
authors.forename: Sergiu
authors.initials: S
authors.lastname: Coseri
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry; D005936:Glucans / Q000737:chemistry*; D010084:Oxidation-Reduction; D012965:Sodium Chloride / Q000737:chemistry; D012995:Solubility; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D005936:Glucans; D012996:Solutions; D014867:Water; D012965:Sodium Chloride; C009109:pullulan; C003959:TEMPO
keywords: Chain stiffness; Intrinsic viscosity; Oxidation; Polyelectrolyte; Pullulan; Tempo