title: Two types of hydrophobic aggregates in aqueous solutions of chitosan and its hydrophobic derivative.
abstract: The aggregation phenomena in aqueous solutions of hydrophobically modified (HM) chitosan, containing 4 mol % of n-dodecyl side chains, were studied by viscometry and fluorescence spectroscopy with pyrene as a probe. The results are compared with those for unmodified chitosan. Surprisingly, fluorescence data reveal the appearance of intermolecular hydrophobic aggregates both in chitosan and in HM chitosan. Nevertheless, these polymers exhibit quite different rheological properties: upon the formation of aggregates the viscosity of HM chitosan sharply increases, while that of unmodified chitosan raises only slightly. The aggregation models for both chitosan and its hydrophobic derivative were proposed. It was shown that in solutions of HM chitosan two types of hydrophobic domains exist: hydrophobic domains typical for different associating polymers with hydrophobic side chains and hydrophobic domains inherent to chitosan itself.
authors.affiliation: Centre de Recherches sur les Macromolecules Vegetales, CNRS, affiliated with Joseph Fourier University, BP 53, 38041 Grenoble Cedex 9, France.
authors.forename: O E
authors.initials: OE
authors.lastname: Philippova
authors.forename: E V
authors.initials: EV
authors.lastname: Volkov
authors.forename: N L
authors.initials: NL
authors.lastname: Sitnikova
authors.forename: A R
authors.initials: AR
authors.lastname: Khokhlov
authors.forename: J
authors.initials: J
authors.lastname: Desbrieres
authors.forename: M
authors.initials: M
authors.lastname: Rinaudo
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry*; D048271:Chitosan; D057927:Hydrophobic and Hydrophilic Interactions; D011721:Pyrenes / Q000737:chemistry; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014783:Viscosity
chemical_list: D001704:Biopolymers; D011721:Pyrenes; D012996:Solutions; D002686:Chitin; D048271:Chitosan; C030984:pyrene