title: Effects of beta-cyclodextrin addition and temperature on the modulation of hydrophobic interactions in aqueous solutions of an associative alginate.
abstract: Novel information about the effects of beta-cyclodextrin (beta-CD) addition and temperature on structural and rheological features of semidilute solutions of alginate and its hydrophobically modified analogue (HM-alginate) is given. Enhanced turbidity is observed for the HM-alginate solutions at high levels of beta-CD addition and low temperatures. The viscosity results revealed cross-linking of the alginate chains at high beta-CD concentrations and low temperatures. Rheological results for the HM-alginate solutions demonstrated that high levels of beta-CD addition and elevated temperatures promoted decoupling of the hydrophobic polymer-polymer associations via inclusion complex formation between beta-CD cavities and the hydrophobic side chains of the polymer. Analysis of small-angle neutron scattering (SANS) results from HM-alginate solutions in the presence of beta-CD suggested that the polymer chains are locally stretched at all of the considered levels of beta-CD and temperatures. The SANS results revealed association structures. The general picture that emerges is that beta-CD addition and temperature can be combined to tune the intensity of the hydrophobic interactions and to cross-link the unmodified alginate.
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway.
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Kjøniksen
authors.forename: Céline
authors.initials: C
authors.lastname: Galant
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Knudsen
authors.forename: Giao T M
authors.initials: GT
authors.lastname: Nguyen
authors.forename: Bo
authors.initials: B
authors.lastname: Nyström
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D003505:Cyclodextrins / Q000737:chemistry; D005782:Gels; D057927:Hydrophobic and Hydrophilic Interactions; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015233:Models, Statistical; D009391:Nephelometry and Turbidimetry; D009502:Neutrons; D009991:Oscillometry; D004364:Pharmaceutical Preparations; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D012212:Rheology; D012542:Scattering, Radiation; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D014783:Viscosity; D014867:Water / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D003505:Cyclodextrins; D005782:Gels; D046911:Macromolecular Substances; D004364:Pharmaceutical Preparations; D011108:Polymers; D012996:Solutions; D047392:beta-Cyclodextrins; D014867:Water; C031215:betadex