Associative behaviour of hydrophobically modified carboxymethylpullulan derivatives.
Hydrophobically modified carboxymethylpullulan (HMCMP) samples were obtained by reaction of small amounts of C16 alkylamine on carboxylic groups of the corresponding polyacid. The molar contents of alkyl chains ranged from 1.3 to 6.8% with respect to the anhydroglucose units (AGU) and the degree of substitution (DS) of carboxylic groups varied from 0.76 to 0.84. Solution properties of the sodium salt of HMCMPs were studied mainly by viscometric and size-exclusion chromatography/light-scattering methods. The low-shear viscosity of modified pullulans in 0.1 M NaCl solutions drastically increases with the hydrophobic content and polymer concentrations and the 6.8% modified sample has a quite pseudoplastic behaviour. These data showed that the polymers aggregated intermolecularly and displayed a compact globular structure in dilute solution. Furthermore, addition of NaCl or ethanol induced a decrease in viscosity although the molecular weights remained approximately constant. These results are consistent with a collapse of the polysaccharide aggregates.
Bataille
I
I
UMR 6522 CNRS Polymères, Biopolymères, Membranes, Université de Rouen, Mont-Saint-Aignan, France.
Huguet
J
J
Muller
G
G
Mocanu
G
G
Carpov
A
A
D000588:Amines / Q000737:chemistry; D002240:Carbohydrate Sequence; D005936:Glucans / Q000138:chemical synthesis / Q000737:chemistry*; D006838:Hydrocarbons; D008745:Methylation; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D012492:Salts; D012996:Solutions; D012997:Solvents; D013329:Structure-Activity Relationship; D014783:Viscosity; D014867:Water
D000588:Amines; D005936:Glucans; D006838:Hydrocarbons; D012492:Salts; D012996:Solutions; D012997:Solvents; D014867:Water; C009109:pullulan; C013553:hexadecylamine