Aqueous Solutions of Native and Hydrophobically Modified Polysaccharides:  Temperature Effect

Abstract

Amphiphilic polysaccharides, obtained by the attachment of various hydrocarbon groups onto dextran, are studied in aqueous solutions. The viscosity of their aqueous solutions is examined as a function of concentration and temperature in the range 25-65 degrees C. Varying polymer concentration, viscosity follows a polynomial development of Huggins equation in which the coefficients can be calculated from the Huggins constant determined in the dilute domain (Matsuoka-Cowman equation). For all polymers, the solution viscosity follows an Arrhenius-like variation with temperature. The activation energy of the aqueous solutions is determined as a function of polymer concentration and structural characteristics (nature and amount of grafted hydrocarbon groups). The variation of activation energy with polymer concentration is shown to be consistent with predictions based on the Matsuoka-Cowman equation combined with the equation of Andrade. This conclusion is extended to other polysaccharides using data from the literature.

Rheology of a reversible supramolecular polymer studied by comparison of the effects of temperature and chain stoppers

“…This was originally derived for simple liquids, 38 but it is applied much more generally. 39,40 Like other processes with an activation energy barrier, the temperature dependence of the viscosity can be described by an Arrhenius-type expression with an activation energy E , which contains contributions from the breaking of bonds and the reptation of chains. Moreover, the viscosity is proportional to ͗N͘ ␣ ͓Eq.…”

Amphiphilic cholesteryl-bearing carboxymethylcellulose derivatives: self-assembly and rheological behaviour in aqueous solution

“…In recent years, interest has grown in amphiphilic polysaccharide derivatives, which tend to self-assemble into nano-aggregates in aqueous solutions owing to their special chemical structures composed of the hydrophilic polysaccharide chains linked with the hydrophobic groups (Durand and Dellacherie 2006;Simon et al 2003). Therefore, the amphiphilic polysaccharide derivatives are promising as a new kind of biomedical materials, especially as the carries for the controlled drug release system.…”

Self-assembly of amphiphilic copolymers containing polysaccharide: PISA versus nanoprecipitation, and the temperature effect

“…In contrast, at 60°C, PHPMA grafts were less hydrated (more compact) leading to a lower Vr (smaller packing parameter) and thus resulting in the formation of lower-order morphology (spheres, Nano-5). Note that dextran does not undergo any conformational change at this range of temperature, 106 that would explain the difference of morphology observed by PISA at RT and 60°C.…”