Aqueous solutions of native and hydrophobically modified polysaccharides: temperature effect

Area of Science:

• Polymer Chemistry
• Physical Chemistry
• Materials Science

Background:

• Amphiphilic polysaccharides, modified dextrans, are crucial in various applications.
• Understanding their solution behavior is key to optimizing their use.

Purpose of the Study:

• To investigate the viscosity and temperature-dependent behavior of amphiphilic dextran solutions.
• To determine the activation energy of these solutions and its relation to polymer structure.

Main Methods:

• Viscosity measurements of aqueous solutions across varying concentrations and temperatures (25-65°C).
• Application of Huggins and Matsuoka-Cowman equations to analyze concentration-dependent viscosity.
• Determination of activation energy using Arrhenius-like relationships and Andrade's equation.

Main Results:

• Solution viscosity follows a polynomial development of the Huggins equation, with coefficients derived from the Huggins constant.
• Viscosity exhibits an Arrhenius-like temperature dependence for all studied polymers.
• Activation energy varies with polymer concentration and the nature/amount of grafted hydrocarbon groups.

Conclusions:

• The observed activation energy variations align with predictions from the Matsuoka-Cowman and Andrade equations.
• These findings provide a framework for understanding and predicting the solution behavior of modified polysaccharides.
• The conclusions are supported by literature data on other polysaccharides.