(678g) Polysaccharide Aqueous Solution Structure and Properties Modulated By Additives

Polysaccharides such as xanthan gum, guar gum, and cellulose derivatives have emerged as versatile materials with vast application potential owing to their inherent physicochemical properties. [1-3] Xanthan gum, derived from the fermentation of Xanthomonas campestris, shares structural similarities with cellulose, featuring a β-1,4-linked glucan backbone. In its molecular architecture, the trisaccharide β-D-mannose-(1-4)-α-D-glucuronic acid-(1-2)-α-D-mannose is linked to every other glucose residue's O(3) position. In water, xanthan gum exhibits conformational transitions from helices (characterized by rigid chains and low viscosity) to random coils (with more flexible chains and higher viscosity) in response to solution pH, ion size, ionic strength, and temperature. However, the influence of salts and temperature on the physicochemical properties of xanthan gum in aqueous solutions remains a subject of exploration. We have investigated the fundamental properties of xanthan gum [3-5] and carboxymethyl hydroxypropyl guar gum (CMHPG) [6] in plain water and in aqueous solutions with inorganic salts or ionic liquids at varied temperatures. In both xanthan gum and CMHPG solutions, electrostatic interactions play a crucial role in the chain expansion in the presence of salts and temperature. However, CHMPG demonstrated salt tolerance and showed comparatively less viscosity change than native guar gum and other polysaccharides, including xanthan gum. These findings offer valuable insights into how various factors modulate the rheological properties and structural characteristics of polysaccharide solutions.

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