Real-time monitoring of the change in stiffness of single-strand xanthan gum induced by NaCl

The conformation of polyelectrolytes such as xanthan gum is strongly influenced by the interaction with the solvent. However, it is essential to consider the ionic composition already present in the molecule. Thus, it is important to study the physical-chemical characteristics of the molecule without other additional factors. In this work, we observed, in real time, using automatic continuous mixing (ACM), the influence of salt concentration on the conformation of the single-stranded xanthan gum (X). The results here confirm that in water, X is single stranded, with Rg and Lp values of 40 and 37 nm, respectively. During the ACM experiment, the salt concentration increased, reaching a limit that changed the conformation to a compact strand, when Rg and Lp decreased to 30 and 29 nm, respectively, with reduction in A2. ACM can be used as a powerful tool to study the conformational transition of polyelectrolytes induced by salt.