Impact of backbone stiffness and hydrophobic chain length of modified xanthan on oil in water emulsion stabilization.

The impact of xanthan chemical modification under both ordered and disordered conformations on oil-in-water (O/W) emulsion stabilization was investigated. While both hydrophobically modified xanthan (HMX) are able to stabilize the O/W interface, a dramatic difference was observed macroscopically. When HMX (ordered conformation) could produce stable emulsions at concentrations down to 0.2% w/w, HMX (disordered conformation) led to unstable systems mostly by creaming whatever the concentration studied. Moreover, in the case of HMX, the role of the grafted chain length was investigated and two different behaviors were observed depending on the grafting unit. It was demonstrated that the cornerstone of these emulsion stability was the rheological properties of the continuous phase which was governed by two main factors: the partitioning of HMX between the interface and the continuous phase and the viscosifying ability of the polymer, the latter being directly linked to the backbone stiffness.