Theoretical Study of Phase Transition Behaviour in Mixed Biopolymer + Surfactant Interfacial Layers Using the Self-Consistent-Field Approach - Food Colloids: Self-Assembly and Material Science - page 255

incompatibility between these two species. The study predicts the existence of
complex behaviour in these layers, involving abrupt changes in the configura-
tion of the macromolecules and rapid adsorption and desorption of surfactant
from the interface, as the bulk concentration of surfactant or the amount of
biopolymer at the interface is varied. We have shown that such behaviour is
associated with the existence of a first-order phase transition in such systems.
The presence of such sudden changes in the composition of the interfacial
films can have important implications for the processing and formulation of
food products, making these more difficult and unpredictable close to the
transition point. It will be of interest in future studies to consider the implica-
tion that the behaviour of such mixed layers might have on the colloidal
interaction that these mediate between emulsion droplets. It is expected that a
similar phase transition may occur at a critical separation distance between the
droplet surfaces. Indeed, for systems involving pure ionic surfactants, such a
phenomenon has already been predicted, 25,26 although the driving force for the
predicted transition is somewhat different to the one arising here in our system.
Future experiments involving ellipsometry or Brewster angle microscopy
may provide further useful evidence for the existence of the phenomenon
predicted here.
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