The influence of gelation on the mechanism of phase separation of a biopolymer mixture

The influence of the gelation of one component (gelatin) on the phase separation and morphology of an aqueous mixture of gelatin and dextran has been investigated. Small angle light scattering and confocal microscopy experiments show that the mechanism of phase separation is similar to spinodal decomposition, even in the presence of a rapid gelation. At temperatures well below the gelation temperature the phase separation kinetics are halted by the gelation, resulting in an immobile, interconnected morphology. This effect is seen as a pinning of the peak in the light scattering data. We also show that the gelation affects the position of the scattering peak, effectively deepening the quench as the gelation proceeds, through an apparent increase in molecular weight. (C) 2001 Elsevier Science Ltd. All rights reserved.