(Invited) Phase Separation in Mixed Polysaccharide Gels

Studies on phase separation behavior for the mixed polysaccharides of kappa carrageenan (k-carr) and iota carrageenan (i-carr) has been reviewed. It was reported that the temperature dependence of G' and G'' for the mixture solution measured by dynamic rheological measurement showed two step increases in cooling process, suggesting the individual network formation of k- and i-carr chains at gelling temperatures (Tg) corresponding to Tg for pure each solution of. DSC measurements for the mixture showed two exothermic peaks at the Tg's of pure k- and i-carr, supporting the individual network formation. Diffusions of a probe polymer added in the mixed gel were measured by gradient NMR with a view to revealing the morphological structure in the gel, but adequate information was not obtained. Particle tracking method for fluorescent particles with diameter of 100nm in the mixture was demonstrated suggesting the formation of phase separated structure with k-carr rich and i-carr rich phases from the micro rheological diversity.