自己組織集合体の相転移に伴う粘弾性と熱的挙動の変化

概要

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Structural development of the ternary self-assembly, comprising cetyltrimethylammonium chloride (C16CA), cetyl alcohol (C16OH) and water, proceeds gradually up to one month. This is monitored by the strain (γ) dependence of the dynamic modulus (G) and the loss modulus (G"). Cohesive energy, EC, of the formed structure increases over weeks. While G increases monotonously with ω, G" exhibits two maxima when plotted against frequency. This is compatible with two arcs in the Cole-Cole plots, corresponding to two respectiv relaxation mechanisms. The relaxation strengths, IH and IL are attributed to relaxation of lamellae and the network of coagulated multilamellar vesicles, respectively. We therefore conclude that viscoelastic behaviors at the higher and lower frequency sides are associated with lamellae and the network of coagulated vesicles. Two DSC endothermic peaks at 61 and 64°C represent the melting point of lamellae and vesicles. When the aging time is less than one day, the melting enthalpy ratio (ΔHL/ΔHH) is less than unity, hence the coagulated structure of vesicles outweighs lamellae. Further increase in the lamellae is consistent with the increase in the relaxation strength ratio (IH/IL) obtained from the Cole-Cole plots.
日本レオロジー学会の論文
1999-09-15