Lamellar-cubic transition of a dihydrazide derivative and its effect on the gel stability.

Abstract

N,N'-Bis(4-n-alkyloxybenzoyl)hydrazine (4D16) was demonstrated to show three different aggregates, i.e. a crystalline cubic phase and two kinds of lamellar structure with layer spacings of 34.20 Å (termed the L1 structure) and 40.85 Å (L2 structure) depending on the type of solvents. Lamellar (L1)-crystalline cubic transition during heating was confirmed for 4D16 showing the L1 structure. 4D16 organogels in cyclohexane and benzene exhibited either a mixture of the L1 structure and the crystalline cubic phase or only one of the two structures. 4D16 gels prepared at a higher concentration or a lower incubation temperature consisted of more lamellar L1 structures compared to those obtained at a lower concentration or a higher incubation temperature. Annealing of the as-prepared 4D16 gels at certain temperatures for different time periods caused gradual lamellar L1-cubic transition, and thus increased the content of the cubic phase in the gels, which showed lower Tgel compared to those of the as-prepared ones. The existence of the cubic phase in 4D16 gels in cyclohexane and benzene destabilized the gels.