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 T_gel compared to those of the as-prepared ones. The existence of the cubic phase in 4D₁₆ gels in cyclohexane and benzene destabilized the gels.