Room-temperature Ia3̄d phase obtained for the binary mixture containing different sizes of siloxanyl terminals.

ABSTRACT

Two types of binary mixtures were examined to optimize the siloxanyl fraction by filling the gap between the two Cub-phase-forming molecules with di- and tri-siloxanyl terminals. Adding siloxanyl to the disiloxanyl system largely inhibited crystallization, increasing the stability at room temperature of the meta-stable Ia3̄d phase obtained by cooling from the high-temperature phase. The effect was prominent for the mixtures containing both di- and tri-siloxanyl compounds. The most prominent result was obtained for the 50 50 mixture; the Ia3̄d phase was quite stable and survived at room temperature after more than 1 year, as if it were like a thermodynamically stable phase.