The role of charged surfactants in the thermal and structural properties of lyotropic liquid crystalline mesophases of [Zn(H2O)6](NO3)2-C(n)EO(m)-H2O.
The mixtures of [Zn(H(2)O)(6)](NO(3))(2) salt, 10-lauryl ether (C(12)H(25)(OCH(2)CH(2))(10)OH, represented as C(12)EO(10)), a charged surfactant (cetyltrimethylammonium bromide, C(16)H(33)N(CH(3))(3)Br, represented as CTAB or sodium dodecylsulfate, C(12)H(25)OSO(3)Na, SDS) and water form lyotropic liquid crystalline mesophases (LLCM). This assembly accommodates up to 8.0 Zn(II) ions (corresponds to about 80%w/w salt/(salt+C(12)EO(10))) for each C(12)EO(10) in the presence of a 1.0 CTAB (or 0.5 SDS) and 3.5 H(2)O in its LC phase. The salt concentration can be increased by increasing charged surfactant concentration of the media. Addition of charged surfactant to the [Zn(H(2)O)(6)](NO(3))(2)-C(12)EO(10) mesophase not only increases the salt content, it can also increase the water content of the media. The charged surfactant-C(12)EO(10) (hydrophobic tail groups) and the surfactant (head groups)-salt ion (ion-pair, hydrogen-bonding) interactions stabilize the mesophases at such salt high and water concentrations. The presence of both Br(-) and NO(3)(-) ions influences the thermal and structural properties of the [Zn(H(2)O)(6)](NO(3))(2)-C(12)EO(10)-CTAB(or SDS)-H(2)O LLCM, which have been investigated using XRD, POM (with a hot stage), FT-IR and Raman techniques.
Albayrak
Cemal
C
Department of Chemistry, Bilkent University, 06800 Ankara, Turkey.
Soylu
Asli M
AM
Dag
Omer
O