Phase behavior of CTAB: o-iodophenol binary system

The phase diagram of the binary system CTAB (cetyltrimethylammonium bromide ): OIPh (o-iodophenol) was investigated by DSC and TG methods along with po larizing-microscopic and visual observations. It was found that CTAB and OI Ph produced a 1 : 3 intermolecular complex in addition to the 1 : 1 complex already reported. Both complexes underwent incongruent melting at about 30 5 K and 365 K, respectively. Another complex of 2 : 1 ratio was observed in the high temperature region, which formed a solid solution of mesomorphic nature with the high-temperature metastable phase of CTAB over Limited comp osition range. The thermodynamics of formation of the 1 : 1 complex in the crystalline state is discussed. (C) 1999 Elsevier Science B.V. All rights r eserved.