Octadecyltrimethyl ammonium chloride

The incorporation of a cationic azobenzene derivative, p-( a> -dimethyl-ethanolammonioethoxyj-azobenzene bromide, into nanoporous silica films and the photochemical reactions of the adsorbed dye were investigated. The nanoporous silica films were prepared from tetramethoxysilane and octadecyltrimethyl-ammonium chloride by the rapid solvent evaporation method which we have reported previously. The adsorption of the cationic azo dye was conducted by casting an ethanol solution of the dye onto the nanoporous silica films. Upon UV light irradiation, trans-azobenzene isomerized photochemically to the c/s-form and photochemically formed c/ s-form turned back to the frans-form upon visible light irradiation. The nanoporous silica films were proved to be an excellent reaction media to immobilize organic photocromic species. 

Tetramethoxysilane (abbreviated as TMOS) and octadecyltrimethyl-ammonium chloride [(C18H37)(CH3)3N+Cr abbreviated as C18TAC] were obtained from Tokyo Kasei Industries Co., and used without further purification. A cationic azobenezene derivative [abbreviated as AZ] (the molecular structure is shown in Scheme 11) was prepared by the reaction between 4-phenylazophenol, 1,2-dibromoethane, and 2-dimethylaminoethanol, obtained from Tokyo Kasei Industries Co. 

A hair rinse is used to add smoothness to the hair and to facilitate styling. It is an oil dispersed in a cationic surfactant/higher alcohol/water system. Figure 3 is a phase diagram of hexadecanol/octadecyltrimethyl-ammonium chloride/water ternary systems at 55 and 75° C investigated by thermal analysis. The G2 phase that exists in a broad molar range exhibits a thixotropic gel that has a lamellae structure below its melting point (see Fig. 4) [41]. 

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