M-~ (2 +) (zn (2 +), Ca (2 +)) Ion-induced Formation Of Vesicles And Their Template Applications

In this paper, three catanionic systems were constructed and the phase behaviors were studied. Vesicle phases induced by the metal complexation interaction were obtained and their template-effects for preparing nanomaterials were explored. This paper includes three parts which will be summarized as following:Part I: Review (chapter 1～2)In recent years, catanionic surfactant systems attracted much interest according to their rich phase behaviors comparing with the single surfactant systems.The catanionic systems were obtained by mixing cationic and anionic surfactants. When being mixed, the strong reduction in area of per head group resulting from ion paring induces the formation of molecular bilayers even at very low concentrations. Vesicles may form spontaneously at the right mixing ratios.Most catanionic systems studied previously contain excess salts formed by the counterions, which produce a high conductivity and ion strength that screens electrostatic interactions between aggregates. As a result, with increasing amount of cationic and anionic surfactants, precipitate often forms when the stoichiometry between the cationic and anionic surfactants is exactly 1. Recent years, especially interest structures have been devoted to the study of salt-free catanionic surfactant systems. The phases that are ionic charged and not shielded by the absence of the excess salt have interesting rheological properties.The salt-free systems can be prepared through four routes. One is mixing two nonionic surfactants. The other one is mixing the acidic surfactants with basic surfactants. The third one is mixing the strongly acidic surfactants with nonionic surfactants which can interact with proton. Finally, the salt free systems can also be induced by the metal-complexation interactions. The salt-free catanionic systems can be obtained by these ways except the first one.