Identification and Characterization of Aggregates Formed by a Partly Neutralized Isophthalic Acid Derivative in Aqueous Solution

Fiber-shaped aggregates were obtained from aqueous solutions of 5-octadecyloxyisophthalic acid neutralized with 1.5 equiv of KOH. The structure of the aggregates in the resulting suspensions was investigated by X-ray and electron diffraction (ED) studies; the morphological observations reported here stem from atomic force microscopy (AFM) studies and from polarized optical microscopy (OM). The aggregate formation was examined as a function of the concentration and temperature of the isophthalate solutions or suspensions. The structure elucidation shows that the aggregates consist of crystals as the smallest subunits. Their structure was determined, and the cell parameters of the unit cell could be established. Furthermore, it is demonstrated that the material obtained from the aqueous suspensions, by pulling fiber-shaped species mechanically, is a continuous sequence of crystals.