Department of Chemistry and Biochemistry , University of Kitakyushu , 1-1 Hibikino , Kitakyushu , Fukuoka 808-0135 , Japan.
Langmuir. 2018 Oct 9;34(40):12109-12115. doi: 10.1021/acs.langmuir.8b02542. Epub 2018 Sep 27.
When a negatively charged sulfonic or a positively charged amine group is attached to calix[4]arene surfactants, denoted as SCal7 and QACal7, respectively, each system forms monodispersed spherical micelles with a defined aggregation number. We postulated that these defined monodisperse aggregations can be adjusted in terms of the coverage, that is, how efficiently can a spherical surface (, hydrophobic domain) be covered with identical caps (hydrophilic headgroup). We carried out small-angle X-ray scattering (SAXS), as well as titration calorimetry and dynamic light scattering (DLS), to observe the morphologies of the mixtures of these two components. The calorimetry showed a 1:1 stoichiometric exothermic reaction with a rather large binding constant. This means that, once the twin is formed from QACal7 and SCal7, these components hardly separate. SAXS showed that the spherical micelles changed to cylindrical ones and then to vesicle shapes as the composition reached a ratio of 1:1. At some intermediate compositions, mixtures of cylinders and plates (or spheres) were observed, which were confirmed by dynamic light scattering. We assume that the twin has a larger packing parameter than the individuals because of the cancellation of the charges between the sulfonic and the amine groups, and thus, the increase of the twin composition induces the entire morphology change, as expected from the packing parameter principle. In the present case, the coverage may be a secondary factor determining the morphology.
当带负电荷的磺酸基或带正电荷的胺基连接到杯[4]芳烃表面活性剂上时，分别表示为 SCal7 和 QACal7，每个体系都形成具有确定聚集数的单分散球形胶束。我们假设这些确定的单分散聚集可以根据覆盖度来调节，即球形表面（疏水区）可以用相同的帽子（亲水头部基团）覆盖的效率如何。我们进行了小角 X 射线散射（SAXS）以及滴定量热法和动态光散射（DLS），以观察这两种成分混合物的形态。量热法显示出 1:1 化学计量的放热反应，具有相当大的结合常数。这意味着，一旦 QACal7 和 SCal7 形成双子体，这些成分就很难分离。SAXS 表明，随着组成达到 1:1 的比例，球形胶束变为圆柱状，然后变为囊泡状。在某些中间组成中，观察到了圆柱和板（或球）的混合物，这通过动态光散射得到了证实。我们假设由于磺酸基和胺基之间的电荷中和，双子体具有比单个分子更大的堆积参数，因此双子体组成的增加导致了整个形态的变化，这与堆积参数原理相符。在这种情况下，覆盖度可能是决定形态的次要因素。
