Leeds Institute of Fluid Dynamics (LIFD), School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, U.K.
Department of Chemical Engineering, Imperial College London, SW7 2AZ London, U.K.
Langmuir. 2021 Oct 26;37(42):12512-12517. doi: 10.1021/acs.langmuir.1c02464. Epub 2021 Oct 14.
We examine the formation and growth of isolated myelin figures and microscale multilamellar tubules from isotropic micellar solutions of an anionic surfactant. Upon cooling, surfactant micelles transform into multilamellar vesicles (MLVs) whose contact is found to trigger the unidirectional growth of myelins. While the MLV diameter grows as ∝ , myelins grow linearly in time as ∝ , with a fixed diameter. Combining time-resolved small-angle neutron scattering (SANS) and optical microscopy, we demonstrate that the microscopic growth of spherical MLVs and cylindrical myelins stems from the same nanoscale molecular mechanism, namely, the surfactant exchange from micelles into curved lamellar structures at a constant volumetric rate. This mechanism successfully describes the growth rate of (nonequilibrium) myelin figures based on a population balance at thermodynamic equilibrium.
我们研究了各向同性胶束溶液中阴离子表面活性剂形成和生长的孤立髓磷脂体和微尺度多层管状结构。冷却时，表面活性剂胶束转变为多层囊泡（MLV），发现其接触会触发髓磷脂的单向生长。虽然 MLV 直径按 ∝ 增长，但髓磷脂的生长时间按 ∝ 线性增长，且具有固定直径。通过时间分辨小角中子散射（SANS）和光学显微镜结合，我们证明了球形 MLV 和圆柱形髓磷脂的微观生长源于相同的纳米级分子机制，即表面活性剂以恒定体积速率从胶束交换到弯曲的层状结构。该机制基于热力学平衡的种群平衡成功描述了（非平衡）髓磷脂体的生长速率。
