214 Bard Hall, Cornell University, Ithaca, NY, 14853, USA.
128 Bard Hall, Cornell University, Ithaca, NY, 14853, USA.
Small. 2017 May;13(17). doi: 10.1002/smll.201603509. Epub 2017 Mar 1.
Hierarchical C colloidal films are assembled from nanoscale to macroscale. Fullerene molecular crystals are grown via seeded cosolvent precipitation with mixed solvent [tetrahydronaphthalene (THN)/trimethylpyridine (TMP)] and antisolvent 2-propanol. The fullerene solutions are aged under illumination, which due to the presence of TMP reduces the free monomer concentration through fullerene aggregation into nanoparticles. The nanoparticles seed the growth of monodisperse fullerene colloids on injection into the antisolvent. Diverse colloidal morphologies are prepared as a function of injection volume and fullerene solution concentration. The high fullerene solubility of THN enables C colloids to be prepared in quantities sufficient for assembly (5 × 10 ). Electric fields are applied to colloidal C platelets confined to two dimensions. The particles assemble under dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency-dependent phase transitions occur at the critical Maxwell-Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced. Structures form as a function of field strength, frequency, and confinement including hexagonal, oblique, string fluid, coexistent hexagonal-rhombic, and tetratic.
层级 C 胶体膜是从纳米尺度到宏观尺度组装的。富勒烯分子晶体通过种子共溶剂沉淀在混合溶剂[四氢萘（THN）/三甲基吡啶（TMP）]和反溶剂 2-丙醇中生长。富勒烯溶液在光照下老化，由于 TMP 的存在，通过富勒烯聚集到纳米颗粒中降低了游离单体浓度。纳米颗粒在注入反溶剂时作为单分散富勒烯胶体生长的种子。不同的胶体形态作为注入体积和富勒烯溶液浓度的函数而制备。THN 的高富勒烯溶解度使得能够制备足够用于组装的 C 胶体（5×10 ）。电场施加到限制在两个维度的胶体 C 板上。颗粒在偶极力、介电泳力和电动力学流的作用下组装。在临界 Maxwell-Wagner 渡越频率处发生频率相关的相转变，其中介质中颗粒的有效极化率大大降低。结构形成作为场强、频率和限制的函数，包括六边形、斜交、字符串流体、共存的六边形-菱形和四元。
