Journal of Colloid and Interface Science, Vol.556, 717-725, 2019
Tannic acid- and cation-mediated interfacial self-assembly and epitaxial growth of fullerene (nC(60)) and kaolinite binary graphitic aggregates
In this study, we investigated the tannic acid (TA)-, Ca2+-, and mica-enabled interfacial assembly of nC(60) fullerene (FWS) and Na-saturated kaolinite (Na-KI) with in and ex situ atomic force microscopy (AFM). The epitaxial growth of herringbone motif, two dimensional (2D) chiral clusters and 3D mounds were detected. pi-pi electron donor-acceptor (EDA) interactions drove the transformation of the FWS, and the symmetry of the muscovite substrate directed the epitaxial ordering of self-assembled herringbone motifs. A ternary mixture of Na-KI/FWS/TA in the presence of Ca2+ produced double-stranded (ds) helices and 2D platelets of chiral clusters with a nano-porous monolayer on K+-treated muscovite surfaces. The weak hydration of exchangeable K+ and stronger electric fields possibly contributed to the 1D and 2D propagation of aggregates. However, the local increment in carbon content due to the nucleation of functionalized FWS on mica diminished the K+-induced electric field effect and facilitated the 3D growth of helical mounds. The diffusion limited mass-transfer of particulates across the Ehrlich-Schwoebel barrier (ESB) and screw dislocation assisted motion of particulates specifically at higher steps aided mound growth. Thus, the structural incorporation of FWS can substantially impede its interfacial transport and produce hierarchical hybrid mineral-enriched graphitic aggregates. (C) 2019 Elsevier Inc. All rights reserved.
Keywords:Self-assembly;Air-water interface;Atomic force microscopy;Cation-exchange;Helical;Chiral-cluster;Screw-dislocation;Fullerene;Kaolinite;Tannic acid