A compound eye-like morphology formed through hexagonal array of hemispherical microparticles where an alkyl-fullerene derivative self-assembled at atmosphere-sealed air/water interface

Ravindra Kumar Gupta; Hidehiko Asanuma; Juan J Giner-Casares; Ayako Hashimoto; Tetsuya Ogawa; Takashi Nakanishi

doi:10.1088/1361-6528/ad4bef

A compound eye-like morphology formed through hexagonal array of hemispherical microparticles where an alkyl-fullerene derivative self-assembled at atmosphere-sealed air/water interface

Nanotechnology. 2024 May 30;35(33). doi: 10.1088/1361-6528/ad4bef.

Authors

Ravindra Kumar Gupta¹, Hidehiko Asanuma², Juan J Giner-Casares², Ayako Hashimoto³, Tetsuya Ogawa⁴, Takashi Nakanishi^{1

2}

Affiliations

¹ Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan.
² Department of Interfaces, Max-Planck-Institute of Colloids and Interfaces, Research Campus Golm, Potsdam 14424, Germany.
³ Center for Basic Research on Materials, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan.
⁴ Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Japan.

PMID: 38749413
DOI: 10.1088/1361-6528/ad4bef

Abstract

Self-assembly processes are widely used in nature to form hierarchically organized structures, prompting us to investigate such processes at the macroscopic scale. We report an unprecedented approach toward the self-assembly of alkyl-fullerene (C₆₀) derivatives into a hexagonal array of hemispherical microparticles akin to the morphology of a compound eye. The method includes casting solvated alkyl-C₆₀compound on an air/water interface followed by controlled evaporation of the solvent under atmosphere-sealed conditions. This leads to the formation of a thin film floating on water with a diameter of up to 1.3 centimeters and exhibiting a hexagonally-packed hemispherical structure with a diameter of approximately 38µm. Various measurements of the formed film reveal that amorphousness is necessary for suppressing uncontrollable crystallization, which affects the microparticle size and film formation mechanism. We tested the feasibility of this approach for the self-assembly of a relatively common C₆₀derivative, [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM), resulting in the formation of a film with a similar pattern of hexagonally-packed larger microparticles approximately 152µm in size of diameter.

Keywords: compound eye; fullerene; interface; macroscopic film; pattern; self-assembly.