Kim, Jin Young Kwon, S. Joon Chang, Jae-Byum Ross, Caroline A. Hatton, T. Alan Stellacci, Francesco 2024-01-20T05:02:12Z 2024-01-20T05:02:12Z 2021-09-05 2016-02 1530-6984 https://pubs.kist.re.kr/handle/201004/124439 In a Langmuir trough, successive compression cycles can drive a two-dimensional (2D) nanoparticle supracrystal (NPSC) closer to its equilibrium structure. Here, we show a series of equilibrated 2D NPSCs consisting of gold NPs of uniform size, varying solely in the length of their alkanethiol ligands. The ordering of the NPSC is governed by the ligand length, thus providing a model system to investigate the nature of 2D melting in a system of NPs. As the ligand length increases the supracrystal transitions from a crystalline to a liquid-like phase with evidence of a hexatic phase at an intermediate ligand length. The phase change is interpreted as an entropy-driven phenomenon associated with steric constraints between ligand shells. The density of topological defects scales with ligand length, suggesting an equivalence between ligand length and temperature in terms of melting behavior. On the basis of this equivalence, the experimental evidence indicates a two-stage 2D melting of NPSCs. English AMER CHEMICAL SOC Two-Dimensional Nanoparticle Supracrystals: A Model System for Two-Dimensional Melting Article 10.1021/acs.nanolett.5b04763 1 NANO LETTERS, v.16, no.2, pp.1352 - 1358 NANO LETTERS 16 2 1352 1358 N scie scopus 000370215200078 2-s2.0-84958225478 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article SELF-ASSEMBLED MONOLAYERS LANGMUIR MONOLAYERS PHASE-TRANSITIONS CRYSTALLINE ORDER LIQUID NANOCRYSTALS SURFACES 2D nanoparticle supracrystals equilibrated nanoparticle film 2D melting hexatic phase