posted on 2024-01-31, 18:20authored byYifan Ning, Shengsong Yang, Dai-Bei Yang, Yi-Yu Cai, Jun Xu, Ruipeng Li, Yugang Zhang, Cherie R. Kagan, Jeffery G. Saven, Christopher B. Murray
The size-dependent and collective
physical properties
of nanocrystals
(NCs) and their self-assembled superlattices (SLs) enable the study
of mesoscale phenomena and the design of metamaterials for a broad
range of applications. However, the limited mobility of NC building
blocks in dried NCSLs often hampers the potential for employing postdeposition
methods to produce high-quality NCSLs. In this study, we present tailored
promesogenic ligands that exhibit a lubricating property akin to
thermotropic liquid crystals. The lubricating ability of ligands is
thermally triggerable, allowing the dry solid NC aggregates deposited
on the substrates with poor ordering to be transformed into NCSLs
with high crystallinity and preferred orientations. The interplay
between the dynamic behavior of NCSLs and the molecular structure
of the ligands is elucidated through a comprehensive analysis of their
lubricating efficacy using both experimental and simulation approaches.
Coarse-grained molecular dynamic modeling suggests that a shielding
layer from mesogens prevents the interdigitation of ligand tails,
facilitating the sliding between outer shells and consequently enhancing
the mobility of NC building blocks. The dynamic organization of NCSLs
can also be triggered with high spatial resolution by laser illumination.
The principles, kinetics, and utility of lubricating ligands could
be generalized to unlock stimuli-responsive metamaterials from NCSLs
and contribute to the fabrication of NCSLs.