YongJoo Kim

Searching for an optimal component and composition of multi-metallic alloy catalysts, comprising two or more elements, is one of the key issues in catalysis research. Due to the exhaustive data requirement of conventional machine-learning (ML) models and the high cost of experimental trials, current approaches rely mainly on the combination of density functional theory and ML techniques. In this study, a significant step is taken toward overcoming limitations by the interplay of experiment and a

In this study, we develop a reactive force field (ReaxFF) for a Si/O/H/F system to perform etching simulations of SiO₂ with an HF etchant. Quantum mechanical (QM) training sets from density functional theory calculations, which contain structures of reactant/product and energies with bond dissociation, valence angle distortions, and reactions between SiO₂ clusters and SiO₂ slab with HF gases, are used to optimize the ReaxFF parameters. Structures and energies cal

In this study, the crystallization behavior of polyvinylidene fluoride (PVDF) in NMP/DMF solvent at 9 to 67 weight percent (wt%) was analyzed by molecular dynamics (MD) simulation. The PVDF phase did not gradually change with the incremental increase in PVDF wt%, but displayed rapid shifts at 34 and 50 wt% in both solvents. The solvation behavior between the two solvents was quite identical from the similar radial distribution functions. However, PVDFs in DMF solvent showed a higher ratio of β p

Abstract The precisely controllable self‐assembly phenomenon of block copolymers (BCPs) has garnered much attention because it yields well‐defined periodic nanostructures with a periodicity of 5–50 nm. However, from both thermodynamic and kinetic viewpoints, it still remains a challenge to develop a BCP material that can provide sub‐10 nm resolution, high pattern quality, fast pattern formation, and sufficient etch selectivity. To address these challenges, this study reports a BCP system contain

We developed a methodology, inspired by the folding of proteins, for the precision synthesis of hairy polymer nanoparticles. High-molar mass and narrowly dispersed graft copolymers were synthesized by graft-through ring opening metathesis polymerization, to incorporate a designated number of side chains and dimerizable cinnamic acid groups. Intrachain photodimerization collapsed the backbone and arrested it into a compact globular conformation, resulting in hairy nanoparticles topologically equi

Single-walled carbon nanotubes (SWCNTs) have gained significant interest for their potential in biomedicine and nanoelectronics. The functionalization of SWCNTs with single-stranded DNA (ssDNA) enables the precise control of SWCNT alignment and the development of optical and electronic biosensors. This study addresses the current gaps in the field by employing high-throughput systematic selection, enriching high-affinity ssDNA sequences from a vast random library. Specific base compositions and

Supramolecular polymerization offers a fascinating opportunity to develop dynamic soft materials by associating monomeric building blocks via noncovalent interactions. We report that polymerization can spontaneously drive the supramolecular polymerization of nanoscale micellar objects. We constructed the patchy micelles via two-step polymerization-induced self-assembly. A horizontal association between the patches results in a 1D supermicellar chain <i>in situ</i> by minimizing the enthalpic pen

Nanoparticle localization in block copolymer model defects is studied using self-consistent field theory simulations. In particular we study the nanoparticle free energy landscape for three different model defects: X, T, Y shape defects. Our results indicate that nanoparticles can be strongly bound to certain locations in these defects. The symmetry of the defects affects in a non-trivial fashion the "stiffness of the trap", with the X shape defect displaying the deepest energy well. The T and Y

Fluorescent molecular rotors embedded in polymer matrices can probe the local changes in the dynamics of the polymer matrix (such as the glass transition of polymers near interfaces/surfaces) that are not accessible from macroscopic measurements. Yet, there is little consensus as to how the fluorescence data should be analyzed, what property the fluorescence intensity actually represents, and what are appropriate/optimal rotors for glass transition measurements. By experimentation with a model f

Archimedean spirals in nanometer scale have shown remarkable plasmonic responses derived from their linear and rotational asymmetry. Despite the unique optical properties of nanoscale spirals, their applications have been limited due to the difficulty in fabricating large-scale arrays with uniform and systematic control of the morphology. Here, we report simulation results of spiral morphologies, which are used to design a scalable fabrication process for nanoscale spirals and predict their plas

Self-assembly behavior of poly(styrene-<italic>b</italic>-4-(<italic>tert</italic>-butyldimethylsiloxy)styrene) (PS-<italic>b</italic>-P4BDSS) block copolymer and the effect of polydispersity on self-assembled pattern quality.