Molecular Dynamics Simulation Study on Self-Assembly of Polymer-Grafted Nanocrystals: From Isotropic Cores to Anisotropic Cores

C Yu and HX Guo, JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 20, 1625-1635 (2023).

DOI: 10.1021/acs.jctc.3c00551

Theself-assembly of polymer-grafted nanocrystals (PGNCs) is animportant method to manufacture novel nanomaterials. Herein, we focuson the self- assembly of three types of PGNCs with differently shapedcores including sphere, octahedron, and cube by molecular dynamicssimulation. By characterizing the positional and orientational orderof the assembled superlattices, we construct the phase diagrams asa function of the grafting density and polymer chain length. For PGNCswith spherical cores, we observe the transition from the FCC phaseto the BCC phase due to the packing entropy of the ligand polymerchains. For PGNCs with anisotropic cores, the close-packed FCC phaseis replaced by the C-BCC phase (octahedral cores) or the C-triclinicphase (cubic cores) due to the directional entropy of core shape.We also study the assembly dynamics by tracking the time evolutionof the positional and orientational order. We elucidate the relationshipof grafting density and polymer chain length to the packing entropyand directional entropy and reveal their important effects on assembledstructures. In general, our simulation results provide useful guidelinesfor the programmable assembly of PGNCs.

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