Abstract
The interactions between nanoparticles and solvents play a critical role in the formation of complex, metastable nanostructures. However, direct observation of such interactions with high spatial and temporal resolution is challenging with conventional liquid-cell transmission electron microscopy (TEM) experiments. Here, a windowless system consisting of polymer nanoreactors deposited via scanning probe block copolymer lithography (SPBCL) on an amorphous carbon film is used to investigate the coarsening of ultrafine (1-3 nm) Au-Pt bimetallic nanoparticles as a function of solvent evaporation. In such reactors, homogeneous Au-Pt nanoparticles are synthesized from metal-ion precursors in situ under electron irradiation. The nonuniform evaporation of the thin polymer film not only concentrates the nanoparticles but also accelerates the coalescence kinetics at the receding polymer edges. Qualitative analysis of the particle forces influencing coalescence suggests that capillary dragging by the polymer edges plays a significant role in accelerating this process. Taken together, this work (1) provides fundamental insight into the role of solvents in the chemistry and coarsening behavior of nanoparticles during the synthesis of polyelemental nanostructures, (2) provides insight into how particles form via the SPBCL process, and (3) shows how SPBCL-generated domes, instead of liquid cells, can be used to study nanoparticle formation. More generally, it shows why conventional models of particle coarsening, which do not take into account solvent evaporation, cannot be used to describe what is occurring in thin film, liquid-based syntheses of nanostructures.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 7213-7221 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 140 |
| Issue number | 23 |
| DOIs | |
| State | Published - Jun 13 2018 |
Funding
This material is based upon work supported by the Sherman Fairchild Foundation, Inc. GlaxoSmithKline LLC, the Air Force Office of Scientific Research awards FA9550-12-1-0280 and FA9550-16-1-0150, and the Air Force Research Laboratory under agreement number FA8650-15-2-5518. B.M. acknowledges support from the Eden and Steven Romick Post-Doctoral Fellowship through the American Committee for the Weizmann Institute of Science. This work made use of the EPIC Facilities of the NUANCE Center supported by the SHyNE Resource NNCI site (NSF ECCS-1542205), the MRSEC program (NSF DMR-1720139), the IIN, and the State of Illinois through the IIN; and the Structural Biology Facility supported by NCI CCSG P30 CA060553 awarded to the Robert H Lurie Comprehensive Cancer Center and the Chicago Biomedical Consortium with support from the Searle Funds at The Chicago Community Trust. We thank Prof. Monica Olvera de la Cruz, Dr. Mykola Tasinkevych, Mr. Yaohua Li, and Dr. Sara M. Rupich (Northwestern University, NU) for helpful discussions and Dr. Christos D. Malliakas (NU) for help with thermal analysis and mass spectrometry. This material is based upon work supported by the Sherman Fairchild Foundation, Inc., GlaxoSmithKline LLC, the Air Force Office of Scientific Research awards FA9550-12-1-0280 and FA9550-16-1-0150, and the Air Force Research Laboratory under agreement number FA8650-15-2-5518. B.M. acknowledges support from the Eden and Steven Romick Post-Doctoral Fellowship through the American Committee for the Weizmann Institute of Science. This work made use of the EPIC Facilities of the NUANCE Center supported by the SHyNE Resource NNCI site (NSF ECCS-1542205), the MRSEC program (NSF DMR-1720139), the IIN, and the State of Illinois through the IIN; and the Structural Biology Facility supported by NCI CCSG P30 CA060553 awarded to the Robert H Lurie Comprehensive Cancer Center and the Chicago Biomedical Consortium with support from the Searle Funds at The Chicago Community Trust.
ASJC Scopus subject areas
- General Chemistry
- Biochemistry
- Catalysis
- Colloid and Surface Chemistry