Abstract
Colloidal clusters and gels are ubiquitous in science and technology. Particle softness has a strong effect on interparticle interactions; however, our understanding of the role of this factor in the formation of colloidal clusters and gels is only beginning to evolve. Here, we report the results of experimental and simulation studies of the impact of particle softness on the assembly of clusters and networks from mixtures of oppositely charged polymer nanoparticles (NPs). Experiments were performed below or above the polymer glass transition temperature, at which the interaction potential and adhesive forces between the NPs were significantly varied. Hard NPs assembled in fractal clusters that subsequently organized in a kinetically arrested colloidal gel, while soft NPs formed dense precipitating aggregates, due to the NP deformation and the decreased interparticle distance. Importantly, interactions of hard and soft NPs led to the formation of discrete precipitating NP aggregates at a relatively low volume fraction of soft NPs. A phenomenological model was developed for interactions of oppositely charged NPs with varying softnesses. The experimental results were in agreement with molecular dynamics simulations based on the model. This work provides insight on interparticle interactions before, during, and after the formation of hard-hard, hard-soft, and soft-soft contacts and has impact for numerous applications of reversible colloidal gels, including their use as inks for additive manufacturing.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 15012-15024 |
| Number of pages | 13 |
| Journal | ACS nano |
| Volume | 17 |
| Issue number | 15 |
| DOIs | |
| State | Published - Aug 8 2023 |
Funding
The authors thank James Jonkman (University Health Network, Toronto) and Ilya Gourevich (University of Toronto) for assistance in imaging experiments and Esther Tsai (Brookhaven National Laboratory) for assistance in SAXS experiments. H.Z., D.N., and O.G. acknowledge Brookhaven Instruments for providing a research platform for static light scattering (SLS) and thank Daniel Napolitano and Daniel Seeman for assistance of the SLS experiments. E.K. and G.C.W. are grateful to NSERC Canada for financial support of this work by the Discovery program. The work of L.L-F. and M.O.d.l.C. was supported by the NSF Center for the Chemistry of Molecularly Optimized Networks (MONET), CHE-2116298. H.Z., D.N., and O.G. used the Material Synthesis and Characterization facility of the Center for Functional Nanomaterials at Brookhaven National Laboratory, supported by the U.S. DOE Office of Science, under Contract No. DE-SC0012704. Small angle X-ray scattering was collected at the Complex Matter Scattering (CMS) 11-BM beamline of the National Synchrotron Light Source II at Brookhaven National Laboratory, which is a U.S. DOE Office of Science User Facility (Contract No. DE-SC0012704). E.K. and G.C.W. are grateful to NSERC Canada for financial support of this work by the Discovery program. The work of L.L-F. and M.O.d.l.C. was supported by the NSF Center for the Chemistry of Molecularly Optimized Networks (MONET), CHE-2116298. H.Z., D.N., and O.G. used the Material Synthesis and Characterization facility of the Center for Functional Nanomaterials at Brookhaven National Laboratory, supported by the U.S. DOE Office of Science, under Contract No. DE-SC0012704. Small angle X-ray scattering was collected at the Complex Matter Scattering (CMS) 11-BM beamline of the National Synchrotron Light Source II at Brookhaven National Laboratory, which is a U.S. DOE Office of Science User Facility (Contract No. DE-SC0012704).
Keywords
- colloidal gel
- diffusion-limited cluster aggregation
- fractal clusters
- nanoparticles
- phase separation
- soft potential
ASJC Scopus subject areas
- General Materials Science
- General Engineering
- General Physics and Astronomy