Self-Suspended Suspensions of Covalently Grafted Hairy Nanoparticles
KAUST Grant NumberKUS-C1-018-02
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Abstract© 2015 American Chemical Society. Dispersions of small particles in liquids have been studied continuously for almost two centuries for their ability to simultaneously advance understanding of physical properties of fluids and their widespread use in applications. In both settings, the suspending (liquid) and suspended (solid) phases are normally distinct and uncoupled on long length and time scales. In this study, we report on the synthesis and physical properties of a novel family of covalently grafted nanoparticles that exist as self-suspended suspensions with high particle loadings. In such suspensions, we find that the grafted polymer chains exhibit unusual multiscale structural transitions and enhanced conformational stability on subnanometer and nanometer length scales. On mesoscopic length scales, the suspensions display exceptional homogeneity and colloidal stability. We attribute this feature to steric repulsions between grafted chains and the space-filling constraint on the tethered chains in the single-component self-suspended materials, which inhibits phase segregation. On macroscopic length scales, the suspensions exist as neat fluids that exhibit soft glassy rheology and, counterintuitively, enhanced elasticity with increasing temperature. This feature is discussed in terms of increased interpenetration of the grafted chains and jamming of the nanoparticles. (Chemical Presented).
CitationChoudhury S, Agrawal A, Kim SA, Archer LA (2015) Self-Suspended Suspensions of Covalently Grafted Hairy Nanoparticles. Langmuir 31: 3222–3231. Available: http://dx.doi.org/10.1021/la5048326.
SponsorsThis work was supported by the National Science Foundation, award no. DMR-1006323, and by award no. KUS-C1-018-02 from King Abdullah University of Science and Technology (KAUST). Use of the Cornell High Energy Synchrotron Source was supported by the U.S. DOE under contract no. DE-AC02-06CH11357. This work made use of the Cornell Center for Materials Research Shared Facilities, which is supported through the NSF MRSEC program (DMR-1120296). We thank Dr. Rajesh Mallavajula for his insights and ideas. We acknowledge Dr. Ivan Keresztes for help with the NMR experiment. We also thank Adithya Sagar Gurram for his help with the DFT calculations.
PublisherAmerican Chemical Society (ACS)
CollectionsPublications Acknowledging KAUST Support
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- The Rheology of Bimodal Mixtures of Colloidal Particles with Long-Range, Soft Repulsions.
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