Abstract

We propose using Transonic Flow Focusing (TFF) to produce 2D and 0D nanomaterials. This technique focuses liquid suspensions into high-speed micrometer-scale jets, combining extremely high shear and elongational stresses in a confined, contact-free zone. For the Graphene Nanoplatelets suspensions and TFF operating conditions investigated here, the process promoted exfoliation without added surfactants or oxidative chemistry. Both graphene monolayers flakes (∼300 −400 nm in lateral size) and monolayer graphene nanofragments with lateral sizes compatible with quantum dots (∼10 −15 nm) were obtained in a single TFF step using isopropanol and pure water. Our theoretical analysis reveals that, during microsecond residence times at the meniscus-jet transition, shear and extensional stresses of the order of 106 s−1 act on the suspended particles, yielding viscous power densities of the order of 1010 W/m3. High-resolution transmission electron microscopy and atomic force microscopy show that the monolayer fraction exceeded 99% for isopropanol and 92.9% for water. These results suggest that TFF can combine solvent versatility with a high monolayer fraction in a purely mechanical top-down process.

Abstract

We propose using Transonic Flow Focusing (TFF) to produce 2D and 0D nanomaterials. This technique focuses liquid suspensions into high-speed micrometer-scale jets, combining extremely high shear and elongational stresses in a confined, contact-free zone. For the Graphene Nanoplatelets suspensions and TFF operating conditions investigated here, the process promoted exfoliation without added surfactants or oxidative chemistry. Both graphene monolayers flakes (∼300 −400 nm in lateral size) and monolayer graphene nanofragments with lateral sizes compatible with quantum dots (∼10 −15 nm) were obtained in a single TFF step using isopropanol and pure water. Our theoretical analysis reveals that, during microsecond residence times at the meniscus-jet transition, shear and extensional stresses of the order of 106 s−1 act on the suspended particles, yielding viscous power densities of the order of 1010 W/m3. High-resolution transmission electron microscopy and atomic force microscopy show that the monolayer fraction exceeded 99% for isopropanol and 92.9% for water. These results suggest that TFF can combine solvent versatility with a high monolayer fraction in a purely mechanical top-down process.

Abstract

We propose using Transonic Flow Focusing (TFF) to produce 2D and 0D nanomaterials. This technique focuses liquid suspensions into high-speed micrometer-scale jets, combining extremely high shear and elongational stresses in a confined, contact-free zone. For the Graphene Nanoplatelets suspensions and TFF operating conditions investigated here, the process promoted exfoliation without added surfactants or oxidative chemistry. Both graphene monolayers flakes (∼300 −400 nm in lateral size) and monolayer graphene nanofragments with lateral sizes compatible with quantum dots (∼10 −15 nm) were obtained in a single TFF step using isopropanol and pure water. Our theoretical analysis reveals that, during microsecond residence times at the meniscus-jet transition, shear and extensional stresses of the order of 106 s−1 act on the suspended particles, yielding viscous power densities of the order of 1010 W/m3. High-resolution transmission electron microscopy and atomic force microscopy show that the monolayer fraction exceeded 99% for isopropanol and 92.9% for water. These results suggest that TFF can combine solvent versatility with a high monolayer fraction in a purely mechanical top-down process.

Abstract

We propose using Transonic Flow Focusing (TFF) to produce 2D and 0D nanomaterials. This technique focuses liquid suspensions into high-speed micrometer-scale jets, combining extremely high shear and elongational stresses in a confined, contact-free zone. For the Graphene Nanoplatelets suspensions and TFF operating conditions investigated here, the process promoted exfoliation without added surfactants or oxidative chemistry. Both graphene monolayers flakes (∼300 −400 nm in lateral size) and monolayer graphene nanofragments with lateral sizes compatible with quantum dots (∼10 −15 nm) were obtained in a single TFF step using isopropanol and pure water. Our theoretical analysis reveals that, during microsecond residence times at the meniscus-jet transition, shear and extensional stresses of the order of 106 s−1 act on the suspended particles, yielding viscous power densities of the order of 1010 W/m3. High-resolution transmission electron microscopy and atomic force microscopy show that the monolayer fraction exceeded 99% for isopropanol and 92.9% for water. These results suggest that TFF can combine solvent versatility with a high monolayer fraction in a purely mechanical top-down process.