functionalization-single-walled-carbon-nanotubes-with-thermo

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

Oak Ridge National Laboratory

Understanding the distinctive phase behaviors in random packing due to particle shapes is an important issue in condensed matter physics. In this paper, we investigate the random packing structure of two-dimensional (2D) snowmen via wax-snowman packing experiments and Brownian dynamics simulations. Both experiments and simulations reveal that neighboring snowmen have a strong short-range orientational correlation and consequently locally form particular conformations. A chiral conformation is dominant for high area fractions near the jamming condition (φ>0.8), and the proportion of the chiral conformation increases with γ. We also found that the attractive interaction does not have a significant impact on the results. The geometry of chirally ordered snowmen causes a mismatch with 2D crystalline symmetries and thus inhibits the development of long-range spatial order, despite the strong orientational correlation between neighbors.

Shape-induced chiral ordering in two-dimensional packing of snowmanlike dimeric particles.

The dynamics of water in polyethylene oxide (PEO)/LiCl solution has been studied with quasielastic neutron scattering experiments and molecular dynamics (MD) simulations. Two different time scales of water diffusion representing interfacial water and bulk water dynamics have been identified. The measured diffusion coefficient of interfacial water remained 5-10 times smaller than that of bulk water, but both were slowed by approximately 50% in the presence of Li(+). Detailed analysis of MD trajectories suggests that Li(+) is favorably found at the surface of the hydration layer, and the probability to find the caged Li(+) configuration formed by the PEO is lower than for the noncaged Li(+)-PEO configuration. In both configurations, however, the slowing down of water molecules is driven by reorienting water molecules and creating water-Li(+) hydration complexes. Performing the MD simulation with different ions (Na(+) and K(+)) revealed that smaller ionic radius of the ions is a key factor in disrupting the formation of PEO cages by allowing spaces for water molecules to come in between the ion and PEO.

Youngkyu Han

Biology and Soft Matter Division,
Neutron Science Directorate,
Biology and Soft Matter Division, Neutron Science Directorate

Oak Ridge National Laboratory

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

Youngkyu Han

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Biology and Soft Matter Division,Neutron Science Directorate,Biology and Soft Matter Division, Neutron Science Directorate

Oak Ridge National Laboratory

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

Biology and Soft Matter Division,
Neutron Science Directorate,
Biology and Soft Matter Division, Neutron Science Directorate