Dynamic light scattering by aqueous solutions of rodlike fd‐virus particles

Soft-mode of charged chiral fibrous viruses (fd)

The frictional forces in suspensions vary depending on the size, shape, and the surface of the particles, which are either charged or neutral. For anisotropic particles with no spatial gradient in the order parameter under external parameters, they exhibit either a continuous phase transition or "freezing" of the order parameter fluctuation. They are known as the collective soft-mode, which has a finite cutoff dispersion where the relaxation time diverges. From microscopic dynamics of charged chiral fd-viruses, the soft-mode is revealed with a rotation restoring "twist", obtained from both polarized (VV) and depolarized (VH) small angle dynamic light scattering. Here, I have found the minimum spatial coherence length at a lower I-N binodal concentration, which is due to the reverse of electrostatic repulsive forces with an increase in the concentration of charged chiral rods.

Slow dynamics of a colloidal lamellar phase

We used x-ray photon correlation spectroscopy to study the dynamics in the lamellar phase of a platelet suspension as a function of the particle concentration. We measured the collective diffusion coefficient along the director of the phase, over length scales down to the interparticle distance, and quantified the hydrodynamic interaction between the particles. This interaction sets in with increasing concentration and can be described qualitatively by a simplified model. No change in the microscopic structure or dynamics is observed at the transition between the fluid and the gel-like lamellar phases.

Characterization of polybutadiene-poly(ethyleneoxide) aggregates in aqueous solution: a light-scattering and small-angle neutron-scattering study

For diblockcopolymers of polybutadiene-poly(ethyleneoxide) (PB-PEO) type, water is a selective solvent. In dependence of the length of both blocks and the block length ratio, these polymers form a multitude of self-assembled structures in solution. In the present work scattering methods are used to investigate the water-soluble polymer PB125-PEO155 . It is found to form long rodlike micelles, which are characterized with respect to the aggregate length L , the cross sectional radius RCS , the radial scattering length density profile sigma r, and the radial aggregation number Nrad. Model-independent as well as model-based approaches are used for the scattering data analysis. From dynamic light scattering (DLS) and static light scattering (SLS) experiments the weight averaged length Lw of these stiff elongated aggregates is determined to Lw=350 nm . Small angle neutron scattering (SANS) reveals a cross sectional radius of RCS=17 nm and in combination with results from the SLS the radial aggregation number is found to be Nrad=70 .