Dynamic Light Scattering and Small-Angle Neutron Scattering Studies of Ternary Rod/Coil/Solvent Systems

Abstract

Dynamic light scattering (DLS) and small-angle neutron scattering (SANS) are used to characterize the structure and dynamics of ternary solutions consisting either of rods or "hairy rod" polymers and polystyrene (PS) coils in a solvent composed of chloroform saturated with (<0.5%) formamide (CF). The rods are poly(γ-benzyl-R-L-glutamate) (PBLG), and the hairy rods are two forms of poly(γ-octadecyl-R-L-glutamate)-co-(γ-methyl-R-L-glutamate) with varying amounts of octadecyl substitution. The DLS autocorrelation functions reveal the existence of two relaxation modes that are interpreted in terms of the random phase approximation theory (RPA) as the cooperative and interdiffusive modes. The two relaxation modes are investigated as a function of the total polymer concentration CP and the relative composition x ) Crod/CP as well as the percentage of octadecyl groups along the polyglutamate chain. The different diffusion coefficients that characterize the dynamics in these systems are well described by the RPA theory of polymer mixtures. In addition, the interaction parameter extracted from both the DLS and SANS experiments is found to be negative. These results suggest an attraction between PS and PBLG molecules and that these polymers are therefore compatible. The hairy rod ternary solution diffusion coefficients indicate that as the percentage of hairs on the rod increases, the polymers become more compatible.

Numerical Investigation of Three‐Dimensional Bubble Column Flows: A Detached Eddy Simulation Approach

“…To name a few interesting examples, these include rod‐like block copolymer micelles,4, 5 biological macromolecular and supramolecular systems such as tobacco mosaic virus6–8 and fd virus,9–11 and multifunctional nanoparticles such as vanadium oxide nanofibers12 and carbon nanotubes 13–15. On the one hand, by studying the dynamic behaviors of probe particles that are immersed in a liquid medium, one can interrogate the properties of the surrounding medium16–18 as well as learn the important particle/medium interactions 19–22. On the other hand, the quantified diffusion coefficients provided by DLS measurements allow determination of the particle shape, size, and size distributions.…”

Novel Self-Assembly of Amphiphilic Copolymers into Nanotubes: Characterization by Small-Angle Neutron Scattering

“…5 Neutron-scattering experiments have been widely used to determine the different shapes associated with the phase separation of block copolymer solutions. [6][7][8] The main field of application of the SANS technique is the determination of the molecular size and shape in crowded environments. In addition, the conformation of complex systems can be determined by fitting a model form factor P(Q) to the experimental data.…”

Neutron and light scattering studies of light-harvesting photosynthetic antenna complexes

“…Smaller (or larger) particles move faster (or slower) and have quick (or slow) fluctuations. Analysis of the scattering intensity fluctuations reflects the velocity of the Brownian motion, and the particle size (i.e., the average hydrodynamic diameter, d(H)) can be then obtained from the velocity using the Stokes-Einstein equation (d(H) = k B T/3pgd o , where k B is the Boltzmann constant, T is the absolute temperature, g is the viscosity of the solution, and d o is the translational diffusion coefficient of the particle) (Hansen and McDonald 1986). Also, certain correlation factors, such as the refractive index of particles in the solution, are sometimes required to be optimized for calculation of the light scattering intensity and analyses of the DLS data (see Eq.…”