Homodyne dynamic light scattering in supramolecular polymer solutions: anomalous oscillations in intensity correlation function.

Dilute solutions of electronically active molecules capable of irradiation-driven supramolecular self-assembly are studied by dynamic light scattering. We detect unusual well-defined oscillations in the long time range of the homodyne intensity correlation function for all solutions that were irradiated with white light prior to the measurements. The oscillation effect is attributed to the local laser-induced heating of the samples due to strongly enhanced absorption manifested by the supramolecular filaments.

Time Allowed for Equilibration Quantifies the Preparation Induced Nonequilibrium Behavior of Polymer Films.

Performance and properties of materials may strongly depend on processing conditions. This is particularly so for polymers, which often have relaxation times much longer than the processing times and therefore may adopt preparation dependent nonequilibrated molecular conformations that potentially cause novel properties. However, so far it was not possible to predictably and quantitatively relate processing steps and resulting properties of polymer films.

Supramolecular self-assembly and radical kinetics in conducting self-replicating nanowires.

By using a combination of experimental and theoretical tools, we elucidate unique physical characteristics of supramolecular triarylamine nanowires (STANWs), their packed structure, as well as the entire kinetics of the associated radical-controlled supramolecular polymerization process. AFM, small-angle X-ray scattering, and all-atomic computer modeling reveal the two-columnar "snowflake" internal structure of the fibers involving the π-stacking of triarylamines with alternating handedness. The polymerization process and the kinetics of triarylammonium radicals formation and decay are studied by UV-vis spectroscopy, nuclear magnetic resonance and electronic paramagnetic resonance.

Theory of surface micelles of semifluorinated alkanes.

Surface structures of semifluorinated alkanes F(CF(2))(n)(CH(2))(m)H (referred to as FnHm) spread on the air/water interface are investigated theoretically. The study is focused on the disklike surface micelles that were recently identified by AFM and scattering techniques at sufficiently high surface concentrations. We show that (1) the micelles emerge as a result of liquid/liquid (rather than liquid/gas) phase separation in the Langmuir layer; (2) the micelles are islands of the higher-density phase with roughly vertical orientation of FnHm molecules (F-parts extend toward air, H-parts toward water) and the matrix is the lower density-phase where the FnHm diblocks are nearly parallel to the water surface; (3) the micelles and the hexagonal structure they form are stabilized by the electrostatic interactions which are mainly due to the vertical dipole moments of the CF(2)- CH(2) bonds in the vertical phase; and (4) the electrostatic repulsive interactions can serve to suppress the micelle size polydispersity.

On the theory of aggregation and micellization: PEO-PVP copolymer in water.

We develop a theoretical approach to micellization of the PEO-PVP block-copolymer in water. This copolymer is a weak polyelectrolyte due to protonation of VP blocks. The theory accounts for non-linear ion screening, and predicts strong position dependence of both ion concentration and the effective Debye length.