Compton profile anisotropies in Bi1.6Pb0.4Sr2Ca2Cu3O10+x superconductor

International audienc

Neutron reflectivity and computer simulation studies of self-assembled brushes formed by centrally adsorbed star polymers

The equilibrium properties of polymer brushes formed by starlike polymers with varying number of arms attached to a surface by their center were studied experimentally with neutron reflectrometry (NR). Polystyrene (PS) stars in a good solvent (toluene) were centrally adsorbed onto a quartz substrate via a zwitterionic anchor group. Increasing the number of arms resulted in significantly lower equilibrium adsorbance, while replacement experiments of a 3-armed star brush by linear chains revealed interesting equilibrium and kinetic features related to the special architecture of star polymers. These results are compared with scaling theoretical calculations and Monte Carlo simulations of centrally adsorbed star polymers that were performed under the bond fluctuation simulation scheme. Several features of the experimental results are reproduced in our simulation study. © 2008 American Chemical Society