Neutron reflectivity study of the kinetics of polymer-polymer interface formation.

We have investigated how the interface width between two thin polymer films approaches its equilibrium state. Neutron reflection for different polyolefin bilayers of various degrees of incompatibility as a function of the annealing time was measured. By tuning the interaction parameter, we have probed both an immiscible polymer couple and systems approaching criticality where the interface is wider.

Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores.

We present a neutron and X-rays scattering study of the phase transitions of 4-n-octyl-4' -cyanobiphenyl (8CB) confined in unidirectional nanopores of porous alumina and porous silicon (PSi) membranes with an average diameter of 30 nm. Spatial confinement reveals a rich polymorphism, with at least four different low temperature phases in addition to the smectic A phase. The structural study as a function of thermal treatments and conditions of spatial confinement allows us to get insights into the formation of these phases and their relative stability.

Molecular dynamics of a short-range ordered smectic phase nanoconfined in porous silicon.

4-n-octyl-4-cyanobiphenyl has been recently shown to display an unusual sequence of phases when confined into porous silicon (PSi). The gradual increase of oriented short-range smectic (SRS) correlations in place of a phase transition has been interpreted as a consequence of the anisotropic quenched disorder induced by confinement in PSi. Combining two quasielastic neutron scattering experiments with complementary energy resolutions, the authors present the first investigation of the individual molecular dynamics of this system.

Evidence of anisotropic quenched disorder effects on a smectic liquid crystal confined in porous silicon.

We present a neutron scattering analysis of the structure of the smectic liquid crystal octylcyanobiphenyl (8CB) confined in one-dimensional nanopores of porous silicon films (PS). The smectic transition is completely suppressed, leading to the extension of a short-range ordered smectic phase aligned along the pore axis. It evolves reversibly over an extended temperature range, down to 50 K below the N-SmA transition in pure 8CB.