Microemulsions display a higher degree of order at planar hydrophilic walls. The oriented lamellae, furthermore, have three times faster relaxations compared to the bicontinuous bulk structure. Grazing incidence neutron scattering techniques were employed to observe the structure and dynamics (PRE 83, 030401 (2011) & PRE 85, 041408 (2012)). By staying below the critical angle of total reflection an evanescent (tunneling) wave allowed for highlighting near surface layers of varying depth. Especially, the depth resolved dynamics using neutron spin echo spectroscopy have been obtained for the first time in this way. Amphiphilic polymers are the most promising additives in microemulsions since a dramatic increase of the surfactant efficiency usually is obtained (PRE 89, 042303 (2014)). For many applications, the impact of the polymer on the near surface functionality of the microemulsion is highly important. The materials to be cleaned usually appear as huge interfaces, for instance in the soil cleaning. The considered diblock copolymer showed enrichment in the near surface region and the dynamics are slowed down. So the viscosity effect of the polymer is amplified at the surface. We speculate that the exposure time of the fluid is increased in a rinsing process. The attraction of larger molecules by the confinement could also explain better binding of receptors of immune cells at hard vessel walls.
h.frielinghaus@fz-juelich.de
