PUB - Publikationen an der Universität Bielefeld

In this study, we investigate the influence of the block copolymer architecture on the bending elasticity of polymer-rich lamellar phases. In detail, we study the polymer-rich system water/o-xylene/Pluronic triblock copolymer/C8TAB and change the polymer while keeping the mass ratios constant. We use neutron spin echo measurements (NSE) to determine κ. With the measurements we determine the relaxation rate Γqz,ZG of the bilayer bending mode and subsequently calculate the bilayer bending modulus κ using the Zilman-Granek approach [Zilman et al., Phys. Rev. Lett. 77, 4788–4791 (1996)]. Moreover, we have investigated the lamellar phases via small-angle X-ray scattering (SAXS) and have analysed the data with the modified Caillé theory to obtain the Caillé parameter η. Based on κ the bulk compression modulus B can be calculated. Increasing values of κ are found with increasing EO and PO block size in the range of 3.8 to 13.4 kBT. The computed values of B are in the range of 103 to 105 Pa.