Molecular mobility in thin films

Molecular mobility in thin films

We use the microphase separation in block copolymers as a route to nanoscopic domains. Microphase separation occurs as a result of the repulsive interaction between the blocks of block copolymer. The domain sizes are determined by the size of the blocks and therefore by the chemistry. Typical sizes are several nanometers. At present we study a special class of block copolymers consisting of an isotropic (polystyrene) and a liquid crystalline block. The method of investigation is dielectric spectroscopy. We have found that cooperative ( alpha and delta) relaxation as well as the local beta relaxation are influenced be the constraints. If the mesogen of the liquid crystalline block is situated within a domain the corresponding relaxation time is shortened.

Relevant publications

  1. S. Zhukov, S. Geppert, B. Stühn, R. Staneva, R. Ivanova, W. Gronskiv Dielectric Relaxation in Liquid Crystalline/Isotropic Block Copolymers: The Effect of Nano-scale Confinement on The Segmental Dynamics, Macromolecules 35 (22), 8521-8530 (2002)
  2. S. Zhukov, S. Geppert, B. Stühn, R. Staneva, W. Gronskiv Dielectric relaxation in isotropic/liquid crystalline block copolymers: effect of nanoscale confinement on the local beta and gamma dynamics, Macromolecules 36, 6166-6170 (2003)
  3. R. Ivanova, R. Staneva, S. Geppert, B. Heck, B. Walter, W. Gronski, B. Stühn, Interplay between domain microstructure and nematic order in liquid crystalline/isotropic block copolymeres, Colloid and Polymer Science, 282 (8), 810-824 (2004)