Structure and Kinetics of Pseudo Block-Copolymers and Ionic Liquids – an In-Situ SAXS Study

AbstraktThis work presents the in-situ SAXS experiments to follow the evolution of nanostructures in novel pseudo-block copolymers and ionic liquids with respect to temperature and temperature steps. A specialized X-ray transparent Peltier – cooling device was developed to realize the temperature steps to enable fast quenching of the samples from the melt to temperatures far below the melting point and to follow the crystallization process by SAXS. The temperature dependence of the materials was investigated for polyisobutylene(PIB)-based ionic liquids (ILs), prepared by a combination of living carbocationic polymerization (LCCP) and subsequent “click” chemistry for the attachment of different cations. All PIBILs exhibit pronounced nanostructural organization at room temperature. In-situ SAXS could determine an order−order (OOT) and/or a lattice disorder−order transition (LDOT) as well as the transition temperatures. The temperature-dependent self-assembly of the structure exhibits a strong dependence on the nature of the anchored cation. The whole process is reversible, with varying relaxation times [1]. Controlled temperature steps were applied to the second material. It consists of PCL (poly(ε-caprolactone)) and PIB blocks connected via hydrogen – bonds appearing between the thymine and 2,6-diaminotriazine groups, linked to the individual blocks. These hydrogen-bonds lead to a so called supramolecular interaction between the blocks [2]. The melting point of PCL is around 55°C and after cooling the material below the melting point the crystallization of nanometer sized building blocks starts. The crystallization kinetics is faster the larger the cooling step. The peak intensities in the SAXS patterns allow the application of Avrami kinetics theory to determine the activation energy of the crystallization process.
VeranstaltungEUROMAT 2013
Art der VeranstaltungKonferenz
Keywords:103009 Festkörperphysik, 103018 Materialphysik, 104018 Polymerchemie
Keywords:1323 Polymerchemie, 1210 Festkörperphysik, 1250 Materialphysik