Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.358, 37-51, 2001
Structure and mobility in ferroelectric liquid crystalline elastomers as studied by time-resolved FTIR spectroscopy
The molecular structure and reorientation of ferroelectric liquid crystalline elastomers (FLCE) in response to an external electric field is studied on a microsecond scale with time-resolved Fourier transform infrared (FTIR) spectroscopy. In order to analyze the influence of the network on the molecular structure and mobility in FLCE, three similar FLC polysiloxanes are under study that differ just in their crosslinking architecture: besides the uncrosslinked polymer we obtain by photocrosslinking FLCE in which the backbones of either adjacent smectic layers ("interlayer") or of the same smectic layer ("intralayer") are preferably crosslinked. It is shown that the crosslinking leads to a slowing down of the molecular mobility which is stronger for the inter-than for the intralayer FLCE. Asymmetries in the reorientation times and/or in the reorientation angles are observed (elastic memory effect). The intralayer crosslinking causes a "locomotive effect": the reorientation of the mesogenic cores precedes that of the backbones.