Müller Carsten, Schubert Christopher P J, Lemieux Robert P, Giesselmann Frank
Instuitute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada.
Chemphyschem. 2018 Oct 19;19(20):2703-2708. doi: 10.1002/cphc.201800537. Epub 2018 Sep 3.
The mesogens QL32-6, QL33-6 and QL-34-6 contain 5-phenylpyrimidine cores and terminal nanosegregating carbosilane end groups of different lengths and are known to exhibit 'de Vries-type' properties of varying strength. We report a systematic study of the influence of the nanosegregating sublayer on the dynamics and rotational viscosities of the collective modes in the smectic A* (SmA*) and smectic C* (SmC*) phase using dielectric spectroscopy. It was found that the dynamics of the Goldstone mode corresponding to phase angle fluctuations are almost not affected while the relaxation time and rotational viscosity of the soft mode are influenced by the degree of nanosegregation. In other words, the nanosegregating sublayer does not influence the dynamics of ferroelectric switching in the SmC* phase, but is critical in inducing 'de Vries-type' properties.
介晶化合物QL32 - 6、QL33 - 6和QL - 34 - 6含有5 - 苯基嘧啶核以及不同长度的末端纳米分离碳硅烷端基，已知它们表现出强度各异的“德弗里斯型”性质。我们使用介电谱对纳米分离子层对近晶A*（SmA*）相和近晶C*（SmC*）相中集体模式的动力学和旋转粘度的影响进行了系统研究。结果发现，对应于相角波动的戈德斯通模式的动力学几乎不受影响，而软模式的弛豫时间和旋转粘度则受纳米分离程度的影响。换句话说，纳米分离子层不影响SmC*相中铁电开关的动力学，但对诱导“德弗里斯型”性质至关重要。
