We investigated one-dimensional and two-dimensional optical diffraction structures fabricated in thin films of a sidechain light-sensitive liquid crystal elastomer (SC-LS-LCEs) by optical holographic lithography methods. The emphasis was on analysis of modifications of the periodicity of the recorded patterns induced by application of an external strain and by temperature modifications. The results show that due to rubber elasticity of the LCE films, relative modifications of the periodicity by 10% can easily be reached. In most cases tuning is reversible and linear with respect to the strain. Temperature induced tuning is most efficient in the region of phase transition from the nematic to the paranematic phase and provides relative periodicity modifications up to 30%.
The field of ferroelectric liquid crystals (FLCs) is one of the most fascinating aspects of the Science of Materials for their
interesting electro-optic applications. Among different chemical and physical properties those related to the molecular
dynamics are very stimulating due to the relationship between molecular motions and macroscopic response to external
fields, such as electric and magnetic ones. In this work, the molecular dynamics of a ferroelectric smectogen, namely
the (S)-2-methylbutyl-[4'-(4"-heptyloxyphenyl)-benzoyl-4-oxy-(S)-2-((S)-2')-benzoyl)-propionyl)]-propionate (ZLL 7/*)
has been investigated by means of 2H NMR and dielectric relaxation techniques. The first method allows us to get
information on the molecular motions in the fast motion regime, in particular the diffusion reorientational motions of the
whole molecule, as well as of the internal motions affecting the phenyl and biphenyl fragments.
The second technique, which covers the slow motion regime, has been used to detect collective motions and fluctuation
modes. This study allows us to have a complete idea of molecular motions in the different smectic phases formed by the
ZLL 7/* mesogens, in particular the paraelectric smectic A (SmA), the ferroelectric smectic C* (SmC*), the
antiferroelectric smectic C*A (SmC*A) and the re-entrant ferroelectric smectic C* (SmC*r) phases. This last phase has
been investigated for the first time in this work, from the point of view of the dynamic behaviour. All results will be
discussed in the framework of the molecular dynamics of ferroelectric liquid crystals, reported in the literature so far.
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