Liquid crystalline polymeric layered

The source of all carbon relevant to the present context is the feedstock of hydrocarbon molecules (aliphatic, aromatic, with and without heteroatoms). Figure 10 summarizes the possibilities for their conversion into black carbon. The chemical route comprises polymerization into aromatic hydrocarbons with final thermal dehydrogenation. This process often includes a liquid crystalline phase immediately before final solidification. In this phase large aromatic molecules can sclf-organizc into parallel stacks and form well-ordered precursors for graphitic structures with large planar graphene layers. This phase is referred to... 

Flexible spacers in the semirigid-rod molecule allow the molecule to orient with order parameter greater than 0.8 when coated and cured upon a rubbed polyimide layer. Kinetics of the photo-polymerization [62,63] and surface-induced orientation [49] as well as mechanical [64,65], optical [59,66,67], and ferroelectric properties [68-70] of the anisotropic networks were thoroughly examined. These investigations were mainly carried out by the Philip s research group and were applied to develop liquid crystalline display devices [58,69]. 

Ferroelectric materials are a subclass of pyro- and piezoelectric materials (Fig. 1) (see Piezoelectric Polymers). They are very rarely foimd in crystalline organic or polymeric materials because ferroelectric hysteresis requires enough molecular mobility to reorient molecular dipoles in space. So semicrystalline poly(vinylidene fluoride) (PVDF) is nearly the only known compoimd (1). On the contrary, ferroelectric behavior is very often observed in chiral liquid crystalline materials, both low molar mass and poljuneric. For an overview of ferroelectric liquid crystals, see Reference 2. Tilted smectic liquid crystals that are made from chiral molecules lack the symmetry plane perpendicular to the smectic layer structure (Fig. 2). Therefore, they develop a spontaneous electric polarization, which is oriented perpendicular to the layer normal and perpendicular to the tilt direction. Because of the liquid-like structure inside the smectic layers, the direction of the tilt and thns the polar axis can be easily switched in external electric fields (see Figs. 2 and 3). 

Supramolecular polymeric complexes without aromatic mesogens can exhibit liquid-crystalline phases due to microphase segregation [112-117]. Complex 32 consisting of poly(4-vinylpyridine) complexed with alkylphenol shows a layered mesophase (Figure 24) [112]. Ionic supramolecular complex 33 based on poly(ethyleneimine) and alkanoic acids also forms layered mesophases (Figure 24) [115]. 

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