smectic phase

smectic phase

[′smek·dik ‚fāz]
(physical chemistry)
A form of the liquid crystal (mesomorphic) state in which molecules are arranged in layers that are free to glide over each other with relatively small viscosity.
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Isotactic polypropylene (iPP) exhibits an interesting polymorphic behavior [1-5], sharing four crystalline structures: monoclinic [alpha]-form [6, 7], trigonal [beta]-form [1, 8-12], triclinic [gamma]-form [13, 14] and smectic phase [15, 16], Among these crystalline forms, [beta]-form is a metastable phase and can only be obtained under the following processing conditions: melt crystallization in the presence of specific heterogeneous nucleating agent (NA) [17, 18], by directional crystallization in certain temperature [19], or from melts subjected to shear [20, 21].
In Smectic phase, the molecules possess directional as well as position order; Smectic A phase, for example, exhibits layered structures.
The values of activation energy in smectic phase at a particular frequency region are more than 250 (KJ/mol), which is similar to the relative conductivity ([sigma]) that showed steep slope in nematic as in smectic phase.
During the heating course, the first endothermic peak at 111[degrees]C was associated with the transition from crystallization to the liquid crystalline phase, which revealed the schlieren texture of the smectic phase. When the temperature was increased to above I21[degrees]C, there was an isotropic transition for the LCER from the liquid crystalline phase.
At high temperature (218[degrees]C), this terphenyl displayed a broad peak (centered around 2[theta] = 20[degrees]), suggesting the presence of a low-ordered smectic phase (SmA or SmC).
Ferroelectric liquid crystals (FLCs) have salient features over the trivial liquid crystals (LCs) because of their tilted smectic phase and the chirality of the molecules [5].
7d and e), or after annealing they exhibited more ordered textures, which could be suggestive of a smectic phase (Fig.
When the layer spacing is between one and two molecular lengths, the smectic phase is designated [A.sub.d], where d here stands for dimer.
The monomers favored an intercalated arrangement to form smectic phase (Scheme 2) (19).
Sample Time (h) [AIBN1 mol [L.sup.-1] [10.sup.-3] p 48 2 (DMAEM[A.sub.79) P 24 1 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) p 24 1 (DMAE[M..sup.79]-b-AZO[M.sub.5]) p 24 1 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) Sample [Monomer] [M.sub.n] PDI mol [L.sup.-1] (GPC) p 12,635 1.09 (DMAEM[A.sub.79) P 0.524 15,228 1.25 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) p 0.282 14,742 1.20 (DMAE[M..sup.79]-b-AZO[M.sub.5]) p 0.134 13,412 1.16 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) Sample Phase transition temperature ([degrees]C) p (DMAEM[A.sub.79) P g51 S88 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) Nl 15 p g48 S79 (DMAE[M..sup.79]-b-AZO[M.sub.5]) Nlll p g41 S78 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) N102 g, glassy phase, S, smectic phase, N, nematic phase.
The structures of mesomorphic phase (the smectic phase [12], [23], paracrystalline [24-26], conformational disorder crystal [27], [28], and microcrystal or nano-crystal [29-31]) rather than the growth of spherulites are formed.
Smectic phase polypropylene is a morphology between amorphous and crystalline phases, and is formed when quenched at a relatively high cooling rate [11] according to the X-ray observations of smectic phase by Ferrer-Balas et al.