Smetic phase

While initiator A (t-butyl) leads to polymers with a reentrant nematic behaviour, Figure 2b, the polymer from the "hexa-fluoro type B (Figure 2c) shows a typical and stable smectic phase with a prolate morphology of the main chain. A prolate phase (typical for smetic phases) is entered first which finally changes to a nematic behaviour in the range of 75 °C. The Ru-initiator finally leads to a high trans atactic polymer (Figure 2a). 

FK5.6.I9 Schematic representation of the structural formation and order-disorder transition for photoactive LBK showing (A) the compressed monolayer on the water surface with densely packed chromophore side chains oriented into the gas phase and the polymer backbone facing the water surface, and (B) LBK transfer from the water to a solid support, resulting in well-ordered smetic-tike (bilayered) multilayer assemblies. (C) After phcnoinduced trars to cts isomerization, a largely disordered struaure is obtained and the layered structure is completely lost (reproduced from reference 72 with permission from Wifey-VCH). 

PPV-b-PS made by anionic polymerization, exhibits the same lamellar morphology observed with copolymers made by ATRP. This result confirms the good architecture control that CRP can provide for these copolymers. This study also confirms the unique transition between ordered lamellae and isotropic phase with the coil volume fraction. However, a transition between nematic and smetic C phases in the PPV lamellae has been also shown. This behavior is characteristic of a weakly segregated system. 

The problem of identifying phases in the area between highly-ordered, smetic liquid crystals and condis crystals is well recognized and often only solvable when a complete motional, structural, and entropic analysis is available. 

Abbreviations K, crystal Sa, smectic A i, isotropic. No distinct DSC peaks associated with the phase transition between the crystalline phase and smetic A phase was observed. ... 

Smetic-Nematic Phase (K) Nematic-isotropic Phase (K)... 

Also, further X-ray studies began to advance knowledge of the structure of liquid crystal phases, particularly smectics. The work of de Vries and Diele should be mentioned, and later on, notably that by Leve-lut and co-workers in France and Leadbet-ter in England (see, for example, [37, 38]), work which culminated in the 1980s in a clear structural elucidation and classification of smetic liquid crystals. This distin-... 

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