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Director Orientation of Nematic Side‐Chain Liquid Crystalline Polymers Under Shear Flow: Comparison of a Flow‐Aligning and a Non‐Flow‐Aligning Polysiloxane
Author(s) -
Siebert Hartmut,
QuijadaGarrido Isabel,
Vermant Jan,
Noirez Laurence,
Burghardt Wesley R.,
Schmidt Claudia
Publication year - 2007
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200700248
Subject(s) - liquid crystal , shear flow , polymer , side chain , materials science , polarization microscopy , flow (mathematics) , crystallography , phase (matter) , scattering , optics , condensed matter physics , composite material , chemistry , microscopy , organic chemistry , thermodynamics , mechanics , physics , optoelectronics
The flow behavior and phase structure of two side‐chain liquid‐crystalline polysiloxanes with the same mesogens but different spacers of either four (PSi4) or six (PSi6) methylene groups are studied in the nematic phase by 2 H NMR, polarization microscopy, and scattering of light, neutrons, and X‐rays. PSi4 is flow‐aligning, forming a monodomain with the director close to the flow direction, whereas PSi6 is non‐flow‐aligning showing a polydomain structure with a preferred director orientation corresponding to the log‐rolling state. The flow behavior of PSi6 is related to the presence of strong smectic clusters. The director tilt in the smectic clusters of both polymers is reported.