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Orientation behavior of smectic polymer networks by uniaxial mechanical fields
Author(s) -
Nishikawa Etsushi,
Finkelmann Heino
Publication year - 1997
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.1997.021980814
Subject(s) - materials science , perpendicular , isotropy , liquid crystal , polymer , elastomer , phase (matter) , condensed matter physics , anisotropy , crystallography , composite material , optics , chemistry , physics , geometry , optoelectronics , mathematics , organic chemistry
Polymer networks showing different smectic polymorphism with either an interdigitated smectic A to undulated smectic A phase transformation or an interdigitated smectic A to double layer smectic C phase transformation are synthesized. Their orientation behavior in uniaxial mechanical fields is investigated by means of X‐ray scattering techniques and thermal expansion measurements. By applying uniaxial extension to the smectic elastomers in the isotropic state ordered smectic networks result with the director uniformly aligned parallel to the strain axis. These networks are optically transparent. Uniaxial deformations of the ordered smectic networks in the direction parallel and perpendicular to the director are performed that also help to elucidate the structure of the smectic phases. We find a reorientation process of layers of the ordered smectic C network. The spontaneous elongation in the direction of the director at the isotropic to smectic A phase transformation of the smectic elastomers is observed by thermoelastic measurements. This indicates that the polymer backbone conformation in the smectic elastomers is prolate in contrast to previous observations of oblate chain conformation in linear smectic polymers.