Pretransitional orientational ordering of a calamitic liquid crystal by helical nanofilaments of a bent-core mesogen.
Mixtures of 8CB (a calamitic mesogen) and NOBOW (P-9-O-PIMB, a bent-core mesogen) have been investigated using differential scanning calorimetry, nuclear magnetic resonance spectroscopy, and freeze fracture transmission electron microscopy. On cooling the isotropic mixture, the NOBOW component phase separates, forming a dilute, random network of helical nanofilaments in the B4 phase with isotropic 8CB material filling the interstitial volume. At lower temperature, but still far above the bulk isotropic-nematic transition of pure 8CB, a significant fraction of the 8CB becomes prealigned on the filament surfaces. We propose that this pretransitional ordering is induced by short-range interactions of the polar 8CB molecules with the NOBOW filaments, leading to the formation of an adsorbed film of orientationally frozen 8CB around each filament.
Chen
Dong
D
Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309-0390, USA.
Zhu
Chenhui
C
Shoemaker
Richard K
RK
Korblova
Eva
E
Walba
David M
DM
Glaser
Matthew A
MA
Maclennan
Joseph E
JE
Clark
Noel A
NA