Figure 4: Diastereomeric domains in a 7O.5*/NOBOW HNF network mixture.

When the isotropic melt is cooled to T=70 °C in a c=50% 7O.5*(chiral, rod-like LC)/NOBOW mixture, the 7O.5* guest is still isotropic but NOBOW forms left- and right-handed HNF domains which have very low negative birefringence and appear dark under crossed polarizers. The scale bar is 100 μm. (a) At temperatures well above the bulk transition to the N*, the (L,R) and (R,R) domains develop birefringence of opposite sign at the Iso* to Iso*_surf transition. (a–d) These signs are maintained at the Iso*_surf to N* transition of 7O.5* where |Δn| grows substantially. (e–h) At the N* to Sm* transition, the birefringence in the (R,R) domain changes sign. At lower temperature, where the 7O.5* is smectic, all the domains have negative birefringence. (j) Transmitted light intensity, I, of the (R,R) and (L,R) domains as a function of temperature. The sampled regions (red and blue circles) have helical nanofilaments oriented approximately 45° from the crossed polarizer/analyser directions. (k) Spherulite birefringence Δn(T) obtained from Δn ∝ √I, with sign determination and calibration using a compensator. The bulk phase transitions of the 7O.5* in the network are indicated as vertical dashed lines on the plots.