Shear alignment behavior of nematic solutions induced by ultralong side-group liquid crystal polymers.
Addition of a low concentration of a very long (430 kg/mol) side group liquid crystal polymer is shown to produce dramatic changes in the flow characteristics of a calamitic nematic liquid crystal. This polymer causes a typical flow-aligning nematic liquid crystal to align near the velocity gradient direction rather than near the velocity direction, corresponding to having a tumbling parameter lambda<-1, for concentrations greater than 7.5% polymer. Such flow-aligning behavior has not been reported previously in a calamitic nematic. The large molecular weight of the present polymer relative to those examined in the prior literature is responsible for these new phenomena.
Kempe
M D
MD
California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
Kornfield
J A
JA