Effect of molecular weight on the dynamic electro-optic properties of polysiloxane liquid crystal polymers

Abstract EN

This study has focused on the electro- optic properties of a series of polymers with differing molecular weight based on the polysiloxane back bone.

It is found that reducing the molecular weight lowers the phase transition temperature and eventually leads to a destabilisation of the nematic phase the effect of reducing the molecular weight of the polymer is to lower the observed threshold voltage.

This may be related to an increase in the intrinsic elastic constant of the liquid crystal polymers it is found there is a strong coupling between the mesogenic side chain groups and the polymer chain and that the elasticity of the polymer chain plays a strong role in the electro-optic properties.

The orientational order of the mesoginic units follows a similar temperature dependence for each of the differing polymer molecular weight, although the magnitude of the order parameter is much reduced as the molecular weight increases the variation in the polymers molecular weight leads to changes in the dynamic of the electro-optic response but these time scales are dominated by temperature and molecular weight effects.