State of Order in Liquid Crystalline Elastomers

The orientation behavior of crosslinked liquid crystal-line side chain polymers is determined by IR-dichroism measurements. In stretched samples the conformation of the polymer main chain and the chemical constitution of the rodlike side chain determine the position of the director in relation to the axis of stress. The order parameter S has the same temperature dependence and is of the same magnitude as in the corresponding uncrosslinked liquid crystalline polymers. The order parameter and the nematic to isotropic phase transformation temperature are independent of the applied mechanical stress under the experimental conditions (elongation up to 50%).