Elastic properties of liquid crystal elastomer balloons

We introduce a method to measure elastic properties of smectic, liquid crys talline elastomers. Freely suspended smectic polymer films containing photo reactive groups are inflated to spherical bubbles and crosslinked by UV lig ht irradiation. After crosslinking, the balloon volume is varied and elasti c properties of the material are determined from the relation between radiu s and inner excess pressure. The influence of the network topology on the e lastic behaviour is discussed.