Nematic Elastomers Cross-Linked by Rigid Rod Linkers

Ideal nematic elastomers can exhibit a soft shape change without stress. Stripe instabilities and semisoft response in nematic elastomers are critically dependent on the thermal and mechanical history recorded during cross-linking. Rodlike linkers are shown to harden elastomers if they are twice-linked, an imposed strain in the second stage seemingly being recorded by the system. This is true if the second stage is isotropic or nematic. Orientation which cannot relax away gives linear terms in the Landau−de Gennes free energy and thus a high-temperature paranematic phase with possible supercritical thermal behavior if sufficiently large stresses are applied during formation.