Nanomechanical function from self-organizable dendronized helical polyphenylacetylenes

Self-organizable dendronized helical polymers provide a suitable architecture for constructing molecular nanomachines capable of expressing their motions at macroscopic length scales. Nanomechanical function is demonstrated by a library of self-organized helical dendronized cis-transoidal polyphenylacetylenes (cis-PPAs) that possess a first-order phase transition from a hexagonal columnar lattice with internal order (phi(io)(h)) to a hexagonal columnar liquid crystal phase (phi(h)). These polymers can function as nanomechanical actuators. When extruded as fibers, the self-organizable dendronized helical cis-PPAs form oriented bundles. Such fibers have been shown capable of work by displacing objects up to 250-times their mass. The helical cis-PPA backbone undergoes reversible extension and contraction on a single molecule length scale resulting from cisoid-to-transoid conformational isomerization of the cis-PPA. Furthermore, we clarify supramolecular structural properties necessary for the observed nanomechanical function.