Nanomechanical Function from Self-Organizable Dendronized Helical Polyphenylacetylenes

• Published in: Journal of the American Chemical Society Vol. 130; no. 23; pp. 7503 - 7508
• Main Authors: Percec, Virgil, Rudick, Jonathan G, Peterca, Mihai, Heiney, Paul A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11-06-2008
• Subjects: Acetylene - analogs & derivatives; Acetylene - chemistry; Dendrimers - chemistry; Microscopy; Models, Molecular; Molecular Conformation; Nanostructures - chemistry; Polyacetylenes - chemistry; Thermodynamics; X-Ray Diffraction
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja801863e

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 (ϕh io) to a hexagonal columnar liquid crystal phase (ϕh). 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.