title: Nanomechanical function from self-organizable dendronized helical polyphenylacetylenes.
abstract: 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 (varphi h (io)) to a hexagonal columnar liquid crystal phase (varphi 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.
authors.affiliation: Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Virgil
authors.initials: V
authors.lastname: Percec
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Rudick
authors.forename: Mihai
authors.initials: M
authors.lastname: Peterca
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heiney
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives* / Q000737:chemistry; D050091:Dendrimers / Q000737:chemistry*; D008853:Microscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D053279:Polyynes / Q000737:chemistry*; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D050091:Dendrimers; C044736:phenylacetylene; D053279:Polyynes; D000114:Acetylene