Functional Hyperbranched Macromolecules Constructed from Acetylenic Triple-Bond Building Blocks

This review article summarizes the synthetic efforts in constructing functional hyperbranched macromoleculesfrom acetylenic triple-bond building blocks. Polymerization reactions including polycoupling, polyadditionand polycyclotrimerization have been developed for the synthesis of new hyperbranched polymers such as polyynes,polyenes, polyarylenes and polytriazoles with novel topological structures and electronic conjugations.Polymers with high molecular weights (up to >1 × 10

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) havebeen obtained in high yields (up to 100%). Whilst their linear counterparts are often intractable, thehyperbranched conjugated polymers are completely soluble in common organic solvents and are hence readilyprocessable by macroscopic techniques. The hyperbranched polymers exhibit an array of functional propertiesincluding strong light emission, stable optical nonlinearity and high photorefractivity. The polymers cangenerate fluorescent images, assemble into supramolecular patterns, and form well-aligned nanotubes. Thepolyynes can be post-functionalized through metal complexation, whose refractive indexes can be manipulatedto a great extent by photoirradiation. The hyperbranched polymer complexes can serve as precursorsto soft ferromagnetic ceramics and as catalysts for carbon nanotube fabrications.