Acetylenes with multiple triple bonds: A group of versatile An-type building blocks for the construction of functional hyperbranched polymers

ABn-type monomers have been widely used for the synthesis of hyperbranched polymers. These monomers, however, suffer from the problems associated with the tendency of their mutually reactive A and B functional groups toward self-oligomerization. We have explored the possibility of synthesizing hyperbranched polymers using An-type monomers, which are stable and easy to prepare and handle, with some being even commercially available. In particular, we have tried to open new synthetic routes to hyperbranched polymers using diynes and triynes as monomers. We have developed metallic [TaBr5, Cp∗Ru(PPh3)2Cl, etc.] and nonmetallic catalysts (piperidine, DMF, etc.) for polycyclotrimerization, polycycloaddition and polycoupling of the acetylenic monomers. We have synthesized a variety of new hyperbranched polymers including polyarylenes, polytriazoles and polydiynes with high molecular weights and excellent solubility in high yields. The polymers exhibit an array of functional properties such as sensitive photonic response, high light refractivity, large optical nonlinearity, high thermal stability, strong optical limiting power and unusual aggregation-enhanced light emission. Utilizing these unique properties, we succeeded in generating fluorescent images, honeycomb patterns, polymer nanotubes, ferromagnetic ceramics, and nanoparticle catalysts.