In polymer chemistry, changing the functionality or properties of a polymer often means starting from scratch with a new monomer. Juan Tolosa, Chris Kub, and Uwe H. F. Bunz of Georgia Institute of Technology report a postpolymerization strategy for creating hyperbranched conjugated polymers that maximizes diversity with minimal synthetic effort (Angew. Chem. Int. Ed., DOI: 10.1002/anie200900980). Conjugated polymers have unique electronic properties that make them attractive materials for emerging technologies such as solar cells, plastic semiconductors, light-emitting diodes, and biosensors. In the new method, the researchers used Sonogashira coupling of a monomer containing an alkyne and two iodine substituents to create a poly(phenylene ethynylene) backbone studded with iodine groups. They then replaced the iodine groups with various alkynes under Sonogashira conditions and demonstrated how the modifications altered the fluorescence properties of the polymers. This strategy should allow researchers to develop libraries of compounds from a single polymer backbone for sensor materials, Bunz says. One approach he plans to try is to functionalize polymers with biological groups such as peptides.