The copper-mediated 1,3-dipolar cycloaddition reaction of azides and alkynes, since Sharpless also known as “click chemistry”, is a highly selective as well as regioselective and very efficient reaction which leads usually to complete conversion and no side reactions under very mild  reaction conditions. Thus, the reaction is especially well suited to modify complex architectures (dendritic structures) as well as linear block copolymers highly effectively and also selectively tolerating the presence of additional functional groups. In the Dept. Polymer Structures a variety of alkyne modified random and block copolymer structures has been prepared which were effectively modified with a broad range of functional and also dendritic features by click chemistry. The highly selective reaction of the cylcoaddition step is here the base for the introduction of multi-functionality in a cascade modification reaction. This allows also the introduction of photo- and thermolabile units as well as of anchoring groups (e.g. for surface immobilization). Also, rod-coil like structures with a chain exhibiting dendritic units were prepared under mild conditions and in very high yields.
Alkyne and azide units at the chain end, originated from functional initiators, have also been used to introduce more complex end functions (e.g. fluorescence labels) and to couple different polymer chains to new types of block copolymers.
In addition, cycloaddition reactions allow also the preparation of totally new linear and branched polymer structures with triazole units in the backbone. Perfectly branched dendrimers as well as new types of hyperbranched polymers have been prepared in this way. For the first time, also kinetic studies on the formation of hyperbranched polymers by click chemistry have been presented.