Higher generation dendrons

The procedures utilized to prepare higher generation dendrons, up to [G-6]-OH and [G-6]-Br are similar to those used for lower dendrons. Characterization details and yields can be found in the original literature [1], It should be noted that dendrons of generation higher than six were not prepared using this procedure due to severe lowering of yields as a result of steric effects. 

Polymer-analogous variants reach their limits in the face of insufficient rigidity of the functionalised linear polymers which can lead to undesired coiled structures. These have to re-assume a linear structure, with an attendant loss of entropy, in order to assure reaction of all the dendrons with the functional groups attached to the backbone. The dendrons are mostly added in excess in order to facilitate complete reaction, which in turn necessitates tedious purification of the products. The additional steric hindrance occurring on attachment of larger dendrons if higher generation dendrons are already located in the close... 

The macromonomer route assures uniform distribution of dendrons along the polymer backbone. Acrylates and styrenes with pendant dendrons proved to be well suited for polymerisation [57]. However, steric hindrance between monomers bearing higher-generation dendrons and the spatial requirements of the end of the chain cause problems The monomer reacts with the chain end only in the case of slight, if any, steric hindrance. Thus the method only provides access to dendronised linear polymers with relatively low molar masses... 

The reactive focal point of the higher-generation dendron may have a limited access to the reactive functionality of the core. 

When a higher-generation dendron reacts, it may prevent reaction from occurring on the neighboring repeat units (due to steric hindrance). 

Higher-generation dendrons gave more effective gelation. 

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