Addition of trialkyboranes on unsatured carbonyl compounds allows the fast synthesis of aldehydes and ketones. The application of this reaction to macromolecular trialkylborane microstructures derived from polyisoprenes and polybutadienes has been considered. The reaction involves the homolytic scission of one of the three C-B bonds leading to the fixation of the oxoalkyl group on the considered carbon. Polydiene macromolecular models have been used to study the application of this hydroboration-addition coupled reaction to the corresponding polymers. They have allowed the synthesis of modified microstructure models by use of diborane as hydroborating agent. Moreover, they have been used to measure the selectivity of the fixation gamma -oxoalkyl group on the modelized macromolecular carbon.