This work deals with the microscopic description of the electronic and geometric structures at the interface between hydrocarbon polymers, such as polyethylene or polystyrene, and a carbon surface, i.e., graphite or carbon black. In order to understand the nature of the local interactions at the interfaces, we performed theoretical calculations, based on both quantum-mechanical ab initio techniques and empirical molecular mechanics techniques. The interfaces between polyethylene and graphite and between polystyrene and graphite are modeled by considering the alkane/benzene and ethylbenzene/benzene complexes, respectively.