The simple approach of LTV-induced coupling of 4-vinylbenzyl chloride (VBC) with the hydrogen-terminated Si(100) (the Si-H) surface provided a stable Si-C bonded initiator monolayer (the Si-VBC surface) for the surface-initiated atom transfer radical polymerization (ATRP). Well-defined polymer-Si hybrids, consisting of covalently tethered polymer brushes of sodium 4-styrenesulfonate (NaStS) and poly(ethylene glycol) monomethacrylate (PEGMA) on single crystal silicon substrates, were prepared. Kinetic studies revealed an approximately linear increase in both graft polymer concentration and polymer film thickness with the polymerization time, indicating that the chain growth from the functionalized silicon surface was a controlled process with a "living" character. Atomic force microscopy (AFM) images suggested that the surface-initiated ATRP had proceeded uniformly on the Si-VBC surface to give rise to a dense and molecularly flat surface coverage. The "living" chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes, consisting of the NaStS polymer (P(NaStS)) and the PEGMA polymer (P(PEGMA)) blocks.