A key challenge in the application of surface grafted polymers to technological problems is their spatio-temporal patterning on substrates. In the past our group has developed several routes leading towards the formation of spatially-modulated polymer assemblies comprising polymers with gradually varying grafting density, length, and chemistry on substrates. All previous methods utilized “conventional” initiator systems such as Atom-Transfer Radical Polymerization (ATRP), where the modulation was achieved by either spatially controlling the distribution of the initiator on the substrate (grafting density gradients) or by utilizing time-dependent growth of polymer brushes by either immersing the samples into polymerization media or removing the medium from the reaction mixture (molecular weight gradients). The chief goal of this project is to develop assembly routes, including heat (azo) and light (iniferter) initiated systems, which would extend our capability to spatially “pattern” polymer molecular weight and density on flat substrates. These new assembly methodologies will facilitate formation of substrates with tailored spatial modulation length scales, ranging from micrometers to centimeters, which will be used for studying protein adsorption, cell adhesion and other phenomena. As an additional feature, we will be able to use these initiating systems, which generally allow for the fabrication of surface-anchored polymers grown via free radical polymerization, to compare the capabilities of controlled/”living” radical polymerization (CRP) by following the so-called reverse atom transfer radical polymerization (RATRP) process.